[IanRogers]

Hi everyone, I have a chinese mill that looks like the smaller brother of an RF-45, but the motor that came with it is toast. I'm trying to source a 3-phase replacement but I don't know too much about motors, and this thing is very definitely not a standard nema size. I'm trying to find a motor that will fit, either as a direct replacement, or if someone can recommend some kind of adapter strategy to use a common size motor...

Anyway some numbers-(I really hope I got the nema dimensions correct)

Shaft diameter (U) 0.5 inches
Shaft height (NW) 1.125 inches

Face diameter (AK) 4.375 inches
Face diameter (P) 5.825 inches

mounting hole diameter (AJ) 5.1 inches
4 holes, 0.4 inch diameter, arranged in a square 3.6 inches on a side

there's a flat on one edge, to clear the mill column. Actual distance from center of shaft to flat is 2.65 inches.

What am I dealing with here?

Any help is incredibly appreciated!

~ Ian

[ninefinger]

Hi Ian,

These mills usually use a metric frame motor. So you have some options:

Check your dimensions against this chart - it seems to me this is a IEC 71 frame motor..http://www.electricmotorservice.net/iechart.pdf

Then find a supplier locally or out on the web. I got a 3 phase chinese motor for my mill when I ordered it from MTW (in Canada like you..) https://www.machinetoolswarehouse.co...log/index.html - I personally think this is fine as the problem with most of the Chinese motors is in the start circuit and capacitors which 3 phase motors don't have. Saved a bunch of money doing it that way too - US / EU / name brand motors cost a lot more but for my hobby machine I'm happy with what I bought.

BTW - I'm not affiliated with MTW in any way - just a customer who got what he ordered ( becoming a rare experience these days...)

Others have posted elsewhere here on the zone drawings for an adapter plate to the nema C face motors (in the IH forum I think) but in my opinion that is not the way to go when you need a motor - if you already own / have a motor then yes it makes sense but to add to the cost of a motor a machined adapter seems like an inefficient, kludged up way to go...I'm all about cheap BTW...

My 2 cents...

Mike

[IanRogers]

You sir, are the man!

All the critical dimensions match, and I'm sure I can cut a flat into the mounting flange to match the one I currently have.

I actually picked up this mill from MTW (MD003+) when they were selling them off, and the motor's never worked from day one. If I'd known then that it'd be two years before I'd actually get a chance to seriously play with the machine I bought, I'd've saved my pennies, and bought one of the newer, shinier mills. Can't fault MTWs service though!

Thanks again for your help, now that I know what I'm dealing with, this should be much easier!

~ Ian