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Old Apr 27, 2011, 03:58 AM
Roto Rob is offline
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Denver, CO
Joined Dec 2005
6,916 Posts
Made a spanner wrench out of 3/4" gas pipe. Lathed the inside diameter. Then milled the slots on the drill press, with an X-Y table. Could have made it a little longer to make it easier to install the nut with the ballscrew. Will just use a pipe wrench instead of the T-handle.

Steps to remove the X axis. Remove the travel stop bolt on the underside of the table, on opposite end from the servo. Remove the limit switch stop bracket on saddle. Remove the ballscrew nut from the pulley end. The opposite end of the ballscrew has flats for a wrench, to hold it when removing the nut. Next slide the table off the slide rails. Set it next to the mill if you did not remove the wires. This leaves the ballscrew and nut on the saddle. Do not turn the ballscrew out of the nut unless you want to repack the ball bearings (like I did). If you do, keep track of the bearings, since they are matched in size. New balls should be installed as a set, and lapped to fit.

To remove the ball nut, and ballscrew from the saddle. Remove the set screw on top of the saddle (it is over the threads to lock the ball nut in place). There is a small plastic nub in the hole under the set screw to protect the threads. Try not to misplace it, mine stayed in place. place the spanner wrench over the ball nut, and turn it out. Mine not stuck, and was easy to remove. Might need some heat if stuck.

For Y axis, remove the control box. Let it hang below, will need to unplug the servo wires. Remove the 2 bolts that hold the limit switch. Remove the two bolts that attach the way covers to the end clamp, and the back way cover unbolt from the saddle. Remove the two clamp bolts. Pull the clamp off the end of the rails. Now the whole Y axis / saddle assembly can slide off the rails. Now you can remove its ballscrew the same as the other axis.

Steps to reball the nut. The ball nut has three return circuts. Has a plastic return button for each circuit. The circuit covers two threads. Remove the plastic wiper on the end of the ballnut opposite the threads. It is held in by a set screw. This is to make it easier to see what your doing. I placed a small amount of grease in the nuts threads, and placed each ball in the circuit with a small screw driver tip. Had a little grease in the tip to hold the ball. Divided the balls into 3 sets. I think I'm missing some balls. 16 in each looked about right, will have to wait for the new balls to figure the number out. Started in the back. ----Be sure not to place a ball in any threads outside of the circuits.---- Reinstall the plastic wiper, but leave the set screw loose so the ball screw can be easily threaded back in. Hold the ball screw vertical. Now slowly thread the ball screw in from the side opposite the threads (the side you just installed the wiper in. I looked down the ball nut with a light as I threaded it in. Looking to make sure the balls stayed in place. If they fall out you will have to start over. Now rotate the nut to see that it turns smoothly. Don't forget to tighten up the wipers set screw. The set screw will tighten the wiper up against the ballscrew. So check backlash, etc. before you tighten it.
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