Power requirement for RF30/31

[matthewsx]

I think DC motors normally use a PWM type controller, typically use a three phase motor with VFD’s. At least that’s what I have on my lathes.

John

 

[Investigator]

I think DC motors normally use a PWM type controller, typically use a three phase motor with VFD’s. At least that’s what I have on my lathes.

John

I think you're right. I obviously have little experience with DC motors and very little with 3 phase. What 3 phase I have a run on an RPC.

 

[djs1234567]

No, VFD won't work on this motor. You, like me have an AC motor or alternating current. VFD's work on DC motors. The only difference the 110 vs 220 volt makes is how many amps it draws. Wiring it for 220 cuts the amp draw in half. (Nowadays I think it's more correct to say 120 and 240 volts, but it's still the same)

If you want to use a VFD you will have to change to a DC motor. If you change motors you have to get same frame for mounting motor and same shaft size to fit pulley, along with cost of VFD.

Thank you so much for taking the time to answer my question. Would you happen to know what motor I should get and what VFD I should get as well? Thanks again

 

[Shotgun]

Thank you so much for taking the time to answer my question. Would you happen to know what motor I should get and what VFD I should get as well? Thanks again

<puts on flamesuit>
For every 10 people here, you'll get eleven opinions on that question. BUTTT. . . .

I selected a treadmill motor. Cause it was FREE. Using a $10 frequency generator with one of the 2100 controllers, I'm able to dial up any speed I want and pull off power for LED lights.
2Hp will do you just fine. I put 3Hp on mine, because that is what was available on Craigslist for free. Even with the column packed with a mix of portland cement and granite gravel, I can still shake the whole machine with some operations. I try not to do that, but I know the machine is the limiting factor, not the power available.
I wouldn't consider this as an option unless you're comfortable wiring up DC power circuits and inventing a way to modify the mounting to make it fit. Making the conversion isn't rocket science, but it isn't trivial either.

 

[djs1234567]

<puts on flamesuit>
For every 10 people here, you'll get eleven opinions on that question. BUTTT. . . .

I selected a treadmill motor. Cause it was FREE. Using a $10 frequency generator with one of the 2100 controllers, I'm able to dial up any speed I want and pull off power for LED lights.
2Hp will do you just fine. I put 3Hp on mine, because that is what was available on Craigslist for free. Even with the column packed with a mix of portland cement and granite gravel, I can still shake the whole machine with some operations. I try not to do that, but I know the machine is the limiting factor, not the power available.
I wouldn't consider this as an option unless you're comfortable wiring up DC power circuits and inventing a way to modify the mounting to make it fit. Making the conversion isn't rocket science, but it isn't trivial either.

 

[Investigator]

Thank you so much for taking the time to answer my question. Would you happen to know what motor I should get and what VFD I should get as well? Thanks again

Brutal honesty here, it's not that big a deal to change belts and speeds. It sounds like replacing motors and wiring speed controls might be a bigger undertaking than just using it as is. Having said that, if you decide to go the swap route there are plenty of helpful folks here who can help walk you through it.

 

[Manual Mac]

I agree with investigator.
although others find it a huge PITA to change speeds or align the head on RF30/31 machines I have never minded it.
if I still did this for a living I would feel different. I would also not be using a RF30/31.
and after using a Bridgeport and a Sharp 10x50 copy for a living for many years I still find my Griz RF31 to be very accurate and a joy to use, and I use it often.
of course YMMV

 

[djs1234567]

I agree with investigator.
although others find it a huge PITA to change speeds or align the head on RF30/31 machines I have never minded it.
if I still did this for a living I would feel different. I would also not be using a RF30/31.
and after using a Bridgeport and a Sharp 10x50 copy for a living for many years I still find my Griz RF31 to be very accurate and a joy to use, and I use it often.
of course YMMV

Don't get me wrong guys, I really like the machine and had no prob aligning the head or traming it. My dad was a machinist for 30 years. I should have listened to him more hahahaha!!!!
If I had the room I would have a bridgeport.

 

[Investigator]

Don't get me wrong guys, I really like the machine and had no prob aligning the head or traming it. My dad was a machinist for 30 years. I should have listened to him more hahahaha!!!!
If I had the room I would have a bridgeport.

For what it's worth, I have had the RF 30/31 whatever the model it is for a few years. I also have a B'port clone 9x42 that I need to replace spindle bearings in before I use it. I'm not in a huge hurry to swap, don't get me wrong I'm looking forward to it but all things considered I don't feel the B'port is such a huge step up that I have to RIGHT NOW. I have been very impressed with the capabilities of the round column machine.

 

[pontiac428]

Ah, yes- I remember you have a knee mill from your shop build thread. Get that thing running!

As for the RF 31, I have always heard PITA this, and PITA that. Baloney, they're great little mills. The round column is laughably easy to deal with (the word needed is "datum", guys), and most of us have had to jockey belts over sheaves at one point or another. At 115v, a 20A circuit is plenty. I'm not sure how many amps a Chinese horse can pull, but I don't recall ever stalling mine. Everything can be cleaned, adjusted, and aligned to produce performance that is surprisingly good. Don't go in with the attitude that you're polishing a turd, when the Rong Fu is really more of a rough diamond that takes some work to bring the shine out of. Once dialed in, they are remarkably capable.