In article , says...
Awl--

I acquired this incredible Engleberg 4" pedestal belt sander, but w/ shot
motor, shot driveshaft, on which I've posted elsewhere.

The replacement motor is proving to be a problem. Direct replacment is
possible, but expensive. (Cast iron finned, 1700 rpm, 143 frame).
Rewinding is expensive.

But I've been finding possible motors, but w/ 3450 rpm, 3 ph, 1 hp.

Would this motor on a VFD be a viable solution? As a direct drive unit, I
don't have the luxury of mixing pulley ratios, so would torque be a problem,
at dialed-down speeds--actually, 50% speed?
Would the higher speeds be any advantage for some materials??

What are people paying for these sized VFDs?

If you install a 1HP 3450RPM motor and run at 1725RPM you'll only have
1/2HP available.

Is the trouble you're having locating a motor a result of the
combination of the CI frame and 143 frame size? I believe a 145 frame
differs only in that the mounting hole spacing parallel to the shaft is
a bit greater.

You can get a basic (non-programmable) VFD in the 1HP range for under
$200. You should be able to get a good used drive for under $100. If you
do buy a used drive, make sure you get the required parameter
unit/programmer/display with it, and that a manual comes with the drive
or is available online.

Ned Simmons