Mini mill & ballscrews

Hello All

I've recently bought a Clarke CMD10 (Sieg X1) mini mill to play with in my retirement. Yes, I know I could have got bigger & better, etc, etc, but for the small stuff I want to do, this is a good starting point. Upgrades will follow but I'd rather learn & become more confident with basics first.

My first issue is with the agricultural leadscrew arrangement on the X & Y. Ballscrews appear to be the way to go but the 12mm ones won't fit and 10mm ones are as rare as an honest politician and cost the same as a third world debt!

On such a small machine, is there any valid reason (not opinion) preventing the use of the more common 8mm ballscrews? I know a 12" deep cut in one pass will be out of the question and I can live with that but could a supported 8mm screw be man enough for general light work & small pieces?

Iain.S

I have a slightly larger mill a Chester 16V and I have changed the z Axis for a 12mm ball screw but i would have used a larger if i could have fitted it in. I think you would have problems with 8mm ballscrew being very light. Usualy the axis nuts are adjustable with a screw to close the nut and reduce back lash. Perhaps you can fit thrust bearings to the handwheel end to reduce any play there.

David

Previous discussions here and here may be helpful

Is it a problem of rough feed or backlash that you want to change the screws for? If backlash as has been said adjust the split nut and spend your money on a DRO.

As Jason says, plus fit ball or roller thrust races to the handwheel bearings. And see Mikes Workshop for many other improvements to the X1 mill.

Are you considering upgrading to cnc? If not I wouldn't fit ball screws as they will not stop the slide moving under load. They are reversible unlike normal lead screws.

Russell

Many thanks for the positive responses chaps. They've been really helpful.

Upgrading to CNC level is a step too far at the moment, so I'll rule that out and stick with manual operation.

The main issue is as Jason suggests, with rough feed & backlash. I've played with the split nut block under the tables to try & reduce backlash but find that it's a very fine adjustment between a sloppy bed & binding screw which is why I thought about ballscrews.

Having scanned the various posts suggested (plus a few others), I think I'll do as you recommend and go with installing bearings & thrust races to the handwheels. A replacement, longer X axis bed was planned anyway, and it'll need a longer screw so I'll start with that. Will order a boring bar & replacement bearing block to play with. Arc is going to have a regular customer over the next few months .

A belt drive conversion kit (mbbilici) & DRO's will be next on the list.

Once again, many thanks.

Iain.S

If not I wouldn't fit ball screws as they will not stop the slide moving under load.

Screws are provided to move slides. Clamps are provided to stop slides moving under load.

Nigel B.

So you fit a ball screw which may allow the work to be dragged into the cutter because the helix angle and friction aren't enough to prevent it. Then try to control it by tightening the gibs?

I wouldn't but to each his own.