Mounting ball nuts
I am about ready to do the final assembly on my mill conversion, one aspect of the assembly still puzzles me. I did a search to see the correct way to mount the ball nuts. According to the THK site the correct way is with the return tube facing down, to reduce torque inconsistency caused by the balls hitting in the return. However I have seen images of assemblies with the return tube rotated 90°, and have also seen the return tubes facing the top in a BP yoke assembly.
I would like to know definatively, is there a correct position for the returns? Is there really a big enough concern over the balls making contact in the returns to cause fuctuations in the torque? Would this be a concern only if you were using marginally sized motors for you axis? Any help would be greatly appreciated.
Well...on my Danaher ballnuts the tube is diagonal.....so the return end depends on the direction you are turning the ballscrew. The inportant thing is to have the returns on the vertical sides and not the horizontal sides.