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 -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
