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Mini Lathe Compound Pivot

Discussion in 'MINI-LATHE & MINI-MILL INFORMATION' started by old toolmaker, May 24, 2017.

  1. old toolmaker

    old toolmaker United States Active Member Active Member

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    I am going to modify the compound pivot of my Micro Mark 7 x 16 mini lathe. The method I am going to use is like the pivot on the South Bend and the Logan lathe. I am tired of cranking the compound back to release the lock screws and its associated issues.

    I know exactly how to go about it.

    Has anyone had gone beyond that to include an engraved degree scale around the bottom of the compound base (maybe 180 degrees) similar to a Logan? This could be done by machining a 180 degree radius portion to the bottom front of the compound base and engraving a degree scale on it.

    I do intend to place the round pivot member closer to the front end of the base.

    Dick
     
  2. royesses

    royesses United States H-M Supporter - Premium Content H-M Supporter-Premium

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    LMS sells a modified compound that does the same thing. Moves the mount hole forward by .875. On my mini lathe (7x16) there is no where to put the engraved scale (I may not be picturing your Idea correctly). I uploaded a pdf on the modification by J W Early just in case you might not have seen it before.

    Roy
     

    Attached Files:

  3. old toolmaker

    old toolmaker United States Active Member Active Member

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    Thanks, Roy
    I read it all the way through. Not sure I want to do the same thing as the original as far as the mounting method with the cap screws going through the compound. That is the part I want to improve. As soon as the cap screws are loosened the whole thing can and does move in several directions because it is no longer bolted solid to the pivot and guided by the pivot.
    Dick
     
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  4. royesses

    royesses United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Dick, that sounds great. Show us when you get it done. I'm always willing to use someone else's ideas to improve the mini lathe.

    Roy
     
  5. old toolmaker

    old toolmaker United States Active Member Active Member

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    I finally completed the modification to the compound pivot on my MicroMark 7 X 16.
    The result far exceeds what I expected and I wish I had done this sooner. It is now very easy and simple to set the angle on the compound. I have made CAD drawings so I have a record of "as built" dimensions.
    I have included pictures. The second picture shows the lathe fixture I made for cutting the angled portion on the brass pins. They are machined on their ends to match the cone of the pivot itself.

    Dick
     

    Attached Files:

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  6. Ken from ontario

    Ken from ontario Canada Active Member Active Member

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    Dick, I like your compound pivot mod, the most complex part of it in my opinion is the making a fixture for cutting the precise angles on the brass pins, do you also have a picture of the "cone" that these pins are to match the angle of?
    Here's another way to improve the compound pivoting action:
     
  7. old toolmaker

    old toolmaker United States Active Member Active Member

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    Hi Ken,

    I don't have a picture of the compound pivot showing the angle. I do have drawings of it but not in a PDF. The angle is 45 degrees.

    I watched your very interesting video. As I understand it, the compound pivot stands proud of the cross slide top by about .001" per your video so it can rotate freely. So then your compound is supported by the round pivot and does not rest on the top of the compound. I did not get a clear picture from the video of how the screw locks the pivot. Could you explain that so I can get a better understanding of how it works?
    How has it worked out so far? Is it rock solid while taking a good depth of cut?

    Dick
     
  8. Ken from ontario

    Ken from ontario Canada Active Member Active Member

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    That video I linked I found on youtube and it was just to show another way to fix the pivoting problem with the benchtop lathes, I have not actually done the mod myself but I'm planing on doing it soon , for now I'm just gathering as much information as I possibly can, then choose a method that works for me, I just got my lathe a couple of days ago ,spent all this time dismantling,cleaning and re-adjusting all the gibs and so on and so forth.
     

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