# An experimental V-4 wobbler



## spuddevans (May 9, 2011)

Some time ago I started designing a little V4 wobbler in Alibre and made a 3d rendering in pdf format to give some idea what I hope it will look like when built.

Click here for interactive pdf rendering

Anyway, over the last few days I have been finalising some of the details and also printing out some plans, and today I have made a little start on this little engine.

The design is to have a V4 configuration, 8mm bore 12-14mm stroke (cant remember which ??? ), double acting wobbler.


I hope to keep a good record of the build with plenty of pics of all the processes, cos I know you all like pics  th_wwp Rof}

Actually, today's progress is pretty boring, just some sizing of stock.


Normally, as many other builders, I would have liked to have started on the most complicated part 1st, which on this build is the main frame, but I am awaiting the arrival of some materials for the frame, so I made a start on the cylinders.

I started by putting the ER32 chuck on the lathe, and gripped a length of 20mm round brass bar in it, squaring the end up, then using my patent-pending method of marking up, I traced a mark at 21.5mm from the end.











I then used a thin parting tool to put a cut in at the mark to a depth of around 3-4mm, it's not important what depth, just so long as it is deep enough to be still there when I reduce the bar down to 16mm.






Then I swapped over to a 6mm round profiling tool ( as recommended by Bogs ages ago, and well worth getting ) and reduced to required size, just needing a quick swipe with some emery to clean up.







Then I swapped back to the parting tool and finished parting off. Then loosen the chuck, extend the bar out a little more, tighten, mark up and measure off another 21.5mm, make the initial parting cut, reduce to 16mm, part off and repeat another 2 times, or perhaps 3 times to give you a spare. (as I did knowing that it will be needed  :big: )







The reason for making the initial shallow cut with the parting tool was just to give me an indication of how far to reduce the diameter of the 20mm brass bar to each time, and to therefore hopefully stop me from trying to cut too long a section down to 16mm. You might have a firm enough lathe to turn down much longer sections, but on my (as yet, completely unmodified, straight out of the box condition) rubber lathe, I have learnt to keep the minimum stock sticking out of the chuck when trying to keep to dimension, and so the visual reminder that putting on a partial parting cut gives is a helpful reminder to me to only turn down one piece at a time. Plus the parting tool is already in the QC changer from parting off the previous blank, so it only takes a moment to do.


These cylinders are not totally straightforward in themselves, as, just to be difficult, I have designed the bore to be offset by 1mm from the center of the cylinder blank, so I spent the rest of my time in the workshop figuring out just how I am going to machine all the features and also in what sequence to machine it, and of course, how to hold it for machining.

Next up will be machining all the cylinder blanks to the same length (hopefully 20mm), and then machining a pivot on the side of each cylinder before boring out the bore  

Anyway, that is as far as I got today, more updates to follow.


Tim


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## John Rudd (May 9, 2011)

These cylinders are not totally straightforward in themselves, as, just to be difficult, I have designed the bore to be offset by 1mm from the center of the cylinder blank, so I spent the rest of my time in the workshop figuring out just how I am going to machine all the features and also in what sequence to machine it, and of course, how to hold it for machining.


Tim,
Hope I'm not teaching granny etc.....

You could offset bore the cylinders in the lathe by using a 3jaw chuck with a suitable packing piece in one jaw....

Or you could use a 4jaw with the jaws suitably offset....

Good luck with the build....


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## spuddevans (May 9, 2011)

John Rudd  said:
			
		

> Tim,
> Hope I'm not teaching granny etc.....
> 
> You could offset bore the cylinders in the lathe by using a 3jaw chuck with a suitable packing piece in one jaw....
> ...



Believe me, I appreciate any and all advice and wisdom offered :bow: Thank you :bow:

I had forgotten about using a packing piece in the 3jaw, I am intending to bore out the cylinder bores on the mill, so no problem with the offset, plus with the cnc conversion I can get a nice slow powered feed to give a nice finish on the bore using a boring head to bring to the final 8mm diameter. I plan to drill it to about 7.5mm and then have the boring head set up for 8mm and then use the CNC to make a few passes at a slow steady feed to eliminate springing.


The slightly more challenging part of the cylinders is the means that the cylinders will attach to the frame and how they pivot. 

Normally, wobblers use a spring to hold the cylinder in place. On this wobbler I intend to use rare-earth magnets that are glued into recesses in both the frame and the cylinder. It is the recess and the means of pivoting that is a little more challenging, for me anyway ;D

It's kinda hard to explain, but the next time I'm working on this I will be machining these parts, so all should become clearer. (or I will be posting up about how I am re-designing it all  :big: :big: :big: )


Tim


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## T70MkIII (May 9, 2011)

Looks like a very interesting design, Tim. Can't wait to see your progress.


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## bearcar1 (May 9, 2011)

I'm intrigued by your method of cylinder retention Tim. Your design has a pleasant appearance to it, although I must admit that the 'batwing' base looks to be a challenge.

BC1
Jim


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## spuddevans (May 10, 2011)

bearcar1  said:
			
		

> I must admit that the 'batwing' base looks to be a challenge.



The lower part of the frame, ie the legs, should (he says hopefully) be fairly simple to machine. It is just made of 2 radiuses, radiai, radii, Curves :big:


I got another couple of hours in the playroom workshop today, and started by mounting my new vice onto the mill, and then clocked it square with a dti, I didnt go crazy, but just got it down to +/- 0.05mm  ;D






I then mounted all 4 cylinder blanks on some parallels and with two pieces of ali at the front and back to compensate for the minor differences of thickness on each cylinder. If you dont put some soft material between the jaws and the workpieces then the slight differences will cause the multiple pieces to not all be gripped the same, which is perfectly fine unless you actually want to machine any of them. The Ali not only protects the brass from the steel vice jaws, but also will squish a little to compensate for the minor differences. 

Anyway, I then I worked back and forth with a flycutter to get all 4 to the same length, 20mm.






I then turned the cylinders on their sides, gripped them in the same manner, and made a few more passes with the flycutter. Here's a shot after I cut the flat down until the required thickness ( 14mm ). Others might prefer to switch to an endmill to get the bulk removed, but as there was only 2mm to remove, and on brass I am able to take 0.25mm depth of cuts with this flycutter, it was quicker to keep using the flycutter. Plus it leaves a lovely silky smooth finish. Don't let the curved lines fool you, they cannot be felt by my fingernail.







Not having a lot of time left I started to set up for the next machining processes. The next thing will be to bore out a 2mm deep, 10mm diameter recess in the center of the flat section, and I will probably drill the inlet/exhaust holes at the same time. Because this has to be done on all 4, I'm going to use my sophisticated vice stop system shown below.






And for making sure that the cylinder flat is positioned true and flat I use another patent-pending system...






It wasnt until I had released the vice after flycutting all the flat sections that I realised that I should have kept them in place and just drilled and bored all the relevant holes using my edge finder on each cylinder and then moving to the right coord's for the holes :wall: :wall: :wall: :wall:


Oh well, you live and learn.

So next will be a boring post ( oh come come! this post has been pretty boring anyway  Rof} Rof} ) and then some silver soldering.


Tim


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## spuddevans (May 14, 2011)

I've made a little more progress on the cylinders.

According to my plans I have to drill the 2 inlet/outlet holes, and also a central 10mm diameter hole. The small inlet holes pose no problem, but the 10mm diameter hole is a little more tricky for me as I found that I do not have a 10mm endmill, and this hole must be flat bottomed. (wasnt that a queen song, "flat bottomed something-or-other" :lol: )

I could've made a 10mm D-bit, but I figured out another way. I do have a 3/8" endmill which is 9.51mm approx in new money, and I also have a boring head that I can set to 10mm.

So here are my tools for this task,






Center drilling the holes,






Boring out the majority with the endmill,






Drilling the 1.5mm steam passages,






Then I swopped the ER32 chuck and mounted the boring head in the mill and then bored out to 10mm, I left the boring head locked at the needed diameter.







Repeat the above steps another 3 times, til you have this.






Then I turned the cylinder upright in order to bore out the bore 

Using my expensive vice-stop to position the cylinders to make a little production line, first up after centering up was center drilling all 4 cylinders,






Then following through with drills up to 7.8mm,






Then I reamed all 4 out to 8mm, I was going to bore them with my boring head but I realised I didnt have a slim enough boring bar for it ( something for the shopping list )






Next I turned up 4 little rings of brass, 10mm OD, 8.1mm ID x 3.5mm depth.






And this is where they fit,






And here are the pieces all together with 4 8mm x 2mm neo' magnets sitting in place.






The magnets will be epoxied in place, and I am considering leaving the rings unfixed, they will fit into corresponding 10mm recesses in the main frame, and the magnetic attraction should keep them all in place.


While I have the vice stop set up, I will probably next drill the 4 holes on each end of the cylinders for fixing the endcaps or glands, then that should be all the cylinder machining operations done.


All that and maybe more (or less) on next weeks show.....



Tim


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## Brian Rupnow (May 14, 2011)

Very cool idea with the rare earth magnets. I will be interested to see how this works.---Brian


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## spuddevans (May 14, 2011)

Brian Rupnow  said:
			
		

> Very cool idea with the rare earth magnets. I will be interested to see how this works.---Brian



Thanks Brian Thm:

You're not the only one, I'm pretty keen to see just how this turns out :big: :big:

Actually, doing some rough experimentation with the 8mm dia magnets this afternoon, I am a little concerned that they will provide too much of a pull, thereby creating too much friction. But I am building in some adjustability to the frame, instead of using a magnet on the frame as well, I intend to use a little disc of steel, and I can vary the size of the disc to suit the magnetism needed.


Tim


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## bearcar1 (May 14, 2011)

Hello Tim, nice concept engine. To solve your friction problem, would a thin washer of Teflon between the magnets help reduce the drag of the metal on metal you are experiencing with using two magnets back-to-back. I rather fancy the idea of the two as opposed to one attracting an unmagnetized piece of steel. Teflon sheets can purchased in supet thin sheets from McMaster Carr. It's a concept that will be interesting to see how it unfolds. Thm:

BC1
Jim


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## spuddevans (May 15, 2011)

bearcar1  said:
			
		

> Hello Tim, nice concept engine. To solve your friction problem, would a thin washer of Teflon between the magnets help reduce the drag of the metal on metal you are experiencing with using two magnets back-to-back. I rather fancy the idea of the two as opposed to one attracting an unmagnetized piece of steel. Teflon sheets can purchased in supet thin sheets from McMaster Carr. It's a concept that will be interesting to see how it unfolds. Thm:
> 
> BC1
> Jim



Thanks Jim, I have got some teflon sheet, but my plan is to have a small gap between the magnet in the cylinder and the steel disc, probably about 0.15mm-0.3mm. The friction I was mentioning was the friction between the cylinder port face (the flat face) and the face of the frame. 

I made a Elmers #25 wobbler ages ago, it runs really sweetly, and I used a spring to hold the cylinder to the frame, comparing the pressure needed to pull the cylinder off the frame, and the pressure needed to pull two magnets apart, I had great difficulty pulling the magnets apart, and even pulling the magnets of the end of a 8mm steel rod was greater than pulling the cylinder off the face of my wobbler.

I do remember that when setting the tension on the spring on the wobbler, when it was too tight it really slowed down or even stopped it from running. Hence my thoughts about using a steel disc in the frame that would be replaceable with alternative sizes to "adjust" the pull of the magnets if needed.


Tim


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## spuddevans (May 16, 2011)

I got a little more done today, namely the drilling and tapping the 32 holes in the cylinders for the packing glands and endcaps.

Having a DRO with a bolt hole function does make the drilling a lot easier, combine that with a vice-stop for repeatable workpiece positioning makes for a relatively easy time.

I got a little carried away with that and forgot to take any in-progress shots of the drilling, Oops :doh:


Then I mounted all 4 cylinders in a vice placed on my tapping stand, and I was really glad to have it. Tapping 32 holes with both M2 taps ( 2nd and bottom ) by hand would've been a nightmare.






As it was, I was able to tap a hole every 20secs, which I thought wasnt to bad. But after tapping 16 holes on the top, then turning them all over and tapping the bottom 16, I started to think if there could be a way to speed the process up a little.

One thing I noticed was that withdrawing the tap seemed to take longer and caused more ache in my arm. Then inspiration hit ( or perhaps it was a particularly bad case of wind  :big: ) and brandishing a hacksaw I made this little mod to my tapping stand.






Then I put a slot screwdriver bit in my cordless drill and selected reverse. Then I would wind the tap into the hole until it reached full depth (just before the squeek) backed it out a quarter turn, then it was just a case of slotting the screwgun onto the newly made slot and 2secs later the tap was out, much easier on the arm!!


So at the end of that I have 4 (hopefully) finished cylinders.





Then I had to retire back to the pc to redo some of my plans to adjust some dimentions on the main frame.


Tim


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## spuddevans (May 17, 2011)

I got a little more progress today, not much to show, just some preperation work really.


I started off by making a little angle plate, this is needed for milling and drilling the internal steam passages in the "V" section. I have got some angled parallels (now there's a funny thing), but I didnt want to stack up 8 of them to make 45 degrees !!!

So I marked up a scrap of 10mm ali plate and rough cut it on the bandsaw, then mounted it on the mill table using a V-block to align it for finishing it.

I 1st up aligned the V-block,




this is taken before milling, and yes I did notice that one edge is not fully fitted into the V-block, I adjusted it and re-tightened it before milling.





Here's the result. I know that it is a little rough looking, but it will do just fine, it will only be used 2 or 4 times, and each time will only be for aligning the frame in the vice, the angle itself will have no pressure applied to it.





Then I turned to preparing the Ali for the main frame. I cut off a piece of 1/2" thick Ali' in the bandsaw, then cleaned up and squared the 4 edges. This just left the front and rear faces to clean up and bring to 12mm. My present flycutter has about a 30mm sweep, so it was not enough for this, so I sharpened up a new piece of hss and mounted it in the larger flycutter ( I have a set of 3 flycutters, up til this point I have only used the mid-sized one )

Tooling ready I took a couple of shallow cuts off each side (0.25mm doc), then checking with mic I reduced the thickness to 12mm. The last pass took off 0.1mm and left a really reflective finish.





Then I spent a while marking out the positions for all the holes to be drilled in the face.






Next time things should get a little more interesting, I will be drilling all the thru holes and then boring on each face the 10mm bore's that the cylinders pivot on, plus some bores for the crankshaft ballraces, then will be drilling the long internal air/steam passages (longest is 46mm)


Tim


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## maverick (May 17, 2011)

That little 45 degree angle block is very handy, don't be to sure you'll only use it 2 or 4 times. I've got 2 or 3 of various size
that are just the ticket every once in a while. Great looking engine also.

Regards,
Mike


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## spuddevans (May 21, 2011)

Thanks Mike, you're probably right, I'll find many more uses for the 45deg angle.


I've got a little more progress made of the frame.

I mounted the frame in the vice on the mill on some parallels and then using an edge-finder I zeroed on the bottom of the frame (actually I zeroed off the jaw of the vice) and then zeroed off one side of the frame blank. I then moved in to the center of the frame and zeroed there. This is because of the way I have marked the dimensions on the plans, working from the center of the frame rather than from one edge.

Then I put a little center drill ( I really must get some proper spotting drills ) in the chuck and center drilled all the holes using the coords off my plans.






Then I set about drilling all the thru holes, and all was going well until a little "plink" sound. Grrrrr, I broke a 1.5mm drill halfway thru leaving a small segment of drlllbit stuck fast. :wall: :wall:








I finished off drilling the rest of the thru holes with a fresh bit, and bored out the larger blind bores for the cylinder pivots and for the ball-races for the crankshaft. Then I turned the blank over and bored out the larger blind bores on that side, then very carefully drilled the failed 1.5mm hole from the other side until I heard and felt the drillbit start to catch the stuck fragment.

I then spent an hour or more digging it out using various methods with not much success until I tried using a pointed V carbide burr. I then very gradually fed the burr into the stuck drillbit until I had bored most of the way through the stuck bit, then I took the remainder of the broken drillbit, ground the broken end flat and then I applied a little persuasion with a hammer and the stuck bit popped right out.


Then I took a couple of pieces of 6mm steel rod for the next step.






These 6mm rods fit into the blind bores for the ballraces, and are used along with the 45degree angle I made earlier to mount the frame vertically in the mill vice as shown, the two HSS lathe bits are there to raise the frame up enough to allow me to get the right angle






Then (once the vice was tightened up) I touched off the 6mm rod with a 16mm endmill, zeroed the DRO and then raised up the Z-axis by 38.87mm (according to my plans the distance from the center of the crankshaft to this edge of the frame is 41.87mm, subtract half of the 6mm rod brings you to 38.87mm) and zeroed again.






Then it was just a case of raising the cutter up and then nibbling my way back down to zero. Then I loosened the vice, rotate the frame and align using the 45degree angle and tighten the vice. Then nibble away the 2nd corner.






I did think about shaping more of these upper arms while having it in this position, but I have some long holes to drill, and want to do that before spending any more efforts, just in case I totally mess up the long boring. The shaping of the outsides of these arms are not critical, so the shaping can wait til later.


Next up will be boring these 4 long steam passages between 38-46mm approx deep, then if nothing snaps or gets stuck, I will be shaping the outer edges of the frame.


One handy tip I have learnt from snapping the 1.5mm drillbit, when I started using the new bit I began rubbing a pencil up the flutes. This seemed to stop the ali welding itself into the flutes, and I re-applied the pencil a couple more times per 12mm deep hole, this seemed to work really well, good old carbon lubrication.


Tim


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## spuddevans (May 22, 2011)

It's amazing just how things go, when I was designing this engine, the part that puckered my cheeks the most was thinking about drilling the long narrow internal air/steam passages, close to 50mm long with just a 2.2mm bit, drilled into Ali' which I know from experience just loves to gum up a drillbit, break it and weld the broken bit deep in the workpiece.

But what do you know, the deep drilling went without a hitch, no breakages, no gumming up, and no breaking through where it shouldnt.

Here's a picture when I'd drilled the last of the 4 deep holes, and I've drawn on it to show where the internal passages meet. Because the passages are offset from each other the passage on the front (green) is not connected to the rear passage (purple) (I just know someone is going to make a joke about that !!! Get your minds out of the sewer and into the gutter with the rest of us  :big: )

I drilled the first 30mm of each hole with a 2.5mm drill, then finished the hole off with a 2.2mm bit. The reason was not only for ensuring the bit wouldnt break, but also made sure that these long holes would break through into the 1.5mm cross drilled cylinder ports. Then by switching to a slightly smaller bit gives a little more room for error on drilling without breaking into the central crankshaft bore.











Then I moved the frame into a vice on the tapping stand to tap the central hole on each arm M2, this is for attaching a cap to cover and seal the ends of the long internal steam passages.






Once that was done I couldn't resist fitting the cylinders and pivot rings to see how it looks. 










Next I will be making some steel inserts to fit into the 10mm pivot bores in the frame to give the magnets something to pull onto. There will probably be some experimentation with the sizing of the steel inserts to get the appropriate "pull force". Then I will be moving back to the cylinders, or rather, to the end caps and packing glands and pistons.


Tim


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## bearcar1 (May 22, 2011)

Tim, I can only imagine your relief of having gotten over the deep drilling without incident, way to go. It is always a pleasure to get over the anxieties that we drum up in our minds over some step or procedure, only to find it to be a piece of cake and all of the worrying was for nothing. You know, I'd be willing to send you a proper pencil sharpener if you wished. :big: I'm anxious to see how your magnet attachment method works out, so far a terrific looking engine. Do you have a plan "B" in mind just in case your original idea doesn't work out as well as hoped? 

BC1
Jim


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## spuddevans (May 22, 2011)

bearcar1  said:
			
		

> You know, I'd be willing to send you a proper pencil sharpener if you wished. :big:



 :big: :big: 

I was going to tell you that I had been chewing on the wrong end of the pencil while drilling the deep holes, but the truth is that I was using it to rub in the flutes of the drillbits to prevent the ali welding to the drill. It worked too, absolutely no problems with ali sticking in the flutes.



> I'm anxious to see how your magnet attachment method works out, so far a terrific looking engine. Do you have a plan "B" in mind just in case your original idea doesn't work out as well as hoped?



I'm anxious too :big: 


A plan "B" scratch.gif  Hmmmm! I dont really have a plan B, just from the initial testing of the magnets, I cant forsee there being not enough "pull", if anything there was way too much pull using 2 magnets attracting to each other, that's why I'm going to try using a steel insert in the frame, then I can vary the diameter of the insert to adjust the "pull" factor.


Tim


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## ChrisB (May 23, 2011)

A really great thread Tim,

Wonderful to see some really nice pics to go along with the great explinations too. A really very interesting looking engine. Looking forward to seeing more progress soon.

Chris


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## spuddevans (May 23, 2011)

Thanks Chris,


I got started on the Endcaps today, and started by chucking some 20mm brass bar in the lathe, and then turning down a section to 13.8mm (the OD of the endcaps) and then turned a tiny 8mm spigot (to fit the cylinder bore). Then I marked up the bar to show a 1.5mm line.






Then I parted off at the line, then repeated 3 more times.

Then I had to clean up the little pip left on from parting, my plan is to mount them into a 14mm ER32 collet and then skim off about 0.1mm off the face. However, as I have tried to chuck up thin items before in my ER32 chuck and have found that without something the same diameter in the rear of the collet, when you tighten the collet up it tends to pull out of true, so I just used one of the endcaps in the other end,






Then I used a plastic handle to "nudge" the endcap into alignment while the collet is only hand tightened with the lathe rotating slowly, then stop the lathe and tighten up.






All four,






Then I took the ER32 collet off the lathe and mounted it on the mill, and drilled the mounting holes.






Then after drilling all 4 holes in the endcaps I couldnt resist mounting one on a cylinder.






Next up will be the packing glands.


Tim


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## bezalel2000 (May 24, 2011)

Nice design Tim
and good drilin 
Just wondering - given that your now some what of a "expert"  :bow: in deep holes, would it have been more expedient to drill the holes before you parted them off?

or all 8 ends for that matter
skewing in the collet would probably be less of an issue doing it that way. :-\

Bez


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## spuddevans (May 24, 2011)

Thanks Bez



			
				bezalel2000  said:
			
		

> would it have been more expedient to drill the holes before you parted them off?
> 
> or all 8 ends for that matter
> skewing in the collet would probably be less of an issue doing it that way. :-\



I did think of drilling before parting off, but these mounting holes are very close to the edge, and any deflection at all could result in breaking through the edge, so I decided to take the route of a little more trouble to ensure no breakouts.


Tim


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## spuddevans (May 31, 2011)

Just a brief update, I found a couple of hours in the 'shop and made a start on the packing glands, or rather, the gland nuts.

I was intending making direct copies of the packing glands as designed by Bog's in the paddleducks build, but as these are quite a bit smaller I had to reconsider.

Therefore I came up with an experimental design ( at least I think it is experimental, I havent seen in used on other builds. Time will tell if there is a very good reason for that :big: )

But just like in the paddleducks plans, I am making the nuts 1st so that they can be mounted on the packing glands for theu drilling to ensure concentricity.


So I started out with some 8mm brass hex in the 3jaw






Then used the round profile tool to form a profile on one end, then centre drilled






Drilled to a depth of 3-3.5mm






Then tapped M4, I had to grind the tips off the taps, you can see an unground tap in the background.






Then part off and repeat 3 more times. 

I then spent the rest of the time I had figuring out how I was going to turn the packing gland. I did make just one, just to see how and if I could make it. And just to tease you here's a pic of it with the other nuts.






These packing glands are of an inverted thread design, ie the exterior thread is on the gland, the interior on the nut. I reaslise that this is not standard, and am half expecting that it will not work quite as well as the more standard version. I have very little room for anything else on this engine, plus I expect this engine will be operating on fairly low pressure (about 5-10 psi once ran in) and so should run ok even without any stuffing in the packing glands.


Next time I will show how I turned the glands (or at least the 3 remaining ones :big: )


Tim


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## spuddevans (Jun 1, 2011)

On to the rest of the Packing glands.

I chucked some 20mm brass bar and reduced a section to 13.8mm ( the required od ) and then reduced a 0.5mm bit to fit the bore on the cylinders (about 8mm)






Then I swapped over for a parting tool and turned a 4mm long section down to 4mm diameter.






Then after parting it off and making the others, I mounted a 14mm collet and reversed the glands in the chuck, then using a tailstock die holder I threaded the 4mm diameter spigot M4 as far as I could get, and then centre drilled the end to form the "V" for the packing.






Then screw on the packing nut made earlier and centre drill it







Follow up with a 2mm drill bit and drill thru both the nut and the packing gland (carefully pecking to prevent drill snappage) and make sure that you keep each nut paired with the gland.

And here all 4 are,






I then unbolted the ER32 chuck from the lathe and gripped it in the mill vice to drill the 4 mounting holes.






And here is the obligitory posed shot with a cylinder (complete with magnet epoxied in place)






Next up will be the pistons and con-rods, crank webs and crankshafts.


Tim


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## bearcar1 (Jun 1, 2011)

Thanks for sharing your 'travels' with us Tim, I like journeys like this.

BC1
Jim


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## spuddevans (Jun 2, 2011)

bearcar1  said:
			
		

> Thanks for sharing your 'travels' with us Tim, I like journeys like this.
> 
> BC1
> Jim



Well thank you for coming along on the journey. I am really enjoying this build, snd hopefully I will have a nice running engine at the end of it.


Tim


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## steamer (Jun 2, 2011)

Nothing wrong with that packing nut. A certain 75 HP steamboat I used to run periodically had packing nuts just like it....a bit bigger :

Dave


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## spuddevans (Jun 2, 2011)

steamer  said:
			
		

> Nothing wrong with that packing nut. A certain 75 HP steamboat I used to run periodically had packing nuts just like it....a bit bigger :
> 
> Dave



Thanks for telling me that Dave, I know that I am relatively new to steam engines and their design, but I had not previously come across this sort of packing nut, I was a little concerned whether it would be ok. But now you've told me that I have a little more hope that it will work ( as long as I've made it ok :big: )


Tim


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## spuddevans (Jun 13, 2011)

At the past weekend I managed to get a little time to play, erm work done.  :big: :big: Just a small update this time, hopefully get more done next time.


I started with some brass bar that was a bit oversize, and then drilled a 1.7mm hole in the center, to as deep a depth as I dare.






Then I blacked up the brass bar, marked off a 5.5mm length, and then tapped the hole M2 for the conrod.






Then part off at the previously marked line, and repeat the tapping, marking and parting off until you have 4. Then I cut 4 lengths of 2mm stainless steel for the conrods.






Then mount the 2mm rods in the lathe to thread each end M2. I put a little spot of tapping lube on the tip of the stainless rod ( after putting a little chamfer on the rod with a file ) and then threaded it with my tailstock die-holder.






Then I cleaned the threads, added a drop of locktite and then assembled the conrods to the pistons.






Next will be bringing the pistons down to final size to match the cylinders, and then starting on the crank-webs and crankshafts.


Tim


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## spuddevans (Jun 15, 2011)

On to truing up and matching the pistons to the cylinders.

I started by mounting a piston-conrod assembly in the ER32 Chuck, but with a couple of washers to space it out from the chuck.






Then I cleaned up the end of the piston and reduced it until it was about 0.1mm oversize, then I put 2 oil-grooves in using the edge of a half-round file, just held by hand to create a shallow groove. ( very important note, any files being used on the lathe MUST have handles installed ) Then I reduced the diameter until the piston just begins to fit into the cylinder bore. ( I was advancing the cross-slide by 0.01mm each pass ) then I used some 800grit wet&dry to just polish the piston until it fitted snugly in the bore.






Repeat that another 3 times and there you go, 





as each piston is matched to a cylinder, I now will try to keep them paired up, each in their own compartment.


It looks like I will have to shorten the conrods a bit, I have another part to make that will screw onto the conrod end that links to the crankpins. So until I have those parts made, and the crankshaft assembly too, the shortening will have to wait.


In view of that I thought I would make a start on the crankwebs. I chucked a piece of 20mm brass into the lathe.






Then I was rudely interrupted by my better half returning home, and so I had to go inside for some lunch. ( just think of all the things we could get done if we didnt have to eat. Would save a fortune too  :big: ) So the rest of the crankwebs will be for the next update.


Tim


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## ShedBoy (Jun 15, 2011)

This engine is gong to look great Tim. Love the build pics

Brock


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## spuddevans (Jun 25, 2011)

ShedBoy  said:
			
		

> This engine is gong to look great Tim. Love the build pics
> 
> Brock



Thanks very much Brock 


I've been itching to get back into the workshop for over a week now, but I believe that you can get tablets from the doctors to help with that :big: :big:

I also must give credit for the design and machining order of the crankdiscs to John (Bogs) :bow: :bow: as it is pretty much an exact copy from John's Paddleducks plans, just made a little smaller.

I got a couple of hours more in the workshop today, and carried on from where I left off in the previous post.

I reduced the brass bar down to 15mm diameter.






Then parted off four 4mm thick discs.






Then I chucked each of them in a 15mm er32 chuck and drilled a 3mm hole in the centre.





I could've just drilled them all before parting off, but the drill could well have deflected during the 25mm depth, and I really wanted to make sure that the holes would be central, so I drilled them all separately.


Then I made up a little jig to hold the crankdisc blanks in order to drill the crankpin holes all in exactly the same distance from the crankshaft centre.






It has to be the easiest jig to make, just drill a 2.9mm hole, press a short length of 3mm rod into the hole, then move the mill table over by 6mm ( half the stroke length ) and lock it in place. Then pop a crankdisc on it and then drill it with a 2mm bit.






Do that 3 more times, and then it is on to machining them into somewhat balanced cranks. I put a 3mm drillbit into the central holes and a 2mm rod into the 2mm holes :doh: then using some 0.5mm shims ( some feeler gauges ) to bring the 2mm rod up a tad. Press the whole lot down onto the vice and tighten.






Then I let loose with a 14mm endmill and nibbled down to what seemed to look ok, zeroing the DRO at the bottom cut. Then turn over and repeat.






Then it was a case of removing any burrs raised, then it was on to cutting the compression slot, this is done on each crankdisc individually, so I used a vice stop. Using the same shims and 3mm and 2mm rods to align before clamping. Then I aligned the slitting saw by eye.






Then I removed the rods and slitted the slot.







Stay tuned for more updates.


Tim


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## spuddevans (Jun 26, 2011)

Got the crankwebs finished off today, not that there was much to do  :big:

I started by drilling and tapping the hole for the tightening screw. Then I took some 4mm stainless rod and turned a section down to 3mm to use for the central part of the crankshaft that goes through the main frame, and a section of 2mm stainless rod for the crankpin.

Then I couldnt resist assembling some bit together, and came up with this,











Next up will be the little "L" shaped pieces to connect the conrods to the crankpins. Then a little final modifying of the length of the conrods. Then the outer frames and connecting pieces. Then just a few hundred more operations and it'll be all done  :big: :big:


Tim


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## Ken I (Jul 25, 2011)

Tim, I see you haven't posted in a couple of months - how's this project coming along.

Inspired by your magnet idea - I've also gone and designed a V4 Wobbler.

I introduced a stagger between the opposite side banks to get the big ends to the crank. I can't see any way around it - yours are in line ?

I used the magnet in the mount attracting the trunnion boss - so I can adjust the clamping force with the clearance between the boss and the magnet - the magnet is a press fit.

Regards,
      Ken


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## spuddevans (Jul 25, 2011)

Ken I  said:
			
		

> Tim, I see you haven't posted in a couple of months - how's this project coming along.



wow!! has it been that long. ???

I haven't had a chance to get on with this build, been working on my house, painting and other such boring stuff :big:



> Inspired by your magnet idea - I've also gone and designed a V4 Wobbler.



Excellent, is there a thread on here documenting/showing it? I'd love to see it.



> I introduced a stagger between the opposite side banks to get the big ends to the crank. I can't see any way around it - yours are in line ?



I have to admit that I am not quite up to speed on all the proper terms, but I think that I know what you are talking about.

On my frame, both sides are identical so that the steam ports are drilled right through from side to side.

I haven't made any more progress on the parts that connect the piston to the crank-pin yet ( are they the Big ends? ), but I envisage a part that kinda looks like a "L" with the bottom of the "L" attaching to the piston, and a hole in the upright of the "L" that the crank-pin fits through. Then with the offset created by that piece, that means I can use the same piece but reversed to fit both pistons on each side onto the crank-pin. ( clear as mud, eh!! )




> I used the magnet in the mount attracting the trunnion boss - so I can adjust the clamping force with the clearance between the boss and the magnet - the magnet is a press fit.
> 
> Regards,
> Ken



Are you worried that the magnet may work loose from a press fit? 


Tim


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## Ken I (Jul 25, 2011)

I'm not worried about the magnet working loose - the forces applied are so small compared to the interference fit.

I have not started a thread - yet - and I'm reluctant to post plans until it all works out - but I will do so.

The photo attatched is the cylinders arranged as a "flat 4" for clarity.

The crank is bolted together and runs in needle bearings.

Regards,
      Ken


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## spuddevans (Jul 25, 2011)

Ken I  said:
			
		

> I'm not worried about the magnet working loose - the forces applied are so small compared to the interference fit.
> 
> I have not started a thread - yet - and I'm reluctant to post plans until it all works out - but I will do so.



I know what you mean about not posting up plans before having successfully got a working prototype, I am in the same boat.

I look forward to seeing how you get on with building and getting it running.

I hope to get back to my build in the next week or so, the domestic duties have started to ease off a little.



> The photo attatched is the cylinders arranged as a "flat 4" for clarity.
> 
> The crank is bolted together and runs in needle bearings.
> 
> ...



Looks good Ken, please do post up more when you can.


Tim


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## spuddevans (Jul 26, 2011)

Today I got started on the little "L" pieces that will connect the piston to the crank-pin. I found a piece of brass approx 18mm x 3.3mm x 300mm, made a rough sketch of what I wanted to achieve, and set to it.






I set it up in my vice on a parallel which was slightly thicker than the brass, so I had to use a second parallel to flesh out the brass to be gripped by the vice. Then I set up a temporary vice-stop and zeroed off the rear of the brass and the end next to the vice stop.

Then I moved to the centre of the 3.3mm width, advanced on the x-axis by 2mm and center drilled, then moved over 5mm and drilled again, repeat until 5 holes were started. Then I swapped over to drill for M2 tapping.






Once all those holes were drilled I opened the vice up and turned the brass onto it's side, pushed up against the vice-stop and tightened it up. Then I removed the vice-stop as it was in the way, and moved to the right coords and drilled 2mm holes.






Then I swapped the drill for a 4mm end mill and milled slightly more than half the thickness away.






Then I tapped the top holes M2.






and then carefully hacksawed,






then I gently hacksawed in the other direction to release them. But prior to releasing them, I cleaned them up as much as possible with a small fine file.

Then I gripped each tiny "L" in the vice and rounded over the bottom end with a file. I made 5 as I thought that would give me one to lose/spoil/have-as-a-trophy, and sure enough I did spoil one.






Here they are in place,











And that's as far as I got. I think next up will be making the outer support frames and some form of a base.


Tim


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## Ken I (Jul 26, 2011)

O.K. now I see how you got around the "stagger" problem with the "L" shaped big ends.

Never look up at the mountain - just keep digging.

Ken


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## Brian Rupnow (Aug 4, 2011)

So, What happened with this engine? Did it run? Is there a video?---Brian


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## Ken I (Aug 4, 2011)

Tim, I've started a thread on my V4 Wobbler inspired by your idea under a work in progress.

Regards,
      Ken


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## cfellows (Aug 4, 2011)

Tim, I notice you have an ER collet chuck on your mill. How do you like that arrangement? Is it an R8 / ER collet chuck adapter?

Chuck


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## spuddevans (Aug 5, 2011)

Brian Rupnow  said:
			
		

> So, What happened with this engine? Did it run? Is there a video?---Brian



Hi Brian, I haven't made any more progress on this yet, I've had another project to work on that is time sensitive, got about another week of that then I will be back on this build.




			
				Ken I  said:
			
		

> Tim, I've started a thread on my V4 Wobbler inspired by your idea under a work in progress.
> 
> Regards,
> Ken



I'll enjoy following that, thanks.




			
				cfellows  said:
			
		

> Tim, I notice you have an ER collet chuck on your mill. How do you like that arrangement? Is it an R8 / ER collet chuck adapter?
> 
> Chuck



I love the ER32 chuck in the mill, it only comes out when I need to use my boring head. The clamping range of the ER collet system is great. It is a MT3 / ER chuck, I got it before I had got a ER chuck for my lathe, but because both my lathe and mill are MT3, so I was able to use it on both until I got my ER32 lathe backplate.


Tim


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## spuddevans (Aug 19, 2011)

Well, I thought I would get my finger out and get on with this build  Rof} Having finished with another time-sensitive project I got back on track with this, I made a start on the two outer frames that fit either side of the main frame.

After hacksawing, squaring, and then flycutting to thickness, some 6mm ali plate down to just over 5.5mm thick, then I marked out for drilling for the crankshaft and 4 mounting posts.






After drilling the holes I then put all 3 frames together, held in alignment by as couple of 3mm drillbits, and clamped them in the vice in order to drill and tap holes M2.5 for attaching the frames to a base.






After drilling for the M2.5 holes I flycut across the bottom as they were very slight diferences between them and while they were aligned with the drillbits I thought it would be an ideal time to skim a tiny cut to level them.






Then I moved them over to my tapping stand and tapped them.






Then I moved on to shaping the outsides of the frames, 1st up was the outer frames. I have to confess, I did have full intentions of machining them manually using a base-plate jig and the rotary table, but as I had managed to get most of the bugs ironed out of my CNC system I decided to use that method instead.

That being said, it wouldn't take much to set up on a rotary table, and I still had to make a little jig plate to attach the frames to so that they can be held securely for machining, which is what I did next. Using a scrap piece of 6mm ali plate, I quickly squared it up and then drilled matching holes for the 4 3mm holes that are also in all the frames, then I tapped them M3.






Then I mounted one of the outer frames onto it and was pleasantly surprised to find that the M3 cap screws aligned quite tightly even before tightening them up, then to make sure everything was held square I ran a dti held in the chuck along one edge of the frame, and again was surprised that it was spot on ( well it was 0.05mm out over the length of the base, close enough for me )

Then I unleashed the CNC and let it do it's thing, just watched and brushed the chips away and squirted a bit of cutting fluid on from time to time until I ended up with this,






After doing the other one and a bit of cleaning up I ended up with this,





I know that the upper circular part is not centered on the crankshaft hole, I may redo that, but will probably use a couple of filing buttons and just hand file it to the right shape.


Then I set up the main frame in the jig and, because there is so much more work involved in the main frame, and some very critical distances involved with the long drilled internal steam passages, I double checked that the frame was still held perfectly square.







That's all I got done, so next will be the sphincter-tightening stage of cutting out the shape on the main frame, either you will hear from me with joy as it has gone well, or you will not hear from me for some time as I have to remake it *club*


Tim


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## Lesmo (Aug 22, 2011)

Nice work Tim and my compliments on a well documented build, (I must take a leaf from your book).
Good luck with the main frame, hope all goes well

Les


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## Ken I (Aug 22, 2011)

Nice going Tim, I like the "ornamental" bits - I tend to design "functional" (read "pug ugly") - I've got to work on my asthetics.

Regards,
      Ken


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## spuddevans (Aug 22, 2011)

Thanks Les, I hope to get on with the main frame shaping over the next few days.



Thanks Ken, I am finding that it is a lot easier to design the pretty bits than it is to produce them, hopefully it will work out ok on the mill.


Tim


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## spuddevans (Aug 31, 2011)

Well, I didnt screw the frame up, but I have slightly mixed feelings as my CAM output that I made for CNC'ing the frame ended up cutting it a bit too close for my comfort. It didnt break through any of the long-drilled holes, but there isnt much left, just enough to smooth the frame.

Anyway, here's a pic of the frame after shaping and then some cleanup with files and sandpaper (yea, my inexperience with CNC is showing, but I've learnt a huge amount on this)






I then marked up the tops of the arms for the frame for drilling the inlet/exhaust pipework that will go to the speed control/reversing valve.






When I attempted to drill the holes for the inlets using a 4mm drillbit, it broke through to the top long-drilled hole in the arm (which is only 1mm or less from the top of the arm) and that pulled the drill off line and made the hole oval. So instead of having a 4mm hole that the copper feed pipe could fit snugly into (soldered to a flange that screws to the top of the arm) I had to enlarge the hole to 6mm using a 6mm endmill ( I should have used a 4mm endmill to start with to prevent it being pulled offline when it breaks into the long-drilled hole )






Then, while I had the vice stop set up I moved over 4.5mm and drilled for tapping M2, then went 9mm the other way (4.5mm the other side of the inlet) and drilled again, then I swapped over to the other arm and repeated the process. Once all hole were drilled I then tapped them M2.






Then I turned up 2 flanges out of brass, I forgot to take any in progress pics but they are very straight-forward to turn, a section 6mm diameter to fit into the holes I just made in the frame arms, and a 12mm flange with a 4mm thru hole for the copper pipe to be soldered into.

Side profile,







Then I had to make a jig up to drill the fixing holes in the flanges. Just a 6mm hole drilled thru some scrap Ali, a 2mm hole drilled 4.5mm away from the 1st hole, and a little pin I have from another jig.






Then insert a flange into the jig and drill one hole,






Then insert the pin to keep the flange from rotating, and then move over 9mm to drill the other hole.






Then I just used some files to shape the sides of the flanges, and here is one in place on the frame.






The flanges are a nice fit into the frame, which when combined with a smear of liquid gasket it should seal quite nicely.


Next up will be some form of a base.



Thanks for watching,

Tim


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