Making a smokebox door using a brass doorknob
James AitkenGauge O Guild
Technical team
I've been busy building myself a model of the LSWR 700 class black motor from the Sanspareil kit. A friend had bought the kit second-hand and passed it to me. It’s an old kit, probably hand drawn and as usual has a few issues, but one thing I discovered was that the cast smokebox door was just a little bit too small for the brass etched ring it was supposed to fit against.
On a visit to Kevin Wilson’s workshop, he was telling me how he makes tender fall plates by bashing a piece of brass or nickel silver on a large diameter brass bar held in a vice. This gave me an idea. Could I find something spherical to form a smokebox door on?
It’s funny how the mind works, because when I was in the garage looking for something else, I found an old cast brass door knob and realised that it would do the job. Craft shops sell hardwood balls of various diameters, so that would be an alternative.
You need to cut the disc of material to the size required, then tape it to the top of the doorknob and bash it hard with a rubber mallet. Don’t use a metal hammer as that will dent the disc. I haven’t tried a wooden mallet but I suspect it isn’t soft enough.
Bash it evenly round the disc. Once taken off the doorknob, lie it on a flat surface to check that it is evenly curved all the way round, and if not put it back onto the knob and bash just the edge that isn’t quite
touching the flat surface.
Once done, round the edge using a file, fit a hinge from some thin scrap brass and suitable rod and decorate as appropriate for the model. This one has four clamps on the bottom edge. It also has two lamp irons but I was waiting for those to arrive in the post.
