Hello Jim You wrote ". . . gear ratios. If there's enough of them you can put on just about any thread pitch you'd want."
True enough, but there are only few American thread numbers or pitches.They are all whole numbers of threads per inch except for some old pipe threads, IIRC. None of them work out to be a multiple or an aliquot part of 25.4 threads/inch, so we can't do 1 mm thread pitch or 0.75, 0.5, etc mm on a lathe made to American thread standards. No lathe is purposely equipped to do non standard threads e. g. 4.25 threads/inch, although it would be technically simple to do so. It would merely require suitable gears and a suitable lead screw. No American lathe that I have seen will cut thirty threads per inch, which is a common threading on British bicycle parts. I have tried on that and failed. I think I have heard of a set of gears and a lead screw for some American lathe that make metric thread pitches doable on that lathe, but that was an odd conversion and not a general condition. So it is not a problem of enough monkey and typewriters or of simply being ornery enough to do it. It is not a problem of enough gears, because there are only so many gears, and all of them have a particular purpose. They are not just out there on the off chance that someone will want some non standard thread. To cut a particular thread, you need the right gears, and there are only so many of them. Lathes will only do what they can do. Look on any change gear box to see the possible threadings. If you need metric threads, you need a lathe that does metric threads. You can't just mess with an American lathe enough until all of a sudden it does metrics, however convenient it might be if you could. _______________________________________________________. Jim Cathey <[EMAIL PROTECTED]> wrote > To: <[EMAIL PROTECTED]>; Mercedes Discussion List <mercedes@okiebenz.com> > Subject: Re: [MBZ] OM603 prechamber cross-threaded edward_baldhead wrote > > > I'm not going to say there's no such animal, but I suspect that lathes > > having the gears and lead screws needed to cut American threads > > do not also have the gears and lead screws needed to cut metric > > threads. > Jim wrote > On a lathe it's all about gear ratios. If there's enough of them > you can put on just about any thread pitch you'd want. > > -- Jim _______________________________________ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
