Its First-Steam-Engine time!!

[SilverSanJuan]

Nicely done. How did you thread those fittings right up to the inside corner? Did you use a die or your lathe?

Todd

 

[Anko]

Thanks people for the good input!

I have returned to class in the university so again I don't have so much time to spend in the engine.

Todd: I use a die in the lathe, the trick to get the threads to the end is to flip the die, in the back face the cutting edge have no countersink and will cut the full teeth from the begining.

For the valve shaft I use a 3 mm silver steel rod, in one extreme needed to be turned to 2mm diameter, to I use a little brushing to prevent flexing.

Because I still dont deciede about the sliding valve material, I just go with Technyl a90, the plastic is very esay to machine so I spend like 20 min on doing it, if it not work I will make another:

I made the eccentric wheel, out of 1020 steel

And I made a redesign of the eccentric ring (is like I totally redesign this engine), from a single ring bolted to a shaft to some more real-like looking part.

Flip

Then I made a terrible mistake, it was sopused that the upper end of the ring was flat to bolt the conection rod, but I round everything!, then with no mood of making the piece again, I came with a simple solution:

And here is:

This engine is close to his end! only left: valve connecting rod, piston, crank piece and flywheel.
and of course a good polish and some minor paint.
(and a much better valve stainles plate)


Saludos!

 

[Maryak]

Very Nice Work Anko

Best Regards
Bob

 

[SilverSanJuan]

That was very clever Anko. A lot of different methods used to make that one part. Whew!

Todd

 

[Anko]

Thanks Todd and Bob for the good input!

I finished the valve asembly, here some photos of the process:

And here is the engine at the moment, because of manipulation there is finger prints and oil in the finish, but still looking good!

The action of the valve is smooth and have a nice sound!

Saludos

 

[Anko]

Hello again!

Now its time to mak the crank piece, out of 1020 steel:

then I set a flycutter to cut the radius of the piece borders, first I measure the heigth of the shank of the flycutter in the V block, then:

(heigth of the shank) - ((shank diameter)/2) + raduis of the total diameter to cut = total heigth of the cutting tip

then, I adjust the cutting tip of the flycutter and by hand I feel how it touched the heigth gauge tip, thats how I set the flycutter to cut the diameter by feel.

More to come!

Saludos

 

[rhitee93]

Very nicely done. K-point for not only adding the detail to the crank, but for doing it in a way that everyone should be able to accomplish with basic tooling.

 

[gus]

After view a few postings and seeing the usefulness of flycutter,must DIY one for my Sakai Mill.

For now make do with 12mm end mill to skim big surfaces.Surface finish with end mill despite light cuts could not be good and I have to manual sanding.Just completed crankcase for .46 aeromodel engine which will take another 4---6 weeks to complete.

Gus from faraway Singapore.

 

[robcas631]

Excellent work!

 

[skyline1]

You say you are not a toolmaker but with workmanship and clever solutions like this you should be. You have a great talent for it. If Electrical Engineering doesn't work out you could consider becoming one.

This engine is looking really good.

A couple of posts ago you were talking about bearing bushes. Bronze is a good material for this but on hard steel shafts you could also use cast iron.

I use cast iron bearing bushes often and they run really smooth on silver steel shafts. They are particularly good for high speeds ( I use them on steam turbines at 30,000 R.P.M.)

They are partially self lubricating due to the free graphite in the iron, If you machine cast iron you will soon know about this your hands will be black in no time !

Here are a couple of pics of one of mine. To give you an idea the crankpin on this is about 3mm Dia. (1/8" actually). you can machine cast iron bar very thin and they are no more difficult than bronze once you get the "feel" of machining it.

If you have problems getting it I might be able to send you a little piece if the postage to Chile isn't too high.



Regards Mark

 

[peatrich]

"I take my time to study the plans, and found some errors in measures and stuff but nothing critical and I make some adjustment to correct them."

Hi Anko, It would be nice to know where you saw the problems with the plan - I am about to start building this as my first engine

kind regards
Peter

 

[gus]

Hi Mark,
Thanks for the tip.Cast Iron Bearing(bush). As Bronze is getting to be very expensive,I was looking for alternative.
Aluminium is not a good solution. My neighbour's father makes Power Press and cast iron is used for the bearings.They last and last. I did asked the old man -------"Why not Bronze?" He walked and laugh------"Good Idea". Some client came in with a used press and it had bronze bushes and all badly worned and he asked for CI bush.This confirmed CI good for bushes.

However Bronze can be custom formulated for for heavy load. Neighbours again. Non-ferrous foundry neighbour kept a
hand written notebook handed down by his grandfather/father and in it,listed are chemical composition for a range of bronze for different application. You just can't walk in and ask for any bronze bush w/o informing him of the application.

Very sad.This trade died off in the early 70s.
I have seen bronze propeller that looked more like Stainless Steel.All about Bronze.

My next Mini Slide Valve Engine will have CI bush.

 

[Anko]

thanks for the tip Mark! here is a question: any type of cast iron will work? as far as I know, there are several alloys of cast iron, what I mean is, there is a special type of cast iron better for this aplication, or just any cast iron saved from the scrap yard will work?

Peter: if you look the plans carrefully, you will find that the engine front side assembly lacks the connection piece between the cylinder and the cross slide base piece, and the blots that unite this pieces are not specified, in position or size, and there is not space to put a bolt eighter!, I have to make a M2x0.4 bolt with a head diameter of 3mm in order to fit, in the cylinder tap is not critical because there is enough space, but you will find that the bottom conection of the cylinder need correction.

Also the plans do not specify the materials, as I find, there is some bad combinations of metals for mechanical aplicatios (brass with brass or aluminium etc..) and well, its something to consider.

The rest its ok, you can make modifications on the design as I did to aboid the "block on block" look putting some curves and radius in some pieces.

If you got any questions feel free to askme!



I made the some sort of experiment with the piston, I made the body out of 1020 steel and put 2 rings made of technyla90, the idea was to make a piston that will not wear the cylinder walls, but why I dont make the entire piston of one piece of technyl? well I just wanted to do a piston with rings, that's the reason

Saludos!

 

[skyline1]

Hi Gus

I agree there are a vast number of different types of bronze picking the right one is a science in itself. Having done so you then get the problem of trying to actually get some which as you say can be difficult and expensive (especially in small quantities like we are likely to use).

Some bronzes are also quite hard to machine and they have a habit of "Grabbing" drills and reamers. I had to do some naval bronze a little while ago and that didn't just look more like Stainless it was almost like machining it.

A peculiar effect sets in with bronze bearings at high speeds as I found out with my first steam turbine. The bronze bearing doesn't wear too badly but it eats the shaft away in no time even hardened steel ones (silver steel in my case).

During discussions with other model engineers about this I had a chance conversation with someone who worked for McLaren. he said they were using cast iron big end shells in full size racing engines because bronze/white metal ones couldn't handle the speeds.

I can heartily recommend C.I. for bearings even though it's not the traditional approach and as you said the life of them is really good. The little engine in the pictures has had many hundreds of hours of running and there is little wear in the big end. Oscillators (Wobblers) are prone to big end wear and "barrelling" the piston due to the side thrust on the conrod.

So if C.I. bearings can cope in Oscillators, full size petrol racing engines and turbines at 30,000 R.P.M.+ they should have a long and trouble free life in a slide valve.

Cast Iron bar is easily available now for just this sort of thing, Or a trip to the local scrapyard will usually furnish a suitable piece.

Regards Mark

 

[peatrich]

Thank you Anko.
There is a build thread of this model on a German forum. The builder silver soldered the side assembly to the cylinder and finished it by wrapping thin gauge metal around the two pieces that is bolted to the side assembly, to cover the join. You are right about the small bolts, there isn't much room.

 

[skyline1]

Hi Anko

The type of Iron you need is Grey cast iron, sometimes called Flake Graphite iron, There is another type of Cast Iron called S.G (Spheroidal Graphitic) or malleable iron. There is an easy way to tell the difference without needing any special equipment. (it's the way old foundrymen used to do it before modern metallurgy labs)

Simply break a small piece off and examine the break, grey iron will be, well, grey, and it will have a grainy surface a bit like a broken sugar cube. It should also break quite easily as grey iron is poor in tension and quite brittle. If you rub your finger over the break a silvery black deposit should come off. This is free graphite in the iron and is what helps lubricate the bearing.

S.G. iron will have a more silvery white break and smoother more like steel. It will also be more difficult to break. If you rub it much less of the graphite will rub out. It takes very little practice to spot grey iron by this method.

Pieces of Cast iron guttering are usually grey iron and are an ideal material for this but avoid plumbing fittings and taps etc. as they tend to be S.G.

A couple of tips on machining it if you have never done so

Machine it at slow speed and dry it needs no cutting oil as the graphite will lubricate the cut.

the tool angles used for steel will usually be O.K. That's what I use. But tools with little or no top rake are recommended for Cast Iron if you fancy grinding one.

Cast Iron (especially in thin sections) tends to get a hard skin during the casting process due to chilling and sand penetration. so the first cut needs to be quite deep to get under it at a low feedrate.

If you've got it right the surface finish will be quite good though not usually bright and polished and the chips will be almost a fine dust. This is not particularly abrasive but should be cleaned off the machine often as it gets everywhere including your hands.

If you do get stuck finding some I can send you a small piece for the cost of the postage, assuming it isn't too high to Chile (shouldn't be)

P.M. me with the size you need and I'll see what I can do. I used to have a little backyard foundry so I've got quite a few odd bits of C.I. bar about (old pouring sprues).

Regards Mark

 

[gus]

Hi Mark,
As a Polytechnic student,I mixed with the neighbourhood tradesmen.A cuppa (cup of tea) would loosen them to reveal their trade secrets.It is true they actually prescribe the chemical composition of bearing bronze to tailor fit.These guys are dead and gone.

1986 When I was Shanghai,visiting the Shanghai Heavy Compressor Plant,I bought the foundry supervisor dinner,he practically gave me all the tips I need to cast Aluminium Traps.Tip----Small piece--730 degrees C & big pieces 730 C Plus the degassing and refining chemicals.Too bad he is not knowledgeable on CI book moulds.

This compressor plant have all kinds of tradesmen. Ferrous and non-ferrous foundrues.Huge 100 foot lathes,humongous planers/mills and jig borers.

For the .46 Glow Plug Aeromodel Engine,I am using Phosphorus Bronze as in print.This material is recomended by American Machinist Handbook.Turning,drilling and boring same was a breeze using normal drills. Engine now WIP. Now adding on cylinder.Will post next week.

 

[skyline1]

Hi Gus

It's quite true, The persuasive powers of "Enginemans best friend" are amazing. Great things have been achieved with a chat and a "cuppa".

I think I would have been like a kid in a sweetshop in Shanghai.

Phosphor Bronze is fairly easy to machine as bronzes go done a bit myself in the past. not too easy to deep drill tho' , but deep drilling is a tricky operation on any material.

Aluminium bronze and some of the the more exotic alloys are quite different animals though they will fight you all the way.

look forward to seeing how your glowplug goes.

Regards Mark

 

[peatrich]

This is the German build thread with some good pics. This is the first time I have posted a link and hope that it works and that it is appropriate to post a link to another forum? The site is in German but I found some useful tips by using Google translate and copying and pasting from the forum.

http://www.modell-dampf-forum.info/forum/showthread.php?t=6768

 

[gus]

Hi Gus

It's quite true, The persuasive powers of "Enginemans best friend" are amazing. Great things have been achieved with a chat and a "cuppa".

I think I would have been like a kid in a sweetshop in Shanghai.

Phosphor Bronze is fairly easy to machine as bronzes go done a bit myself in the past. not too easy to deep drill tho' , but deep drilling is a tricky operation on any material.

Aluminium bronze and some of the the more exotic alloys are quite different animals though they will fight you all the way.

look forward to seeing how your glowplug goes.





Regards Mark

Hi Mark,

Just made a near fatal blunder.Spent the last two hours kicking myself.Should have followed the prints. While drilling crankcase top to take the cylinder,I discovered error. Just came up with a rework/salvage scheme.
Foto attached.