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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Mini Lathe > Build Thread: HF 8x12 variable speed DC motor conversion
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  1. #1
    Join Date
    Mar 2010
    Posts
    156

    Build Thread: HF 8x12 variable speed DC motor conversion

    I am starting this thread to document my conversion of my HF 8x12 lathe to variable speed.

    I was able to pick up a kb multi drive for cheap. The model is KBMD-240d. It has the capabilities of the kb controller that has been posted about in another thread and puts it all together in one box: forward, reverse stop and power + an led to show when it is has power going to it. It can run either 110 or 240 v and run both 90v and 180v dc motors up to 2hp.

    I got one on ebay for 70 bucks with the optional heatsink thrown in and added the accessory forward-brake-reverse switch for 50 bucks. A bit more than doing the diy route but everything is in one place and it can run a variety of motor sizes via power resister.

    Pics:

    Front:


    Heatsink:


    Inside:


    Terminal:


    forward-brake-reverse switch installed:


    I also picked up a ge industrial motor on ebay. I am still learning as I go so I hope it will work but the price was right.

    From the ad:

    Amps:10.5A/0.76F RPM: 1725 Frame: 56 Volts: 90A/100F

    Pics:




    I was reading about shunt motors and they are reversible + variable speed capable. The controller is compatable anyways. Any thoughts on whether this is the best type to use or not would be appreciated. I am waiting for it to be delivered. I will post more after I get the motor.

  2. #2
    Join Date
    Dec 2003
    Posts
    24223
    It looks a bit well used so I would inspect the brushes and commutator when you get it.
    One thing you should be aware of with wound field motors, if you lose the field connection for any reason while running, the motor can take off in a runaway condition, they have been known to self destruct when this happens, higher end drives have a field loss detection to prevent it, and shut down.
    Otherwise GE made good motors.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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