boiler leak

I am having a second go at making a boiler ( never again ) The first was a disaster , At second attempt , soldered the tubes OK , soldered one end in the barrel , looks OK , but the second end must be a bit slack i , The solder runs through and wont bridge the gap in places I am thinking of putting in a narrow copper ring and hoping at will seal on that . What to more expert makers think ?

Thank goodness we have the shed to play in these days

Some more detail on the size and design of the boiler would be useful. Perhaps a picture or two.

Apart from your ring suggestion, 2 other possibilities.

1. Copper tube can be expanded in diameter using a drift with a gentle taper.

2. Silver solders are available which form a larger fillet than the lower melting point types. They are less "runny". This could help.

Pickle/clean the new joint areas well.

[This posting has been removed]

its a 4 inch diameter boiler barrel . I have already unsoldered it once and made new flanged , end plates and reduced the umber ot tubes but to get the tubes and ends into the barrel once they have been assembled together the flanges cant be too tight or they wont go down with out too much pressure .

I am ok machining engine parts , and I can silver solder a bike frame , but boilers have been a step too far for me . . If I cant get this to seal its going in the scrap bin and put it down to experience . Luckiy I do have a ST 504 and an up right boiler I hade a lucky ebay buy from which when cleaned up and new fittings made works well ,

Phil

[This posting has been removed]

It needs to be a tightish push fit. If it isnt then when you apply heat to a boiler of this diameter the shell will expand a lot quicker than the plate and the gap is too big. This wasnt a problem when people used to rivet and solder. On bigger loco boilers I use rivets at a few key points to stop things moving and then remove them when completed. This is one I completed over the weekend but sadly Tim cant come and collect it right now.

Thats a boiler photographed three years ago...uploaded wrong photo but same soldering, we use different burners and pressure gauge syphons now....just in case anyone notices!

Boiler material is expensive Philip and it would a great pity to just bin the whole thing.

I think (?) you are saying that your tubes are either too loose or too tight in the flanged end plates when you assemble them. The tubes should be a free 'sliding' fit and this should be checked before any attempt to assemble or braze parts together. They certainly shouldn't be hard to push in but make sure the flanged plates are de-burred. A tube 'end' can be enlarged with a tube expander and a number of expander designs have been published (in ME) over the years (sorry - I don't have details to hand at the moment)

Take your time but stick with it - its very satisfying when you finally manage to overcome an obstacle like this one.

Regards,

IanT

Ian it isn't the tubes in the end plate , they seem ok its the flanged end plate in the boiler tube , I have found a but of 1/8 copper rod , I will try soldering that round the joint , if that doesn't work then its hello mr scrap man

Phil

[This posting has been removed]

[This posting has been removed]

sounds as if I might as well chuck it under the bench and get back on my Red Wing engine , Working in the cylinder head now !!

Philip - have sent a private message.

my boiler end plate sorry I cant see how to make it smaller

Use a ball pein hammer on the outside to close up the gap. The copper will be soft after the previous heating

Duncan's suggestion is a good one but go gently as soft copper moves very easily.

If it was me I would use my stock of Easy-flo No 3 but as this is no longer obtainable I've waited to reply until I had more info. Well, that came this morning in an email from Johnson-Matthey who say that the equivalent is Argo-braze 502 which is normally used to braze carbide tips but can be used on copper.

It has 50% silver and melts at 660-705 deg C.

This is similar to Easy-flo No 3 but without the cadmium. I always use Tenacity 5 and find that the 'solder' has a very runny component that flows into the gap followed by a more pasty substance that is sluggish and forms a nice fillet and is excellent for making simulated 'castings'.

Brian

Edited By Brian H on 06/04/2020 10:54:18

We don't know what alloy the OP used, so I'd try with the lowest melting alloy (630/660) so as not to melt the joins that are already made causing more holes. For some reason I used to understand, you have to get it hotter to melt it second time, so with care it should be possible to fill in the (closed up) gaps without causing more. Apply the heat to the outside of the shell, not to the side with the solder on

Edited By duncan webster on 06/04/2020 11:40:17

its in the pickle , will try again this afternoon