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Mill lead screw thread size

lead screw pitch size

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kevin parr08/04/2022 17:23:13
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8 forum posts

Hello all ,Hope your keeping safe.

I have a chester 16 milling machine and i want to convert the x-axis to have a stepper motor so it does all the hard work for me so how do i find out what lead screw or ball screw to get i have taken the bed off to get at the lead screw ( sorry if that the wrong name ) but there are no markings on it to tell me what the pitch is so how do i find out this information

many thanks for your time

kevin

Martin Connelly08/04/2022 17:38:16
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2137 forum posts
222 photos

The pitch does not really matter. You adjust the stepper motor steps/step rate to suit the pitch. The thing to look at is the diameter that you can fit in and the size of the associated ball nut. If you intend to use the ball screw manually as well then you may need to make a new scale for the handwheel. Adding a DRO would make the handwheel scale redundant and would be a far better option to go with a motor driven leadscrew, you can traverse large distances without having to count revolutions of the lead screw.

Martin C

DC31k08/04/2022 18:09:56
686 forum posts
2 photos

What Martin says is correct, but if you do need to know the pitch of your existing one, put it back together, make a mark spanning the moving bit and the fixed bit, turn the handwheel ten full turns and measure with a ruler how far it has moved. Divide that measurement by ten to find the pitch.

Martin's point about the nut is to be taken very seriously - often the biggest challenge with a conversion of this type is finding the space to fit the nut in - a ball nut for any particular diameter screw is considerably larger than a conventional nut for the same diameter.screw.

Les Jones 108/04/2022 18:12:02
2257 forum posts
156 photos

You can work out the pitch from the graduations on the hand wheel scale. The pitch is the distance travelled for one revolution of the hand wheel.If there are no graduations measure how far the table moves for 10 revolutions of the hand wheel and divide that distance by 10.

Les.

John P08/04/2022 18:24:38
406 forum posts
257 photos

Posted by kevin parr 08 04 2022 17:23 :13


Hello all ,Hope your keeping safe.

I have a chester 16 milling machine and i want to convert the x-axis to have a
stepper motor so it does all the hard work for me so how do i find out what
lead screw or ball screw to get i have taken the bed off to get at the lead
screw ( sorry if that the wrong name ) but there are no markings on it to
tell me what the pitch is so how do i find out this information

many thanks for your time.
kevin

From what you have written here you don't need to
replace the lead screw at all as it seems you only
want the stepper motor to provide a power drive.

As the machine it seems will still be used as a manual
machine a ball screw is more trouble than it is worth.

John

JasonB08/04/2022 18:31:30
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Moderator
22751 forum posts
2653 photos
1 articles

As John P says it sounds like you just want an X-axis power feed so no need to change screw or nut, just make an adaptor so you can get drive from the stepper to the opposite end of the screw to the handle. Arrange some form of clutch or way to disengage the stepper so you can still use the handwheel when needed

Peter Greene 🇨🇦08/04/2022 18:41:32
513 forum posts
6 photos
Posted by DC31k on 08/04/2022 18:09:56:

Martin's point about the nut is to be taken very seriously - often the biggest challenge with a conversion of this type is finding the space to fit the nut in

... that and the fact that when you have the table apart to do the modifications that you almost certainly will have to, you really need another mill to do said mods.

frown

duncan webster08/04/2022 19:00:22
3989 forum posts
65 photos

You don't need a clutch, just wind the stepper round by hand at the same time with the driver disabled. My leads crew is 0.1 pitch, driven 1:1 by stepper via tooth belt

not done it yet08/04/2022 19:10:44
6812 forum posts
20 photos

Weelll, when I put a windscreen wiper motor power feed on my Raglan, all I needed to do was arrange a disconnect-able drive to the end of the feed screw and connect the drive to the table and feed screw.

I simply drilled and tapped the non-hand-wheel end of the feed screw, when the mill was apart. Nothing more needed. Same screw, same feed screw nut - it is only a power feed.

kevin parr08/04/2022 20:20:51
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8 forum posts

Many thanks to everyone who has replied i have a lot to take in but a power feed looks like the way to go

thanks again

kevin

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