Rivett 1030F Voltage Conversion

medsar · May 29, 2018

I recently purchased a Rivett 1030F and I am working on getting all the kinks worked out. It was originally wired for 220v 3 phase from the factory and was converted to 440 3Ph at some point in its life. I bought the machine with a 15kva 220->440 3Ph transformer. Unfortunately, the transformer has a ground fault in it. I have a 10hp RPC that supplies 220v 3Ph and the machine has a 5hp motor. I am at a crossroads -- I can either buy another transformer (probably a 6kva or 9kva) and spend a decent amount of money or I can convert the lathe back to 220v 3Ph. I have checked the wiring specs from the wiring diagram from Rivett along with the actual wires in the machine and they are capable of handling 220v amperage. Changing the voltage on the motor is the hardest part. It would require moving the motor/clutch skid partially out of the machine because the motor wiring box is exactly in the wrong place (hidden behind the support column). I think it would require making a special pair of skates to move the skid a few inches to get access to that wiring box. If anyone who has removed the motor out of a 1020 or 1030 has any suggestions or better ideas, please let me know.

This begs the question --> Is it worth it to convert it back to 220v 3Ph or should I just spend the green to buy a new step up transformer?

Cal Haines · May 29, 2018

medsar said:
I recently purchased a Rivett 1030F and I am working on getting all the kinks worked out. It was originally wired for 220v 3 phase from the factory and was converted to 440 3Ph at some point in its life. I bought the machine with a 15kva 220->440 3Ph transformer. Unfortunately, the transformer has a ground fault in it. I have a 10hp RPC that supplies 220v 3Ph and the machine has a 5hp motor. I am at a crossroads -- I can either buy another transformer (probably a 6kva or 9kva) and spend a decent amount of money or I can convert the lathe back to 220v 3Ph. I have checked the wiring specs from the wiring diagram from Rivett along with the actual wires in the machine and they are capable of handling 220v amperage. Changing the voltage on the motor is the hardest part. It would require moving the motor/clutch skid partially out of the machine because the motor wiring box is exactly in the wrong place (hidden behind the support column). I think it would require making a special pair of skates to move the skid a few inches to get access to that wiring box. If anyone who has removed the motor out of a 1020 or 1030 has any suggestions or better ideas, please let me know.

This begs the question --> Is it worth it to convert it back to 220v 3Ph or should I just spend the green to buy a new step up transformer?

kpotter went through almost the exact same thing with his 1020S (serial number 332). He tried the transformer route with a 7.5 HP RPC, but the current inrush on the transformer kept stalling the RPC and tripping the breaker. It only took an industrial electrician friend of mine about an hour to switch it over from 440 to run on Kevin's RPC. I would definitely go the route of converting the machine to 220. There are others here that are much more knowledgeable about Rivetts and should be able to help you with the details, but I would be very surprised if you have to pull the motor to do it.

http://www.practicalmachinist.com/vb/monarch-lathes/rivett-1020s-440volt-173259/
http://www.practicalmachinist.com/vb/monarch-lathes/rivett-1020s-running-189391/

Cal

rustytool · May 29, 2018

I removed the entire drive system from the base on my 1020s.
It's been awhile but as I remember I just removed the bolts securing it to the base and the whole steel plate holding the drive system just slid out riding on the cross members of the base.
I did need to have pallet jack ready when it came all the way out.
But if your only moving it a few inches I don't think you need any skates.

medsar · May 30, 2018

>kpotter went through almost the exact same thing with his 1020S (serial number 332).

I saw that thread (rivett 1020s 440v) but I missed it that he switched the lathe over to 220 3Ph. Oops. Sorry about that. Those pics are very nice.

>It's been awhile but as I remember I just removed the bolts securing it to the base and the whole steel plate holding the drive system just slid out riding on the cross members of the base.

I am glad to hear that you were able to slide the drive system on the cross members. I know what you are talking about. It appears as if it was designed to do just that. Since the drive system is mounted on thick plate, I was worried that I might not be able to slide it. I'll give the slide a try -- I think it will work.

Halcohead · Jun 2, 2018

Just saw this. In case you aren’t done yet:

The drive plate has two piece of angle iron welded to the bottom, so it slides even better than it would on just the plate. Just make sure to let it down slowly with the jack screws and don’t forget to disconnect the clutch lever. Once it’s down on the rails it’s pretty straightforward to slide out, I think I did mine by hand (but a small prybar will certainly do the trick).

AgainstTheGrain · Jun 6, 2018

I am going through the same process on a 1020F. That wiring box is not easy to get to.
I also had additional question about the wiring. Mine is wired 440v from the factory, but the control motor is wired 220v. I assume that there must be a step down transformer for the control. Does anyone know where it is, and what is the best procedure for dealing with it?

thermite · Jun 6, 2018

Halcohead said:
Just saw this. In case you aren’t done yet:

The drive plate has two piece of angle iron welded to the bottom, so it slides even better than it would on just the plate. Just make sure to let it down slowly with the jack screws and don’t forget to disconnect the clutch lever. Once it’s down on the rails it’s pretty straightforward to slide out, I think I did mine by hand (but a small prybar will certainly do the trick).

This... is even easier than a 10EE, where we have to get a pair of loose angles UNDER and still pry the motor feet over a fastener or two if we don't get it angled just so for its journey.

In at least the MG-era, and this MAY OR MAY NOT apply to a Rivett - there were also stacked shims that need to be preserved for each of the motor's four feet. Otherwise one has the tedious job of re-storing the pulley alignment so the belts track true.

2CW

thermite · Jun 6, 2018

AgainstTheGrain said:
I am going through the same process on a 1020F. That wiring box is not easy to get to.
I also had additional question about the wiring. Mine is wired 440v from the factory, but the control motor is wired 220v. I assume that there must be a step down transformer for the control. Does anyone know where it is, and what is the best procedure for dealing with it?

If the Mark One Eyeball cannot spot it right away, put a phone or camera onto any cheap "selfie" stick and get shots behind stuff. It will be about the size of your fist +/- and look like ta da . a transformer!

Pre-euro-voltage ++ many-mains-feed options era, it may only need paralleled windings switched to seriesed or the reverse. All you need to confirm those ordinarily is some form of continuity tester or Ohm meter, if-even. You are just using it AS ALREADY PLANNED, not designing it from a clean-sheet of paper.

mpmar_bt · Jun 8, 2018

I did not find a step down for mine. The single phase control motor was wired through one of the main motor coils. My guess was that the main coil acted as a resistor to pull the voltage down.

I can't guarantee I was right on that. I got the main motor re-wired for low voltage and found it was drawing 10 amps just running and one of the coils had distinctly lower resistance. Maybe shorted. I ended up temporarily swapping the drive unit out for a Reliance RPM motor.

Later, when I have more time I'll dig into that.

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medsar · Jun 8, 2018

AgainstTheGrain said:
I am going through the same process on a 1020F. That wiring box is not easy to get to.
I also had additional question about the wiring. Mine is wired 440v from the factory, but the control motor is wired 220v. I assume that there must be a step down transformer for the control. Does anyone know where it is, and what is the best procedure for dealing with it?

I am in the process of converting mine back to 220 (just ordered some heaters and need to change the wiring on the magnetic brake). I found that the control motor was 220v single phase and the single phase was generated off the main motor which then supplied the control motor. I spent a lot of time scratching my head when looking at the wiring diagram and the control box at the rear of the lathe thinking the same thing you were. It wasn't until I took down the wiring box in the main motor that I discovered what they did.

Thanks to everyone who replied. I did just as y'all suggested. I lowered the skid down onto the rails and then moved it around with a bar. It was still a bit too heavy for me to move around with my hands. I didn't have to unbolt the motor and I didn't have to mess with the wiring conduit. All good things.

AgainstTheGrain · Jun 12, 2018

That is good news. Keep us posted on the progress; it has been quite helpful to me. Thank you.

thermite · Jun 12, 2018

medsar said:
I found that the control motor was 220v single phase and the single phase was generated off the main motor which then supplied the control motor. I spent a lot of time scratching my head when looking at the wiring diagram and the control box at the rear of the lathe thinking the same thing you were. It wasn't until I took down the wiring box in the main motor that I discovered what they did.

That's rather clever, actually. Even "basic". The tap for it is probably usable on many dual-voltage motors. So long as the load is minor, the motor would barely even notice it.

One less component - a control transformer - to buy and find a place to park, SEVERAL fewer wires to "get wrong" or even have to route and terminate at all.

medsar · Jun 12, 2018

thermite said:
That's rather clever, actually. Even "basic". The tap for it is probably usable on many dual-voltage motors. So long as the load is minor, the motor would barely even notice it.

One less component - a control transformer - to buy and find a place to park, SEVERAL fewer wires to "get wrong" or even have to route and terminate at all.

The motor in these lathes is massive compared to the HP rating. The control motor is tiny and causes a minor load (as you mention). Since the motor is overbuilt, the motor doesn't notice it (as you mention).
When I discovered what they did, I had a similar light bulb moment. It's a simple solution that reduces the amount of things can go wrong/replace.

thermite · Jun 12, 2018

medsar said:
The motor in these lathes is massive compared to the HP rating. The control motor is tiny and causes a minor load (as you mention). Since the motor is overbuilt, the motor doesn't notice it (as you mention).
When I discovered what they did, I had a similar light bulb moment. It's a simple solution that reduces the amount of things can go wrong/replace.

Side effect was to trip a similar "Eureka" on the French Gal that had dealt Milacron a surprise hand. Nothing to do with the Rivetts, but..

As-acquired, the HBX-360-BC had a grubby, and long-serving Phase-a-Matic static-not-really-converter hung onto it. Quite reasonably, he'd attempted to aside that excuse for abuse of a load motor and test the motor off a proper 3-P source, ended up with some smoke and drama.

Turns out, in checking to see if the French had done a similar cleverness to parasitize the 7 HP 220/440 spindle drive motor to operate the tiny point-five HP electric tracer motor that..

The as-built "Schema D' Execution" (formerly) glued inside the rear electrical cabinet is NOT actually the way it WAS built!

Thankfully, actually! And I was going to make a new drawing anyway. Old one wudda been black-line Ozalid on Mylar or such, still flexible, but fading and yellowing, so.

"Stone Soup parties" and "Serendipity".

Sound nice. Work even better when one is so blessed!

mpmar_bt · Jun 13, 2018

This is good to know. I had traced the wires back to the control relays in the electrical cabinet, but no further. And had made the assumption (yup, I know) that the source of the power was the usual and hadn't tried to trace the wiring back any further.

Useful lesson in seeing what's actually there as opposed to what you expect.

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