# Prototype three rotor steam impulse turbine



## Bogstandard (Mar 5, 2008)

This is going to be a quick and dirty exercise, design and make on the run (but I will make sketches as I go).

I walked into this one with my eyes closed. It was on one of my model boats sites, where an American chappie wanted to build a 10ft long warship, but have a pair of steam power turbines in it.

The criteria being, steam driven, as clean running as possible, easy to operate plus easy to build and service, with no special materials required.

So I came up with this







Steam in one side, using a control valve to give fwd/rev and throttle. Exhaust on the opposite side.

The control valve will be a modified version of the one I designed for my piston valve engine. The outer casing will be ali, rotor of brass and a shaft of ground stainless, running in stainless shielded bearings. The expected size of this proto will be around 3" long (not including shaft length) and 2" square.

The expected RPM of the full sized version (about 2x the size of this one) when running thru a 100 to 1 gearbox will hopefully be between 35K & 40K, giving an output speed of 400 rpm at the 3" props.

This will be, if anyone wants to follow suit, a good exercise in precision turning, boring, milling and rotary table work. Just for the colonials, I will try to remember to do it in imperial, or at least give imperial sizes to use instead, as most of my cutters are metric.

Unlike the other one I built last year, this one will be a lot safer to run, with the bearings being buried a bit deeper.

Now for a search in the stash box for the materials.

John


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## Brass_Machine (Mar 5, 2008)

I will definitely be watching this one!

Eric


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## Bogstandard (Mar 5, 2008)

If anyone else wants to sing along with this tune, I went thru my stash this evening and found almost everything that is needed for the main turbine, the control valve is made of scrap bits and bobs of brass, so no need to worry about that yet. Fastenings are what I have in stock and will use whatever is necessary, there will be no requirements for anything special (as far as I know at this moment).
All my materials that I use will be metric, but I will be stating the nearest imperial sizes so you shouldn't have any troubles.

Here is a pic of the recycled materials that I will be using.







#1 - 2 x 3/16" bore (or to suit) stainless bearing with stainless shields (to fit shaft #2)
#2 - 3/16" diameter s.s. shaft (can go up in size a bit, but not smaller)
#3 - 1 1/2" diameter brass rod to make rotor (you will need about 1 3/4" long, but leave on billet if possible (for holding in lathe)
#4 - Approx 2" cube of ali for main chamber
#5 - A piece of 1/2" thick ali plate, 2" x 2" to make the exhaust chamber
#6 - A bit more plate to make end plates for rotor chamber and to mount the bearings into

What is not shown is the material for making the nozzles, that will be about 3/16" to 1/4" diameter brass and about 6" will be required.

If you are only ever going to run this on air, you can make almost everything out of whatever you want, but I would suggest drill rod for the shaft and something heavy for the rotor. I have only used this variety of materials because it will have to be able to resist the corroding effects of live steam, with no lubrication added.

Tomorrow I will be making the rotor and shaft.

John


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## deere_x475guy (Mar 5, 2008)

Interesting John I am sure lots of us will be watching this one. Glad to see you back at it and take it easy for awhile with the shoulder.


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## cfellows (Mar 5, 2008)

John,

I'm looking forward to seeing how this one goes together. Your single rotor turbine was a very nice looking (and working) project. This one should be even more enjoyable to watch you build.

Chuck


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## Bogstandard (Mar 8, 2008)

You got the idea, now for the hard bit, putting it into practice.

Just a bit of a warning before I start. I am expecting to lose my internet connection fairly soon, but hopefully not for very long, so don't worry if I don't post for a bit, I will still be taking piccies and I will play catchup when everything is stable again.

A slight change to my build materials, the #3 was a nice piece of brass, but a paying job came up, and it was used for that. So I have put my masochist coat on and I am going to make the rotor out of PB1.


Now to start in ernest. 

The first grotty sketch is for the rotor, no details about the pockets yet, that will be sorted later. The rotor will be like an extra wide flywheel, with a recess at either end and holes drilled thru to lighten it and get the mass on the outside to retain its momentum.






This next pic shows the recesses in (using my flywheel recess tool) and a hole wacked thru the centre. I am not too worried about the OD to within a few thou because the rotor case is going to be bored to the OD of the finished rotor.
The hole wasn't reamed or bored, it would be rather difficult boring this length being such a small diameter. The shaft is a sliding fit in the hole, but needs to be made to an interference fit, so what I am going to do is knurl up three raised portions on the shaft and secure it together with force fit and loctite. If I made the hole 1 thou under to begin with, I would expect the shaft to bend as it was being forced in, by doing it the way I am suggesting, I expect to get a good solid fit with no damage to the shaft. Also I will be making the basic rotor first, then fitting it to the shaft, followed by final turning to size, this will ensure I will be fairly close to balance and won't have any unexpected wobbles.
The marks on the side are for where I want to do a bit of rough turning so I don't have to do any heavy stuff when it is mounted onto the shaft.






Here it is in the chuck, roughing out to 50 thou deep with my parting off tool, this will save having to have any heavy cutting pressure onto the assembled rotor, and maybe deforming the shaft.






Rough cut and ready to go onto the RT to have the lightening holes drilled.






Is everything understandable so far?


John


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## kellswaterri (Mar 8, 2008)

HI John,
this looks like a very interesting build, cant say I will get to build, it but I will certainly be following yours...Hope you are recovering well...
All the best for now,
              John.


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## BobWarfield (Mar 8, 2008)

This is very interesting!

I've never seen a model steam turbine. I love the use of brass, but I've gotten shy about it of late due to costs. I guess I should just suck it up and soldier on!

I hope someone will build a Tesla turbine sometime too. 

Best,

BW


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## Brass_Machine (Mar 8, 2008)

BobWarfield  said:
			
		

> ...
> I hope someone will build a Tesla turbine sometime too.
> 
> ...



O/T I think Wes (powderkeg) has been designing and casting some parts for a Tesla turbine. I believe he has the intentions of selling said castings...

Eric


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## Bogstandard (Mar 8, 2008)

Just done a bit more, trying to get most of it done before I have to go offline.

I must apologise for a few of thes pics being out of focus, but I don't get to see them until the end, and by that time it is too late to go back and reshoot.

This is the first out of focus one, but what it is supposed to show is the drilling of the lightening holes thru the rotor. I put 8 x 1/4" into it, at 45 deg apart, and they worked out perfectly.







This is the drilled rotor, thank goodness that is over, drilling phos bronze is not my idea of fun. Had a few sticky moments with these, but brute force got me thru.







Now the next stage, the shaft. I made this one 4 1/2" long, it will be trimmed down at the very end to whatever length is required. What I have done is put the shaft in approx half and half then marked the outside face positions on the shaft.







Take the shaft out and use the marked positions to find where I want to put the knurling to form the gripping area.







Here is my clamp type straight knurl in operation. It takes very little indeed to raise 2 thou for the grip, in fact the knurl wasn't even properly formed, but more than enough for this job.







Position of the raised knurls in relation to the rotor.







Another out of focus one, looks like my cam doesn't like the miller.
Anyway, what I have done is centred the drill chuck over the shaft and closed it up. Between the chuck and the shaft is a bit of ali scrap.
I put a ring of loctite around the shaft where it enters the hole, so when the shaft is pushed in, it will pick up the loctite and take it into the hole with it.
It takes very little force using this knurled method, if it was a lot I would have used my press to do it.







A lovely assembly job if I must say so myself. It spins up on the bearings really nice, and is only a couple of thou out of true. The next step, after it has dried out overnight is to get it into the collet chuck and true it all up, plus do the final forming of the recesses.
Please don't criticise the condition of my 'precision' tooling. These are the ones I use for my silver soldering, and are not normally seen.







For the next thrilling installment, tune in tomorrow, same time same place.

John


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## Bogstandard (Mar 8, 2008)

Had an hour or so, so jumped to the shop again and finished off another stage.

This first one shows the rotor skimmed up and trued, with the correct recesses machined in. If you are going to try one of these and don't have a collet chuck, it can be done in a 4 jaw, but remember that the shaft is the datum to set to, not the rotor.







Ready for the milling stage. I have just checked out the free running on the bearings and it looks very promising, about 1 minute run down from around 10k. I have also noticed that the bearings are so free, that I should be able to do the balancing on the setup as shown.







Definitely no more machining tonight.

John


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## Bogstandard (Mar 9, 2008)

Today, I should not have bothered.

Went to the shop nice and early, coughing away with the local sparrows. Caught the cat and give it a going over just for luck.

It didn't work.

Turned on the mill and my Y axis readout wasn't working. I was using a squirty bottle for coolant yesterday for drilling the holes, and some had found its way into the slide.

Took it off, give it a good strip down and clean, works like new. But one thing I didn't realise was how badly these things are made. The machining inside looked like someone had done it with a dremel and a carbide burr. But anyway it now works.

So sets up the RT for horizontal work and duly started machining the first round of pockets, after struggling a while with the PB, I got onto the last pocket and duly fluffed it.
In fact to a state where it was not 'fixable'. Caught the cat again, and did a blame recovery exercise on the poor devil, but he now knows how to keep out of my way when something goes wrong.
So to save wasting a total morning, I decided to use this duff one as an experiment.

So went to the next area and cut 12 pockets instead of the 18 I did on the first one. See pic to see what it looks like.






This was duly mounted up into bearings and given a dose of air into each set of pockets in turn. My first turbine was made with pockets like the ones in the middle, and it works fine. Thinking I was going to get the same sort of result, deep pocket, good power and runup, shallow, less power and a long runup time. The results were totally the opposite, the shallow pocket run up as though it wanted to fly, at least twice as fast as the deep ones, and the power was still there.

So this morning wasn't a total failure after all (sorry cat).

Using my failure for experimentation has really pushed me up the learning curve on this type of motor.

I reluctantly raided my outside stash and hacked off another lump of 2" brass, and I will proceed to make another rotor.

So one days delay.

John


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## cfellows (Mar 9, 2008)

John,

That's an interesting result. I would have agreed with you and thought the deeper pocket would give more power and faster run up. I wonder if the result you got was because the air jet was hitting more pockets at the same time on the 18 pocket side?

Chuck


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## Bogstandard (Mar 9, 2008)

Chuck,

I honestly think it is something to do with the flat area at the back of the deep pockets, causing like a dead area, whereas the shallow ones actually run into each other, so rather than having an interupted pulse of air, it is allowing a smooth transition from pocket to pocket. When I put air onto it, you could hear it 'popping' between pockets on the deep ones.

I will know better when I get the correct nozzles made for it.

John


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## Bogstandard (Mar 9, 2008)

Now back on track, knocked up another one, in a slightly different machining order (just in case it happened again).


What this sketch shows is the depth and position of the pocket in relation to the rotor. 
If the middle set is done first (fwd drive), then the outside set (2nd fwd drive) with the 10 degree offset between the two. When they are both completed, just swap over end to end and carry on machining in the same direction, you should find that the reverse pockets will be machined facing in the correct direction and it will be in the right position on the rotor.
Sorry about the shape of the circle but I was trying to use my right hand.






What it should look like when machining the pockets.






The good and the bad together.






The finished rotor. Get the hard bit over and done with, and the rest is plain sailing.






Lots of things to do tomorrow, so don't know if anything will get done in the shop.

John

Forgot to mention, I used a 3/8" end mill for the pockets.


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## Bogstandard (Mar 11, 2008)

The bit about balancing this rotor is here

http://www.homemodelenginemachinist.com/index.php?topic=1552.0

John


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## Powder keg (Mar 11, 2008)

Looking good Bog! I can almost see the video)

Wes


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## Bogstandard (Mar 11, 2008)

Wes,

Maybe by the weekend I will have it running, but not under controlled power. It will take nearly a week to make the controller. A lot of very careful measuring and planning in that, I have got to relearn my geometry to get the port in exactly the right position. That is the problem with a few of us as we get older, new stuff pushes the old out of our ears, and it just gets lost.

Just hope the damned thing runs as planned. Mind you with only one moving part (excluding bearings) there is not much that can go wrong.

John


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## Bogstandard (Mar 12, 2008)

I have been hurting my brain a bit more, thinking how to make this drag out a bit rather than wham, bam, that's it.

There are so few components in this engine I can do a lot of piccies to cover everything.

So I have decided to turn it into a little bit of an instructional build, showing newbies, in not too technical terms, how I achieve what I do.

But please bear in mind that this is the way I do it, someone else might do it an easier and better way, it is what I am happy with.
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The rotor is done and dusted.

The next major part is the outer casing. No drawings for this because it is rather easy to remember, there are only two dimensions for the block. Each side is 1 3/4" wide by 2" long.

Here is the raw block of ali, rough cut on the bandsaw out of a much bigger lump. It is about 1/4" oversize in all directions. What I am going to be doing is turning this rough block into a precisely sized block with all faces square and parallel to each other. This technique can also be used for getting square out of round with the same results.






When starting work like this ALWAYS check your fixed vice jaw for running parallel to the spindle cut.
I do it by putting a good solid parallel into the vice, set up a DTI to run against the parallel (you could use a normal dial indicator with a plunger if you can get it in). Tweak up the vice holding bolts, enough to stop it moving about, but with a slight tap the vice can be moved. 
Position the DTI in the position as shown and wind the Y axis (back and forwards handle) until the DTI starts to register a reading. Reset the rotating dial to the zero position and then wind the X axis (side to side handle) so that the DTI is run along the face of the parallel. If the pointer starts to go anticlockwise, tap the left hand side of the vice near the tightening handle with a soft hammer until the pointer moves to the zero position. Return the DTI to the start position, re zero the dial and try again. If the pointer on the dial goes clockwise as you move right to left, the right side of the vice needs a tap.
Just keep doing this until you get no or very little movement on the needle while you track the full length of the parallel. Tighten up on the hold down bolts and recheck. If it still runs with no deflection, your vice is set up to perfection.
I always do this check whenever I start a job. No need to slacken of, just pop a para into the vice and do a quick check with a DTI. Tweak if needed.






The above didn't really need to be done with this job, as it is all flycutting top face work, but it is always nice to see how it is done.

Anyway, back to making something.
Pop the hunk of metal into the vice with one of the side faces upwards (the ends are done later), and rest it on a couple of matched para's. Tighten up. Nothing spectacular, just so that we can face the first side.
This pic shows what is needed. A flycutter (not essential, but for big faces like this it is an advantage). A nice dead blow soft hammer for tapping the job down onto para's, and a bit of lube for helping the cutting along. Ali can be a bit of a dog to get a good mirror like finish, so razor sharp tooling and lubricant are the right things to use. For ali, paraffin is the recommended cutting fluid, WD40 is now starting to be recommended as well. Because it is so expensive to use willy nilly, I always make up my own cutting fluid. It is white spirits with about 5% 3in1 oil, and I find it works really well. Dab it on the job when needed, whilst keeping well away from the spinning cutter.







This is what the profile of my flycutter is like, it was shown to me a long time ago and I use this shape all the time, it works in the same way as a round nosed turning tool to produce mirror like finishes. On ali, and a nice rigid machine, 0.100" (100 thou or 2.5mm) can be hacked off in one go, not recommended for beginners to do, but it is there if needed. On a job like this I tend to stick with 50 thou and below. Most people use a more standard straight edged bit in their flycutter. As I said before, I do it the way I am used to.
Back to the job in hand, take a facing cut across the top until all the old cutting marks are gone, then put a very fine cut of say 1 or 2 thou, with some cutting fluid in the mix and take a nice slow feed, fast cutter swipe across the face. You have cut your first datum face.






The first thing to do when it comes out of the vice after every operation, is fully deburr the part, and clean down around the vice jaws. One bit of swarf can knock all your faces out of square.
I am a great believer in marking things up, just so that I don't get confused between operations.
The face I have just machined is marked up D1, standing for datum face 1. I also mark on the end of the block where the datum face is.
Shown also is the most vital part of getting the bits square, a bit of soft round bar. I usually keep this in the channels on my miller table so it is always there, ready for use.





Now we set up for cutting the second side, to be square to the first. Datum face 1 goes towards the fixed vice jaw, the bit of round is put against the job and the vice is tightened up. Just do a rough tap down onto the para's (there is only rough faces against them still). Now do your cleanup and finishing cuts like was done on D1.







Datum 2 is marked up the same way as D1. These two faces should be totally square to each other.







Now mount the block into the vice as shown. D1 goes to the fixed jaw, D2 goes down onto the para's and rod inserted and vice tightened. Now is the time to gently tap D2 down onto the paras until both paras are just gripped.
Now you can machine the top face down to give the correct width of 1.750" between now D3 and D2. Take it down gently when getting close and do a finishing cut of a couple of thou. If you haven't got a mic to measure while still in the vice, the block can be taken out and measured any way you wish to get a reading. As long as the block is put back in the same position, and tapped down onto the paras you won't be far out.







If you have done it right, the faces D2 and D3 should be parallel to each other at the correct measurement and the corners between the datum faces should be totally square.







The bit of round bar is now no longer needed, there are three datum faces that are worked with. 
The last datum to be cut goes against the fixed jaw, the first down onto the parallels. Tighten up and tap down. Take the last face down to the same setting as the previous facing cut (to 1.750" thickness). Fully deburr all around and check your sizes and squareness. You should be pleased with yourself if all sides are parallel and square.






I have set this shot up just to show how to get the ends square to the sides. This is the bit where the previous setting up with a DTI is needed, if the vice jaw doesn't run parallel to the cutting stroke you end up with off square ends. 
Set the block down onto para's with a small amount protruding out of the end of the jaws (make sure the para's stay within the jaw area, otherwise you will end up cutting steel as well). You can then face across the ends to bring them to squareness and length (if you have a cutter long enough to reach from the top of the face to the bottom). I don't like this method because it usually gives a real crappy finish. There are other ways, like standing the ends up in the vice and flycutting the end faces, but the blocks have to be got perfectly vertical first. That is why I go over to the lathe for end finishing.







What I do is mount the job into my four jaw, it doesn't need to run true, near enough is good enough. Pack the jaws with the same type or softer material than the job. I normally use Pepsi Max cans cut up with scissors (If I tell Pepsi about this free advertising, do you think I will get some freebies). In this case I didn't have any to hand, so I used brass shimstock instead.
Face the end, then turn it A over T in the chuck and face and bring to length.








Job done, with one obvious mistake. Because I used brass instead of ali for protection pieces, I have a bruise mark on a nice clean face. It will easily be eradicated with a swipe across some very fine W & D, but it shouldn't have happened in the first place. Typical, always making extra work for myself, just by being lazy. 







The next instructional bit will be how I bore the big hole in the end.

John


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## DickDastardly40 (Mar 13, 2008)

All fantastic informative stuff, thanks.

Some questions questions come to mind in a sort of devil's advocate kind of way from my experience of operating full size turbines (up to 30,000 SHP a long time ago). It's entirely possible that these points have been considered or are not a problem due to the relative small size of the project.

What sort of steam it the builder of the boat intending? Superheated will obviously be hotter and you may get thermal expansion issues not just radially but axially. Saturated may cause water droplet impingement issues or a puddle in the casing.

Are two ahead stages going to be sequentially valved to admit steam to one then the other or steam will pass from one stage and then to the next? 

How will the astern stage be sealed from the ahead steam and how will the ends of the casing be sealed to prevent steam leagage?

Is the steam going to be total loss or will there be a condenser to return it to feed water, if total loss how will the steam exit the ahead and astern stages?

Control between ahead and astern and the firing of the boiler may need careful 'weighting', if the rotor is spinning ahead fast, to go astern or stop in the water, first the rotor must be braked to a stop before changing direction. When at 'stop' full size turbines need to be rolled ahead under steam to maintain even heat and prevent hogging. If ahead and astern valves are both shut the firing of the boiler will need to be reduced to prevent lifting of safeties. 

None of the above are meant as any sort of criticism, just some quid pro quo from my erstwhile experience, please continue to fascinate us with your progress.

Al


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## Bogstandard (Mar 13, 2008)

Al,

A lot of questions to be answered there

I am talking about on this build about a total loss impulse turbine, compared to maybe a reaction turbine that you were involved with. In my impulse design the steam (or air) is totally finished with within about 3/4" from the injection nozzle and the propellant is scavenged out of the case fairly quickly. With a reaction turbine, the steam is continuing to work thru the whole blade system of the engine (just like an aircraft gas turbine). There is also a big difference when working with small engines such as this.

The boiler system I am leaving to the boat builder. He has suggested he will try a standard boiler system first and if not enough volume to keep the engines going, he will then go to a flash boiler. In my trials it will be carried out with a standard gas fired vertical boiler.

The nozzles for the forwards part will be fed simultaneously, so giving , in practice 36 pockets at 10 degree spacing, whereas the single reverse rotor will be working on 18 pockets at 20 degrees apart. The change of direction will be caused purely by switching steam from fwd to rev and vice versa. I am hoping this will give about a 4 second delay from switching to spinning in the opposite direction, slight faster when going from rev to fwd.

Any collected moisture with be automatically blown out of a small drain at the bottom of the case. There will be slight leakage of steam thru the bearings, hence the use of stainless, but this will not be an issue as far as I am concerned. In larger engines, galleries and seals can be introduced to prevent this sort of steam transfer, but in a model of this size and non complexity, it is not a viable proposition. but hopefully a sytem of collection grooves will be used that fill with water to form a spinning o-ring type seal, similar to oil grooves on a steam engine piston.

I too worked with full sized turbines, but the aircraft engine variety.

I hope this has explained what I am trying to achieve. This is a proto after all.

John



John


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## DickDastardly40 (Mar 13, 2008)

Bog,

You have all the bases covered as I suspected you would, as I said I was only trying a bit of devil's advocacy.

Thinking back is the impulse type of rotor called a 'curtis wheel'?

Thanks for taking the time.

Al


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## Bernd (Mar 13, 2008)

Great tutorial Bogs. Even I learned something there.

I don't want to hijack this thread,so I'll make it short. If anybody wants to hear the full story I'll relate it in the General area. That lead hammer reminds me of a story my dad told me about the new apprentice that they sent to the heat treat room to have a lead hammer heat treated because it was to soft. I'm sure you all know that he came back with just the handle. :big: :big: :big: :big:

Bernd


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## Bogstandard (Mar 13, 2008)

Al,
I have no idea of what a Curtis wheel looks like,and after a quickie search on the net I am none the wiser.
Mine works on a Pelton wheel basis, but mine are machined as small pockets, unlike the one shown here, this one is being driven very inefficiently.

[youtube=425,350]tFiFBbMJsfw&hl[/youtube]

John


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## Bogstandard (Mar 13, 2008)

This is going to be one of those long boring (sorry about the pun) bits of text about how to put great big holes in a defenceless lump of metal. Putting it on a slimming regime from the inside out.

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First off, we've got to find where we are going to be putting the hole and mark it up so we can find it again when we come to put the holes in it.
This first pic shows some of the tools than can be and are used to get the centre position marked (this is where I want it, in the centre, if you want to put it in another position you can use the same sort of techniques).
First off, put something on the metal so you can see the markings as you put them on. I use marking out blue, but coloured broad tipped permanent markers do just as good a job. I use a blue marker for covering up mistakes on my marking out, rather than redoing the full face.
I tend to use either a height gauge or a centre square for this type of job, so I will concentrate on those two bits of kit.









A height gauge is one of the most important bits of kit IMHO that is needed in the shop, either digital for the lazy ones, or a manual one like this for people that won't spend the money for the other type. Both do an equally good job of putting lines on bits of metal in the right place. They can also be used as very good precision hammers (just joking of course, I use my digital verniers for that job). But if you can read a vernier, there is really no difference between the two. On this job, where all sides are perfectly equal, the side length was measured, divided by two, set the vernier to that figure and scribe a line across the blued face, turn the job thru 90 deg and repeat the marking, to double check I went round all four sides, and as you can see, they all line up perfectly.
They really need to be used on a totally flat surface. My marking out table is a genuine cast iron one that I also turned into a tapping stand, isn't it great, dual purpose machinery. But a sheet of plate glass does just as well. For many years I used the platen glass out of an old photocopier, until I dropped a lump of the heavy stuff onto it. Steel and glass don't mix.







The other bit of kit is called a centre square, another piece of essential equipment.
These are really designed for finding the centre of round bar, but if you are using perfectly square bar, it will do the job admirably. They are usually fairly cheap to buy and are a worthwhile investment if you are building up a stock of tooling.
I have shown how they are used, just scribe a line along the blade, and you can see that the centre matches up perfectly with the one done with the height gauge. So either method could be used in this case.







So we have the centre. Now that centre mark has to be made into something that can be used to locate things into it.
I will just bring up a point here. Basically there are two types of point on a centre punch. One at 60 degrees and the other is 90 degrees. We need to use the 90 deg type, no arguments on this one, the 60 deg is for marking out edges of things, like edges to be filed to, the 90 deg one is made that way so that it accepts the 90 deg points of other tooling.
That out of the way, how do we get that point exactly on the centre as marked. I will explain the method I use. Your centre punch should be sharp pointed, blunt and rounded over is no use at all. Put the tip of the punch into one of the first lines that were scribed on the face, and drag it down the line (you will find, if sharp enough, that it will follow the line with ease) towards the centre marking, as it reaches the centre you will feel it hit the later scribed lines. Lift it upright without moving the tip and give it a light tap with a hammer. Get a loupe or magnifier and look at the dimple you have just made. You can almost guarantee that it is near the crossed centre, but not exactly there. So what you do now is gently move the mark until it is spot on where it is needed. This is done by using the hammer and punch and drive the spot towards where you want it to go. Do not be heavy handed, just a gentle tap. Eventually by looking at the magnified image you will see when the dimple is exactly in the right place. Put the punch into this dimple, totally upright, and give it a good wack with a hammer. You should end up with what is in the pic.







It took all that effort to get just one little spot marked on the end of a bit of metal. If it was done wrong, then everything that follows will be out. As experience is gained that spot can be within 0.001" of where it should be, and tolerances that tight are acceptable.
I will just tell you now, a few days ago I would not have been showing you how to do this using a four jaw on the lathe, it would be being bored using the miller and a boring head. It is now I can use both hands that this is possible.
So, lets introduce the metal to the four jaw. Mount it up as shown, a thin parallel at the rear of the block (more on this later), a piece of soft shim between the jaws and the job (no drinks can again, but this is a bit of soft ali litho plate). Tweak up the jaws but not too tightly.







Unless your are very lucky and the sun shines out of you know where, the centre punch mark will be way off centre when the chuck is turned.
There are many varied ways of doing the next stage, with all sorts of weird and wonderful gizmos and dingdongs, but the one I will show is the generally accepted method of doing it here in the UK (we've been at it a bit longer than the colonials, and we don't accept new methods lightly).
The reason for this method is that there is usually one of these centres knocking about the place, so why not use it, save your money, this is just as accurate. I have tried all sorts, wigglers with points, pointed edge finders, play dough with pins in, spring loaded doodahs with bells etc. I always come back to this.
Set up as shown, and by tweaking the jaws (slackening on one, tightening the opposite) on the chuck get the runout to as low as possible. I class 1/2 thou as acceptable.
Take all the setting up gear away, remove the parallel from the rear of the job (more on this later). You are now nearly ready to start cutting metal.







Put a big centre in the end of the metal, and wack thru with the largest drill you have got. I must invest in a set of blacksmiths drills, I love putting big holes in things.







The next two pictures go hand in hand. You always use the largest boring bar you have that will do the job. So you may not have set it to correct height yet. If you use a QT toolpost it is dead easy. Get your favourite facing tool that is already set to height, lock your spindle if you can, if not, do this very gently so the spindle doesn't move. Using the facing tool, scribe a small line on the metal as shown in the first of this pair of pics.







Mount your boring bar into its tool holder and bring the height up to the line marked on the job. Perfect tool height achieved in seconds. I always have trouble with my biggie bars if doing it by normal methods, because the tips are angled downwards. doing it this way solves the problem.







Again the next pair of pics are linked.
I have a home made saddle stop fitted to my machine, the square lump with bolts sticking out, to the left of the saddle. If you have one of these, use it to stop the boring tool going too far thru the job and hitting the chuck. If you haven't got one of these fitted, be careful, and expect some time in the future to cut some nice circular bits out of your chuck. Go to the next pic.







This is a close up shot of what I was on about, with the stop set, the tooling cannot hit the chuck.
I will now mention 'more on this later'. The boring bar has to penetrate all the way thru the job, if there wasn't a space caused by the thin parallel, the boring bar would hit the chuck as soon as it got to the end of the hole. This is a safety area for the tool to run into. It is needed if the hole being bored is larger than the hole thru the chuck.







Now the best bit is here, metal to be cut.
All safety spaces have been created, everthing is set to length. Now start boring thru. As much as the machine will take at this stage, finer cuts later on. As you start to get to finished size, take finer and finer cuts. On this job it doesn't matter about a good finish until the rotor fits into the hole. On my very very expensive set of boring bars (kindly donated by a rep, for recommending them to the boss), they have holes going right thru them, so cutting fluid is fed into the back and emerges just behind the replaceable tip. A real neat idea, but in this case not used, after each boring run, I just stopped the machine, cleaned out the curly swarf and painted in some of my 'ali mix', then carried on until I was at the right size for the rotor to fit snugly into the hole.







The rotor, nice and snug in its future casing. But this is no use to me, I need about 5 or 6 thou running clearance to allow for expansion of different materials while being powered with hot steam.







The final cut to give me this clearance was duly keyed in and run back and forward thru the hole a few times at the same setting. This not only gives a nice finish, but also takes out the remaining metal left behind by 'tool springing'. So you end up with a nice shiny parallel bore.







JOB DONE.






Next will be putting the rest of the holes in the casing, and maybe making the converging nozzles.

John

PHEW!!


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## Bogstandard (Mar 15, 2008)

Sorry I never put the expected post up yesterday.
With my new found mobility I actually burnt myself out in the shop, so yesterday I just took it easy, surfed a bit and slept a lot.

What I would like to suggest, is that as I am doing this post showing how I do the things I do, if anyone else has a different or better or easier method of doing what I am showing, please do a small write up post in the tips and tricks section, and pop a link to it in this post. That way people will be able to choose the method that serves them the best, with the equipment they have.

I am not perfect, I do things that are my way, to achieve what is needed, and in no way am I trying to influence people how to do things. I can only suggest. 
No animosity will be shown to anyone who does this, in fact I condone it, I might be able to learn a few tricks as well. There is a mass of untapped knowledge amongst the members on this site, so if you can, set it up, take a few piccies, do an easily understood write up (so even I can understand it), and pop it in a post. You never know, you might start to enjoy doing it, as I do. The main plus side is that newbies will have a chance to learn how to do things, and so won't have the stigma of being a newbie for any longer than is necessary.

John


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## Bogstandard (Mar 16, 2008)

I am starting to get very lazy, two days behind with this project, must get my a**e into gear and start moving.

Today it is getting the smaller holes into the rotor chamber to feed steam/air in and get rid of it as soon as it has done it's work. The energy in this design I am making will only be playing on the rotor for half an inch of movement at the most, then it is discarded. So you will see with the first sketch that the steam will be fed in, hit the rotor, move it a bit, then it will be straight out of the first exhaust. If a bit gets past this first one, I am hoping that the second one will scrape most of the remainder away. What I don't want to happen is to get a build up of pressure in the chamber.






This next sketch shows the position of the holes required. I have left the chamber at 2" long to allow me to work from a central point, the chamber will be reduced to correct length after all this work is done.
For the second set of exhaust holes the datum is moved 3/8" towards the centre of the chamber, then the required 20 degree angle is put on to give me the tangential exhaust to hopefully scrape away the left over steam.







Theory over, time to get it done. As you can see from the next two pics I have blued up and marked where all the holes are positioned. I still do this even though I use DRO on my mill. It is a double check to make sure that I am drilling or machining in the right place, and is a good practice to get into. You never know when your DRO might go down and you have to do it manually. A lesson here. Before all the whizzbang stuff came along, this is how it was all done, if you can learn to do it manually, it will stand you in good stead. Gizmos make life easier, and if you want to go down that route, do so by all means. But don't forget how to manually do things.













This is a standard drilling setup to put the holes in for the nozzles. I first drilled into the chamber with a 1/8" drill, then using a 3/16" end mill I milled down for 0.200" to give a stop for the nozzles to be made and to allow for a grub screw to be fitted from the top to allow the nozzle to be held in position.
While I was in the vice I turned the job thru 90 deg and popped a small (0.020") into the centre of the chamber on the base to make a small drain hole, just to get rid of any water that might condense out.







Switched over to the RT in horizontal mode. I squared it up basically with an engineers square to the table edge (this is only near, and relies on the base of the RT being totally square). Then the RT was set to zero, inside jaws fitted to the chuck and the block mounted on using a square to get it near.







This is where you get everything spot on. DTI in the drill chuck, bring the Y axis into play and get a reading on the clock. Now track left and right using the X axis and tap the RT base (with a soft hammer) until you get no deflection across the whole face. Now using the quill, take the DTI up and down and get the job perfectly upright by slackening slightly on the chuck jaws and very gentle tapping on the job to get it tracking perfectly up and down. Tweak up jaws and recheck.
Now the exhaust holes were drilled (making sure I didn't hit the chuck jaws as the drill penetrated into the chamber).







Now I went back to the first hole drilled, moved 3/8" towards the centre and rotated the table 20 degrees to give me the correctly positioned hole. This is repeated for the other two holes. The two fwd holes will be the same direction on the RT, the reverse will require you to turn in the opposite direction. It all depends which way round the block was first mounted as to which way the RT has to be turned.







Inlet jet side







Exhaust side








This shot shows the chamber on the inside, you can see the tangential exhausts and nozzle inputs. If you look carefully on the bottom face you can just see the small drain hole and grub screw holes.







I have put the rotor in the casing to show how it will work. If you look carefully you can see the inlet nozzles on the far side. The pressure comes in, hits the uprights on the pockets and pushes the rotor forwards, it only travels a very short distance before the next face is in position to have pressure on it. It goes just over TDC and starts to escape thru the first large exhaust, the second exhaust port catches any that was missed (I hope). 
The bluing is to show me which end 1/8" has to be removed to get everything spot on and tight.







The next stage for this job is to fit the end plates. Normally I would make square ones and just wack them on. But because I lost all my pictures a while back about making flywheels out of plate, I am going to do the same sort of thing for making the end plates, just to show the technique to people who haven't had the chance to see it done.

John


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## ChooChooMike (Mar 17, 2008)

Bog - your photo's and documentation on your build are OUTSTANDING !! Please keep it up - I'm sure I speak for many here - we're learning tons !!

Mike


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## Bogstandard (Mar 17, 2008)

Thanks Mike,
Glad you are enjoying it and hope it is explaining things in a different light.
You just might like this one.

----------------------------------------------------------------------------------
I will just explain what I will be doing on this post. 

I will be showing how to get a circular disc out of a lump of plate. Round bar can be fairly expensive in the larger sizes, but if you don't mind putting a bit of work in, they can be made almost any size you want. Ideal if you want to make a flywheel. The reason I am showing this, is that last year I did almost exactly the same post about getting flywheels from plate. But unfortunately I lost all my pictures on photobucket, and didn't have a backup to replace them. It can't happen now, I have a full backup in two separate places now. 
The other reason you might be asking is, why make round endplates for a square engine. There is method in my madness. The rotor on this engine has only 0.003" between it and the outer casing. So by using a round disc, it can be loaded onto the lathe and concentric holes and spigots can be machined to much finer tolerances than if it was square and put either into a four jaw or the milling machine. After the disc is machined, it will be a fairly easy operation to make it square to fit the engine.
----------------------------------------------------------------------------------
So rather than beating my gums any more, lets get on with it.

First pic, shows rotor casing and a chunk of plate that was rough cut from a bit of a jig a mate gave me.







In this next one I have already blued up, done a rough scribe around the casing, found the rough centre, and using calipers, scribed a line so that it encircles the square and popped a small centre into the rough middle. If you were making a flywheel, you would scribe your diameter (slightly oversize) and put the centre in. The rest of this is relevent to all.






I could have just cut between the two circles and ended up with a couple of squares. But to save time and stress trying to do large interupted cuts on the lathe, I did a rough cut out on the bandsaw, a few minutes doing this saves a lot of minutes and anguish on the lathe.







Flip 'em over and stick some masking tape on the back, to the nearest thou, just as I have done. This is going to be the friction pad between the chuck and the job.







Now to set up the lathe.
Put a piece of stock in the chuck jaws, and push it into the jaws as shown. The size of stock that is required is that when the jaws are tightened up, the outside of the jaws should be a bit smaller than the finished diameter of the disc, nothing special, near enough is good enough. Tighten the chuck jaws.






This will only work if you have a rotating centre as in the pic, don't attempt this with a solid centre. There is a bit of a trick to the next bit, but it is simple if followed correctly.
Bring the tailstock towards the head but leave enough room for the saddle to be able to be moved to give the cut across the side face of the job. Lock up the tailstock and wind forwards, as you get near to the chuck feed the centre drilling in the job onto the rotating centre, and carry on winding forwards on the tailstock until the job is gently trapped between the centre and chuck jaws. Turn the chuck, the centre should turn with the job and there should be no wobble on the tailstock ram. If there is a bit of wobble, retract the ram and repeat. Once all is running true, put some pressure onto the job using the tailstock ram. When you turn on, the centre should be rotating and the ram should have no wobble.
This technique is called friction turning, and is safe. I have turned items up to 2ft in diameter and weighing many pounds, but not on this lathe, I have a max of 10" diameter.







Mount up your favourite tool, and set it so that it can cut across the whole side face plus a little bit and not go too close to the chuck, just put the saddle in the position you will end up at, and rotate the chuck by hand to make sure nothing will foul. I use my saddle stop in this situation, but if you haven't got one, be very careful as you will be working in areas around the chuck you don't normally go.
If doing an interupted cut, 10 thou is OK, if the job stops turning, take a bit of cut off and come in again, but a bit slower feed. This is the reason I trim mine down. From the outset I can take a cut of 20 thou with no problems.
Machine down to your desired size. You can even polish the edges if you want to, but keep your knuckles away from the chuck.







Down to size, a quick deburr with an emery block and it is ready for making a flywheel or WHY.







These are the plates being used for mounting the bearings into, and also the engine will be supported on these end plates, so they have to be fairly substantial. In this shot I have already removed 1/8" from the length of the casing by mounting it into the four jaw and facing to length. 







The next job will be getting these end plates to accept the bearings.

John


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## Bogstandard (Mar 18, 2008)

This post will be about how I obtain very close tolerances on large round bits using my lathe.

As mentioned before, the engine I am designing and making is made to fairly tight tolerances in places, in some cases no tolerance at all, it has to fit together perfectly.
So I will let you into my little world to show you how I do it.
-------------------------------------------------------------------------------------

This first picture shows what maybe a few of you have never heard about. They are called soft jaws. They are bought as extras for your self centering chucks. Not all chucks are supported, so when I buy a new chuck, if soft jaws are not available for it, I go for one that has. All my self centering chucks have soft jaws, from this four jaw one to the 3" one I use on my rotary table. These, as far as I am concerned, are one of the most important parts of the precision turning arsenal that I possess.







So, how are they used?
The jaws are not like your normal very hard ones, and are usually made of free cutting steel. This allows you to machine them to hold the circular parts that you have.
The jaws are tightened down onto a bit of bar stock, as shown. The bar stock is selected on size to allow you to either bore a new recess on a clear bit of face, or modify an old recess slightly, to allow a good fit for the part to be machined. By tightening down onto the bar stock, your are basically locking the whole jaw and scroll set into a solid mass and at an exact position. So when the part is tightened into the recess, it again locks everything together, in exactly the same position as the boring was done, so perfect concentricity is retained. They don't need to be very deeply bored, because the surface area contact is a lot more than normal. It is not recommended to use these soft jaws as you would normal ones, the machining on the pointy bits is not usually very accurate, and besides, with the metal being soft, it cannot grip too well just on the points.
After boring the machined area must be deburred very well. This is the part that takes the time.
A set like this would last, if old borings are modified to suit the job, very many years, most probably the life of the chuck. The jaws are usually longer than standard sets, so when the face becomes full of all sorts of borings, you face them all off and you can start all over again.







Now back to making the high precision ends for my new motor.
The previously machined plates were put into the custom bored recess in the chuck jaws. The centre drill was taken up another size, just in case the friction turning was slightly out, and followed thru with a 3/8" drill.







The disc was skimmed very lightly both sides, just to clean them up and get them totally flat. I am not worried about the thickness of these discs, as fine tuning takes place a bit later.
The centre hole was then bored out until it was just a little smaller than the ID of the outside race on the bearing.
The discs have to have a spigot machined on them that fits into the rotor casing. If this was done before the bearing housing was machined the soft jaws would need to be rebored to take account of the spigot, so the bearing hole has to be done first.







I am using flanged bearings, so they are not too critical on boring depth, anything that is either to length or just over will do. If standard bearings were to be fitted, they would be bored to a depth of 3/4 of the width, this would allow the bearing to produce its own sticky out spigot, just like the ones I am using.
The holes were very finely bored until the bearing was a finger push fit in the hole. Too slack or too tight is not what is wanted on this engine.







The bearing fits perfectly.







Bearing removed, disc flipped over in the chuck and a 0.050" high spigot is machined on the face. This has to be machined, yet again, very precisely on its diameter, to a 'wringing' fit in the bore of the rotor casing.







This is what it should look like if done correctly.
Now make another one exactly the same for the other end.







This little beastie is starting to look menacing.
So I took a chance, because there are no internal spacers yet, and put a bit of air onto it. In fact more than a bit, and it ran almost exactly as I wanted it to. But without all the other bits and full bearing rigidity no definite results. 
Very promising is all I will say.







The next job will be getting the bearings and end plates fixed into their correct positions.

Then it might start flying.


John

Footnote.

After double checking this post, I noticed that I showed boring to depth for the bearing and putting the spigot on, I had used replaceable tipped tools. 
This sort of tooling usually has a very small rad on the tip, so doesn't cut a totally square corner. For bearings it doesn't usually matter, they are most often made nowadays with slightly rounded corners to cater for the rounded corner holes. But in the case of the spigot, I had to make sure that the large hole in the rotor casing had a good chamfer on the edge to allow for the non square corner. If you are using ground up tooling with sharp points, this problem would not occur.

I mentioned this because, if ever you are using replaceable tipped tooling to make your little engines and something just won't sit down tight, face to face, it just might be a matter of making a little chamfer to cater for this radius.


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## SmoggyTurnip (Mar 19, 2008)

I don't understand why the soft jaws are more precise than hard jaws. Doesn't it all boil down to how well the part is dialed in ?


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## Mcgyver (Mar 19, 2008)

SmoggyTurnip  said:
			
		

> I don't understand why the soft jaws are more precise than hard jaws. Doesn't it all boil down to how well the part is dialed in ?



Smoggy, it looks like its a 4 jaw self centreing chuck he's using, not a four jaw independent. in a four jaw independent, you're right, wouldn't matter. dial in with a 10ths indicator and all is good. in this case i can see the advantage of the soft jaws, he creates not only axial concentricity, but also the way the jaws have been machined creates a radial step to set the short pieces on, like a built in spacer.


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## Bogstandard (Mar 19, 2008)

Thanks for that Mcgyver, I should have mentioned that it was a four jaw self centering. People automatically assume it is an independent four jaw, just because of the number of jaws.

I would like to add that Smoggy is right, you can just redial it in with an independent. But with soft jaws you can take the job in and out and flip it over without having to redial each time, also, because you don't have the gripping area too deep, and if you are careful with the depth of cut, you can work on fairly thin jobs on both face and sides in relative safety, without fear of the chuck 'letting go'.

John


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## Bogstandard (Mar 19, 2008)

This is only a short post tonight, a bad case of the lazies got to me today.

I will just explain what I am going to be doing.

In the last post I got the end caps onto the casing and the bearings a nice concentric snug fit into them. To stop the bearings popping out or rotating in their recesses, I am going to make a cover that tightly fits over the protruding flange, plus I want to make the recess for the flange very slightly shallow (only 1 or 2 thou) so that it 'grips' the flange between the rotor end cap and the bearing cap, to lock it into place, I could use a bearing lock product, but I want to get the bearings out fairly easily, as I expect this engine will go thru them at a fair rate if it is used a lot.

I have decided to pep the look of the engine up a bit, as it does look a bit sparse.
I know Marv doesn't like the word B***G, so in an act of respect for a very knowledgeable man, and just for this post, I will call it visual enhancement.
Ali and brass give a very nice looking contrast, so for this engine I am going to make the bearing cap a little over the top, but it should look right when it is finished.

To start off with I mounted a lump of large hex bar into the 3 jaw.






The end was faced across, and a spigot 1/2" diameter by 1/4" long was machined on the end using a round profile tool, just to put a bit of curve onto the engine.







This was duly parted off leaving a hex flange on the part just over 1/8" thick. A second one was made straight afterwards.







This gave me two rough part bearing caps. They were duly put into my collet chuck, gripping on the spigot and the hex end was faced across, so that I could measure the thickness.







Two caps, faced off, showing roughly how thick the mounting flange should be.







These are the end caps, with a dimension on them that is the amount of material required to be removed to get the mounting flange to the correct thickness of 1/8".







You might ask, why didn't I drill the hole thru for the shaft before I parted it off. This will be explained in the next post, all I will say is that what is not seen is the critical bit, visual enhancement can look after itself.

John


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## mklotz (Mar 19, 2008)

John,

Aw, go ahead and use 'bling' as much as you like. Just remember, though, at the first mention of rhinestones, I'm outta here.  :


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## Bogstandard (Mar 19, 2008)

Thanks Marv,

I promise, no rhinestones.

John


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## BobWarfield (Mar 19, 2008)

mklotz  said:
			
		

> John,
> 
> Aw, go ahead and use 'bling' as much as you like. Just remember, though, at the first mention of rhinestones, I'm outta here. :



Aha, the Liberace of the model steam set.

BW


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## DickDastardly40 (Mar 20, 2008)

Bogstandard  said:
			
		

> a bad case of the lazies got to me today.



Everyone is entitled to a day off, with your output your lazy day doesn't even equal my most productive.

Regards


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## Bogstandard (Mar 20, 2008)

Al,

I am not at work at the moment, so I use the shop to kill time and stop my brain going addled. When I eventually get back to work, I will be just like the rest of the members, grab a bit of time here and there.

John


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## Bernd (Mar 20, 2008)

John,

I went back and checked how you wrote up the use of soft jaws. Might want to mention why a piece of stock was used to clamp the jaws on. I know why, but thought you would explain it better. I think some of the members have never seen this method used and what the procedure is and why you clamp on a piece of stock while boring out the jaws.

Regards,
Bernd


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## Bogstandard (Mar 20, 2008)

Bernd,

Thanks.

Done.

John


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## Bogstandard (Mar 20, 2008)

Another short post again, but did manage a couple of hours on it.

You might be wondering why I have stopped doing the sketches. The reasons being are that what I am doing with the casing ends and bearing caps can be made to whatever you want, as long as it does the correct job, has some sort of ball races in there, and they are made to very tight tolerances. The only real critical bit was the rotor and casing, these bits can be made by looking at how I am doing them.
I finished the last post with basically, it is not what is on the outside, it is what is within that is the critical bit.

All the operations in this post are done from beginning to end without removing the part from the collet chuck. The second part is done the same way. This ensures all the critical bits of the machining are in perfect concentricity (they all have exactly the same centre), and everything is square to each other.
-----------------------------------------------------------------------------------

The first stage is to get the part as true running in the chuck as possible.
The face was cleaned off to the depth that was required to get it down to 1/8" thick. The outside bit of the part doesn't matter if it is a couple of thou out, that is there for cosmetic reasons and tolerances that small won't be noticed on a 'blinged' part.








This out of focus shot shows me setting up the grooving tool (my flywheel recess tool) exactly square to the face of the job. You could use a normal boring tool, it is just that I prefer this method to get my recesses to perfect depth and squareness.







In this shot I have already drilled thru the part with a clearance drill for the rotor shaft, it will be the ball races taking the bearing load, not these bearing caps. But from the outside it will look like the cap is the main bearing.
I then bored down, to a width slightly larger than the OD of the inner race of the bearing and about 20 thou deeper than the thickness of the bearing flange (if it was plain ballraces that were being used, it would be bored to a depth of 20 plus the amount the bearing was protruding from the casing cap). This is to ensure nothing interferes with the free running of the inner race.







The recess for the flange (or bit of the bearing sticking out) is now bored. It is bored to the depth of the flange minus 1 or 2 thou, and a very snug fit on the outside of the flange. The reason for not going to full depth is that when the bolts are tightened down on these end caps, the bearings will be physically trapped against the casing end, this will stop them moving in any way or form. As good as loctite, but easier to remove when needed.







This picture shows how far I got in just over two hours. Precision takes time. Never rush it, or make do. If it isn't right do it again. That is why, in this picture is another bearing cap blank, just in case. This time, it wasn't needed.
If you look at the bearing cap with the bearing on it, you can see the smaller recess put in to allow the inner race full clearance.
At the back is what it will look like when assembled (with bolts of course).








If I don't get my expected engineering visitor, I will get back into the shop and get these to a stage where they bolt together. Then it is just a matter of knocking up a few nozzles and a couple of internal bearing spacers and we should be ready for the initial vid of it running.

John


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## Bogstandard (Mar 21, 2008)

I will just explain something. When you design an engine like I am doing here, on the run, and not using cad, but using experience and little sketches as you go along, you have to be about four or five moves ahead in your mind. A hole put in the wrong place now, can cause havoc later on.
That is why sometimes I stall on putting up posts, I sit down in the shop for a few hours going thru the build in my head. I find, even with these time outs, I can knock out a working engine a lot quicker than trying to get it all down on paper first.

--------------------------------------------------------------------------------------------

Another post full of holes. 
I can't believe how long it has taken me to get all the bolt down holes done. But I did have a bit of a slip up last night and managed somehow, to get an hole, half an hole out (well the centre drilling was), but I fixed that after mulling over how to do it overnight, and got it fixed with no more than a redrill with the centre in a different position (the correct position) and by the time the hole was drilled and tapped the mistake had been machined out. Saves having to make new parts.
So this post is all about getting 20 little screws into the right position.


I started off bluing up the areas that needed marking. 
The first job was to get a corner to corner line on the main chamber, and find a position at one corner, on the line, that a hole could be drilled in all eight corners safely, without interfering too much with the other holes in the block. A position was found, and a measurement taken from the outer corner, to the hole position.
A chamber end was put onto the chamber and two opposing corners were scribed onto the back of the disc. These corner marks on the disc were duly joined by using a centre square, and by measuring from the scribed corner, down the centred line, the position of the required hole was pop marked in one position only. Only one disc needed to be done. Explanation later.
The hex caps were stood up on one of the faces and using a vernier height gauge, the centre line between two opposite points was found, this was done on each in turn. A good position for a mounting hole was found and duly marked and centre popped on each cap.
The pop marks can be seen in the pic.






Now onto the rotary table, set up in the vertical position.
There is no need to centre it under the drill chuck, but the chuck on the RT has to be perfectly centred on the RT table. Mine is spigotted to the centre hole and clamped down.

Now to drilling. The cap was mounted into the self centering chuck, the RT was set to '0', then the centre in the drill chuck was put directly over the pop mark on the cap by moving the x & y table controls. Once it was perfectly over the mark, the table locks were tightened.
Then it was a matter of drilling the hole, fwd 60deg on the RT and drill the next, and so on until all six were done. The new cap was put in the RT chuck, but the chuck was only just 'nipped' up. Now the cap was turned in the chuck jaws until the pop mark was directly under the centre drill. RT chuck fully tightened up, and the holes were drilled as before.







The marked up chamber cap was mounted, RT to zero, and centre drill located as before, hole drilled, move 90 deg, next hole, continue until all four holes are drilled.
Notice here that the locating spigot is facing upwards, as that was the side the markings were on.







Now comes the later explanation. Because thefour holes can be anywhere on the PCD (pitch circle diameter), I can just drill the four holes without going thru the set up procedure, I just used the same drilling position as the previous one. Notice that the outside face is being drilled first.







Because the outside face was drilled, I now put an end mill into the chuck, and duly made a recess for the cap screws on all four holes. Once they were finished I put the drill back into the chuck, put the first casing cap into the RT chuck, with the outside face upwards, and duly relocated the cap into the same drilling position by locating the drill in a hole and tightening up the RT chuck. The recesses for cap screws were then machined. That was how the twenty holes were drilled, now to get the screw holes drilled and tapped in the right positions







Casing was blued up, and put into a large v-block. Using the height gauge again, the exact corner to corner height was found, and duly marked on all eight corners.
The end caps were fitted, and eyballed down the holes so that the centre lines run exactly thru the eyeballed centre of the holes. Without disturbing the position, a fillet of superglue was put between the casing and end cap to hold them together. 







Once the glue was dry, I put a transfer punch (these are bought as sets and come in very close sizing to get the right size for the hole, and consist of a hardened rod with a centre point on the end) down the holes and made a pop mark onto the end face of the casing. The opposite end was done in the same manner. Once all eight marks were in position, I went to the drill press, centred and drilled to depth all eight holes (it was at that point I made my mistake). They were then tapped for the fixing bolts.
The scribing marks you see on the ends were made by me as a double check that they were in the correct position.







Casing ends are bolted on , the bearing caps are located, with the bearings in positon, the top face was levelled while the casing was on a totally parallel spacer. Once double and treble checked for being level, the superglue was used again to lock the parts together. This was done on both ends. Once everything was dry, the holes in the caps were spotted thru with a drill. Everything was then disassembled, and the casing ends were drilled and tapped to take the bearing cap screws.







Here are all the bits ready to go together.







The whole lot that have been made so far. Only three nozzles and two rotor spacers to be made. So getting a definite run tomorrow, and see if all the hard work and planning was worth it.







It might seem that this post was a total waste of time and energy. But to the novice, it does show that with a few basic tools, and a little bit of thought and forwards planning, holes can be put in components fairly easily and accurately.

Wacked out John


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## Brass_Machine (Mar 21, 2008)

Bogstandard  said:
			
		

> ....
> It might seem that this post was a total waste of time and energy. But to the novice, it does show that with a few basic tools, and a little bit of thought and forwards planning, holes can be put in components fairly easily and accurately.
> 
> Wacked out John



Woah woah wait a second there John. Posts like this are never a waste of time. At the very least they are inspiration to some of us. So keep them coming.

Eric


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## Divided He ad (Mar 21, 2008)

Hi, as an ultimate newbie I am going to have to say this is so far from a waste of time it's not even measurable!
you may remember me a little? I was the one who recently commented on the grin I had when I saw your single turbine running on the "Tube" and then had a great fasination with the two treadle engines....(Thank you for your suggestion of this site) I have started my simpler one already 
This tutorial has inspired me so much i am going to attempt something similar (I will add my own flair!! ;D) as soon as I have finished my current one.
Thank you for this very well put together and selfless undertaking. :bow:

Ralph. 

P.S. You gotta have "BLING" ;D


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## Bogstandard (Mar 22, 2008)

Ralph,

I definitely remember you, and welcome to the site.
It really pleases me to hear that my offerings have inspired someone to have a go.
Why not introduce yourself in the welcome section, and let everyone else know you are about, I am sure you will get a good welcome.

If you are contemplating making a turbine, keep it simple and keep it safe. Bearings will be your limiting factor, so make sure you bury them deep and rigid, so no one gets hurt if one does decide to blow.
My next post will be about the very simple, but most important part, the converging nozzle.

John


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## Bogstandard (Mar 22, 2008)

I lied, it is not the nozzle this time, but the rotor spacers.

These sit either side of the rotor between the rotor and bearings.
I machined them to allow a side to side movement of 0.002" of the rotor, this was to allow the rotor and shaft to expand slightly, without putting any side loads on the bearing races.

A couple of these pics are a bit blurred, must be old age setting in. 
On this first one I have turned a bit of bar down to couple of thou smaller than the centre hole in the casing cap. I also turned on the end of the bar, a small spigot, 20 thou high and just larger than the centre race on the bearing. This is to allow it to turn with the bearing but only ever be in contact with the inner race part.







The end cap was put onto the bar, and pushed on until the bar touched the bearing. A mark was put on the rod to show the rough length it needs to be.







Here is the next shaky one. What I have done, in the area that the spacer will fit inside the casing cap, I have turned 4 grooves, 15 thou deep and 50 thou apart. What I am hoping, if any steam does get into the bearing area, water vapour will be trapped in these grooves, and due to centrifugal force, be thrown out of shape to form like a series of liquid o-rings, thus preventing any large amounts of liquids reaching the bearings. When the end caps are eventually squared off, I might drill down with a fine drill, form a small drilled reservoir at the top and put a bit of oil in there, might be a bit better than trying to seal with water.







It was parted off just a bit longer than needed.
Not shown was that a second one was made the same as the first. Holes the same size as the main shaft drilled thru them, and the parted end cleaned up. Both were then made exactly the same length, by taking material off the parted ends.







To work out how much was needed to bring them to correct length, I put both end caps on (without the rotor installed) and measured the overall length of the motor.
The spacers were put on the rotor, and that was then put into the casing. One end cap was alredy bolted to the chamber, so the other one was put onto the central shaft and pushed towards the casing as though I was going to tighten it on. The spacers actually stopped the cap going all the way, so I then took the overall measurement again, in the same position that I took it from the first time. A 0.026" difference. This told me take take off each spacer 13 thou, plus 1 thou for clearance. 0.014" was duly taken off the parted off end of each one.
The whole lot was reassembled, and spun over by hand. Perfect.









To keep my word, I knocked up a very basic converging nozzle, fitted it to the centre (fwd) rotor and wacked some air thru this little monster.
This vid shows the results.
I actually turned my compressor off before I started, just to keep the noise down (little chance of that with this thing running), but what it meant, on the second runup, there wasn't enough air left in the tank to get it on the boil.

Enjoy it.

[youtube=425,350]YpcQ4JinhzI[/youtube]


Deaf John


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## zeusrekning (Mar 22, 2008)

Holy **** man !!! Pardon me, but this was one of thoses projects I just didn't seem to have intrest in. But John's in depth write up kept drawing me in. I had no Idea at all what you were building to start with. I'm facinated! I love the sound it makes. I'd could listen to that whine all day. 
Very impressive. Not I get to start at the beginning and read no stop start to finish. 

P.S. You don't write with a british accent.


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## DICKEYBIRD (Mar 22, 2008)

Noice...very, very noice indeed. Luv it! 

So, I may have missed an earlier mention of it but are you building the speed reduction gearbox as well?

Fabulous! ;D

Cheers,
Milton


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## Bogstandard (Mar 23, 2008)

Milton,

What you saw on the vid isn't anywhere near its output. I ran it up for just a little bit longer before I shot the vid, and all of a sudden it hit its power band, and started to run away. A quick shutdown was called for.

The thing this runup did show was my static balancing had worked, and very little vibration showed up. But I did notice that the bearings really need a grease repack. I can easily make a little tool to do that without having to take the shields off.

I will be coupling it to a variable speed gearbox (if it can take the speed) to work out what is required to get the motor running at optimum speed and giving the required revs. Then make a basic gearbox, based on the results.

That is a fair way off yet, and won't be shown on here, except at the final stage. Other projects are starting to rear their ugly heads, and customers are starting to look forwards to delivery.

John


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## d-m (Mar 25, 2008)

This is like watching a good episode of lost and being left to hang at the end till the next week cant wait for more!!!!!!!!!!!!!
Dave


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## Bogstandard (Mar 25, 2008)

Dave,

I am sorry about that, but that is what happens when you catalogue a live build. You are seeing it after a couple of hours of it being done.

I have to design the next bit, only then can it be made.

Body and mind (plus unwanted visitors, like over the Easter weekend, and again in half an hour) all contribute to the delay.

But hopefully between my medico meetings this week I can get a lot more done.

Lost John


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## zeusrekning (Mar 25, 2008)

John, that is one of the most amazing parts, maybe even more than the work you do.
It is so hard to design on the fly while also being able to document procedures you may not have already proven out. I've noticed with the project that I'm working on that there is alot of ,"let me see if this is going to work", before I even take pics. Plus with my Patience level and memory it is hard to stop working for fear I might miss that needed revelation.
Keep it up! :bow:
Tim


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## Bogstandard (Mar 25, 2008)

I was going to do such a lot in my shop this evening after getting rid of the unwanted, then just as I was walking out, my mentor turned up, wanting to know what I had been doing to poor defenceless bits of metal. So it wasn't a very productive evening after all. 

So here is one of the most boring posts yet.
Just a sketch and one pic. But it might explain the direction I am going in.

I will just show you what I am doing with this sketch. A converging nozzle is required to speed up the pressure coming in, whether it be air or steam. In an ideal world the nozzle would be similar to the one at the top. The air/steam comes in from the RHS, and squeezes down to go thru the small central hole, thus increasing the velocity as it goes thru the smaller hole (the same happens when you press the plunger on a syringe). Just past this small hole the nozzle starts to open out slightly to the finished size of nozzle (this area where it squeezes down and then opens up again is called a venturi). As the gas starts to expand again into this slightly tapered up area, it speeds up even more (the gas is trying to get out of the restriction and so speeds up to do it all the quicker). I hope I have explained this enough in laymans terms, just so everyone can understand the principle. In fact it is all to do with increase and drops in pressures.
So the next part of the sketch shows how I have tried to replicate the principle. I could spend hours grinding up very fine D-bits to get it spot on, but in this case, what I am doing works, not quite as well, but good enough. I am using the drill point to give me the taper for the lead ins and outs.







I could have showed machining the outside of the nozzles to size, and then drilling holes of different sizes thru them, but I thought that would insult your mentality, because I am sure you are all capable of doing those operations.
So what I have done is taken a very exciting pic of a finished nozzle held in my gnarled old gripper. This is a real treat for you, not everyone gets to look at a bit of stepped brass in an old farts hand.
I would have shown you all three that I made, but I thought that might be a bit too overwhelming for a few of you.

It's the bits that you can't see that are important.






Now that bit is over and done with, I promise, after I get back from the clinic tomorrow, I will do something a bit more exciting, maybe watching paint dry.

John


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## Seanol (Mar 25, 2008)

John,
Excellent build and documentation. I have added quite a few mental tools to my arsenal.

A question: Would the nozzle design parallel a NACA duct in round mathematically? I.e. a 1 to 3 ratio of rise to run? http://www.revlimiter.net/mods/duct.html shows an example.

I have always been interested in aerodynamics and this seems to be a common theme with regards to intakes.

Just wondering,
Sean


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## Bogstandard (Mar 25, 2008)

Sean,

It is nearly 40 years since I got my qualifications in aeronautics and aerodynamics, so the answer to your question has to be, I have no idea, sorry. The theory would be way out of date by now any way, and dementure is setting in fast.

What you are showing in the URL is in fact (when I was into things that flew) a standard low drag intake. But I am sure with all the latest gadgets available, the aerospace people have come up with a more efficient design. Maybe trolling around modern day fighter pics and searching for say 'diverging intake design' would give you an idea of the shapes they are using nowadays. But some of the stuff that comes up, especially in the aeronautical side just might be a bit hard going. I have trouble myself nowadays, understanding stuff that is too technical, whereas at one time I could soak it up like a sponge.

Those intakes work in the opposite way to the nozzle principle except where it comes out of the nozzle. The way they work is by taking high speed air and slowing it down to an acceptable level to be used inside the engine bay, otherwise if it was the other way around (like the nozzle works), the hood would be blown off in seconds, caused by pressure build up once a respectable speed was reached. One thing I do know is that in a converging/ diverging nozzle, if the calculations are way out, you can reach the point of a mach1 shock wave, in which case everything goes pear shaped.

John


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## gilessim (Mar 26, 2008)

John ,you may have mentioned this in your fascinating post but did you use ceramic bearings?

Giles


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## Bogstandard (Mar 26, 2008)

Giles,
Rather too costly I am afraid, so I stuck with some standard bearings that I know the details about.
Because these ones have old grease in them, they do feel and sound a bit rough. But as I said, I know how to make a dead easy tool for recharging them with grease, and I will show how to make one after this is finished. Then it should run a lot smoother.
I am hoping this will hit a power band around 30-35k RPM, so bearing selection should be easy. But from my trials with it, I just might knock up an ali rotor, to see if the lower mass will allow a faster acceleration. As I said, this is a proto, so will be played about with. But as built, it is giving a nice running turbine, very close to my expectations.
I must get a proper tacho on it when it is finished, mine only goes up to 29K, it was designed for model aero engines.

John


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## AllThumbs (Mar 26, 2008)

I have heard of guys puting bearings in a container containing oil, then vacuum all the air out of the container. Once you remove the vacuum, oil gets sucked into the space once occupied by air in the bearing. Is that how your tool works bog?

E


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## Bogstandard (Mar 26, 2008)

AT,

Nothing as complicated as that.

It will be a quickie make, manual jobbie, to be used with a grease or pressure oil gun.
A couple of hours work and a bit of metal. You will be able to make them to fit almost any bearing within reason.
I won't go into details yet as it will distract me too much from this post, and I need to get this little thing up to speed first. 

John


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## SandyC (Mar 26, 2008)

Hi John,

As always, a superb piece of engineering and I have no doubt it will deliver a fair power output when finalised.

You mentioned your tacho only going to 29K.... is it an optical unit?...i.e. one that uses the prop blades as impulse source. (assuming a 2 blade prop would mean 58K impulses).
If so, then by using a disc (attached to the engine shaft) with only 1 reflector on it you could double the max count, if you see what I mean.

You also mentioned possibly making a new rotor from ALI, to see if it will accelerate faster.... probably true...however, ALI and STEAM are NOT good bed mates.... not quite so bad on air, although even this can be pretty abrasive.

Just thoughts.

Keep up the great build, and hope the BONES don't give you to many more problems....you could sure do with a respite from all that.

Best regards.
SandyC &#160;;D ;D


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## Bogstandard (Mar 26, 2008)

Thanks for that Sandy,
It is always nice having a steam mentor in the background.
I have a wonderful piece of titanium that could be used, but with so much machining on it I think it would end up in my recycle bin.
The ali rotor was in fact just for an exercise in seeing how much faster the acceleration could be made. If and when the matched pair are made, they will be done in bronze, but skinned down a lot more than the rotor in this one. In fact they might be made hollow with supports inside the ends. I have a massive glut of bronze bar at the moment.

I hadn't thought of using a reflecting strip on a disc. It would definitely be safer than using what I usually do (don't ask). I will try it.

Thanks again for the input.

John


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## Bogstandard (Mar 26, 2008)

Away we go with another bit of this saga.
What I am going to be doing here is planning for the next bit to be made, but before it could be fitted, the casing has to be brought up to a nearly finished state.

What you see here are the makings of the exhaust system, but normally I would make a proper bent up job of it, silver soldered, the works. But this is just going to be a way of getting the gases away, hopefully with no back pressure. Just a big lump of rough cut ali and a couple of bits of 1/2" ali tube. This will not be made yet, if you remember, earlier in this post, I said that most of the mountings will be done by using the solid end plates as the fixing area. So that takes us onto the next pic.








What I have done here, is mark up the block and end plates so they go back into the same position. For this I used a drill point instead of the usual pop mark. A pop mark usually throws up a small crater edge which requires flatting down, by using a drill point a quick wipe over with a scotchbrite will knock off anything that is sticking up.
The next job was to blue up the end caps as shown, and reassemble without the rotor. The top and two sides of the block positions were scribed onto the blued end caps, then taken apart again. That is what is shown here.







The end caps, before being hacked down needed a bit of blingy turning doing. Much easier to do while they are still round. So they were mounted into the same bored soft jaws that were used to put all the precision stuff on them, and the bit of facing was carried out. This not only removed all the old scribe marks but made a nice boss feature on the face. Both ends were done to the same settings.







In this one, I have been to my bandsaw and cut off the excess material on the outside of the lines. Then reassembled the caps on. Notice that I haven't removed the bit off the bottom face.







Because the only flat and square areas now on the assembly are surrounded by rough cut end caps, I just can't tap it down onto parallels. I came up with a small v-block that the casing will sit on, and be tapped down on to. On the jaws of the vice I used a bit of double sided tape to stick two small HSS lathe bits that will sit between the end caps and so keep the block square.







This is how it all sits in position, a bit precarious, but if only small cuts are taken on the top face, quite acceptable.







A flycutter was used to bring the end caps to size, then the final cut just took a minute amount off the rotor casing. The first side done.







V-block got rid of, two bits of lathe tooling taken off the jaws, one piece was put down where the v-block was. The face that had just been machined (and deburred) was put against the fixed jaw, a bit of bar was put between the moveable jaw and the job. Tightened up, tapped down onto the bit bit of lathe tooling and the side face was machined the same as the top face was done. It was flipped over and the second side was machined. This now gives me three sides (top and both sides) to work with.







Now onto a solid milling base. Job tapped down onto a para. The bottom bit of the end cap was flycut down to give a nice flat base.







A radius edged cutter was fitted and the remaining curved bit of the end cap was machined away.







The job was flipped around and the same settings were used to get a nicely formed, solid base, for mounting the engine onto a baseplate.







Now just waiting for the exhaust to be made.








To follow will be the making of the exhaust system, I hope.


John


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## rake60 (Mar 26, 2008)

Great stuff here John.

I'm looking forward to every "next post"!

Rick


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## Bogstandard (Mar 27, 2008)

Rick, glad you are enjoying it, I know I am.

What I am mainly showing here, are my way around problems, using just the basics what you have around the workshop. These ways can be used not just on this build, but anywhere a bit of machining of this sort has to be carried out.

Smooth, close fitting and matching parts can make a basic engine into a real looker.


John


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## CrazySteamer (Mar 27, 2008)

Hi John.

Ive been following your progress, and it all looks good. Ive got a three inch scale model road locomotive, and the some orignals have a steam terbine on the side to make electrisity for the headlights.

Ive started making a single rotor terbine of simmilar design to yours, but with 50mm diameter rotor, (This makes it more or less in scale) made from steel with 20 pockets. This gives a similar sized pocket to yours. It will be running on 5mm protected roller bearings (I had a couple lieing around). The covers will also be fixed on in a slightly diffrent manner - just to increace orthentisity.

Ive got a couple of queries for you.
You were saying that when you were running it up, you reached the power band of the rotor, I was wondering what sort of rmp this was at. I have a motor that Im going to use that should make 12 volts, at about 24000 rpm - was hoping this would be within the turbines power band, or do I have to put a gear reduction in - or find a diffrent motor? Obviousely because my rotor is bigger than yours the power band will be slightly less.

Another thing I was wondering about was how much power the turbine would create. You were talking of making some bigger ones and putting them in a boat. This must take quite a bit of power.

I was hoping for about 20 watts from my terbine - this means I can have a couple of 5 watt headlights, a couple of 3 watt lait lights, and still have a bit left to put in the canopy so I can see what im doing. I will be running on steam at 200 psi - which is considerbly higher, than what you were running at - but I was going to throttle it back a lot at the nozel, and hopefully increace the effishancy a bit. Also wondering how much steam you think the turbine will take?

Do you think there will be any isseues with cavitation? I could always throttle it back at a controle valve, and have a bigger nozel on the terbine, this would in affect put a degree of superheat on the steam, at the pressuer drop.

The terbine seems quite noisey, I was hoping for a quite humm from it - any idears for a silencer.

Finaly, Im wondering about the life of the terbine, at that speed it cant be long, after 5 - 6 hours it will have gone round a million times, I was hopeing for the life to run into the hunderads of hours?

Any advice would be greatly aprceated.

Simon


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## Bogstandard (Mar 27, 2008)

Hi Simon,

Welcome to HMEM.

You have asked such a lot, I just don't know where to start.

The first thing, I won't know anything definite about this turbine until it is fully finished.

The second thing, is I am not a turbine designer, but someone who takes an idea to fruition, by using a few known parameters. It might not be super efficient, but it will definitely work. So a lot of your questions I just cannot answer.

I can tell you, you will not be able to silence it to a hum in the space you have available. It is just the way fast turbines have to run. If you throttle the exhaust to quieten it, you will stop the turbine running efficently. Bearing whine is also a hard thing to cover up.

I will be using a gearbox to drop the speed right down to turn model boat propellors.

I honestly think you have gone the wrong way with yours.

On model locos, because like you, they have very high pressure steam. They use very deep pockets but a lot less of them, only five or six, plus a diameter of about an inch, and use pure steam power to turn them at a much lower speed, driving the generator direct or even stepping up the speed by use of a gearbox, to run a faster generator. This would keep the noise down to acceptable levels. Maybe that is the direction you should be looking at. I am sure if you do a search for turbines on a model loco site you will get a lot more useful information on higher pressure turbines for models than I could ever hope to supply you with.

I am running mine at a very low 40PSI, so the speed has to be a lot higher to get it to its power band.

I made my first one last year, and used it to drive a high speed, precision dc motor as a generator. It gave out 17 volts, but I didn't measure amperage. It has a rotor of 60mm diameter, and is running on about 40psi. This vid shows it all.

[ame]http://www.youtube.com/watch?v=KW6V7JWbQwk[/ame]

I am sorry I couldn't help you any more.

John


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## Bogstandard (Mar 28, 2008)

Hacking metal again for this post. I am going to be making the exhaust. It might not seem to be an important item, but if I get it wrong and 'strangle' the gases, I will get back pressure to the engine, and give what little efficiency it might have, a hefty backwards jolt. If that does happen I will just have to redesign.

---------------------------------------------------------------------------------------------

These are the bits I will make the exhaust out of. A lump of rough cut ali and a couple of bits of ali pipe. You might ask, why a longer bit of ali pipe, well I have already spotted a minor problem a few operations away, so that will give me a quick fix. It pays to plan ahead.
I have done a quickie sketch on the block to show what it will eventually look like.
I won't be showing how I get the block all square and parallel because I showed how that was done in an earlier post. So the next pic shows the block all square and ready for the next op.






The block is all square, and I have drawn on it the basic layout of what will be required for the next op. I find that doing this helps to prevent silly mistakes when mounted onto the machine. 
If you notice at the back, is my notebook. You can't see the writing on there very well, but it is a total machining order for all the drilling operations. Size of drill, exact position on the block for each hole, depth of holes and the correct order to drill them in. I did all this by holding the block and planning it out by using the sketch drawn on it. So basically, I can mount it in the vice, get the central location and then just merrily drill away, using the coordinates shown in my little book. Once again, it pays to plan ahead.






All drilling finished, now to get it fixed to the engine.






I am a firm believer in keeping things simple, but accurate. To make sure the mounting bolts line up perfectly and the block will sit in the correct position on the engine. I lined up the block against the engine by resting them both on the surface plate, and used a rule to align the block with the casing end caps. Without disturbing them, I put a fillet of superglue along one edge to tack them together. 
Aluminium, when cleaned, forms a new oxide layer within seconds. So when you come to remove the glue, you will find it just peels off, bringing the oxide layer with it, it just cleans straight off, and does no damage at all. 
Time for a fag, cup of coffee and a quick surf on HMEM, just to allow time for the glue to dry.
When dry I spotted thru with a drill the same size as the hole. The block was given a slight tap to separate them. The spotted holes were drilled and tapped into the engine end plates.






The exhaust block shown here has been blued and the position of the exhausts from the engine were marked on it. This was done by using the height gauge and a vernier to transfer the hole positions. Then a cutting area was marked on. It was then freehand cut on the miller.






I will just explain what I was doing on this pic.
The block was tapped down onto a pair of paras. Because I want the holes to go all the way thru the block, the paras have to be removed before going all the way thru. So what I did was to cut down with the milling cutter (this one is a four flute slot drill, you cannot use an end mill for drilling down into solid material because it hasn't got a full face cut on the end) until there was only about 10 thou before cutting all the way thru.
I roughed out all the material in the hole, all down to the same depth, then cleaned up the edges to the marked lines. The final operation for the hole was to tap out the parallels without disturbing the block, then punch thru the last bit of metal and do a cleaning cut around the hole. The reason for this was that the parallels would have been machined as well if they were left in there, but the main one was that all the heavy machining was done while still supported by the paras, only very light machining was carried out after the paras were removed.
The block was remounted into the chuck with the paras, and the same operation was carried out on the second hole.






This pic shows the finished block with the detected problem showing in the bottom of the big cutout. By planning well ahead, I had detected that this square hole would penetrate into the reverse exhaust passage, but by now using a longer tube, this cutout will be sealed and everything will be as though it had never happened.
Why cut the holes all the way thru the block?
I decided that when this exhaust is fitted and sealed to the engine, I will require access to allow inspection of the rotor without a full stripdown, and to clean out the exhaust itself.
So I will be fitting a nice brass access/cover plate to the exhaust block.






Just a few mounting bolt holes to drill, baseplate to be made, oil passageways to be drilled and the mentioned plate to be made and fitted.
The engine will then be finished. The controller will then be needed, but I will be using a modified one of the type I fitted to my piston valve engine, I already know what mods will be required, so that will be a fairly quick but precision job. 

Exhausted John (pun)


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## Bogstandard (Mar 30, 2008)

On the last post I had reached a stage to start finishing off the engine and putting on a few final details.


The first thing you will notice on this shot is that I have fitted the exhaust pipes. If you look at the big square hole, you will see how the tube has effectively sealed the hole that had broken thru. Also a bit of brass plate had been blued up. Not shown, but what I did was mark where I wanted the mounting holes to be, squared up the plate and very accurately drilled the clearance holes. The reason for the accuracy is because I want to flip the plate over when finished to reveal the good side, and the holes will still have to line up, all nine of them.






Normally I would stick the plate to the block with a dab of superglue, but in this case I didn't want to risk damaging the good side, so I used double sided tape instead. The holes were spotted thru with a drill. To get the plate off, I just flashed over it with my blowtorch, to get it warm, and it just peeled apart with no problems, and no damage.






The spotted thru holes were drilled to depth and then using my tapping stand, all nine holes were finished off, plenty of tapping oil, because ali has a bad tendency to grab.
You can also just notice that I have put a bit of tape onto the face sitting down on the surface plate. It only takes a minute bit of swarf to get between the finished face and the plate and it will be scratched very badly. Why make work for yourself, when a little thing like putting on a bit of tape is so easy to do.






On this shot, you can see why I wanted to protect the face. It is in fact a piece of engraving plate, and it comes ready polished, with a protective plastic covering that is removed to show the nice lustre. I am lucky in that there must be an engraving firm in my area, and this is always available at my scrap dealer, for normal scrap price. I don't use a lot of it, but it just gives this side of the engine a bit of a lift in the looks department.






A big leap on this shot, a lot has been done. Very small drain holes were drilled underneath the exhaust, these are to automatically drain any steam condensate that settles in the bottom of the exhaust chambers.
Small holes were drilled from the top of the end plates, down to where the rotor spacers pass thru the end plates. I mentioned in an earlier post that I might have them running with oil in there, to form a barrier to stop the steam reaching the main bearings. These small holes were opened up on the top face with a larger drill to form a small oil cup.
The major bit was to make a baseplate for the engine.
The next few shots show the engine from different angles.


















I have got the engine sitting in my claws for this shot, it gives some relativity of size.






The main part of the engine is now finished. On final assembly it will have all the screws replaced with stainless ones. I only usually use these black ones for engine assembly during build, they will be used again, for the next build.
I ran the engine up again with the new exhaust on, it ran about 50% quieter, the expansion chamber and change of direction worked really well, with no sign of back pressure or performance loss. In fact it sounded as though the speed had increased, but that might be because I could actually hear things this time.

I am now about two weeks over on this project, mainly because I am dragging my a**e at times. So this project has to be finished this week.
Tomorrow I might do a little build showing the adapter for regreasing bearings, then carry on with the control valve build. Just depends how I feel.

John


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## Powder keg (Mar 30, 2008)

This is coming along nicely John! I'm really enjoying your post's)

Thanks, Wes


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## zeusrekning (Mar 30, 2008)

Looks great John. I really like the way the exhaust looks.
Tim


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## Bogstandard (Mar 30, 2008)

Thanks Lads,

I would call it the 'brutal' look.

John


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## Divided He ad (Mar 30, 2008)

John, 

I want it!!

That looks FANTASTIC! :bow:


Ralph.

I'm going to have to steal ( I mean ask your permission!) the plans etc on this one ;D


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## wareagle (Mar 31, 2008)

Bog,

As usual, you are doing supurb work there. Thank you very much for taking the time to do the write ups and take the pictures as you go along. That is a huge time commitment in itself. Each new post is eargerly awaited. 

It won't be long until you have it up and running, and no doubt it will be a performer!


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## Bogstandard (Mar 31, 2008)

> I'm going to have to steal ( I mean ask your permission!) the plans etc on this one



What you see is what you get. In the post, all major or critical dimensions are given.
Everything after that is make to fit. If I did plans for everything it would take forever.

If it helps, use it. I don't charge for anything.

The bit to come for the control valve will have dimensions all over it.

Got to go out soon, I have to buy some grease nipples for the regreaser project.

John


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## zig 2007 (Mar 31, 2008)

i have been following this project very closely and am amazed at the quality of this engine  :bow:all hail Mr standard


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## Bogstandard (Mar 31, 2008)

Zig,

Many thanks for the praise, but it isn't really needed.
There are a lot more gifted people than myself on here, it is just that I show every little step on the way to make an engine.
Just enjoy what you read and see, and hope it helps you to become a maker of model engines.

John


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## CrazySteamer (Mar 31, 2008)

Hi John.

Turbines looking good.

Mine although has the same sort of rotor - has turned out quite diffrent to yours - of course because im fitting mine to a model traction engine it has to look authenric. I have a 55mm diameter rotor with 12 steps. I have been experementing with nozel angle, and design.

I have found that mounting the nozzel slightly lower than you have is benafishel, but the main thing I have found is that making the diverging section of the nozzel taper outwards is much benerfit. My nozzel starts at 4mm and then goes down to 1.2mm (Of course the drill puts about a 45 deg taper here). Then the nozzel opens out to about 2.5mm at a 12 deg taper. I made this using a silver steel d shaped taper reamer that I knocked up.

I think its well worth the extra 10 mins to make a taper reamer, as I found the pick up speed was greatly improved after Id done this.

I found that using this consideration I managed to get 3 watts running at 6 volts, and 12,000 rpm (Its blody noisey thou). This was running at about 80 psi air pressure.

I also found that air consumprion wasnt too bad.

I think id be able to get about 6 watts at a little more pressure - but I ran out of 6 volt bulbs. However I think under steam pressure the performance will be greatly improved. I think im going to fiddle with the nozzel a bit more when I get it under steam power. Im going to try reducing the throat to 1mm (Thats my smallest drill), and putting a longer opening taper on the diverging section (Mabey takingit out to 3mm at 12 deg).

When I get the turbine under steam pressure ill take a few photos, and put them on here (when Ive worked out how).

I was very interested in yr exhaust, and I think I might fit somthing simerler. (Mabey with some rock wool packing in ther somwhere to help with the noise).

Hope you dont mind me steeling yr idears
When you get it finished let us know what sort of power yr getting?

Simon


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## Bogstandard (Mar 31, 2008)

Simon,
I wouldn't try putting anything in the way of the exhaust gasses, all it will do is strangle the engine.
The way to silence a turbine is to expand the gases and make them change direction. That is why I mentioned in my previous post to you, where you need space to silence a turbine. On jet turbine test beds, the silencers used are the size of large houses, with very complex baffles inside. 
You could put an outer casing on the engine and fill the gap with rockwool, that would help to silence bearing whine, but not exhaust.
Yours is actually fairly slow running, I am hoping to have my one between 25 to 30K RPM on 40 psi. I don't want it any faster because it will be going to a gearbox, and I don't know how the gears will stand up to that sort of speed.

John


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## Bogstandard (Mar 31, 2008)

I mentioned earlier that I would show how to make a bearing re-greaser.
It is here.

http://www.homemodelenginemachinist.com/index.php?topic=1681.0

John


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## steamer (Apr 1, 2008)

Hi John

Well done!  I really like how the turbine came out...I do hope to see her soon steaming along at high speed.

Is there a boat in this guys future?

Dave


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## Bogstandard (Apr 1, 2008)

Dave,

No future for this test bed, my own collection.

There will be a nautical home for it's siblings.

John


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## steamer (Apr 1, 2008)

Great!

There will be more....I think a model "Turbinia" or a sister would be fascinating!
 ;D

Dave


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## Bogstandard (Apr 2, 2008)

Not been able to get in the shop to do any machining, it will most probably be the same tomorrow as well.

But to pass a little time and give you lot something to look at, I went over my plans of the control valve that I used on my piston valve engine and rough sketched it out, converted it to imperial and modified it to control this engine in proportional fwd/rev.

This little unit, by drilling one more hole and swapping over which port goes to what pipe, can be used to control a double acting oscillator or piston valve engine. It has the advantage of being totally sealed, unlike the two crescent types that are normally used, that leak everywhere. It could also be used at a push, like a speed control valve that I fitted to my mill engine. But with a small design change could be made into one that did a perfect job.

Here are the rough sketches I have made. I found a ruler at one point and used it, but I slipped back easily into my bad habits of a 'fag pack' sketches.

This will be all lathe and RT work, and I will show in fine detail how to make one.
-----------------------------------------------------------------------------------------

This sketch shows what the unit will look like, plus a cross section of how it fits together. 
Because of the close limits and coupled with the o-ring, a leak free unit should be obtained.







These are the dimensions for the outer case, I will be making mine in metric, but these will work perfectly.
The centre bore is not over critical as the spool will be made to fit. But it must be lapped to give perfect concentricity with no taper in the bore, plus make the bore walls as smooth as possible. I will be trying to get the spool and bore within 0.001". The closer the better.
This has to be the first part to be made, everything else is made to fit this piece.
No assembly holes will be drilled in it until the end caps are made, the reason for this is that they can all be dropped onto the RT table and drilled all exactly the same.






These are self explanatory, and the bit to take notice of is how the o-ring recess is made. The 0.004" squeeze on the ring is what gives the unit its sealing ability.






The spool is not made until the other three bits are finished, and is made to fit.
The two final stages will be to cut the two slots, and then relap to the bore after the pipes have been silver soldered into the outer case.






I haven't shown the control arm because it is a personal preference, so I will be making one before final assembly of all the parts.

So that's your lot for this one. Next time I will be making this little wonder.

John


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## andrewh (Apr 3, 2008)

John,

I've been following with interest and admiration, and now registered - so I can say so!

As before I like your sketching - it is a great way for me (at least) to visualise and work out waht matters and what could foul.

At school we were required to sketch and draw graphs without rulers - the physics teacher insisted that the world didn't operate to straight lines, and a thin perfectly straight line on a graph was a "claim to spurious accuracy" He may not have been entirely right but one person at least remembers!

So thanks for the sketches - very comprehensible and clear

Hope you are able to machine when you choose

andrew
and no - I havn't dremelled my pockets yet!


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## Bogstandard (Apr 3, 2008)

Andrew,
Thank you, and welcome to the home of help.
I would suggest you introduce yourself in the welcome section. Some people might not read this post, so by advertising yourself in there, you will get a warm welcome and people will be able to see who you are.

With regards to sketches, I find that people (myself included) find it easier to visualise how a part should look rather than trying to work it out from 2D drawings. It is also wrong, the way I dimension the sketches rather than doing correct drawings, but what the hell, we are not taking exams here, just trying to pass information across as easily as possible.

John


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## andrewh (Apr 3, 2008)

John,
Thanks, always intended to do that as a courtesy to a new forum.

As you say (and show) getting the process into shape and steps will help with "surprise management"

andrew


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## Bogstandard (Apr 4, 2008)

gents,

a bit of bad news i am afraid. this post will have to remain on hold for a while.

i have been having troublw with my hand the last few days and after lunch today, just after i had a skype call from al 'dick dastardly', i have now gone a bit too far and my hand is now numb all over. so effectively making it almost impossible to use machinery. it seems that the muscle build up exercises that i have to do to stop the pain has actually caused more damage to the nerve frm my neck that goes past my shoulder joint.
at least i can surf and answer a few posts by using a one finger left hand technique. 

i will have to see if stooping the exercises will allow th return of use.

john


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## AllThumbs (Apr 4, 2008)

I hope it gets better soon John.

E


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## gilessim (Apr 4, 2008)

Sorry to hear that John but I'm sure all will come back, sometimes as they say, it has to get worse before it gets better!

all the best, Giles


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## zeusrekning (Apr 4, 2008)

First the writers strike, now this. :'(
Just kidding John, give your hand a break and work the mind for a while. I hope it feels better soon.
Tim


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## Bogstandard (Apr 4, 2008)

gents,
many thanks for the well wishes.
i have been suspecting this was going to happen for the last few days. so what i am doing is stopping the exercises and hope that will allow movement again.
i know you all mean for the best, but if you could hold back a bit on the well wishing, so it doesn't clog up the post, i would most appreciate it.
i will get back to it as soon as i am able.

thanks again

john


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## Bogstandard (Apr 6, 2008)

Today I ended up with a good dose of house fever, I was seeing swarf before the eyes.
So with just two fingers working, I managed to get a couple of hours in the shop.

I have already mentioned before that this little control valve that I am making, is ideal for all sorts of control situations on the little air/steam driven engines we make. So if you need to know how to modify it to suit, don't be afraid to ask.

This post only covers how to make the outside bits, but don't worry, plenty of piccies to look at.


This is the stuff I am going to make it out of. I have a glut of hex, so I am going to get rid of some doing this job. A piece of 5/32" copper annealed pipe, an o-ring (only one needed) and four screws. I have already changed my mind when I was making these bits, and I will be using eight of the little ones like the ones on the engine, you can still make it like shown on the drawing though.
I have taken a lot of pictures because there are some parts that need to be explained in detail.







First off was to face the end of the bar, then turn down to the required diam of 3/4" for a length that I could use to get all three casing pieces out of, plus a little bit. It was then parted off.







I had to improvise this afternoon, I didn't have the strength in my fingers to mount up my RT, so instead I used my square 5c holding block instead, This will do the job admirably as I only want to drill a couple of cross holes.
Using the skinny back stop, the block was pushed back to it, vice tightened and the block tapped down onto a parallel. Using the edge finder the centre of the block was located. The finder was then used on the previously faced end of the bar and the drill chuck was located 5/16" in from the face. Using a centre drill and a 1/8" drill, a hole was put right thru the bar. The block was rotated in the vice by 90 deg., pushed back to the stop and was duly tapped down onto the para. Another 1/8" hole was drilled until it met the other cross drilling in the centre of the bar. 







A quick swap over to a 5/32" slot drill and a recess was formed to a depth of 1/8", This is the socket that the copper tube is going to be silver soldered into. The other two ends of holes were given the same treatment.







The collet and bar was then transferred back to the lathe for boring. 
You don't have to use a collet chuck, as long as your normal chuck is something like. I will be showing further in the post how to keep everything concentric if using a normal chuck.
A hole was drilled to a depth of 1" and the hole was gently bored to the required diameter of 3/8". A few unmoved settings cuts were carried out, just to make sure tool spring hasn't caused any problems. The reason I didn't cross drill afterwards was so that no burrs were left in the hole, by drilling first, they were automatically cleaned up by the boring process.







I used a piece of bar that was 0.001" under 3/8" diameter to check size. Once it was a close sliding fit, I knew it was near enough.
The faced end was marked up as a datum face, to inadvertently stop me taking any metal off it, and the piece was parted from the bar. It was reversed in the chuck and faced to perfect length.







The main block as far as can be done at the moment.







Back to the left over bit.
It was faced off and a spigot machined on the end, 1/16" high and a nice snug fit in the bored 3/8" hole. It was parted off leaving a bit of extra material for bringing back to correct thickness, This was put to one side until the next piece was finished, then the end was machined to give the required 1/8" thickness.







This is the bit that has to be machined in the correct sequence, otherwise, because of the very tight tolerance on the internal bits, if the concentricity is more than 0.001" out, you will be in deep doodoo.
The operation starteth.
Face off the end.
A spigot 3/8" high and 3/8" wide is machined on the end.
It is then parted off with about 1/4" thickness left for machining.







Now this is where everything is kept concentric.
The just machined spigot is mounted into the chuck, and the thickness of the flange is brought to 3/16" thick. From now on, the part will not be moved in the chuck until it is finished.
A 1/16" high spigot, with a nice tight fit in the bore is machined on the end.
A hole is drilled slightly undersized and followed down with a 5/32" reamer.







The recess for the sealing o-ring has now to be made.
I couldn't find my correct o-rings, so I winged it. I did have some silicon 1/8" bore by 1/16" cross section, 'that will do me' thinks I.
So I stretched it over the required 5/32" rod and measured what the ring ended up at. The measured OD of the ring on the rod was to be the OD of the recess, and the stretched cross section measurement, minus 0.004" compression allowance was the depth for the recess. This was duly made into the end of the piece. This will give slightly more drag, but it won't be noticeable.







This is what it looks like fitted.
Job done. 
All the necessary bits are concentric. The outside can take care of itself, it is what is on the inside that matters.







Three of the critical parts made.







This is the rough position it will sit in when mounted onto the engine.






This is a very good exercise in forwards planning. Write down the sequence of machining before starting, and you won't have any surprises.


I have arranged for my mate to come down in the morning and mount up the RT for me, so as long as he doesn't get too many beers down his neck tonight, I stand a chance of getting some more done tomorrow.

John


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## Bogstandard (Apr 7, 2008)

Got a little bit more done today, not a lot, but it was a very accurate day, so time had to be taken.


I won't bore you with reducing the stock from hex to round, but I will say one thing. This bit of scrap turned out to be a length of my stock ali bronze, but because it had been used as a knocking stick I didn't recognise it at first, but noticed as soon as I started cutting. One thing that it does do is heat up fairly quickly when machining, so because I was being very accurate today, I had to leave it to cool down before measuring, so the job took a lot longer.
I rough cut down to about 2 thou oversize, then very gradually brought it down to size, just so the outer casing was a push fit over it.
You might say that I have a lot of material sticking out of the chuck, but this had to be done to keep concentricity with the 5/32" diameter control rod. This was machined on the end without taking the material out of the chuck. BTW there was no detectable size difference between the end of the sticky out bit and the end near the chuck. That is how your machines should end up after years of tweaking. 







Here are the two bits on the end of the rod. I draped a bit of the swarf over it to show how this type of material cuts.







I didn't part it off as usual, I have learned from past mistakes with this stuff. I just rough marked it and cut it off on my bandsaw.
This shows the bits, just as my friend turned up to mount my rotary table, about seven hours late.
Just after this Giles and myself made first contact thru Skype. It is always nice to put a name to a face. But luckily for Giles my video wasn't showing on his screen. Nice flycutter Giles.







Back to the job in hand.
This outer case needs holes drilling lengthways down thru it, at 45 degrees offset from the cross drilled holes that were put in before.
So this is my secret weapon to achieve the setup. A bit of silver steel (drill rod) and a small piece of softwood. The steel really needs to be a fair fit in the cross holes.







The first thing I did was to set my RT to 315 degrees. You will see why later.







The rod was trapped in the cross holes by putting the piece of wood in as shown, not too tight, just enough to hold it, if you wack it in there, it is liable to put a curve in the rod.







This weird assembly was then mounted into the RT chuck, resting on a bit of HSS tool steel, to keep the rod above the tip of the jaws, and it was eyeballed along the rod to get it roughly in line with the table slots. The chuck was nipped up, and the DTI was set up as shown (I suppose you could use an edge finder, but i use my DTI for everything).
The table was moved to run the DTI along the rod, and the position of the piece was 'tweaked' in the jaws, until very little runout was detected along the length.







0.0005" over about 1.5" was close enough for me.
The RT was then rotated to the zero position. This put the part in the chuck with the required 45 degree separation from the cross holes.







Now was the time to centralise the RT to my drill chuck.
Because I had a nice concentric hole thru the piece, I decided to use that to save me some time. I mounted a rod just a tiny bit smaller than the bore into the drill chuck, and the table controls moved until the rod just went nicely into the hole.







By using the above trick, it put me within 0.002" of central, so it was time and energy saved all round.
The table was offset on the y axis by 9/32" (0.281", I memory serves me right) and the four holes were drilled thru the block.






Without moving any table settings, the two end plates had their four holes drilled in each.






Holes thru the main chamber tapped to size, and the whole lot assembled to check for fit.
Rather good.
If you don't blow your own trumpet, no one else will blow it for you.






The next job will be to finish off the inner spool and get a bit of silver soldering done. 
My man has been booked for tomorrow to remount the vice. Just hope he is on time.

John


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## Powder keg (Apr 7, 2008)

Looks great John!


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## Bogstandard (Apr 7, 2008)

Thanks for the compliment.

I forgot to mention in the post.

As you already know, I am making this in metric, but actually trying to describe it in imperial for our US cousins. I noticed that I have done a slight miscalculation, ever since making this part. If you go by the sketches I made, and drill the assembly holes with 1/8", even though it will work, you might be better using 3/32" instead, it gives a little more room for bolt head size. If you do use 1/8" you might have to turn the head down in diameter slightly.

John


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## Bogstandard (Apr 11, 2008)

This is the final and monster post on the build. The reason is that it is two posts joined together.
This part deals with the last bit, the control valve, and in fact is the only part on the engine that was made in imperial sizes but still using metric fasteners. One of the main reasons was that my pipework was imperial 5/32" (only a minute difference from metric 4mm) and I thought I may as well make this bit imperial as well, but it does show that parts can be made in different standards and still fit together easily. A clear case of not being perfect, but use what you have in stock and make it how you want.



So this is where I started off. The three parts of the outer casing were bolted together and an overall size obtained.
By going from the sketch, this should have measured 0.875", but I think it is close enough, even temperature or finger pressure can change what the reading is, so I measure three or four times, just to make sure I am within tolerance.







On this one, I faced off the end of the overlength, rough cut spool valve. leaving it about 0.025" overlength. Very gently deburred, mounted into the casing, and some screws put in to clamp it all together.







It was then remeasured to show me how far overlength it really was. This measurement showed that it was 0.026" longer than the inner cavity length.
A very fine facing cut was taken to give me an idea of accuracy, I removed 0.021" which if correct should leave me at 0.880".







This last measurement shows me that I am almost spot on, and now need to do a final cut of 0.007". This will take the spool to internal cylinder length with a 2 thou end float.
This was duly carried out, the o-ring fitted and the unit rebuilt with the spool inside.







This is the assembly. The spindle was turned and a slight drag from the o-ring was felt. Good enough for now.







It was taken apart, yet again, and the spool measured up accurately. A machining program was worked out to put the groove in the centre of the spool length, and to leave a land in the centre of the spool measuring 5/32" wide. This land is used to block the inlet port of 1/8" diameter, plus a dead area of 1/64" either side to make sure of very little internal leakage.







Normally I would have used my RT, but because my vice was fitted, I decided again to use my 5c square block with a back stop. An edge finder was used on the end, and the 1/8" milling cutter put spot on in the centre by using my little calculations.







The cutter was touched on, and the slot cut to the depth shown on my bit of paper.







Once one side was cut, the block was flipped over and repositioned against the back stop. The next slot was then cut. Very careful deburring was carried out, I needed the edges of the slot to remain very sharp to help prevent internal leakage. It doesn't matter about the internal finish of the slot because it is only a transfer port.







This is what the finished spool looks like before reassembly, yet another time.







This is the stage where the control valve and engine are first brought together. A few extra bits had to be made. The first one was a new reverse nozzle. This was because I had forgotten to allow for the mounting of the connection tube diameter, so I designed and made a new one to fit the bill. That is what comes of being a smart a##e and trying to plan too far ahead. The other piece was a small manifold to bring the forwards nozzles together to allow for running off one input tube.







A dry fit of all the machined bits was done, and trial and error tube bending and cutting carried out, and soon all the parts were in their final positions.
Now comes the almost tricky bit. Getting them all stuck together so that they make one big piece. So here comes the dreaded silver soldering.
I have no troubles at all making up assemblies like this. If you can follow how I do it, I can almost guarantee good results. But please try your own methods as you wish.







I made myself a small brazing hearth on my worktop. The pieces were cleaned by a quick rubover with scotchbrite in the areas to be joined. My Tenacity 4a flux was mixed with a few drops of water and a drop of washing up liquid to form a nice creamy paste. The flux was painted onto the cleaned areas, including down the holes, not a lot was used, just enough to coat the joining areas.
For 99% of my silver soldering needs, I use 0.5 mm diameter silverflo wire. Here, I wrapped it around the tubing I was using to form a tight spring shape. This was then snipped along the edge to give small circles of wire. On assembly of the parts, the wire was slipped over the assembled parts and pushed down into position at the joint line, as shown in this pic.







The blowtorch was directed onto the largest part of each assembly, not directly at the silver solder. As the brass parts warmed up the silver solder automatically melted and flowed into the joint thru capillary action. The solder and flux will always flow towards the heat. 
You can see from the picture, no big blobs of whatever anywhere, just nice clean fillets of silver solder. The heat was only applied for a few seconds, until the larger parts were just changing to a dull red colour. It all happens very quickly, one thing you should never do is put too much heat into the part.







The control valve was stripped down yet again. The just silver soldered bits were cleaned as before on the areas to be joined, and the assembly was put together, using the firebricks and other bits of metal to hold the assembly in the correct positions. As can be seen, the silver solder and flux was applied just as described before.







This picture shows perfectly where the flame was played onto the largest piece and the colour of that piece just as the solder began to flow, a couple of seconds later the flame was taken away. The part was left for a minute to cool down naturally, then quenched in a bucket of cold water.







This is the assembly just out of the clean cold water quench. It shows how the flux has penetrated and cleaned the necessary areas and the silver solder has flowed perfectly into the joints and formed nice clean fillets. If you look into the bore of the control valve you can see where the flux has penetrated thru. No silver solder was taken into the bore because there was just enough to make the joint, with no unnecessary solder to flow into areas of importance.
This was then dropped into a citric acid pickle bath for half an hour.







Out of the pickle, a quick wash in clean water and it was ready to be cleaned down. No files needed, just a quick wipe over with smooth scotchbrite.
It was then tried for fit on the engine, you have to be careful with assemblies like this. After having a fair amount of heat put into it, you will find that the metal is still rather soft because it is in its annealed state. You have to be careful you don't bend the pipes, as it will soon collapse into a flattened shape.
Because of the flux penetration into the spool cylinder, the spool and cylinder were given a quick lap together using T-Cut. After a good clean down, the final assembly of the control valve took place, and checked for operation. It worked perfectly, no internal or external leaks, and a nice control of pressure flow.
But it did need another bit to be made.







The control valve needed a nice snazzy handle, so I thought, one of my new glass slingshot marbles would make a real cool knob for the top.
So a quick grip in a collet, a bit of clean water for coolant, and the tungsten drill had a 2mm hole wacked into the back end of the marble in no time.







A tiny bit of mill and lathework, a quick threading job and some spit and polish, plus a tiny amount of loctite and the control handle was in position to be tried out.
Once everything had been tried out and found to be operating correctly, the engine was assembled with all the new parts, given a dose of oily rag and put out for a photoshoot.







Here is Butch the Invincible, ready to flex his muscles and charm the onlookers.







The Butch is leaving the building.






Is it really, really, honest and truthfully finished?


Not really. This little engine has a final purpose as a testbed, but that will have to wait for some time in the future when my time allows. The build on this engine has gone way over my time budget, and I am glad to get to this stage.

I do need to do some tacho and runup tests on it and make a vid for display on here. But due to my tacho being affected by fluorescent lighting, making it give spurious readings, all the runs need to be done outside. But no way am I doing it in the rain that has been coming down in bucketfulls all day. Maybe tomorrow.

Questions will now be answered, as I have a few answers ready, now that it is finished.

John


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## Kactiguy (Apr 11, 2008)

Beautiful work. It has been fun watching the build and I personally learned tons. Thanks for taking the time to show us all the steps.


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## cfellows (Apr 11, 2008)

You've been busy. Loved the book, can't wait for the movie!

Chuck


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## wareagle (Apr 11, 2008)

Excellent thread! I appreciate the time spent to take us along the journey. The video of this bad boy will be the icing on the proverbial cake. 

Bog, you are an inspiration!!! :bow:


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## Divided He ad (Apr 11, 2008)

Impressed would be an understatement!!! :bow:

Just two questions....

1) How were the inlet manifold pipes fixed into the aluminium body?

and 

2) Have you got the fanfare ready for the start of the vid' ? I think both yourself and Butch deserve one ;D (The beginning to 'jump around' by House of pain springs to mind!)



Ralph.


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## Bogstandard (Apr 11, 2008)

Thank you very much for your comments. I do hope that this does give inspiration to people to try something on their own.
This post wasn't done as an exercise to make one of these engines, but one could be made if you follow the basic instructions and ask a few questions.
It was to show, that with a little lateral thinking, mind numbing problems can be sorted fairly easily with just a few basic machining tools, bits you have about your workshop that you wouldn't have thought of using, and working out a sequence of machining. At times, a pencil is more powerful than a cutting tool.

If you look at the top of the main block, just above the fwds nozzles, you will notice two grub screw holes. There is one below the rev nozzle as well. They hold it all together.

I would also like to point out the reason I use stainless fasteners most of the time.
Three reasons, the first is they look nice, second is that they are almost as cheap as normal fasteners, and the third and most important, stainless screws like this, have a natural tendency to 'grab' into the material it is being tightened into, so I save a lot of time, effort and money not having to use Loctite to stop it falling apart.

No fanfare, but maybe a bit of 'Hell' by the Tiger Lillies.

I was going to call it 'Marvus Aurelius', but I didn't have enough rhinestones to put all that on the side. Maybe the next one.

John


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## mklotz (Apr 11, 2008)

Bogstandard  said:
			
		

> I was going to call it 'Marvus Aurelius', but I didn't have enough rhinestones to put all that on the side.



Then the music damn well better be something from Wagner. A selection from _Das Rhinegold_ would be appropriate since that's where rhinestones get their name (not to mention I suspect you are a bit of a Nibelung since you like shiny objects so well  )


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## Divided He ad (Apr 11, 2008)

Apologies John, Just went back on a read through, found it on page two ... figured it must have been here somewhere... It's been a while since I read that page!! 

'Hell'... cool tune (Interesting taste! :-\ ... sounds a bit like miss piggy to me!! Good lyrics though ;D )

Odly enough I watched 'Gladiator' this afternoon... The Ceaser in parody was in that! 
'Marcus Aurelius' Found some good quotes on my little net quest though... 
'Because a thing seems difficult for you, do not think it impossible for anyone to accomplish. ' 

You see you got me wondering what that was all about ...I think I was looking too deep!? (was it just about the bling fairies? ;D )


Now Marv just posted and I got more stuff to look up.... man this post is an education ??? (still got to do my maths homework too!! :big: )



Ralph.

(Maybe a bit of Richard Strauss from '2001'? :big: )


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## Bogstandard (Apr 11, 2008)

Marv,

I am a big softy really, Wagner is a bit harsh for me, I prefer Verdi.

Ralph,

The tune and trio was first brought to fame in the film Plunkett and Mclean. I have been following this one off trio for many years. If you want something a bit way out, that is what to go for. I think I have every track they have ever released.

It was a play on words - Marcus - Marvus, and Marv just loves rhinestones. He can't get enough of them, and would bathe in them if he could.
John


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## mklotz (Apr 11, 2008)

Bogstandard  said:
			
		

> Marv,
> 
> I am a big softy really, Wagner is a bit harsh for me, I prefer Verdi.
> 
> It was a play on words - Marcus - Marvus, and Marv just loves rhinestones. He can't get enough of them, and would bathe in them if he could.



Wagner harsh! Bite your tongue you philistine. 

I believe it was Mark Twain who coined the world's best left-handed compliment with his assessment, "Wagner's music is better than it sounds."

Oh, and I only bathe in American beer. It's the only thing to do with the vile stuff - it's undrinkable and too weak to remove paint or rust.


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## Bogstandard (Apr 11, 2008)

Marv,

What would the world be like if we all had the same taste in music, and who would choose it in the first place. Could you imagine everyone singing along to 'tiptoe through the tulips' by Tiny Tim (could he just be the Nibelung you mentioned, he would be the right size, going by his name).

Big John


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## Bogstandard (Apr 12, 2008)

At last, had a break in the weather, so I will tell you how it went.

My little compressor is starting to turn up its toes, after twenty years of continuous use, the poor thing is ready to be recycled. It is struggling to give me 30psi, even running continuously. So I couldn't get any meaningful readings from the tacho.

It gave a reading of 16,500 RPM with the compressor gasping for breath trying to keep up with the turbine. So until another is purchased, that will have to do.

But already I have data from this one major trial. Three rotors are not needed, two will be perfect. The weight of the rotor is fairly critical, if I can get it to half the weight, I think it will be ideal. The nozzles worked just as I expected, spot on, and the control valve worked faultlessly.

So all round, a good days running, and going from what I saw and heard, the speed should definitely be well above 30k RPM, just as predicted.

So out with the hankies to dry your eyes, as you say goodbye to this little motor. The music on the vid is a Welsh lullaby.

[ame]http://www.youtube.com/watch?v=1_Ey8v7fgig[/ame]

John


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## Powder keg (Apr 12, 2008)

Very good job John!!! That handle you made is cuter than a bug! And the exhaust works great! It inspired me to get working on my Tesla turbine a bit today)

Later, Wes


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## mklotz (Apr 12, 2008)

Absolutely fabulous, John. Outstanding! I'm green with envy.

Two questions...

I may have missed it in one of your original posts but is the final form of this engine intended for a model ship? If so, what sort of model? Will it be a model of the Turbina (I hope)? 

Is that Charlotte Church singing? I have most of her CDs and she's just fabulous.
The Welsh certainly have a knack for singing. Regardless, it's a great choice of music for the video (much better than Wagner).


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## rake60 (Apr 12, 2008)

Beautiful John! 

Rick


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## Bogstandard (Apr 12, 2008)

Thank you gents.

Just to answer Marv's questions.

I was asked by an American gentleman to build a pair of turbine engines to power a 10ft long destroyer model. I told him I would build a prototype to see if it was a viable proposition to power a model in this way. Hence what you are seeing is the test bed prototype.
I think you have the wrong gender Marv, she is in fact a he before his voice broke. I can't be positive, but I am almost sure it is a young Aled Jones of 'Snowman' fame. It was a track from the film 'Empire of the Sun', and yes, the Welsh have perfect voices for this sort of music, even when talking in their native language, they sound as though they are perfectly in tune.

John


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## wareagle (Apr 12, 2008)

Bog,

Very nice work! It is a shame the compressor was trying to lay down, but I would say you have a very successful prototype there even at 30 or so psi. The control valve is astonishing - very simple design, yet very effective.

The exhaust of the turbine is much quieter than I expected. The manifold and pipes do a great job of quieting it down it appears, and even on a rapid reverse.

The music on the video was fun. I thought it sounded like a track from Empire of the Sun when I watched it and you confirmed that with your post above. Haven't seen that movie in years, but it had an amazing sound track. Great choice and a nice video intro as well.

Once again, thanks for taking all of us along for the build. I am sure that every person watching the "show" has picked up something to help them out in the future. I know I certainly did! And that's not possible unless someone takes the time to document, picture, and post the project through all phases as you have done here. 

So here's a big warm :bow: for all of your efforts!


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## Divided He ad (Apr 12, 2008)

:bow: :bow: :bow: .... Now that's a video with style!! and a damn good choice of tune ;D

Congratulations John on a fantastic job well done. This whole post has sent my brain into overdrive wanting to borrow your ideas and add a few of my own... Thank you very much.

Now all I got to do is get my lathe fixed and finish what I already started, then I really got to try to do one of these!! ;D 


Ralph.


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## Bogstandard (Apr 13, 2008)

Thank you all again for the inspirational comments. In an upper crust voice 'One has to do ones best, you know'.

Ralph,

If you want to try a basic turbine, I built one before on here, and gave me the insight to build this one.

http://www.homemodelenginemachinist.com/index.php?topic=244.0

Much easier and quicker to make, that one only took three of my days.

No speed control, and it goes like stink.

John


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## Divided He ad (Apr 13, 2008)

Thank you John, I have just read through it and will use the information from both and see what I can come up with.  ;D (think I'll avoid Tattoomike's approach though!  )

I've been ill and housebound since Tuesday and the first time I tried to get back out into the shop Saturday afternoon the main drive belt snapped on my lathe. 
So when I finally get that sorted I'm going to start on my treadle engine again... I will finish this one before I start another!! 



Ralph.


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