Rewired lathe, VFD controls via OEM controls

[paul s]

I notice the lack of variator dial - did you remove the variator, and if so, can you give some detail on how that was done and if there's any torque penalty at low speeds?

By the way, I had the same issue with my South Bend/VFD - the VFD input for forward was latching, but not reverse; I never did overcome that.

Paul

 

[FliesLikeABrick]

I notice the lack of variator dial - did you remove the variator, and if so, can you give some detail on how that was done and if there's any torque penalty at low speeds?

By the way, I had the same issue with my South Bend/VFD - the VFD input for forward was latching, but not reverse; I never did overcome that.

Paul

Hey Paul thanks for your interest. The variator was already removed prior to when I bought the lathe, and a prior owner had attached a VFD to the headstock with a bracket. However, the general solution appears to be to remove the variator, move the output pulley from the variator over to the motor, and mount the motor where the variator used to live (on the isolated platform)

My post about repairing the headstock oil leaks on my machine has at least one picture that shows this
https://www.hobby-machinist.com/thr...-colchester-chipmaster-harrison-10-aa.104393/

Is there anything specific you want pictures or information on? I'm happy to gather what information I can

As for the VFD - yeah it seems in general that most VFDs expect the latching to be external, the manual for the individual VFD is an invaluable resource. On this VFD (which came with the lathe but I found the manual online), it had options for sustained (externally latched) fwd and rev run inputs; another option for sustained (externally latched) fwd/rev and on/off inputs; and a 3rd option for self-latching (external momentary inputs) start/stop in combination with externally-sustained reversing input

That last one is best for a setup that wouldn't require additional relay logic -- you can set that one up with two momentary pushbutton switches (one NC, one NO), and a SPST toggle switch for fwd/reverse. If you have not already looked into this, I think these options are pretty typical and the manual for your VFD would reveal the specifics. Below are screenshots from the manual for this VFD, for example.

In the case of my Chipmaster, I wanted to implement the VFD inputs using the original lathe's eletromechanical controls so I opted for the first option 4.1.2a -- where the original motor-run contactors (fwd and rev) just closed the path to the terminal 3 and 4 inputs, each fed from the terminal 5 "common"

 

[FliesLikeABrick]

As far as torque penalty - I can't say for certain since I never ran it with the variator but I am pretty sure that yes I am losing noticeable torque under about 400 or 500rpm on the motor, so I end up switching to low gear and running the motor at full speed to get ~300rpm on the spindle.

Or I'll change tool, feed, or depth of cut to reduce my torque requirement - if it can accomplish the necessary goal.

So far this compromise has suited me well, and realistically I don't have another option... and as a hobbyist amateur my requirements are generally flexible

 

[geoffm]

As far as torque penalty - I can't say for certain since I never ran it with the variator but I am pretty sure that yes I am losing noticeable torque under about 400 or 500rpm on the motor, so I end up switching to low gear and running the motor at full speed to get ~300rpm on the spindle.

Or I'll change tool, feed, or depth of cut to reduce my torque requirement - if it can accomplish the necessary goal.

So far this compromise has suited me well, and realistically I don't have another option... and as a hobbyist amateur my requirements are generally flexible

For my Chipmaster, I used a larger 900rpm 6 pole motor and overspend it to 50% over mains frequency. This provides a good range without the noticeable torque loss of the 1400 rpm 4 pole motor. My vfd is an older v/f control type. A modern vector drive is better with a bigger useful range and more low-speed torque.

 

[FliesLikeABrick]

For my Chipmaster, I used a larger 900rpm 6 pole motor and overspend it to 50% over mains frequency. This provides a good range without the noticeable torque loss of the 1400 rpm 4 pole motor. My vfd is an older v/f control type. A modern vector drive is better with a bigger useful range and more low-speed torque.

That is a great idea. If I ever need to replace the motor on mine or solve the low-end torque issue - I will definitely look for a slower motor. I would rather have better low-end torque than be able to hit the 3000rpm max speed which just isn't needed for the kinds of work I do with this machine. Perhaps I will look for a smaller pulley for the motor, as that would also help the current motor but I would probably need to look for new belts at an oddball length...

 

[paul s]

I'll try working with the variator to start, probably use a VFD for the phase conversion.

Someone on ebay is selling 1 litre bottles of the magic variator fluid - will that be enough?

Paul

 

[paul s]

Ryan - what did you do regarding the wiring from the disconnect output to the input of the coolant pump contactor?

 

[fixit]

It would be nice to have a tachometer right beside speed control

 

[FliesLikeABrick]

Ryan - what did you do regarding the wiring from the disconnect output to the input of the coolant pump contactor?

I had originally disconnected that wiring because I didn't want to accidentally send single phase 240 to the 3 phase coolant pump. Then later when I wanted to use the coolant contactor to control a 120v mist system, I wired the 120v transformer output to be used as input to the coolant contactor. I have a video that talks through the chipmaster controls changes at

if you haven't seen it

 

[paul s]

Thank you Ryan - I just watched the video. For now, I won't be reinstalling the coolant pump, so I'll just leave those connections as is.

I notice that you have the one shot oiler on your apron - I've got a question regarding, and I'll PM you, so as not to take the thread here off track.

Paul