Leadscrew nuts

This topic has 11 replies, 5 voices, and was last updated 17 February 2017 at 13:38 by Mike Poole.

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16 February 2017 at 19:50 #284669
Peter Simpson 1
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@petersimpson1
My Tom Senior Light vertical suffers for a 2.5mm backlash on the Y axis, does anybody know who / where I could get a new leadscrew nut manufactured ? I could fit a DRO but would like get the backlash down to more tolerable levels.
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16 February 2017 at 19:50 #25083
Peter Simpson 1
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@petersimpson1
16 February 2017 at 20:10 #284672
John Chapman 5
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@johnchapman5
My Tom Senior needed a nut purchased a couple of nuts from Roton in the states PM I might have a spare nut.

John
16 February 2017 at 20:22 #284674
Mike Poole
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@mikepoole82104
Is there really 2.5mm of backlash in the nut or is there some other part that is loose like the nut or screw mountings letting things float around a bit?

Mike
16 February 2017 at 20:33 #284675
Peter Simpson 1
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@petersimpson1
Hi Mike,

I'm sure the 2.5mm is in the nut.. I measured 2.5mm in various positions across the full travel of the table. There is only 0.6mm backlash on the X axis.
16 February 2017 at 20:47 #284676
Anonymous
It does seem a lot, what is the pitch of the leadscrew? One would have expected the X-axis to wear more than the Y-axis as it normally gets more use.

Andrew
16 February 2017 at 20:54 #284677
Peter Simpson 1
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@petersimpson1
Not sure of the pitch I will remove the table tomorrow and do some investigations.
16 February 2017 at 21:01 #284679
Mike Poole
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@mikepoole82104
What I was thinking Peter is that 2.5mm is likely to be near the pitch of the screw although I am not familiar with that mill. It seems common practice is for the nut to have a boss that fits a hole in the casting and is often retained with a bolt. If this has come loose maybe the nut can float around giving the effect of backlash. The screw must also have a method of axial location so that no motion is lost. If the screw pitch is 1/10" then it would be very close to total failure if the pitch is any finer then the nut would already have failed. The nut being loose or the screw floating in its mounting would give the same effect in all positions. It might be worth a bit of investigation before investing in a new nut.

Mike
16 February 2017 at 22:25 #284691
Chris Evans 6
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@chrisevans6
Buy a length of lead screw and a suitable nut from one of the many suppliers. Cut to length and turn the ends to suit. Adapt the bought nut to suit your requirements.

I have already done my lathe cross slide and next up will be the Bridgeport mill as it is now running out of adjustment. It will be a fraction of the cost of a genuine spare part.
17 February 2017 at 09:47 #284724
Peter Simpson 1
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@petersimpson1
Mike

I stripped the machine this morning and as you suggested the lead screw nut had worked loose. When refitted and tested the backlash is now a respectable 7 thou.

Many thanks Peter
17 February 2017 at 09:58 #284726
Anonymous
The simplest solutions are the best.

Andrew
17 February 2017 at 13:38 #284768
Mike Poole
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@mikepoole82104
Apart from a bit of time that makes a cheap and simple fix. 7 thou sounds very reasonable, glad it was nothing serious

Mike
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