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Old 04-11-2009, 08:11 PM   #1
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Default A small steam engine

Hi

Since I finished my small boiler I haven't had a lot of time in the workshop, domestic duties, amongst other things, getting in the way. I also enjoy woodwork and am at the moment making a mahogany veneered and inlaid side table to match the coffee table I made a while back. I have some ideas as to the type of engine I would like to build to go with the boiler but don't seem to be able to find the time to get on with it at the moment. So I have decided to go back to basics and build a simple steam engine. Something that I can do in the odd half hour here and there without getting too complicated. I have the two books BUILDING SIMPLE MODEL STEAM ENGINES by Tubal Cain that I read from cover to cover a few years back so dug them out and had a quick flick through again. I have also searched through some of the excellent little wobblers on this forum and looked at a few plans I have. I have settled on building a small vertical centre flu boiler and a horizontal oscillating engine. Nothing original I'm afraid, I openly admit that I have pinched ideas from all of these sources. I will not be working to any plans as such, just making it up as I go along. The project will be made mostly from the scrap box so will be adapted to whatever I have. The boiler will be very low pressure, around 15psi should be enough to run a litle engine. I will use the hydraulic pump I made to test my other boiler to test this one as well. I will include some drawings as I go along and photographs from start to finish. So here we go.

I have a piece of 2 inch dia. 20 guage (.037) copper tube 4 inch long, that'll do. A piece of 15mm 23guage (.02 copper pipe 7 3/4 inch long and a bit of copper plate 20 guage (.037)



Lightly centre dot and scribe two circles 2 3/8 dia. on the copper plate. These are for the boiler top and bottom plates. I have allowed for a 3/16 inch flange.



Centre a scrap of oak on the lathe face plate.



And screw on from behind. I use fat self tapping screws with washers, they have deep threads and bite into the wood tightly.



Cut the two copper plates out as close to scribed circle as possible.



Centre and hold the copper circle on the face plate using a revolving centre in the tail stock and a scrap of oak to apply pressure and turn to size.



The completed discs.



Turn a piece of alluminium (or whatever you have) to make a former to flange the plates. The size needed is the internal dia. of the coppper tube less twice the thickness of the copper plate.



Anneal the two copper plates and then form the flange with a soft mallet.



The top and bottom plates formed.



I have decided to fit three bushes in the top plate. One threaded 1/4 x 40 which will be for the safety valve. Two others threaded 3/16 x 40, one for the steam outlet and the other for a small pressure guage. Two futher bushes threaded 1/4 x 40 will be fitted down the side of the boiler tube for a water guage. I may not fit a pressure guage, although it would look nice, but its much easier to fit the bushes now than try to do it later. The same goe's for the water guage, if I dont get round to making one I will just fit plugs to the bushes.

Heres the bushes made from phospher bronze.





Thats it for now. I'll keep posting as and when I get a bit more done.

Cheers

Rich



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Old 04-11-2009, 08:20 PM   #2
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Default Re: A small steam engine

Nice one Rich - well up to the standard we have come to expect from you!



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Old 04-11-2009, 11:09 PM   #3
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Default Re: A small steam engine

Good one Rich.
Hope you don't mind if I build in parallel so to speak.
After all they say imitation is the sincerest form of flattery.
BR

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Old 04-12-2009, 06:35 PM   #4
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Default Re: A small steam engine

Hi

Thanks for the compliment Tel, much appreciated

Hey BR, no problem at all. By watching my antics you should be able to make a better job of it than me!

I missed one of the dimensions off the bush drawings. The right hand one, the one made from 1/4 inch phospher bronze is turned down to 7/32 inch to form the shoulder.

Cheers

Rich

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Old 04-12-2009, 08:03 PM   #5
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Default Re: A small steam engine

Looking good Rich!

Please take us along as it progresses.

Rick

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Old 04-14-2009, 07:51 PM   #6
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Default Re: A small steam engine

Hi

At the Easter holiday I work good friday and have tuesday off instead which meant I got a couple of hours in the shop today.

I started by drilling the holes in the top and bottom plates. Firstly I chucked the plates in the lathe and lightly centre drilled them to find the centres.



Holding circular items well clear of the mill table to give adequate drill clearance is always a problem, this is how I did it. First cut a disc of 12mm ply the same as the internal dia of the end plates.







Then glue the disc to a scrap of 3 x 2. drill a couple of 10mm holes.



Then clamp the plate in the mill and centre it under the chuck using the previously centre drilled mark. I just lined it up by eye, nonedd for absolute accuracy here.



Drill out the centre hole using a step drill.



Move the table and then drill the two 7/32 holes.



Reposition the clamp and drill the 9/32 hole.



The bottom plate only has to have the centre flu hole drilled. The step drill I have has 2mm steps 10 12 14 16 etc, but not a 15mm to suit the size of the centre flu. I drilled out to 14mm and then had to re-chuck the plates and skim out the last 1mm with a boring bar.



The finished plates.



All the copper parts are now in the pickle bath.

I then started on the safety valve. A small boiler and engine like this really only needs something very simple like a bronze ball on top of a tube with a spring and adjusting nuts underneath which are inside the boiler when fitted. The problem with this type is that to make any adjustments the valve has to be removed, adjusted and re-fitted and tried again. Its very time consuming to set them correctly. I decided to make one similar but smaller to the type I made on my small boiler project which can be adjusted from the top without the need to remove it.

Face the end of a piece of 3/8 hex brass bar.



Turn down to a dia of 5/16 for 1/2 inch. I used a small round profile cutter to give a bit of shape.



Centre drill then drill through 1/8 to just over 1 inch depth.



Note I'm using the tail stock DRO I made.

Drill with a 5mm drill to a depth of .450



Then using a 5mm milling cutter finish the hole to a depth of .5 inch. The mill cutter will give a flat bottomed hole.



Part off to about 1 inch



Re-chuck and drill 5.5mm to a depth of 1/4 inch and tap 1/4 x 32.



Turn it round in the chuck. Note use of card to prevent marking.



Turn down to 1/4 inch dia 1/4 inch long and thread 1/4 x 32



The eagle eyed among you may have noticed that I have threaded the safety valve 1/4 x 32 but I have specified a 1/4 x 40 bush? Change of plan here. The safety valve will be used as the filler for the boiler so will get a fair amount of removal. I figure a 1/4 x 32 thread will be stronger than the 1/4 x40 so I have made a new bush 1/4 x 32 to suit. I have also made it a bit longer.



The valve body so far



Chuck a piece of scrap steel, drill and tap 1/4 x 32



Mount the valve into this with a copper washer



Transfer to the rotary table in the mill



Cross drill with a 5/32 drill



Chuck a piece of 1/4 round brass bar and drill through 1/8 and then thread 1/4 x 32.



Part off a piece about 1/2 inch long and screw into the valve body. This will be used to adjust the tension on the spring.



I'll knock up some drawings when I get time.

Thats it for today folks.

Cheers

Rich







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Old 04-14-2009, 08:54 PM   #7
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Default Re: A small steam engine

Rich,

Super thread. Very timely for me as I will shortly need to start on the copper boiler for my build of Rudy's Steam Tractor. Keep 'em coming!

Dennis

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Old 04-16-2009, 11:57 PM   #8
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Default Re: A small steam engine

Love that safety valve.
BR

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Old 04-18-2009, 07:18 PM   #9
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Default Re: A small steam engine

Hi

I had a good few hours in the shop today so got a fair bit done. I continued with the safety valve by making a spring. I made it out of 26 guage bronze wire.



Hold a 1/8 round steel rod in the lathe and push the end of the bronze wire into the collet to hold it and with the lathe in its slowest gear wind a spring.



Stretch it out a bit.



Then cut a piece off.



I have used a 3/16 stainless steel ball in the valve. Assemble the valve with the ball, spring and adjuster. Make a lock nut from 5/16 hex brass bar.





You could use a stainless steel spring if you have one. I may have to shorten/lengthen my spring a bit when I get to the final setting up. A bit of trial and error.

Back to the boiler. Its been in the pickle for a few days. It looks pretty in pink.



I set up the boiler barrel in the mill to drill two holes for the water guage bushes. The top bush is about 5/16 from the top of the barrel and they are spaced 2 inches apart.





This is a little jig I made to hold the two bushes in alignment on my small boiler project so is being used again here.



Here it is set up ready for silver soldering the bushes in.



Heres the boiler parts together, fluxed and ready to silver solder.



You can see I have wrapped silver solder wire around the parts.



Turn it over and silver solder the bottom plate in. Note I have pushed the plate inside the boiler barrel about 3/16.



After a quick pickle and scrub up it looks ok.



I have made up a set of bungs and adapters ready to hydraulic test it. I will be attaching a pressure guage and the pump.



This is the hydraulic pump I made which will be used to test the boiler.



Cheers

Rich

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Old 04-18-2009, 07:44 PM   #10
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Default Re: A small steam engine

Thanks Rich, this is really nice. I didn't even know Phosphor Bronze spring wire existed!

The hydraulic pump is very nice as well , do you have any plans for it, or is it your own design?

You give me hope - I noticed you have an ML7 and the things you do are truly inspirational! - I have to get a bit more experience on mine.

Regards, Arnold



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