Rotating Ballnut - design ideas

[Andrew Wilding]

deep groove is usually in the description of the bearing. On closer inspection of the diagram that you linked the bearing you have shown probably is a deep groove. These are the norm but still not ideal for use in an application where relative to radial load the axial load is significant.

Some more thought (sorry if all this has been covered in other threads)

Moment of inertia is proportional to diameter squared so I am surprised that there is much difference between the shaft and nut? I am sure you have done the sums.

Is the moment of inertia significant when compared to the mass of the 'carriage' (when calculating acceleration)?

If you have to tension the shaft to raise its critical frequency then will have to start considering beefy shaft support bearings, I can now see why the rotating nut idea is appealing!

a 2000mm leadscrew poses a lot of design challenges even when cost is not an issue (which I assume is, if you were as poor as I was when I was a student!) have you considered other methods with feedback or your real accuracy requirement? One solution maybe to use a rack and pinion/belt and calibrate the travel using a dial indicator and blocks of a known dimension. The smaller the increments the better idea you would have of variation along its length. Even a crude survey (100mm steps?) would give you significant improvement in accuracy. Obviously this would require a decent home switch.

I look forward to seeing your solutions. This is not an easy project too keep in budget but will be satisfying when cracked.