[Galane]

I'm looking for an 8mm diameter ball screw with at least 140mm / 5.5" travel, with a compact nut. The channel in the saddle of a 9x20 looks like it can be milled out to just over 3/4" wide without compromising the strength of the dovetail. With a compact nut the sides of the channel wouldn't need to be cut straight down. Could cut through the back end of the saddle to mount an end bearing on the outside.

I've found some sources for new ones like that but my bank account puckered up tight at the $400~600 price! For that I could buy the Thompson kit with ball screws and some motors and drives.

[RCaffin]

You get what you pay for.

Have you tried eBay? Caveat Emptor of course.

Cheers
Roger

[bozidar22]

Did a google search and found this.

R0801 C7 ballscrew - Miniature Ballscrews (6-12MM Diameter) - C7 Ballscrews - Ballscrews - Mechanical

[RCaffin]

Just be aware that the C7 grade of ball screw is really only suitable for opening windows. The specs are really sloppy. That's why they are cheap. (C7 and up are rolled; c5 and down are ground.)
The smaller the number, below 7, the better. Look it up.

Cheers
Roger

[louieatienza]

C7 is .002"/ft, not too bad. They do make some ground screws with C7 rating though not common. Some folks rebuild them with slightly larger balls to take up slack but that requires careful sizing of balls.

I do have in my possession a NSK ground ballscrew, 8mm dia, 2mm lead, with FK8 bearing C3 accuracy all NOS I give you a deal on.. Don't remember the travel or OAL....

C5 about .0005", C3 about .0002"...

[jfong]

I have 46" travel NSK ground ball screw that is marked C7 that I bought on eBay for cheap. I plan to use it on a CNC that will be only be cutting wood. I think it should be good enough for that purpose. My guess is that it was suppose to be a higher grade ballscrew but did not pass tolerance. Anyway it probably better than the rolled Chinese ballscrews.

[Galane]

C7 is .002"/ft, not too bad. They do make some ground screws with C7 rating though not common. Some folks rebuild them with slightly larger balls to take up slack but that requires careful sizing of balls.

I do have in my possession a NSK ground ballscrew, 8mm dia, 2mm lead, with FK8 bearing C3 accuracy all NOS I give you a deal on.. Don't remember the travel or OAL....

C5 about .0005", C3 about .0002"...

If it's a foot or so long I may be interested.

[louieatienza]

What happened to the 5.5" of travel?!

[RCaffin]

Hi Louie

Well, maybe 5.5" of travel, plus 3" for a longish anti-backlash nut, + 2" for turning down at one end for bearings and pulley, plus a little bit at the other end to go in a loose housing, might come close enough to 12"? It's amazing how dimensions add up.

Cheers
Roger