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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Build Thread - BV20L 9x22 Lathe CNC Conversion
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  1. #13
    Registered
    Join Date
    Oct 2013
    Posts
    484

    Re: Build Thread - BV20L 9x22 Lathe CNC Conversion

    If a person hung the motor on a hinge off the back of the lathe, the weight of the motor will tension the belt automatically. Grizzly did this often on their 12" lathes. It's not hard to modify what you have now and makes it a snap, once the sheaves are aligned, to pull the belt up a tad and roll it into a different groove..all without having to fiddle around with adjustments or a tensioner...the motor weight provides the 'oink'!

    Stuart
    "THE GRIZZ" photo album - https://goo.gl/photos/yLLp61jooprtYzFK7
    Youtube - https://www.youtube.com/channel/UCT2lq9obzEnlEu-M56ZzT_A

  2. #14

    Join Date
    Mar 2019
    Posts
    11

    Re: Build Thread - BV20L 9x22 Lathe CNC Conversion

    The hinged mechanism could work, though I am trying to minimise the amount of footprint the lathe takes up, maybe a ratchet/pawl style tensoner or even gear driven high/low.

    I'll leave it the way it is for now as it is functional, i'd like to focus on the CNC conversion, then maybe I can get the machine to do some of the work instead of me doing it all the time. :cheers:

  3. #15

    Join Date
    Mar 2019
    Posts
    11

    Re: Build Thread - BV20L 9x22 Lathe CNC Conversion

    So before I pull this apart again to CNC, I thought it would be a good idea to do a quick test cut to ensure there wasn't any issues with spindle bearings.

    I fitted a new 3 jaw chuck and had to adapt my quick change tool holder from my other lathe to the compound. I had a old bolt laying around that proved to be adequate with some minor modifications.

    I was impressed with the cut quality, I was manually feeding with the hand wheels and ran the motor at 80 Hertz.

  4. #16

    Join Date
    Mar 2019
    Posts
    11

    Re: Build Thread - BV20L 9x22 Lathe CNC Conversion

    Here is some of the CNC Hardware that I may or may not use.

    Still need to decide on the motors, The motor I have in the photo I was planning to use for the Z. It is a Nema23 or 24? How to I work out what size motors I need. Do I direct drive them or use some sort of reduction drive via pulleys and a belt? Assuming I will need a smaller motor for the x axis, would it still be nema 23/24?

    The ball screw for the Z is 25mm in diameter, any issues with using such a large size for this? I notice some choose to also run two ball nuts, is this a good idea?

    X axis ballscrew is 12mm diameter, it will be a tight fit, the ball nut might need a bit of grinding and may need to mill the cross slide a little as well. I thought it was too short initially but then I was thinking I could mount the idler bearing inside the compound instead of on the outside. If this is not a good idea, I could just buy a longer screw and mount the bearing on the outside, they are cheap enough.

    Was planning to mount the X motor at the back of the cross slide, possible with some sort of reduction drive.

    The drivers are M542's which should be ok.

    Here are some photos

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