[Route21]

How do measure the length of ballscrews for x- and y-axis for RF31 table?
I think the length that sellers write is "the overall length" inclusive end-blocks taps. Can anyone give me a hint how to measure? Or perhaps you know the correct length.

[SCzEngrgGroup]

How do measure the length of ballscrews for x- and y-axis for RF31 table?
I think the length that sellers write is "the overall length" inclusive end-blocks taps. Can anyone give me a hint how to measure? Or perhaps you know the correct length.

The length you require depends very much on the design of your supports. One end needs to be supported both axially and radially, the other end radially only. The screw length will be slightly less than the dimension between the bearing inside races, with enough extending beyond the outside of the bearings for your pulley or motor attachments. If you plan to keep the stock bearing supports (not always a good idea....) then use the stock screw as a reference, changing only the part where the pulley/motor mounts as required.

Regards,
Ray L.

[Bubba]

When I converted my RF31, I made the Y screw extend through the webbing at the back under the column by drilling a hole in the web. This way, there is no way on God's green earth the ball nut can get back far enough to start loosing balls! I now wish I had made the hole bigger and also gone through the back of the base. Then I could put a tube sleeve on the screw and it would be protected from swarf and coolant!
ON the X axis, I messed up and put the mount for the servo offset and pulleys flat on the end of the table. This cost me about 1.5" of travel. If I had made my bearing block and servo mount out from the end of the table, I could have regained that extra bit of travel (that I could have used several times!)

[pete from TN]

On my lathemaster cnc buildup I basically took the length of the mill table itself, added in the amount of distance I figured I would need to machine the flat area for the two angular contact bearings on one end, the threaded portion for the locking nut, and then however much I figured I would need to get a pulley on the end. Then on the other end of the table I wound up machining the factory cast endcap for a sliding fit of a standard bearing so i just added enough to make sure I had the length to go thru the bearing and then about 1/2 inch more. If you are gonna machine your own screws as I and others here have done then get of course a length longer than you need as you can always cut off the rest. If I were gonna do a RF31 conversion I would seriously look at the plans made by Jeff at homecnctechnologies? ( homecnc.info) I think it is. His plans are for an rf31 specifically I think but all of these mill drills including mine are the same basic layout so you could alter the plans for any of them I would suspect... Good luck and make sure you post a build thread here...peace