On 7 Feb 2016, at 22:04, Ken Strauss wrote: > There was an article in Model Engineer Magazine (British publication) on > doing it at home. See Volume 176, Issue 4017, page 464. I have a scan of the > article but it is too large to post. > >> -----Original Message----- >> From: John Kasunich [mailto:jmkasun...@fastmail.fm] >> Sent: Sunday, February 07, 2016 4:47 PM >> To: emc-users@lists.sourceforge.net >> Subject: Re: [Emc-users] Any idea how they machine these? >> >> A post on this page: >> http://yarchive.net/metal/artillery_thread.html >> >> says: >> >> In full size practice the male and female threads are SCREWCUT (not > Milled) >> on specially adapted, relieving lathes with an interrupted indexing > motion. >> This usually takes the form of a special, heavy duty, "geneva" type > motion. >> Contemporary accounts speak of "great crashings and bangings and sudden >> shuddering stops" accompanied by a tool point that moves in and out, under >> cam control, to cut the various thread diameters. >> >> >> >> On Sun, Feb 7, 2016, at 04:35 PM, John Kasunich wrote: >>> >>> >>> On Sun, Feb 7, 2016, at 04:18 PM, andy pugh wrote: >>>> Maybe I should have been more explicit about the question... >>>> >>>> How do you machine an internal part-thread that ends hard against a >> shoulder?
Easy. mount the tool upside down, and start at the blind bottom. A relief groove with a width of of 1 thread pitch is helpful but not absolutely necessary. Works a treat. A second way is to use a thread mill (and I mean a proper thread milling machine) and mill the thread starting at the blind bottom. I've done it externally, using both methods, and internally using the single point tool, but there is no reason why the thread mill would not work. My own thread mill would probably need an extended shaft to reach inside a deep hole, and the cutter would need a minimum diameter of around 50mm (2inches) to get inside the hole. Photo of my home-made thread mill here: http://www.screwcutting.com/The%20Book/Chapters/chapter10.html Marcus >>>> >>> >>> Very carefully :-) >>> >>> This pic >>> http://www.eugeneleeslover.com/PAGE_56_Figure_5B10_C.JPG >>> shows that there was a bit of a relief groove. Cutting speeds in >>> those days were slower (no carbide). They may have simply run the >>> parts slow enough that a rapid-retract toolholder could pull clear in >>> the time it took to travel the width of that groove. >>> >>> >>> >>> John Kasunich >>> jmkasun...@fastmail.fm >>> >>> ---------------------------------------------------------------------- >>> -------- >>> 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 >> >> >> -- >> John Kasunich >> jmkasun...@fastmail.fm >> >> > ---------------------------------------------------------------------------- > -- >> 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 ------------------------------------------------------------------------------ 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
