Has anybody here done enough witch-wanding to have a good idea of how much it can change, say, the rear space of a frame. Is changing a 130 rear space to 135 within it's capabilities (the bridges haven't been installed)?

Any other tips, like how hot (color), do you do it in steps, that sort of thing. Do any videos exist? I have the witch-wanding article in BQ V12, No. 4 but I thought I'd seen a video somewhere, too.

I'll report the results of a test I've set up, and plan on doing today, with a BB shell and a couple of chainstays but if anybody else has experience to share it would be helpful.

Hat tip to Freddie Parr who mentioned this technique a long time ago. He was a good guy.

Thanks in advance.