Rockwell Milling Machine Repower
A while back I made a “transmission” for my Rockwell milling machine (#21-100), the original motor was 3 phase and DOA. The conversion took the original 6 speeds, 370 to 6300 rpms, to 24 speeds, 125 to 6650 rpms. In much more user friendly speeds and somewhat even steps between them. While this worked out very good, the original motor I was using was a 1/2 hp motor, that I had in stock, seemed to bog down, at times.

I started the search for a new motor, I did all of the usual, local suppliers, most of the 1hp to 1-1/2 hp motors were in the $275-$325 range. More than I originally wanted to spend on a $500 milling machine. I was walking through Harbor Freight, and saw their electric motors, now normally I avoid anything from HF, that has a power cord or take batteries, but as it was company money, I said what the hell. So I bought with a 2 yr extended warranty a 1 hp, 56 frame, 1800 rpm, reversible, 120/240v single phase motor (part #68288), with a coupon, a 2yr extended warranty and sales tax, it was about $135.

Well, its been over a yr since, I installed the new motor, it has worked flawlessly, even after long milling sessions, the motor is never too hot to touch, the amp draws are below the max stated, its very quiet and incredibly smooth, it running on 240v single phase. So far I very impressed, is it a true 1 hp motor, or is it a 1 hp based on small Asian horses, I’m not sure, but it is definitely more powerful than the 1/2 hp Dayton, I took off.

Personally, I have about $40-$50 in this repower, mostly bearings and a few pieces of hardware, the company wrote the motor off as an expense. I have another motor, I recently acquired, a 1-1/2 hp, 56 frame, 1725 rpm, 120/240v single phase. I‘m not sure if its necessary to change to the bigger motor, but its there as an option.

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