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Single phase to 3 phase conversion on Modern GH1440W lathe

John Conroy

John Conroy

member
Premium Member
I've been thinking about doing this since I got the new lathe a little over a year ago but a few things have happened lately to push me toward starting this project. First was the capacitor failure I experienced on the single phase motor that came with the lathe. Second, my wife and I got back from California on March 10 so we are in voluntary self isolation for a couple of weeks. Next was the link PeterT posted a while back to the Clough42 YouTube video series on installing a VFD. I've been shopping around for a used 3 phase motor but had no luck finding anything with a realistic price. I was going to buy another Huanyang VFD like the one I used for my mill but they have gone up in price since then and I didn't want to wait weeks to get one direct from China. With some web searching I found a company called Emotors Direct where I purchased a Teco-Westinghouse motor and compatable VFD online and picked up at the Edmonton Teco-Westinghouse warehouse the same day. I made arrangements with the warehouse people so I didn't have to get out of my truck during the pickup to maintain "social distancing". All the other components have been ordered from Amazon. The motor was priced lower than any of the used ones I found. The VFD was priced a little higher than a Huanyang but no de-rating is needed according to T-W. What that means is you can use a 3HP rated VFD on a 3HP motor. With Huanyang most people suggest going up 1HP on the VFD rating to be sure it can handle the current the motor requires, I bought a 4HP Huanyang VFD for my 3HP mill motor. The end result is I have a motor and VFD from the same manufacturer with 3 year warranty and no worry about the compatability of the 2 components. This project will probably a week or so and I will update here as I go.
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Watching as I’m looking to convert my mill to 3-phase.


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By the way, I was pretty impressed with the service I got from Emotors Direct. I had problems completing the purchase online but the issue was easily corrected by phone and they offered a 10% discount on my first purchase which saved me $75.
 
Thanks John, that’s the company of I’m looking at ordering from.


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I learned quite a bit about motor frame sizes during my research. There are different standards for frame and shaft sizing, some use NEMA standards, some use metric standards called IEC and some use a mixture of both. I learned that the single phase motor I have is one of the latter. The actual frame of the motor fits NEMA size standard 184T but the shaft is 28mm instead of 1-1/8". You can find all the dimensions for Nema or IEC motors online. The motor I bought has a 182T Nema frame . That means the width of the bolt pattern is the same as the old motor but the lengthwise dimension is 1" shorter. I could have bought a 184T motor with the same specs but the price was significantly higher so I elected to buy the 182T bolt pattern and drill/tap 2 holes for the rear motor hold down bolts. The motor mount plate on this lathe is amhuge chunk of cast iron so strength is not compromised. I used my welding table to help lay out the the hole patterns and to get the new 1-1/8" ID pulley aligned to match the old motor. The new pulley uses a split tapered bushing to mount to the shaft and the belt grooves are deeper to accomodate more than 1 belt size so I aligned the center of the new pulley with the old one.

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It took me a while to figure out a method to get the pulley aligned the same as the old motor. I put both motors side by side with bolts in the fŕont mount holes and used the protruding bolts to align them the same as if they were bolted to the mounting plate. I used a couple of 123 blocks aligned with the center web of both pulleys and làyed a straight edge across the leading edge of the blocks. It took a couple of trys because the pulley moves
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on the split bushing as you tighten the mounting bolts but I got it within a few thousandths of the old one
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The tag on the old one says 45kg or 99lbs. The new one says 96lbs. I lifted them both onto the bench yesterday and the new one feels heavier.
 
Nice conversion post! Very instructive! I'm kinda lucky; My mills are 3PH, and I share a VFD between them (and other machines) as they all have 2HP motors....

Did you buy a Teco 510 to control the motor?
 
JohnC, does the NEMA, IEC & other motor standards refer mainly to the frame/bolt pattern dimensions or also include motor shaft particulars like OD, extension length, key dimensions etc.? Was your sheave replacement necessitated by it being a better system or you just plain couldn't use the one from the old motor?

I'll be watching with interest, stay healthy!
 
Dabbler said:
Nice conversion post! Very instructive! I'm kinda lucky; My mills are 3PH, and I share a VFD between them (and other machines) as they all have 2HP motors....

Did you buy a Teco 510 to control the motor?
Click to expand...

Thanks John, yep I bought the Teco L510. the exact model number is L510-203-H1-U which specifies it is for 240 Volt single stage input power and to power a 3HP three phase motor.
 
PeterT said:
JohnC, does the NEMA, IEC & other motor standards refer mainly to the frame/bolt pattern dimensions or also include motor shaft particulars like OD, extension length, key dimensions etc.? Was your sheave replacement necessitated by it being a better system or you just plain couldn't use the one from the old motor?

I'll be watching with interest, stay healthy!
Click to expand...

The NEMA and IEC specs cover most dimensions including frame size, mounting bolt hole spacing and shaft diameter. You can find the specs here.

https://www.engineeringtoolbox.com/nema-electrical-motor-frame-dimensions-d_1504.html

https://www.baldor.com/~/media/files/brands/baldor-reliance/resources and support/backcover.ashx

I would have just bored the pulley ID from 28mm to 1-1/8" but I would need a lathe for that LoL. Seriously I would have needed to broach a keyway also so I just bought a new pulley.

I hope everyone stays healthy, this virus is serious. My son in laws Grandma died from it in Vancouver yesterday.
 
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