COLUMBINE'S BOILER

[Robert Hornby]

Well, that went better than expected. I put on my larger nozzle (25mm) that I use with the drag saw (for reasons that I turn the flame down quite low and there is very little roar and there is still enough heat to keep steam up). I digress, I had no trouble in achieving the heat required and the soldering went very smoothly.
Next job to rig up a pressure test fixture, I used to have one that I used on the drag saw boiler but not any more. I will test it to 100 psi, so fingers crossed.

The set up.

Looking OK

Job done

Robert

[Robert Hornby]

The pressure went well with no leaks, I left it at 100 psi pressure for 2 hours. The next job is to make a hardwood former to press the 2mm thick shell ends into shape, 4” dia with a return of 8mm. I am going to have a go at pressing these instead of hammering the return (as I did on the drag saw boiler) to save lots of time not to mention gas as I had to anneal a dozen times or more. The local car garage has a press and will let me use it – nice guy.



Flue under pressure

Robert

[steamer]

Nice job Robert.   Didn't set the 25mm tip but that's the tool for the job.

...but tell me that's not a compressed air line?
Dave

[SandCam]

Hi Robert,

Well done on getting the centre flue done and pressure tested.

2 things though... it is not good practice to use a test pressure above 2 x working pressure... it just overstresses the part unnecessarily.

I hope that you are not using compressed air for pressure testing... that can be extremely hazardous... it is much safer to use cold water (ambient temperature).
A leak with pressurised water will just produce a small dribble before the pressure drops to zero... compressed air can rip a joint apart with anything larger than a pin hole... even more likely with a large boiler shell under test.

Stay safe.

Best regards.

Sandy.

EDIT, I see Dave beat me too it on the compressed air issue... good for you Dave.

[Robert Hornby]

OK, thanks for that Sandy, and yes I am using air for the test, not thinking about the possible risks . I will do as you suggested and use water for the next test.
One other thing has anyone any thoughts on whether to use any lubricant (Vasaline?)on the wood former when pressing the copper ends?
Robert

[Robert Hornby]

The formers for the dished ends are now made and ready for the press. The metal plates on the base former is to prevent the hard wood from splitting as I am sure it would if they were not there. I have annealed the copper so hopefully all will go according to plan.


The holder for the base.


Turning the base


The white plastic pin is for locating the parts to keep then under control


ready for the press

Robert

[Ramon Wilson]

Nice work on the flue Robert - did you just let the lower torch stay fixed and allow the heat to rise or did you have an assistant to help.

My ends needed four annealings - it'll be interesting to see if yours will go in a 'one-er'. I'm intending to dome the ends on the gas tank - whats the thickness of copper you're pressing?

I'm still awaiting tube for the uptake before I can get going again

regards - Ramon

[Robert Hornby]

Ramon,
I didn’t have an assistant so rigged up the gas torch holder at a fixed position at the lower end of the tube, and allowed about 5 minutes for the heat to soak up to the cross tubes. The dished ends are 2mm thick and hopefully doing the job tomorrow. I will certainly let you know how I got on.
Robert

[SandCam]

Hi Robert,

Looks like you are almost set to go with your end plates.

One thing though... it is not really clear in your pictures how much of a radius you have got on outer edge on the male half former... it looks quite small on the screen.

You need a minimum inside radius of 1 - 1.5 x the plate thickness on your end plates or you may end up with stress fractures.
 When pressing... lubricate both sides of the copper with something like 'copper eeze' (the stuff they use for lubricating the slides on car brake calipers)  which will help a lot with metal movement and prevent the plates getting stuck hard on the formers.

I would also recommend a couple of extractor pin/punch holes in both halves of the former to aid extraction.

Hope it all goes well for you.

Best regards.

Sandy.

[steamer]

While not exactly obvious Sandy....there looks to be a nice generous radius on the tool in the tool post.

Dave

[K.B.C]

Hi Robert,
I have never been a fan of pressing the boiler ends in one go ever since I witnessed 1/8" thk ( 10swg ) end plates x 4.75" dia being pressed on a Hydraulic press, the dies were made of steel and the builder didn't anneal the plates before pressing.
The result was hair line cracks in the end plates, on pointing this out I was informed that it was all to be S/Soldered anyway and the solder would fill in the cracks, at this point as it was the first time that I had witnessed pressing end plates, I kept my own counsel and walked away.

I would still heat and anneal before every pressing, my preference is always to anneal and hammer over the dies several times, the hammer starts to bounce when the copper needs to be re-heated.

Just a word of caution, it would be a shame to ruin the end plates after all your work.

George.

[SandCam]

Steamer wrote,

While not exactly obvious Sandy....there looks to be a nice generous radius on the tool in the tool post.

Dave

Hi Dave,

I'm not trying to be deliberately picky ... as you should know.

Yes I agree the tool in the toolpost does appear to have a generous radius, however, I was concerned that this may only be a 3/8" or less wide tool bit... which would suggest a radius of perhaps 3mm max.

This would be far too small for the Female part... which would need to have a bend radius of some 4 - 5mm (Assuming an inside bend radius of 1 - 1.5 times the plate thickness on the inside of the endplates).

Also the radius on the Male part looks a little small.

I just felt it was best for Robert to check this, since it would be a shame to go ahead and end up with a cracked flange, for want of a little extra radius work.

I would also recommend doing the pressing with at least 3 annealing cycles and not try doing it in one hit... copper work hardens extremely quickly when bending... as you know.

Keep Happy.

Best regards.

Sandy.

[Robert Hornby]

Firstly thank you once again Sandy for your constructive comments, and yes the radii were a bit small so I attended to this before going ahead. Having annealed the plates to a dull cherry red I high tailed it to the garage and more importantly his press.
The press is a 10 ton job but it went so smoothly with only minimum effort on the pump handle I estimate only a quarter of its capacity was used. I used Vasaline for lubricant. I am very pleased with the forming and after dressing up the excess they fit like a glove. There will be a generous gap for the silver solder so all is well. I still have to bore out the center hole to suit the fire tube and drill three small holes in the top end for the steam outlet, safety valve and whistle.


The ends as they were formed


Ditto


Turning off the excess


Ends completed

Robert

[Ramon Wilson]

Nice work Robert    thanks for the update - glad it all went smoothly for you. Bet I'm not the only one who thinks you made some nice pie dishes though   

I'll give it a go on the gas tank ends.

Ramon

[Jo]

Bet I'm not the only one who thinks you made some nice pie dishes though   

  Clearly another who should be banned from the kitchen.

Robert, Turning that excess looks a bit scary, especially as copper is a bit snatchy, would it not have helped to leave the copper on the former to give it some support.

Jo