S7 leadscrew

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S7 leadscrew

This topic has 5 replies, 3 voices, and was last updated 18 April 2016 at 07:53 by richard 2.

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16 April 2016 at 15:19 #234838
richard 2
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@richard2
Hi everyone

The leadscrew on my S7 is very difficult to turn making advancing of the carriage 0.001" very difficult.

The carriage moves smoothly and easily, everything is oiled (including my hands- courtesy of the Swiss made oilgun) but still no joy.

Does anyone have any suggestions, please?

What has happened to the Yahoo "Myford Groups" – I cannot get any joy there.

Regards and thanks to everyone.

Richard.
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16 April 2016 at 15:19 #12673
richard 2
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@richard2
16 April 2016 at 15:36 #234841
John Haine
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@johnhaine32865
I assume that you have disengaged the leadscrew from the spindle with the tumbler reverse? It will still be driving all the feedscrews, and in the "wrong" direction as the gearing from l/s to spindle is "up". If you just want to use the l/s handwheel for small movements, best to disengage the screw from the gear train by slackening off the banjo and sliding out of engagement.
16 April 2016 at 16:50 #234851
John Haine
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@johnhaine32865
Posted by John Haine on 16/04/2016 15:36:54:

I assume that you have disengaged the leadscrew from the spindle with the tumbler reverse? It will still be driving all the feedscrews, and in the "wrong" direction as the gearing from l/s to spindle is "up". If you just want to use the l/s handwheel for small movements, best to disengage the screw from the gear train by slackening off the banjo and sliding out of engagement.

Apologies, I should have said "driving all the changegears"!
16 April 2016 at 17:06 #234852
Simon Williams 3
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@simonwilliams3
I'm just wondering if you have the half nut engagement adjustment set too deep. The half nuts have an adjustable stop by means of an allen screw and a spring, if this was allowing the half nuts to clamp down on the thread instead of just engaging it this might give you the symptoms you describe.

HTH Simon

Edited By Simon Williams 3 on 16/04/2016 17:07:21
18 April 2016 at 07:53 #235057
richard 2
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@richard2
Many thanks, everyone.

Went into the workshop and realised that, the vendor would have had the lead-screw off to shorten it.

So i managed to adjust the half-nuts (more or less by guesswork as I do not know how it should be done) as when I engaged them the lead-screw was even stiffer to turn; I loosened the nut on the lead-screw hand-wheel and tapped it slightly away from the bracket (using a short piece of ali rod and a plastic hammer) and it spun round with no stiffness at all.

So job done and the lathe is now lovely to use and I can move the carriage 0.0005" according to the DRO.

Many thanks to all you good people and I am off to the workshop to make a couple of 3/8" BSF screws.

Richard.
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