Pultra lead screw

Dell, mine is metric,but your nut looks rather long. I wonder if yours was made with the intention of being cut into two at a later date. If not , can you see a purpose for the grub screw holes?

dave.

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I had the same thought, Dave … but you expressed it so well that I shall just add +1

MichaelG.

Edited By Dell on 07/10/2022 21:41:18

Dell If you "search" this site for "pultra" ( stripped thread) there is one identical to yours.

dave

Another useful reference from this forum: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=146290

MichaelG.

This might be handy for general reference:

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MichaelG.

Dell, the anti backlash idea is not to put a twist in there, but to adjust both sides together (and parallel) to remove thread siackness.

dave.

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The shoulder slides neatly into the recess … which prevents tilt between the two components.

The adjustment is designed to be axial

MichaelG.

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Edit: __ Dave posted whilst I was typing that

Edited By Michael Gilligan on 07/10/2022 22:59:17

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Sorry to intrude, Dell … Was that line meant for NDIY’s attention ?

MichaelG.

Dell ,I think I have seen the reason for your confusion. You effectively have through holes for the grubscrews. If you look at the earlier pics you will see the smaller threaded piece has no grubscrew holes. That is what the grubscrews bear against. You probably had them bearing against the topslide casting.

dave.

Here is an extract from Pultra paperwork it seems they changed the nut to two piece in the 60’s and to metric .

And yes sorry Michael it was for NDIY

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Those are interesting references, Dell

Thanks for sharing them

MichaelG.

Hi dave

I can see the logic when the nut is 2 piece but with the 1 piece if they are adjusted up evenly then all you are doing is moving the nut out not taking any slack up unless it’s adjusted at a slight angle, even then it’s not taking slack it’s just making the nut tighter on the thread.

anyway my friend has decided to sell me some metric dials leadscrews and 2 piece nuts so I can convert my on to metric and have bigger handles.

thanks for all the input Dell

Dell, I know this has dragged on a bit,but could I ask one more question? I could kick myself for not asking sooner,but does your other slide look the same?

dave

Looks identical in the picture but until I get it I can’t be sure.

Dell

This is what I have coming hope they fit.

Dell

No, I meant does your present cross slide look the same as your present topslide regarding the feed nuts?

dave

Edited By david bennett 8 on 08/10/2022 13:17:29

Edited By david bennett 8 on 08/10/2022 13:18:12

Sorry David

I misunderstood yes the nuts are identical, the screws I have coming have two piece nuts and I think that is a much better idea.

Dell

Well the metric leadscrew and nuts arrived the reason for the earlier crosslide only having one single nut is that the leadscrew also screws into the brass part in the centre of the slide, and the later ones don’t hence the 2 part nuts, also the leadscrew nuts on the later metric ones are larger although the are very similar shape, hence the later metric lead screws and nuts won’t fit earlier slides.
Dell