Thanks, Andy, I now see that I can get as old as a gnu and still learn dazu... Never seen anything like that counter, and wouldn't know where to mount it on the lathes I know. It's a good idea to make a run out groove that way - I usually have to cut it right in the beginning (with a parting tool) before threading starts. But that's the way apprentices learn using a lathe hereabouts. I have seen dozens of them passing through our shop over the years, 3 years each, without anyone mentioning a thread counter.
Peter Am 02.04.2014 16:12, schrieb andy pugh: > On 2 April 2014 14:39, Peter Blodow <p.blo...@dreki.de> wrote: > >> I don't even know what threading dials are and where they are installed, > Here is a typical one: > http://www.practicalmachinist.com/vb/attachments/f25/5191d1216225324-thread-dial-specs-9-junior-9-inch-thread-dial.jpg > > It simply counts the leadscrew threads as they go past. On an Imperial > lathe you can normally re-engage the half-nut on any mark for an even > TPI and on any numbered mark for any odd TPI. > > So, cutting a thread you engage the nut (on a numbered mark for an odd > TPI) and let the carriage move down the lathe. > At the shoulder you disengage the nut and either let the tool cut a > run-out groove or try to do a synchronised retract on the feed screw. > You then move the carriage back past the start of the thread, watch > the thread gauge rotate, and re-engage the nut on a suitable mark. > > On an Imperial lathe there is a single fixed gear on the counter. On a > metric lathe there are sometimes three gears, and you set the counter > to the right height to engage the correct one. The problem is in > knowing which is the correct one.... > > This is a picture of the tell-tale from a metric lathe with 56T and > 60T gears, you can see that some pitches can only be re-engaged at one > particular mark. others at even marks, and some at any mark. > http://members.optushome.com.au/terrybrown/Media/Projects/LatheP1695.jpg > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
