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.

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

… 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.

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.