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Practising flanging the plates Marking out the plates Cutting out the plates Clamping the plates Forming the plates Annealing the plates Forming the plates Part 2. Trimming Smokebox Tubeplate Boiler Barrel Planishing Plate flanges Boiler TubesOr try one of the other pages on building Spencer :-
Machining the Driving and Coupled Wheels
Spencer Start page, frames, Axle boxes, painting wheels
I practised flanging some plates for a small
boiler I had got when buying another project. They came with steel formers and I made a reasonable
job of them though the top corners were creasing a lot. This is them after 7 cycles of annealing and
bashing.
John Baguley identifed them as being for LBSC's Annie Bodie design which he happens to have castings for so I decided to leave them and donate them to him for finishing.
Despite reading Alec Farmers "Model Locomotive Boilermaking" book I made a big mistake when making out the plates. I should have marked out 6mm from the former on the 1.5mm plates (firebox plates) and 8mm from the former on the 2mm plates (throat plate,back head and smoke box plate) Instead I erred on the side of caution and used 15mm for both. This was to cause me much grief
Marking at 15mm
I had bought a set of bench shears for very little money (off that ebay again!) and had managed to find a space for them on the dirty bench. They a very handy for cutting and trimming sheet metal. The scribed line was inked over with a permanent marker pen and then the plate was parted from the main sheet.
The shears are used to trim up the plate as close to line as possible.
The smokebox tube plate was the easiest to do.
I'd noticed other builders using G-clamps to keep the former tight against the backing sheet so copied the idea. This helps to keep it rigid which is essential for forming clean curves. Note the clean and uncluttered working conditions - essential for good results!
I had a quick attempt at forming the plates but as you can see they hardly moved it's probably best to always anneal first. Note the small home made cross pein hammer.
I quench the plates in a bucket of cold water as suggested in Alec Farmers book this removes most of the oxidation.
After forming a second time.
After forming a third time.
After forming a fourth time.
After forming a fifth time.
You can see the material starting to buckle in the top corners this is because the metal there has to be shrunk. I decide to remove some of the excess metal (though not enough!) Using a hacksaw, I found it was easiest to cut the top edge first with the former supporting the plate. As the copper is pretty hard it's quite tough to cut through I found a bit of WD40 helped a lot.
Then the former was removed allowing easier access to the sides. Note use of soft vice jaws.
Here's the cut plates ready for another annealing.
After forming a sixth time.
After forming a seventh time.
At this point I realised I had really cocked up with the excess metal so cut the plates down again using the hack saw. This is with the 1.5mm plates cut down to 7.5mm (6mm flat and 1.5mm for the bend) and the 2mm plates cut down to 10mm (8mm for the flat 2mm for the bend)
I should have set my calipers to 6mm and 8mm when drawing around the formers rather than 15mm! This is the wastage:
I managed to get my girlfriend to take a few pics whilst I was annealing the plates so here you can see the setup.
Here's a good picture of the hearth itself, made from Thermalite blocks. These are a common building material here in the UK and are cheap as the proverbial chips. They are excellent insulators the only downside is they will absorb water so I keep mine under cover when not in use.
I've just removed the heat here and you can see the plate has reached red heat.
After heating to red the plates are quenched in cold water this removes most of the oxide layer.
With the flanges at a more sensible size the forming went a lot quicker and after three annealings the smoke boxe plate and the inner fire box plates were done. The Outer plates needed one extra cycle.
I then took them to show our clubs boiler maker and he thought they were okay. The flanges need to be planished to lose some of the low spots and general tidying up.
The flange was untidy so I mounted the plate in the three jaw and used a parting tool to tidy it up. Note the steel pad and rotating centre applying pressure.
The tube plate was a tight fit on the 3" dia copper tube I will use for the Boiler barrel so skimmed off a few thou in the lathe.
The 3" copper tubing for the boiler barrel was a bit bashed around so I annealed it and straightened it out using the handle of the bench shears as a former.
This looks a bit better!
Next job is to square up one end of the tube. I use the overlapping paper trick which I got from baggo's site.
To stop the annealed tube getting crushed I utilised a handy bit of wood.
A fresh bit of paper was needed whilst filing the end square, the tubeplate also helps to get things right.
With one end square I was able to mark out the length of 6".
It was now possible to use the smokebox tube plate to support the tube (as well as the wood!)
The second end was sawn and filed to size. Easy!
The Boiler inspector had suggested planishing the flanges as they were pretty dinged up from all the flanging.
The planishing hammer in it's element, I found you don't need to anneal so often compared to flanging the plates. The domed end of the hammer is very useful on high spots.
Here the plates are planished and filed to give a good surface to Silver Solder onto. One of the outer plates isn't filed as I still have to form the second flange for the barrel
The tubes were pretty quick to make. I squared off the ends by eye, and then measured off 6" again to match the barrel length.
I rigged up a support to make sawing a bit more accurate, the end of the wood is square so guides the blade. Easy!
Heres the set of tubes, I've cleaned up some of them with emery, they will all get a pickling before soldering.
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