Making Ballscrew supports:

Grae-Tech 

I started with a 25mm x 80mm block of 6061 and cut a 20mm hole for the shaft to pass through, then bored the Outer diameter bearing surfaces out to 29.99 mm with a precision boring  head.

 

I made the bearing block with the stock clamped to a mounting plate. That way I knew that all of the circles cut had the same center point. The bearing was then a gentle press fit into the block.

Below is a CAD drawing I have completed to try and explain the concept behind the shaft support bearings and bearing block. The drawing is a cross sectional view of the assembled shaft.

 

 

The basic ballscrew has a 22mmx 10mm plain shaft where the angular contact bearing sits.

 

The blue part is a nut with a very fine thread (M10 x 0.75) The purpose of the nut is to tighten against the green part, which is a sliding collar. The collar is pushed to the right. The collar sits loosely over the unused section of 10mm shaft, but is pushing hard against the inner race of the angular contact bearing, slamming it into the shoulder of the ballscrew shaft. The bearing is pushed tight up against the shoulder where the actual ballscrew thread starts. I applied a lot torque to the nut to clamp the angular contact bearing into place.

 

The Nut and collar effectively hold  the AC bearing on the shaft, but they only apply pressure to the inner race of the bearings, allowing the outer race to move independently.

 

The next drawing describes the bearing block.

Now that the AC bearing is firmly attached to the screw shaft, the outer race of the bearing must be fixed to the machine.

 

The Yellow part is the bearing block, which grips the AC bearing’s outer race, and firmly pushes it into the light blue part, which is the support bracket that bolts onto the milling machine and the motor stand offs. I machined the bearing block so that the AC bearing protrudes 0.05mm above of the face of the bearing block.

 

The inner race is free to move independently of the outer bearing race.

Text Box: Shaft spacer
Text Box: M10x0.75 thread
Text Box: Plain 10mm shaft