Tuesday, 7 February 2012

How to make an ashpan (3)

Part 2 of this series covered the marking out and cutting of the ashpan base plate. Now the the curved walls needed to be rolled to the right radius and welded in place.

Until now, I'd never seen, let alone used, a sheet metal rolling machine so this was a bit of an adventure.

Sheet metal rolling machine
The rolling machine is not difficult to use; the front two rollers are adjusted to be parallel and to grip the metal being rolled. A third roller at the rear is positioned using the handles at each end. To create a bend, the metal sheet is wound through using the handle on the right and progressively forced upwards by the rear roller. After a few passes with the rear roller being raised each time, the correct curve can be created.

One or two problems can arise; the sheet has to be put in exactly at right angles to the front rollers otherwise a twist is created in the sheet that is hard to correct; it is possible to create an uneven curve or too tight a curve. I found I had to feed the sheet back in to take some of the curve and twist out before re-rolling to the correct curve. Some twist did remain and so one of the walls is slightly angled in - not critical but I like to do better.

There is also a good deal of hammering to get the curve at the ends beyond where the rollers can reach - not pretty but effective!

Apologies for no video of this - it was pretty physical and not conducive to camera work! (Oh OK, I forgot!).

Skipping ahead to after the walls had been rolled and welded in two parts to the base plate.

Base and walls welded together (MIG for inside corner weld)
Right hand inside MIG weld
Left hand inside MIG weld (not quite so tidy!)
MIG welding was good for the inside weld because of the length involved and the need for filler to be used to build up the corner strength.
Left hand outside TIG weld
TIG welding was ideal for the small outside corner weld; two 3mm thick plates corner to corner don't want anything heavy duty and only a small amount of filler! The welds came out pretty tidily but certainly benefited from cleaning up with an angle grinder.

Joint in the two side-wall pieces
The two side-walls had a small gap to be filled between them. I used a MIG welder for this, filled the resulting holes with an oxy-acetylene torch and tidied it up finally with an angle grinder. MIG can be a beast at times!

Then I discovered I'd missed my vocation in life; rather than an ashpan, I seem to have created a simply amazing GONG! I'd left the ashpan leaning against the bookcase in my hall at home (I have a very tolerant wife!). On tapping it with a finger (or later a rubber mallet), I was greeted with a marvellously musical ringing tone. Try this (best on headphones, loud, or on a home cinema system!). (Also on YouTube).

video
After all the work finding and renovating a whistle, perhaps it won't be needed after all (although perhaps a gong is an unconventional method of locomotive greeting!).

To be continued!

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