19/4/20 (tonight) 10pm BBC4

[valvekits]

Thanks for giving us the heads up that it was on Jeffrey, it’s the first time I have seen it.
I noticed that they were fabricating the disc holes by some kind of high pressure water injection.
I have had small holes laser cut in sheet steel but under high magnification you can see tiny melted fragments around the hole perimeter which are like volcanic lava, and difficult to de-burr.

Eddie