Rotating Ballnut - design ideas

[m_c]

If you're using a double row angular contact bearing, then it doesn't need preloaded, as they come preloaded.
Provided the orange and red bits tighten together onto the inner race, and the blue and green bits clamp the outer race, then that design will work fine.

The only purpose the second bearing has, is to provide support to the shaft to stop it being pulled/deflected by the stepper/belt.

[Jonathan]

If you're using a double row angular contact bearing, then it doesn't need preloaded, as they come preloaded.

Are you sure about that, I was worried about what I posted here:

According to the SKF site the axial internal clearence for a 40mm bore double row angular contact bearing is 11um. So that's like having 11um end float on the screw if I used the design with the single bearing. I'm not sure how bad that amount is - it doesn't sound like much. C2 clearance bearings only have 2um clearance.

Here's the link:

http://www.skf.com/skf/productcatalo...ogue=1&lang=en



On a related topic, do you think 2 ballnuts like I drew in #13 is sensible for a router? It should enable backlash, and endfloat from the above, to be eliminated I think.