Been working on the frame and plates for the boiler.
I followed the recipe for the frame - using brass angle strip, but decided to silver solder the joints (I ran out of csk screws, and did not find that the screwed joints were very strong anyway).
The top and rear plates are from that "strange" material I scrounged from a metal fabricator's scrap bin. Turns out it is 301 stainless (1.5mm thick). Hence the problems in drilling/machining out the odd holes for the boiler top fixtures. It cuts easily with a chop saw (cheapo angle grinder with Bosch 1mm blade from APT - cuts beautifully). The front plate needs two large cut-outs :- for the boiler end plate and fire hole door below. Doing that work in 301 stainless is really going to be a pain, so I shall use some 2mm aluminium alloy sheet I also scrounged. (I know - in the recipe, T.C. says not to use ally. but I have nothing else and 2mm thick should be strong enough) The side plates will (probably) also be from the stainless - but they also have a number of air holes to be cut in them.
The chimney is copper water pipe in a flange of bits of larger diameter pipe from the scrap box - all yet to be finished.
Thanks Paul. I've got two brands etching primer/thinners which I have used before on brass fittings for a ship (airbrushed) - I never seemed to get a good result from using it though. I may leave the outside plates as "polished" - if I can bling them up enough.
Had a lot of problems lately so time in the workshop has been curtailed for a while.
Next on the list is a means of firing the boiler.
TC's article suggests using Meta (solid fuel) in a custom burner tray. Simple and easy to make and something I might try later on if I can source the tablets - (HELP PLEASE?) any help on this would be appreciated.
I would really like a rectangular ceramic burner/lpg system, but cannot afford this now.
The only other alternative is a spirit fired system with wick type burners. Much good information and ideas gleaned from books by Stan Bray, K.N. Harris and the really old re-print booklet by G L Pearce. I managed to locate a source of fat - candle wicks and the larger - flat (former Aladdin paraffin heater and paraffin - lamp) wick in our local ironmongers - at very good prices. Armed with a few lengths of each type, I decided to fabricate a spirit burner.
The burner/tank is an amalgum of ideas illustrated in those books, including a modest heat - sink/finning I silver soldered this from lengths of brass and copper tube and made a little tank - tilted slightly to keep a feed dribbling through the delivery pipe - which is cross-slit at the base of each burner using a slitting disc in my Dremel.
I made "hats" for the burner tubes, slotted to take the paraffin wicks.
I test fired the burners with meths and surgical spirit (too oily I found out!!) The burner worked o.k. but the wicks didn't seem to trim well to provide a clean flame.
Whilst trawling the net for help, I found a reference to loco spirit burners for O and 1 gauge (American), using porous refractory material as a plug - type wick in the burner tubes. Thermalite block as a suitable material came to mind. Light, not too crumbly and easy to cut and shape. A trip to our local builders' yard and an explanation to a bemused foreman, and I was presented with a giant block to work on.
It cut very easily with a carpenter's saw, and I mounted an off - cut on the cross slide, supported by the tailstock drill against a "trephine" made from copper tubing to fit inside the burner tube. Teeth simply filed across the edges.
Now all I have to do is file a semi - circular step in the bottom of each "plug" and cut to length. Will post more after further experimentation - I think it ought to work!!