[martin_05]

I might need to replace the motor on my RF30. I rewired it for 220V. It ran fine for hours. When I plugged it back in something sparked inside the motor. It wasn't even on...which is weird enough.

Anyhow, I pulled the motor and will be taking it apart over the next few days. I was already concerned that the motor might have been the source of some vibration. So, in the spirit of considering all options, I would like to look into what I might be able to replace it with.

I have 220 V single phase in the garage.

Is there an inexpensive VFD / Variable speed option?

Perhaps go down to a single belt and drive it with a nice three phase motor and VFD?


Thanks,

-Martin

[Fastest1]

Sure get a 3 phase motor and a VFD. You will enjoy the variable speed obtained and you can run it on single phase. Buy a quality motor.

[martin_05]

Suggestion?

[Fastest1]

We have to find out what type of mount the existing motor has. What HP rating, shaft size and your budget.

I put a new motor and vfd on my lathe years ago. Seems like I have around 3-4 hundred in the combination. Ebay is your friend.

[Fastest1]

Look under Baldor the mount style is called a 145T. Most are 7/8' shaft and the pulleys are metric. Do you have a way to bore the original pulleys? Check ebay and surplus center

[Bubba]

Martin,
Back when I got mine, I got a package deal from Dealers Electric.
Back then, sensorless vector drives were a real premium and I didn't go that route. Today, I definitely would get a sensorless vector drive as it allows improved low speed torque. I might also look at a slightly larger motor again to have more torque in the low speed ranges. I replaced my original Chinese 2hp motor on my RF31 with a Leeson 2hp 3ph. IF I were to redo it today, I probably would go with a 3hp and sensorless drive. There are lots of good drives out there but I would stick with known good suppliers and tend to shy away from the inexpensive drives that you find on ebay. Of the two that I have, both are Teco's and they work fine off single phase. As a matter of fact the EV7200 that I got for my lathe doesn't even have a three phase input.

As mentioned above, ebay can be your friend as I got both the motor and drive for the lathe off there.

PS: yes the original motor had a metric shaft on it and the Leeson has imperial. I reamed out the original pulley to fit. It is my intention someday to make new pulleys to better match the speed range and have fewer belt change positions.

[martin_05]

Martin,
Back when I got mine, I got a package deal from Dealers Electric.
Back then, sensorless vector drives were a real premium and I didn't go that route. Today, I definitely would get a sensorless vector drive as it allows improved low speed torque. I might also look at a slightly larger motor again to have more torque in the low speed ranges. I replaced my original Chinese 2hp motor on my RF31 with a Leeson 2hp 3ph. IF I were to redo it today, I probably would go with a 3hp and sensorless drive. There are lots of good drives out there but I would stick with known good suppliers and tend to shy away from the inexpensive drives that you find on ebay. Of the two that I have, both are Teco's and they work fine off single phase. As a matter of fact the EV7200 that I got for my lathe doesn't even have a three phase input.

As mentioned above, ebay can be your friend as I got both the motor and drive for the lathe off there.

PS: yes the original motor had a metric shaft on it and the Leeson has imperial. I reamed out the original pulley to fit. It is my intention someday to make new pulleys to better match the speed range and have fewer belt change positions.

Would you go with a higher RPM motor as well? In other words, 3HP and 3,600 RPM max?

Looking at a Hitachi WJ200 drive. They seem to get solid reviews everywhere I look.


Thanks,

-Martin

[Bubba]

In no way would I go with a 3600 rpm motor. Remember, HP~RPM*torque. So a 3600 rpm motor will have half the torque of an 1800 rpm one and you essentially loose the practicality of overspeeding your motor due to bearing and balance problems. I routinely run my 1800 rpm motor in the 3600 range but there is no way I would run a 3600 class motor at 7200 rpm!

Right now, with 2 belt changes using the factory pulleys, I have a speed range of about ~120 to 4100 rpm. This was done by realigning the motor so the smallest pulley was aligned with the second down from the top pulley on the jack shaft. The belt between the top of the jackshaft is hooked to the top of the spindle pulley. Now belt changes are made only for the motor to jackshaft to either the afore mentioned top pulley on the motor or the third one down on the motor to the bottom one on the jackshaft.

Hope the clip below helps:
Attachment 271308

[martin_05]

In no way would I go with a 3600 rpm motor. Remember, HP~RPM*torque. So a 3600 rpm motor will have half the torque of an 1800 rpm one and you essentially loose the practicality of overspeeding your motor due to bearing and balance problems. I routinely run my 1800 rpm motor in the 3600 range but there is no way I would run a 3600 class motor at 7200 rpm!

Right now, with 2 belt changes using the factory pulleys, I have a speed range of about ~120 to 4100 rpm. This was done by realigning the motor so the smallest pulley was aligned with the second down from the top pulley on the jack shaft. The belt between the top of the jackshaft is hooked to the top of the spindle pulley. Now belt changes are made only for the motor to jackshaft to either the afore mentioned top pulley on the motor or the third one down on the motor to the bottom one on the jackshaft.

Hope the clip below helps:
Attachment 271308

Ah, makes sense. Need to put on my thinking cap. I know this stuff!

Must have more coffee. Must have more coffee.


Thanks,

-Martin

[Fastest1]

Another way of viewing what Bubba is saying is that the motors rpm rating is @ 60hz. The VFD will allow you to exceed that dramatically if desired say 200hz?

[Bubba]

Now we are getting into that area of discussion that "can" elicit a lot of views.
"Assuming" we have an inverter rated motor, I believe the common sensuous would be that you can "safely" overspeed up to 200% of rated or 120 hz for a 60 hz motor and I have also seen several were they feel the max would be ~100 hz for a non rated motor. Of course if your dealing with a specific design motor such as some of the spindle motors, then they are rated at 400 hz.
But as stated earlier, I would be hesitant to run a conventional motor over about 3600 rpm due to bearing ratings and balance considerations.

[martin_05]

I was starting to research the difference between inverter rated motors and regular folk.

Yeah, I was wondering about the WJ200 being able to go up to 400Hz. Probably not kind to motor and bearings. I'm sure Mach 3 has a speed limit setting.


-Martin

[Bubba]

You set the speed limit in the drive. Mine at least and from what I remember from helping a friend with a WJ00 ??? has min and max parameters that can be set. IF you think that is the drive your going to get WJ200, google for a manual and be prepared to sit with a LOT of coffee or whatever depending on your state of mind to try and understand the parts you really need. (Ignore the rest:})

[Fastest1]

I was in no way suggesting operating at 200hz or above, just that it is possible. Your comfort level during that high of an rpm would be non existent.
Mach will do whatever you set for the max of the pulley.

[martin_05]

Happy to say that my single phase motor is OK. I somehow made a mess out of converting from 110V to 220V. With the motor on the bench rewired and tested for straight 110 and 220 and all is well. The motor does exhibit vibration I am just not happy about. Not sure if it is the bearings. Could not tell without taking it apart. I suppose I could. On the other hand, I am committed to switching over to a 3 phase 2 or 3 HP motor with a VFD. I probably shouldn't waste too much time on this one.

I'll document the wiring in my build thread just in case it might help someone else in the future.

I continue to search for a good and reasonably inexpensive 3 phase motor. There are a few candidates out there. I am starting to think I might want to wait a bit and buy a brand new motor. I really don't want to deal with someone else's problem when it comes to that department.


-Martin