A small steam engine

Discussion in 'A Work In Progress' started by firebird, Apr 11, 2009.

  1. Apr 11, 2009 #1

    firebird

    firebird

    firebird

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    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 (.028) copper pipe 7 3/4 inch long and a bit of copper plate 20 guage (.037)

    [​IMG]

    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.

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    Centre a scrap of oak on the lathe face plate.

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

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

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    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.

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    The completed discs.

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    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.

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

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    The top and bottom plates formed.

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    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.

    [​IMG]

    [​IMG]

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

    Cheers

    Rich
     
  2. Apr 11, 2009 #2

    tel

    tel

    tel

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    Nice one Rich - well up to the standard we have come to expect from you! Thm:
     
  3. Apr 12, 2009 #3
    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. :bow:
    BR
     
  4. Apr 12, 2009 #4

    firebird

    firebird

    firebird

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    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
     
  5. Apr 12, 2009 #5

    rake60

    rake60

    rake60

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    Looking good Rich!

    Please take us along as it progresses.

    Rick
     
  6. Apr 14, 2009 #6

    firebird

    firebird

    firebird

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    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.

    [​IMG]

    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.

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

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    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.

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    Drill out the centre hole using a step drill.

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

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    Reposition the clamp and drill the 9/32 hole.

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    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.

    [​IMG]

    The finished plates.

    [​IMG]

    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.

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    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.

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

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

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

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

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    Part off to about 1 inch

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

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

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

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    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.

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    The valve body so far

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

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    Mount the valve into this with a copper washer

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    Transfer to the rotary table in the mill

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    Cross drill with a 5/32 drill

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

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    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.

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

    Thats it for today folks.

    Cheers

    Rich







     
  7. Apr 14, 2009 #7

    4156df

    4156df

    4156df

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    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
     
  8. Apr 17, 2009 #8
    Love that safety valve.
    BR
     
  9. Apr 18, 2009 #9

    firebird

    firebird

    firebird

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    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.

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    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.

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    Stretch it out a bit.

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    Then cut a piece off.

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    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.

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    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.

    [​IMG]

    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.

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    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.

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

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

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

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

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    After a quick pickle and scrub up it looks ok.

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    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.

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

    [​IMG]

    Cheers

    Rich
     
  10. Apr 18, 2009 #10

    arnoldb

    arnoldb

    arnoldb

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

    The hydraulic pump is very nice as well :bow: , 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
     
  11. Apr 18, 2009 #11

    firebird

    firebird

    firebird

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    Hi Arnold

    Yes the pump is my own design. I have just finished making a small boiler for which I needed a pump to hydraulic test it. You will find a complete build of the boiler here on this forum in the A WORK IN PROGRESS SECTION under the heading A SMALL BOILER. There are plans for the pump there as well, this link should take you to right page. http://www.homemodelenginemachinist.com/index.php?topic=2092.120

    Cheers

    Rich
     
  12. Apr 18, 2009 #12

    arnoldb

    arnoldb

    arnoldb

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    Thanks Rich & VERY VERY much appreciated! :bow:

    Regards, Arnold
     
  13. Apr 19, 2009 #13
    Hi Rich
    I see that you changed from phosphor bronze to s/s for the ball in the
    safety valve. Is this just a case of whats at hand, I hope so because
    s/s is all I have.
    Really enjoying this build and thread.
    BR

     
  14. Apr 19, 2009 #14

    firebird

    firebird

    firebird

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    Hi BR

    I have some SS and Bronze balls in 3/16. I forgot to mention that you should fit a steel ball to the valve and then with a small punch tap the ball to seat it in the valve body then change the ball for a bronze one. I just decided to leave the SS in place. If it leaks a little I can give it another tap. Nitrile balls seem to be favoured now because they seat and seal better than the metal ones. I have a couple of nitrile balls that I bought at a show but I'm b******d if I can find them at the moment. I have just fished the boiler out of the pickle where its been all night and noticed that the silver solder hadn't taken all round the top plate. I had a few minutes to spare so re fluxed it and and gave it another go. You should never rush these jobs. It's soldered OK this time I think but there is more sliver solder around the top than I would like, looks a bit messy. I'll have a go at cleaning it up later but I must take care, the copper aint all that thick.

    Cheers

    Rich
     
  15. Apr 19, 2009 #15

    firebird

    firebird

    firebird

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    Hi

    after re soldering and another pickle it looks ok.

    [​IMG]

    [​IMG]

    I annealed the copper washers before fitting the bungs and adapters.

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    The bungs and adapters fitted with the pressure guage and pump piped up. The boiler is held to a wooden stand with a plastic strap. The guage is the last thing to be fitted. The boiler filled with water and the hand pump operated until water comes out of the guage pipe (the highest point) then the guage fitted. This way very little if any air remains in the boiler.

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    I pumped the pressure up to 40psi, which is double the maximum pressure it will run at. A successful test, no leaks and the pressure held.

    Heres some video

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    About 15 minutes later.

    [​IMG]

    I made another adapter and fitted the pressure relief valve. After playing about with the adjustment I got it to blow off at about 18 psi. That will do for now. I know it works ok so it can now be set when under steam.

    [​IMG][/U

    Cheers

    Rich



     
  16. Apr 19, 2009 #16

    cfellows

    cfellows

    cfellows

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    Great job, Rich! Maybe I missed this, but, did you calculate the release pressure of the safety valve or are you using the "cut and try" method?

    Thx...
    Chuck
     
  17. Apr 19, 2009 #17

    firebird

    firebird

    firebird

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    Hi Chuck

    Calculated of course, ;D ;D ;D ;D then stick it in and try it. Actually I have the bronze wire in several guages and have some experience from my other small boiler project so you could say a calculated guesstimate.

    Cheers

    Rich
     
  18. Apr 20, 2009 #18

    firebird

    firebird

    firebird

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    Hi

    I have started on the burner tonight. I have a piece of brass tube around 1 5/8 dia so chopped a piece off that 1 1/4 high. I will make a couple of brass flanged plates in a similar fashion to how the boiler plates were made. I have measured the internal dia of the tube and measured the thickness of the brass sheet I have (.032) and made a former from some steel bar.

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    Mark out the brass sheet and cut out 2 pieces.

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    Turn them to size.

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    The pieces so far.

    [​IMG]

    Cheers

    Rich
     
  19. Apr 20, 2009 #19

    Majorstrain

    Majorstrain

    Majorstrain

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    Superb work Rich,
    I was hoping you would do a burner :)

    Cheers,
    Phil
    Soon to build your boiler, burner, and pump. :bow: :bow: :bow:
     
  20. Apr 21, 2009 #20

    firebird

    firebird

    firebird

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    Hi

    Just enough time tonight to do a bit of brass bashing. firstly though the brass discs have to be annealed. You have to be careful here when heating the brass. Keep the flame moving until the brass just begins to glow red then stop or you will end up with a molten lump. Brass is not so forgiving as copper.
    Anyway once its annealed tap it over the former to make a flange.

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    I held them in the lathe on the former and turned the sides until they were a nice slide fit in the tube. Because the brass tube is thin walled I don't want to have to force them in.

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    The top and bottom plates, one fitted in the tube.

    [​IMG]

    Cheers

    Rich
     

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