Corbin Dunn
Redwood Monkey

VFD South Bend Lathe Upgrade: Part 1: Motor and VFD selection

Machining

The 110v motor on my SouthBend 13” tool room lathe from the 1950’s is slowly dying. It stalls a lot, and I’m forced to take really light cuts, even in aluminum. It slowly decreases speed after prolonged use and eventually stops. It also usually stalls on start, so I have to give it a starting spin by hand to get it going. I’ve also been a bit unhappy about not having a precise speed control. So, it is time to upgrade! Here’s the original motor installed and after I pulled it out:

 

IMG 0220

 

 

IMG 0223

 

 

It is 1 phase 110/220v Marathon Electric 1.5 HP motor with a 184 frame, wired at 110v; just rewiring it for 220v may have helped, but it is nearly dead. Here’s a great site explaining frame sizes: https://www.engineeringtoolbox.com/nema-electrical-motor-frame-dimensions-d_1504.html

My goal was to upgrade a bit to a 2 HP motor and get a VFD. I wanted to get something with the same frame size of 184, in 2 HP, ~240 volt 3 phase, and around a similar RPM of 1800. I just couldn’t find anything for a descent price; everything was at least $300 used, and skyrocketed up from there if it was new or surplus. So, I had to opt for a different size.

Eventually I stumbled across Dealers Industrial Equipment and ordered this motor: Marathon Electric 2 HP, 1800 RPM, 230/460  Volts, ODP, 145T; Only $120, and I figured I can adapt the smaller 145T frame to work in my housing.

I got the cheapest 2 HP VFD, which also had a good price from Dealers Industrial at $173 on sale: TECO Westinghouse 2 HP, 230 Volts, 1 Phase, IP 20, Teco, L510-202-H1-U

Toss in $79 for shipping and I’m currently at $372.00 — a bit higher than my original goal of around $300, but it should be an awesome upgrade.  

I’m also thinking of ordering a MatchTach tachometer. This way I can actually see what speed the VFD is putting out; otherwise, I will have to guess…

Stay tuned for part 2.

 

 

 

 

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