On 8 Feb 2016, at 10:04, andy pugh wrote: > On 7 February 2016 at 23:37, Marcus Bowman > <marcus.bow...@visible.eclipse.co.uk> wrote: > >> Easy. mount the tool upside down, and start at the blind bottom. > > Sorry, I am not quite understanding your description? >
Yes; apologies; my rather quick response was a bit cryptic... For an internal right-hand thread, the problem is often that the tool feeds into the hole from the right, and bumps into the bottom of the hole. It would be the same for an external thread bumping into a shoulder on the left. Machine the hole to the ID for the minor diameter of the internal thread, then create a clearance groove of 1 pitch width, and just deeper than the thread height, at the bottom of the hole. That blind bottom still a problem if your reactions are as slow as mine, so, unless you have auto-disengagement for the leadscrew, avoid the problem by cutting the thread from left to right, starting with the tool in the clearance groove, applying a cut, and feeding outwards into fresh air. Run the spindle in reverse. The tool can either be mounted against the front wall, upright; or can be mounted against the rear wall, but inverted. (I think I have those the right way around...) I've used this method on both internal and external threads, with front and rear toolposts and with the tools the right way up or upside down, to suit the directions of cut,and it works a treat. The key is to cut away from the blind end or the shoulder (and to take care with spindle direction and tool orientation, both of which can cause local overheating of the brain's visualisation processing area). All much easier with CNC I dare say... Marcus > -- > atp > If you can't fix it, you don't own it. > http://www.ifixit.com/Manifesto > > ------------------------------------------------------------------------------ > Site24x7 APM Insight: Get Deep Visibility into Application Performance > APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month > Monitor end-to-end web transactions and take corrective actions now > Troubleshoot faster and improve end-user experience. Signup Now! > http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
