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12th August 2014, 01:11 AM #16Cba
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- Aug 2007
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Yes, still need a "run out" groove to start. I leave the half nuts closed for non-native threads, so no difference in this regard.
Yes if it is a deep shoulder you need to stop before hitting it when reversing, then turn the chuck manually (or slow down with the VFD or use jog). Agree it is a bit a hassle with those lathes that do not have variable speed nor a back gear to slow below 100rpm. If its only a shallow shoulder, I retract the cross slide far enough to clear.
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12th August 2014, 09:44 AM #17SENIOR MEMBER
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- Jun 2011
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- Australia east coast
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12th August 2014, 03:13 PM #18
Hi Ewan,
Enjoyed watching your video. Neat trick. I made up an adjustable stop, and run low speed to do the same job, but the advantage of running the other way is better finish due to higher speed.
Just to clarify something, you can do metric threads on an imperial lead screw and disengage the half nuts.... the trick is knowing when to re-engage them, in other words which time around on the thread dial is correct.. If I recall correctly I think Stuart did the maths on how many revolutions were required.... it got complicated real fast... in the end it was obvious that it was easier to leave the half nuts engaged and reverse back.
Ray