[bmklawt]

How do I tell if this is a ground or rolled ball screw, My first thought was it is a ground ball screw but then I noticed the groove on the land which I have seen on a lot of rolled ball screws.
All I know for sure about the ball screw is it is at least 12 yrs old.

If it is a rolled ball screw is it worth sending out to be ground, if that is even possible with a rolled screw.

[RICHARD ZASTROW]

Appears to be a rolled ball screw. I would ASSume a rolled ball screw could be rolled over-size then ground to final dimensions later.

I do not know if a rolled to final dimension ball screw can be ground as a substitute for an original equipment ground ball screw.

Maybe mikeKilroy knows.

Dick Z

[hub]

It's rolled. The extra groove comes from the rolling process. (I don't know why exactly).
The ground screws I have do not have the extra groove.

Hub

[RomanLini]

It's rolled. The extra groove comes from the rolling process. (I don't know why exactly).
...

Yep. The "extra groove" you described is the space between the displaced material, displaced from the middle of the grooves to the outer edge during rolling.

[mike_Kilroy]

Appears to be a rolled ball screw. I would ASSume a rolled ball screw could be rolled over-size then ground to final dimensions later.

I do not know if a rolled to final dimension ball screw can be ground as a substitute for an original equipment ground ball screw.

Maybe mikeKilroy knows.

Dick Z

ha!just cuz we r thomson screw distributor? i can say i never heard of someone grinding a rolled screw... why do it? for more accuracy I assume? but i think the .003" typical (OTOMH) per foot accuracy of a rolled screw is due to the rolling process: it goes thru a threader and so it comes out other side stretched and schrunk up some; ground screw has .0003" (IIRC) per foot typiucal becasue it is ground to exact dimensions, not forced/oozed thru a threading head. so seems to me like grinding rolled screw cannot help accuracy cuz the threads are in the wrong place.

but maybe some of the screw rebuilders in MI CAN do this? they take worn out screws and weld in new material, then come back and machine it down again....