Thanks for the friendly and helpful replies, lots of useful food for thought. I have to say I've haven't yet used any of the Silverflow alloys so I'm perhaps pre-judging them on what I've heard. I have used Argo-braze 56 simply because I was able to get some very cheaply and have fount it rather difficult to use compared to Easyflow, of which I still have a few preciously guarded sticks. To be fair though Argo-braze is a specialist application material not intended for the general purposes I use it for. The suggestion by Durhambuilder of using vermiculite board for heat containment triggered a thought so I tested the heat resistance of some of the missus's gardening vermiculite and found it has potential for piling up around the job like the old books advise with coke, I also like his method of encasing the barrel in a chimney liner.

I would still be interested in knowing what equipment others have used to successfully silver-solder similar boilers before I invest in a torch.

Ian.

Thanks again for the replies.

Les, The "Boiler Making Hearth" thread is interesting, one post mentions using a barbecue which is exactly what I am using at present, mine is lined with radiants from old gas fires, I will need a larger one for the planned boiler though. I'll also get some thermalite blocks from B&Q as they are said to work well at very low cost.

Julian, it is encouraging to know that your Sievert equipment did the job, I think the cyclone burners may achieve a higher flame temperature than the standard power burners as they are the only ones recommended by Sievert for brazing, although they quote much smaller maximum pipe sizes than a boiler barrel! Unfortunately the 3526 burner is now discontinued, the largest now being the 3525 with a 10kw output. I will be watching ebay for a used one though. I noticed two gas bottles in your photos and did wonder if you were using 2 torches. I don't know what Calor's exchange policy is at the moment but hopefully I can temporarily swap one of both of my 6kg caravan propane bottles for larger ones.

Ian, I do have a copy of Alex Farmers excellent book, acquired at great expense as it's apparently something of a collectors item now. Unfortunately, as you say he uses oxy-acetylene which in these days of H&S and fire safety legislation is very difficult in a domestic environment. For me it's a definite no as quite apart from the cost I simply do not have the space to comply with BOC's risk assessment requirements for storage of acetylene cylinders. I also hate to think what my home insurers would say about it!

Ian

Cheers Ian, I know they introduced some restrictions a few tears ago meaning cylinders could only be exchanged within "groups" however the following year my local supplier told me that policy had been abandoned.. I hope that is still the case.

Thanks Julian for your informative reply.

At the weekend I managed to acquire another calor gas bottle and traded an empty propane for a full large one, also purchased a decent used Sievert torch and a quantity of Silverflo 55 so I'm getting organised. I already have the copper sheet for the plates and so made a start on flanging the backhead at the weekend. It was surprisingly easy getting it up to annealing temperature packed in refractory blocks but as you have said the heat throwback is considerable and I did feel something like a fireman on a full size loco.

I am planning to produce the tapered barrel by rolling it round a wooden former of the correct shape, my plan was to use a plain castelated joint but your much appreciated comment on the acceptability of this type of joint means I will need to seek advice before committing myself. I have no objection to using a jointing strip either internally, externally or even both. The biggest problem with the barrel at the moment is buying, or at least paying for the large sheet of copper from which to make it! I do plan to use plain silver soldered stays fitted before the doorplate and backhead go on.

I totally agree that the temperature can be better judged indoors but my confined space means I will have to work outside, at least in the later stages of the job which will mean avoiding sunny days. I can't see that having having much effect on available hours though and it will at least save having to use a patio heater to keep others warm!

Thanks again,

Ian.

Hi Bob,

thanks for your comment. unfortunately I doubt that storage heater bricks are ideal as they are designed to absorb and hold as much heat as possible meaning that quite a lot of heat would be wasted heating the blocks as well as the boiler up. I think a lightweight refractory material such as vermiculite which has both heat resisting and insulating properties would be more suitable. I've read elsewhere that some model engineers have found ordinary lightweight concrete building blocks to be perfectly satisfactory and given that they're the size of six bricks and about a quid each I'll be trying some.

Ian.