On 8 Feb 2016, at 12:49, Peter Blodow wrote: > In other words, you pretend to cut a left-hand thread but have the > machine run in reverse so it turns out right hand? > Peter Blodow > Yes; kind of.... I prefer to think of it as cutting a right hand thread upside down (or is that inside out?). There are four factors: spindle speed, direction of feed, tool upright or inverted, and tool facing the front wall or the rear wall. Where the tool must traverse out of the hole and the blind end is at the spindle end, the ones that work for me are: spindle reversed and feed towards the tailstock; and [tool upright, facing the front] or [tool inverted, facing the rear]
If you use a thread mill it just takes the place of the single point tool, but mills (or flycuts, essentially) rather than forming the flanks with a stationary tool. Unless you have the kind of giant tool arrangement mentioned in John Thornton's post. The mind boggles. Marcus > Am 08.02.2016 11:42, schrieb Marcus Bowman: >> 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 >> > > > --- > Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft. > http://www.avast.com > > > ------------------------------------------------------------------------------ > 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
