VFD setup: Brook Crompton motor, Teco vfd

[Splat]

Posted this in the Grizzly sub but figure it may get more looks here. It appears my stock G4003G motor is on the way out. I replaced the capacitors and the motor still has trouble getting and maintaining anything over 500rpm. I've thought about taking the motor to a local shop to see about refurbing it but I've been thinking of just going to VFD 220v 3 phase. Dealer's Electric has this Brook Crompton drop-in replacement metric motor but I know nothing about them. For the VFD I'm considering this Teco N3-202-CS-U. The motor's a lot more than I want to spend but I can drive to Dealer's Electric which negates shipping charges. Any opinions or recommendations? Thanks.

 

[Dave Paine]

Forum member mksj has a thread on his lathe upgrade to VFD and 3 phase motor. He used an Hitachi WJ200 VFD. My local machinist friend followed his lead to convert his G4003G and used the same VFD. Not sure of the motor. I am not finding the thread, but if mksj sees this post he will likely link.

I think Brooks Crompton may be a decent brand.

If you are able to replace the motor pulley with a pulley using NEMA frame and shaft diameters, you may save some money with a NEMA 3 phase motor.

 

[Splat]

Thought about going with a 56 or other NEMA frame but I'd need to open up the pulley bore diameter to 24mm and maybe play with the mounting holes on the new motor. Doable, yes.

 

[MikeInOr]

That motor is 46 lbs... with a big heavy cast iron casing I believe. Are you sure it will fit?

Pardon my comment if you are already familiar with motors... that motor is TEFC (Totally Enclosed Fan Cooled) which is great in that it will keep the swarf, dust, grease and grime out... but it makes it a much bigger motor. Open frame (exposed windings) motors are generally considerably more compact in the same hp range. Is your current motor open frame or TEFC?

I believe 56 frame usually has a 5/8" shaft. 24mm is just under an inch. I think you would need a bushing on the shaft. I had a table saw that came with a bushing between the motor and pulley. The pulley wobbled because the bushing had wallowed out over time. I don't like to use bushing between motors and pulleys. What is the current pulley on the motor like? If is is just a single or double pulley I would just buy a new pulley with the motor so the shaft size and hole in the pulley match. H Bushing pulleys are a really nice way to go as they keep the pulley concentric with the shaft very well.

https://www.surpluscenter.com/Power-Transmission/Pulleys/Split-Taper-Bushed-Bore-Pulleys/

https://www.surpluscenter.com/Power-Transmission/Pulleys/Split-Taper-Bushed-Bore-Pulley-Hubs/

145 Frame usually has a 7/8" shaft, I don't think you could effectively make a bushing that thin for your current pulley. I think you would have to go up to a 184 frame for a 1 1/8" shaft which would allow you to bore out your current pulley.

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

If you are just planning on running the motor in one direction (forwards) the TECO is fine. I went with the Hitachi WJ200 VFD because I know it can be programmed to make (near) instant reversing feasible. I do not know if the TECO's will be feasible for (near) instant reversing.. it very well could be. If (near) instant reversing isn't important to you I think the TECO would be fine.

 

[Silverbullet]

With the vfd do you need the original pulley. Isn't that a good reason no belt changes . If I can do mine I'm going to a 3" motor pulley or smaller.

 

[Splat]

Thanks Mike, and guys. I gotta measure the pulley diameters. Keep forgetting to do that because work's been crazy this week and going in all different times. That's some good info there, Mike, and once I measure everything it'll give me a better avenue to look at.

 

[MikeInOr]

It looks like the original motor pulley is a single diameter double groove pulley already?
http://cdn0.grizzly.com/partslists/g4003g_pl.pdf

Is the spindle speed changed with gearing in the head?

In the diagram showing the motor the motor does look like a TEFC (pretty distinctive look). The motor in your original post is very likely a drop in replacement.

 

[Splat]

Yep on the pulley Mike. That's why I was thinking of going with the metric one I posted. Drop in fit. It's way more than I want to spend but I figure buy better and cry once...hopefully.

 

[mksj]

The Brook Crompton is a very good metric motor, probably a bit better built than the other metric motor commonly used for a replacement which is the Leeson metric series. Both are VFD rated. TEFC is the same as most lathe motors, so a reasonable frequency range is 20-80Hz. I would not run the lathe spindle over 2000 RPM because of the splash lubrication. Most likely will need to replace the stock motor pulley if a different size or possibly rebore it, easier to buy a new one. I usually recommend going maybe 15-20% smaller pulley (depends on a number of factors), and then pushing the motor to 90 Hz on the top end, this gives a wider sweet spot for the variable speed. The Teco N3 is a very good VFD, but I have not used this model before. Performance wise I would consider it equivalent to the WJ200. You will need a braking resistor in this application.

Previous old post with a G4003G VFD conversion, one of several. There was an old schematic you may consider using. Let me know if you have any questions.
https://www.hobby-machinist.com/threads/g4003g-going-3-ph-vfd.34549/

 

[Splat]

What a royal PITA this is turning into. Local shop doesn't have the metric Brooks motor in stock so I'd have to pay shipping anyway. I'm wondering if I should just go with a Nema 56 motor and get a similar sized single pulley to my stock one and just use one belt. I'd have to monkey with the motor mount for the 56 frame but should be doable. This is for a 2HP motor though so unsure if this would be wise.