lathe with clutch on VFD, starting torque for spindle?
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  1. #1
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    Default lathe with clutch on VFD, starting torque for spindle?

    Hi,

    Thinking about putting a lathe like a Colchester 13" on a VFD. I'm familiar with setting up this type of machine with true VFD start/stop, as my current lathe (Kent TRL) is setup that way.

    On the true clausing colchester, the motor would always be running at full 60hz frequency, but then the "matrix clutch" would engage to quickly start and stop the spindle.

    I suspect this would be OK, but the motor (5hp 1800rpm or so) would be very lightly loaded until the clutch engages, and then have the torque load to accelerate the entire geartrain, spindle and part to full speed. Presumably the clutch would mediate this power transfer somewhat, so it wouldn't be instantaneous.

    To be clear I'd be using a good quality drive, Yaskawa probably. Something appropriately sized for the load but hopefully not need to be oversized.
    -Phil

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    I run my Colchester Chipmaster as you describe. I even have the VFD dialed down to 50 Hz to mimic UK power. I have run the machine this way for 20 years without any issue whatsoever. I can snap the clutch in or feather it in, high or low ratio on the variator, forward, reverse, start with the clutch already engaged, and there’s no issue. I do have a braking resistor.


    Sent from my iPhone using Tapatalk

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    I am doing the same vfd conversion on my Smart Brown 1024 and wondering if there needs to be a "free run " switch to contact the lever as the clutch shifts from low to high under speed. Does Colchester use the same Coventry Matrix system as the S and B - ZC 25 ? Dave

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    Best way to deal with this issue, Phil... is to just put the VFD on it, set it up, and use it. You could run the motor in constant speed, or you could leave the clutch engaged and let the VFD do all the work... it'll work fine either way!

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    Best of both world in my opinion. Using the clutch to feather in a tap is mighty handy.

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