Northumbrian Build Thread

[peteh]

OK - I have made the first (expensive?) cuts, measured at least 3 times ;D and have done a single heat and bend, and then promptly ran out of gas

Nice to have a cooler day for a change

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[Smifffy]

Rock'n'Roll Pete!

[Jim]

Good on ya Pete.
I thought I'd exhausted all excuses for not doing any more boiler work then right on cue you come to my rescue by giving me a new one. 'running out of gas'. Sadly though it comes too late ..I got a refill yesterday. ;D ;D

You're doing a great job Pete and should have Northumbrian up and running in no time.

Jim

[peteh]

Glad to be of assistance Jim I'm not after a speedy build ( as I'm sure everyone can tell!) This is a big learning curve and 'little steps' works for me. I can't get the gas filled until next weekend

[doubletop]

Feb 17, 2013 9:24:34 GMT peteh said:

.............. and then promptly ran out of gas

Australia, the height of summer and no gas? That's a national crime isn't it? Or is it a case of one too many barbies?

Pete

[peteh]

Sacralidge I'm sure - havn't had a BBQ for over a year - I prefer not to have to fight the flies for my meat . However my main torch is MAPP gas and not propane so wrong gas bottle.

[Shawki Shlemon]

Pete , now you are starting the boiler , remember one very important thing and that is clean surfaces before silver soldering and no hurry .You are doing fine and you will get there .

[doubletop]

Pete

On the MAPP torch. Would I be right in saying it would be one of those stand alone units with its own cylinder? I'd suggest you won't get enough heat out of it. The other guys who've done more of this stuff may be able to advise you but I'd suggest that even for this small job you'll need some serious heat to get everything up to temperature.

If you've not done silver soldering before also get some scrap and give it a go to see what happens. For example make an extra smokebox tube plate and an off-cut of the boiler barrel and solder it up. No point in spoiling your boiler. You are unlikely to damage it but why mess up the main job with runs of silver solder you don't want.

Go to the home baking section at the supermarket and get some citric acid. Find a suitable container that will take the boiler barrel, and the other parts. Mix citric acid with water to a saturated solution and throw the parts in there once they are made. They are then guaranteed to be clean enough when it comes to the soldering. chuck them back in after they've cooled a bit and they will be ready for the next stage.

No doubt you know all that so I'll stop rambling............

Pete

[peteh]

Hi Pete,

Done plenty of Silver Soldering with this torch, using MAPP gas burns hotter than the standard butane cylinders. Got plenty of citric acid powder as well, usually cheaper from homebrew places

Never hurts to reiterate useful info so ramble away

[peteh]

Managed to get the propane torch going and did a little more on the boiler barrel (spent most of today making/fixing a new down pipe). Then realised I hadn't made a set of formers for the firebox end so drew it up and did some rough sawing ready for tomorrow (holiday here in W.A.)

[peteh]

Boiler barrel finished

[peteh]

started flanging the firebox plates and having a bu**er of a time of it. Everytime I hit the side flange in the top flange comes out - whats the secret? I have annealed the plate around 6 times now and am getting nowhere with the curved areas or top! Photo later (got to pick up Daughter from Uni.

[Shawki Shlemon]

Pete ,
I am no expert but have some experience in this . I generally do each plate by annealing 3 to 5 times . This is what I do
1- Anneal the plate bright cherry red and dip in the water , clean .
2- Two formers are required , one to shape on and one to support ( the other side of the plate )
3- I use wooden mallet to do the job , when the mallet springs back , the plate is hard , back to annealing
4- I remove mallet marks with the linisher .For the tube plate I remove the marks on the lathe a very light cut or you can use the smooth milling file .I hope this helps .

[RLWP]

Mar 4, 2013 6:42:25 GMT peteh said:

started flanging the firebox plates and having a bu**er of a time of it. Everytime I hit the side flange in the top flange comes out - whats the secret? I have annealed the plate around 6 times now and am getting nowhere with the curved areas or top! Photo later (got to pick up Daughter from Uni.

Can you rest a weight of some sort against the bit that is springing out? A big hammer head would do, or a lump of steel. Something to put a bit of momentum into the part you don't want to move.

You may run out of hands doing this

Richard

[jma1009]

hi pete,
shawki is absolutely right.
i find the inner firebox plates the most difficult to form. dont worry about the sides to start with.... get the top curves and top done first say 3/4s formed before touching the sides. the sides are easy and best left till last, and cause problems if you try to do all round at the same time as you have found. the copper must be held tight against the former so you need something of the right shape pressing against the outside of the plate. i also make the plates longer than required, fixing a few screws in the bottom into the former and through where some of the tubes go and firebox door. the slightest movement of the former against the partly flanged plate will push the flanges back out. a few hefty biffs to start with are better than being gentle! i can usually get the plate 1/2 formed at the first annealing...it's getting it that last amount that requires lots of annealing. towards final shape on the curves you might only get 2 or 3 bashes before annealing again. straight sides will obviously move a lot more at one annealing...so you have to concentrate on the tougher curved corners first.
cheers,
julian

[doubletop]

Pete

The plates need to be a dull cherry red and then dunk them in water, it doesn't matter if you don't quench but it speeds up the cycles and as Shawki says it keeps them clean. They should be pretty pliable to start with and you could bend them slightly with your fingers

I just clamp the copper sheet against the former in the vice and work round gradually bringing the flange. Once the anneal goes off reheat and go again. Anneal a batch of plates together in one heat, wack them all then re-anneal and so on. That way you are not spending too much time going back and forth.

You'll be amazed how well you can work them. A wrinkly flange as the metal is compressed may look like a lost cause but can be worked until all the wrinkles go. Don't worry too much about getting the depth right. I make the flanges oversize when you are done clamp the plates flat on the mill table and machine them to the correct height. Far easier than faffing about trying to get them right with a hammer. I have done it on the faceplate on the lathe but running round the edge on the mill is easier. Don't re-anneal before doing this they need to be hard otherwise the mill may snatch the soft copper.

This was from another boiler

Rough cut plates



raising the flanges in the vice



A batch completed



Milling flanges to height



Done



Hope that helps


Pete

[peteh]

Thanks you gentlemen for your quick replies. I think I have found the main problem in that my initial plates were too deep. Oz codes require 3x minimum plate thickness from the tangent point of the radius, since the radius is minimum 1 plate thickness this generally means we need 4x plate thickness. For the firebox this means 4 x 1.6mm = 6.4mm, mine are around 35mm deep

I think once I bring down the height of the sides it will be all good ;D

I'll put it down to being over cautious and making sure I had plenty of metal spare

[peteh]

Firebox plates - 35mm high !

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[RLWP]

As you can see, because you are forcing a segment of a circle into a cylinder, there is a lot of metal trying to flow in that corner. Cut thos flanges shorter and you'll find things much easier

Richard

[peteh]

cheers Richard