Pete Keillor wrote:
....
Below is a link to the manual for Marathon Black Max motors, ...
Table 3.4 for the recommended
maximum for those motors. ...

Thanks - good link! A couple of interesting things the
- for *belted" loads, their limit is 125% of rated speed. I'd guess
that's because of the radial bearing load. I'm going to go ahead and
ignore that.
otherwise (direct load), for my frame:
- a 3600 rpm motor has a 7200 (120 Hz) limit
- a 1800 rpm motor has a limit of 5400 (180 Hz)

I think that I'll compromise between the 125% limit and the 200/300% and
limit the 3600 to 150% (90 Hz, 5400 rpm) & the 1800 to 200% (120 Hz,
3600 rpm).

Thanks,
Bob