Saturday, March 31, 2007
Whatever, the Armstrong chimney looked like it had been filled in with lumpy earth so excavation would be needed.
I carefully measured to find the centre and then tried to drill out with a single reasonably sized drill bit. This isn’t the first time I’ve done this and I know the pitfalls. Start in the wrong place and you’re going to be trying to carve away the leftover infil on one side. Use too large a bit and you go through the sides as the chimney tapers. Too small and there is a fit lip left at the top.
Even the drilling is fraught. In a perfect world a pin vice would be employed for ease of control, but who owns one big enough for the required bit ? Even if you did, working through the lump of metal would be really hard work.
My solution is to use an electric screwdriver with a chuck. The bit rotates slowly so you keep control – or at least stop if you start coming out the side.
I didn’t quite get this right but the repairs with a wipe of low melt solder are easy and the resulting chimney is pretty nice. Most importantly it looks hollow.