[kn6za]

Made a bit more progress on the carriage and ball screw mounts.

I must say, the travel down the length of the z axis is so smooth! These INA rails and bearings are great!


I got the ball screws from linearmotion2008 on ebay, and I am pleased with them so far. The angular contact bearings in the fixed end support are NOT preloaded so a spacer was made to set the preload within the bearing set. Once this was completed the screw has a very stiff feel. I dont have servos mounted or drive couplings completed yet so I cant tell exactly what the backlash is. I dont expect to get a real reading on the actual backlash until I get the system ready to fire up electronicly and thats a far bit off in the future.

Just locking the rotation of the 20mm screw and pushing back and forth on the carriage revealed about .0001 - .0002 of deflection with what I estimate to be 50 - 60lbs of force applied. Before the spacer was added to the bearings this movement was .005"! These screws are both the double nut variety, and I am glad I went with that option.

I went with 20mm srew on z axis and 16mm screw on the x axis. The 20mm was very staight, the 16mm not so much. There appears to be about .007 runout at the free end of the 16mm screw. Wont know how much this affects operation until I get the linear rails cut down to fit the top of the carriage, and the cross slide mounted up.

Got the servos in, and they look great. I got 4 of these at $25 each. could not pass up getting some extras as i only need 2. at this price I took 4!



The encoder is 200line, so that will come off, and a 2000 line heds unit will be adapted to the shaft with an am26c31 quad line driver board to carry A/_A, B/_B and index/_index channels back to the kflop control.