Had a go using motorcalc sheet but does not look right.

[irving2008]

That does sound a bit excessive

Should be 0.2 seconds (I think).

The value of 0.02 seconds was taken from a document which I can't find now, from a major CNC manufacturer qualifying small, medium and large machines. The 0.02sec was the spec from the medium machine. Its possible that 0.02 is a bit aggressive, but 0.2 is def too slow.. The reason for using a time rather than an absolute acceleration is to make the acceleration dependent on the maximum speed, as thats where the torque is required.

I have worked out another way to estimate acceleration based on pocketing a circle, obviously to maintain feed rate as the radius reduces the rate of change of linear direction X/Y is directly related to increasing acceleration in the individual axis. This calculation shows an acceleration requirement approximately 1/2 - 1/3 (depending on the radius of the pocket) of that given by using 0.02Sec, suggesting 0.04 - 0.06Sec might be a better value. I shall be updating the sheet with the revised numbers shortly.

Yes those bearings look very good value. If you do go with them, I would be interested in a review.
For now I am going to go with your Mk 1 method, If I have permission to use your plans of course.

I am going to use the £4.95 12x32x15.9 one in my rotary table conversion; although I could get away with an open bearing there, the bigger bearing makes the machining slightly simpler and i prefer the sealed one for peace of mind. Of course you can use my plans, the technique is common.