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Thread: Motor with clutch for home shop machines?

  1. #1
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    Default Motor with clutch for home shop machines?

    When I watch videos of the big iron lathes and even the similar size lathes to what I have but which are more seriously intended for commercial shop use I see that the common setup is a motor that starts and runs constantly for the whole time and that the lathe is clutched in and out and often has a brake built into the action of the clutching handle. (Edited- WOW! that was a long sentence!)

    I'm just wondering if anyone has modified their "home" lathe to add such a clutch and perhaps the brake as well.

    Seems like it would make things a lot easier on the poor motor.

    Or does the use of a 3ph motor and VFD effectively replace such a clutch and brake setup?

  2. #2
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    My small (7x12) home lathe uses a DC motor and so it comes to a stop when turned off.

    The bigger one (9x20) has a belt drive with a handle to take the tension off to stop it. The motor does spin all the time. When I get a round Tuit I will replace the motor with the Consew brushless DC motor that I bought two years ago. Then the belt will only need to be moved to change gear ranges.

    Dan
    Measure twice. Cut once. Weld. Repeat.
    ( Welding solves many problems.)

  3. #3
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    Quote Originally Posted by BCRider View Post

    Or does the use of a 3ph motor and VFD effectively replace such a clutch and brake setup?
    Yes. This is a new and better way. The soft start and electronic braking of a VFD is just better. I modified a colechester lathe by removing the brake and clutch and never looked back.
    "...do you not think you have enough machines?"

  4. #4
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    VFD is better solution in almost every case today. Clutch packs wear, need adjustment etc. Pretty often the solution for aging belt variator or worn clutch pack is to install VFD.

    I have clutch on my small 11x24 Kerry lathe.. Never used it for "real", only time I'm touching it when it starts to slip. Have to engage/disengage it couple of times to make it work properly again.

  5. #5
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    The smoother start also minimizes undesireable motion in the carriage, crossfeed, etc.

  6. #6
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    Quote Originally Posted by Glug View Post
    The smoother start also minimizes undesireable motion in the carriage, crossfeed, etc.
    Hear hear, I have to lock the crossfeed on my small lathe if I really want to hit anything within 0,02mm. Otherwise its jumping around randomly when I start the lathe

  7. #7
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    On a big lathe (or any lathe, really), one should spin the chuck one revolution
    to just check if anything is going to hit or make contact with part of the lathe.
    Not so much a problem with shafts, but odd shapes like castings is where this
    step becomes most important. Also good to start an odd shaped piece gradually
    to check for imbalance.
    With a friction clutch, the user had direct control of the speed and torque that
    gets applied to the chuck. With a VFD, you hit the button, and you are committed
    to the motion that it is programmed to give you, unless you hit the stop button.
    With a clutch, the control is all right there, instantly. Any sense of something
    going wrong, the user can back off the clutch lever in an instant. Much quicker than
    hitting a stop button. This is why a clutch is always better for a manual lathe.
    The variety of work is so large, and no one wants to roll a 200 pound chuck and
    probably much heavier workpiece over by hand to check for interference.
    A VFD just can't do that.

    -Doozer

  8. #8
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    Quote Originally Posted by Doozer View Post
    On a big lathe (or any lathe, really), one should spin the chuck one revolution
    to just check if anything is going to hit or make contact with part of the lathe.
    Not so much a problem with shafts, but odd shapes like castings is where this
    step becomes most important. Also good to start an odd shaped piece gradually
    to check for imbalance.
    With a friction clutch, the user had direct control of the speed and torque that
    gets applied to the chuck. With a VFD, you hit the button, and you are committed
    to the motion that it is programmed to give you, unless you hit the stop button.
    With a clutch, the control is all right there, instantly. Any sense of something
    going wrong, the user can back off the clutch lever in an instant. Much quicker than
    hitting a stop button. This is why a clutch is always better for a manual lathe.
    The variety of work is so large, and no one wants to roll a 200 pound chuck and
    probably much heavier workpiece over by hand to check for interference.
    A VFD just can't do that.

    -Doozer
    You can do pretty much that also with VFD if you just want, takes just bit more effort in setup. You could also add torque control to the "virtual clutch lever" if you want but that is not going to work with the cheapest 80$ chinese VFDs. Tap and crawl at 1rpm with full torque or crawl at 5% limited torque if you wish..

  9. #9
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    Quote Originally Posted by Doozer View Post
    On a big lathe (or any lathe, really), one should spin the chuck one revolution
    to just check if anything is going to hit or make contact with part of the lathe.
    Not so much a problem with shafts, but odd shapes like castings is where this
    step becomes most important. Also good to start an odd shaped piece gradually
    to check for imbalance.
    With a friction clutch, the user had direct control of the speed and torque that
    gets applied to the chuck. With a VFD, you hit the button, and you are committed
    to the motion that it is programmed to give you, unless you hit the stop button.
    With a clutch, the control is all right there, instantly. Any sense of something
    going wrong, the user can back off the clutch lever in an instant. Much quicker than
    hitting a stop button. This is why a clutch is always better for a manual lathe.
    The variety of work is so large, and no one wants to roll a 200 pound chuck and
    probably much heavier workpiece over by hand to check for interference.
    A VFD just can't do that.

    -Doozer
    Better quality VFD's have multiple "program" capabilities.
    The Toshiba unit on my big lathe is set up for jogging. I just push the momentary "jog" button (MAZAK labeled it "Inching")
    5 rpm that stops with braking as soon as I release the button. Faster than a lever!

    So yes, a VFD "can do that". And like lathes that come with differing spindle drive designs, VFD's come with differing features.

  10. #10
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    Quote Originally Posted by danlb View Post
    My small (7x12) home lathe uses a DC motor and so it comes to a stop when turned off.

    The bigger one (9x20) has a belt drive with a handle to take the tension off to stop it. The motor does spin all the time. When I get a round Tuit I will replace the motor with the Consew brushless DC motor that I bought two years ago. Then the belt will only need to be moved to change gear ranges.

    Dan
    Dan, my own lathe has a belt drive head too. But I never thought of using the belt drive as a clutch. I suppose it would work but it's not really a good option for me as the belt tensioning lever is directly behind the chuck. To use it as a clutch I'd have to get in close to the spinning work with both my chest and arm and it would be just asking to go for a ride. First on the lathe and then right after that in an ambulance... or more likely a hearse....

    Sounds like if I were to go for any sort of upgrade that the hot setup is a 3ph motor and a VFD with the right sort of features.

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