29-08-2020, 10:00 PM
(29-08-2020, 08:51 PM)Bob Culver Wrote: The tricky part is turning thin discs in the lathe from sheet (other than parting off from solid). What was your technique? Can be dished by hammering into a hollow or hole in a block of wood .I tried that some time ago, turning blanks from a steel bar, but it was very difficult to get them right - and dishing them into a turned hollow was not successful. The brass ones I made had vertical sides with flat tops and bottoms - but made to be a very tight fit, assembled with a smear of Araldite and driven into place with a hammer and punch. Having made one a firm sliding fit as a trial, the next was made 0.005" oversize, frozen for a couple of hours and fitted to a hot cylinder head. The brass core plugs in the spare head that I examined had material peened over the edge of the hole - and so appear to have been made with either a narrow top-hat section or just surplus material sticking up above the level of the head.