Clarke cc 1225, leadscrew backlash

[westlin]

I bought a clarke cc1225 milling machine second hand last year. Its ok but alot of play in the screws. I want to convert t a cnc set up but is there a replacement screw setup i could fit to remove the play. New screws probably wont make a difference amd with a 7 month lead time is there a better option (other than a new machine)

[timo]

Westin,

I believe that for CNC, ballscrews are the way to go.

Tim

[uuu]

Two places where play can occur: end-float of the leadscrew, and sloppy fit of nut.

In your cnc conversion, you could eliminate the end-float by fitting thrust bearings - which you'd be fitting anyway if you went for ballscrews. If the nut is sloppy because the leadscrew itself is worn, it means a new screw, because if you can tighten it in the loosest place it may seize elsewhere. If the screw is good, then fitting two nuts with adjustable spacing can very much reduce the backlash.

See Roger's cnc thread here for some good pictures of a ballscrew conversion. Challenge A is to find enough space for the nut. Challenge B is to keep the budget reasonable - ballscrews come in a wide range of prices.

If your Clarke machine is a round-column one, you may have quite a challenge motorising the Z-axis. It will be hard to maintain alignment raising and lowering the whole head, so you may have to try motorising the movement of the quill. It will be hard to remove the backlash in the rack-and-pinion drive system here.

Wilf