Busy Bee CX603 VFD?

[canuck750]

I have a small knee mill that looks just like a Busy Bee CX603, belt driven, single phase, 1hp, 110v motor. The mill is fitted with a DRO on X,Y and Z axis. There is no tachometer.

I would like to have a variable speed drive without moving the belts around and be able to reverse the motor by means of a simple switch.

I have watched a couple YouTube videos showing various small mills converted to 3 phase motors with a VFD, most seem to use a 220v - 3 phase motor, either of 1 hp or 2 hp, and a simple tachometer added with a magnet type pickup reading from one of the belt pulleys. Challenges appear to be programming the VFD.

Being of very limited electric knowledge has anyone completed a complete installation on one of these mills and do you have a list of components used and advice for a novice?

Is it necessary or advantageous to use a 3 phase motor?
Do I need to fit a 220v motor?
Is there a reason to install a 2hp motor over a 1 hp?
Several videos indicate the new setup causes the DRO to malfunction, any thoughts on this?

Thanks in advance for any help!

 

[TorontoBuilder]

I have a small knee mill that looks just like a Busy Bee CX603, belt driven, single phase, 1hp, 110v motor. The mill is fitted with a DRO on X,Y and Z axis. There is no tachometer.

I would like to have a variable speed drive without moving the belts around and be able to reverse the motor by means of a simple switch.

I have watched a couple YouTube videos showing various small mills converted to 3 phase motors with a VFD, most seem to use a 220v - 3 phase motor, either of 1 hp or 2 hp, and a simple tachometer added with a magnet type pickup reading from one of the belt pulleys. Challenges appear to be programming the VFD.

Being of very limited electric knowledge has anyone completed a complete installation on one of these mills and do you have a list of components used and advice for a novice?

Is it necessary or advantageous to use a 3 phase motor?
Do I need to fit a 220v motor?
Is there a reason to install a 2hp motor over a 1 hp?
Several videos indicate the new setup causes the DRO to malfunction, any thoughts on this?

Thanks in advance for any help!

Yes you need a 3 phase motor and VFD. 220v 3 phase tend to be lowest cost option. Two HP can throw wider face mills, or just use the tool time adage, More power

The programming is easy if you buy a teco westinghouse or other well documented VFD.

The tach is as simple as you say, but use array of magnets for greater accuracy at low speeds.

 

[slow-poke]

I have converted two mills from the original single phase to VFD driven 3-phase. I echo the comments above. Not sure how difficult it would be for you to get 240V from your circuit breaker box?

There are other advantages beyond the variable speed; smoother, fast braking, reversable and the motor is typically more reliable. After using both I would not hesitate for a second to do the conversion. I would choose a VFD with external brake resistor and sensorless vector control, this is a common feature on anything but the cheapest VFD. You will likely find a 1.5HP motor adequate, but a 2HP will offer more low speed power when turning a large diameter tool at slow speeds.

Your comment about the DRO is interesting. I have had no issues with my DROs. That being said the good DROs use differential signalling that have good noise immunity and the okay DROs use single ended quadrature encoding that is not quite as good and the really lousy DROs use a variety of serial protocols some with no error correction that are just a mistake waiting to happen when there is even a hint of noise. I have used DROs that use both differential and single ended with VFDs and they work flawlessly.

Do be aware that VFDs do radiate EMI that could effect any electronics that is susceptible to electrical noise, however if you:
1) Keep the cable between the VFD and motor short
2) Make sure your VFD, motor and electronics are all well grounded

It's really unlikely you will have a problem.

Beyond access to 240V (a 15 or 20A circuit is suitable), you will need a $5 pot for speed control, a toggle switch for forward/reverse, a couple of pushbuttons, one for start and one for stop and an E-Stop for emergency stops. If you use the external brake for really quick spin downs you will need a 100W resistor about $10 or so.

Your probably going to hear "make sure you get a VFD rated motor" I would ignore that and get whatever motor you can for the lowest cost. I have used very old non VFD motors and they barely get warm even when used at slows speeds. For larger motors or continuous production type settings the VFD rated motors might make sense.

I think we have similar mills.

 

[canuck750]

Thank you for the advice, much appreciated. I need to start shopping for a 3 phase motor.

 

[DavidR8]

Alas if only cheap 3-phase motors were ever available on the island.

 

[TorontoBuilder]

I have converted two mills from the original single phase to VFD driven 3-phase. I echo the comments above. Not sure how difficult it would be for you to get 240V from your circuit breaker box?

There are other advantages beyond the variable speed; smoother, fast braking, reversable and the motor is typically more reliable. After using both I would not hesitate for a second to do the conversion. I would choose a VFD with external brake resistor and sensorless vector control, this is a common feature on anything but the cheapest VFD. You will likely find a 1.5HP motor adequate, but a 2HP will offer more low speed power when turning a large diameter tool at slow speeds.

Your comment about the DRO is interesting. I have had no issues with my DROs. That being said the good DROs use differential signalling that have good noise immunity and the okay DROs use single ended quadrature encoding that is not quite as good and the really lousy DROs use a variety of serial protocols some with no error correction that are just a mistake waiting to happen when there is even a hint of noise. I have used DROs that use both differential and single ended with VFDs and they work flawlessly.

Do be aware that VFDs do radiate EMI that could effect any electronics that is susceptible to electrical noise, however if you:
1) Keep the cable between the VFD and motor short
2) Make sure your VFD, motor and electronics are all well grounded

It's really unlikely you will have a problem.

Beyond access to 240V (a 15 or 20A circuit is suitable), you will need a $5 pot for speed control, a toggle switch for forward/reverse, a couple of pushbuttons, one for start and one for stop and an E-Stop for emergency stops. If you use the external brake for really quick spin downs you will need a 100W resistor about $10 or so.

Your probably going to hear "make sure you get a VFD rated motor" I would ignore that and get whatever motor you can for the lowest cost. I have used very old non VFD motors and they barely get warm even when used at slows speeds. For larger motors or continuous production type settings the VFD rated motors might make sense.

I think we have similar mills.
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Oh that is a nice looking shop, dramatic lighting and all.

 

[DavidR8]

My shop is small but I'm just thrilled with the way it works, I keep tweaking it when something can be improved. Electronic section and mechanical section, saws and grinders in an adjacent room, and supplies room also adjacent. In my previous house everything was spread out part in garage, part in basement and part in office did not work well at all.
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I’m so envious of you folks who have electronics knowledge and abilities!