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Poor man's DRO?

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  • Poor man's DRO?



    Now this is a mans poor DRO. It may be cheap, but it allowed me to hit within 8/10s on the last two parts I made .

    I am going to have to save my pennies and get a real one. It turned a 30 minute job into a 10 minute one with much better accuracy.

    At this point I have only one concern. The indicators are mounted to the lathe way and saddle with magnets so they can be repositioned or removed easily. Is this liable to cause problems with the indicators or the lathe?

    Tim

  • #2
    Problems? Like getting the swarf off the magnets?
    "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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    • #3
      Originally posted by mickeyf
      Problems? Like getting the swarf off the magnets?
      Not so concerned with removing swarf from the magnets, it comes off readily. More like permanently magnetizing the ways so that is is more difficult to remove swarf. Or magnetizing the gears in the headstock so that they will attract metal bits out of the headstock oil.

      Tim

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      • #4
        Cast iron isn't particularly good at retaining magnetic flux. As soon as a magnetic field is remove, cast iron magnesium drops quickly. Other steel parts around the lathe are another story though. And the cast iron can "transmit" the magnetism to other parts. I have a bench-top demagnetizer for tooling and an old degauss coil for things that are large. My coil is from the mid 60s when it was a common necessity if you owned a color TV.

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        • #5
          Tim, You can never have too many tools. There are always going to be applications where one works better than the other. I have a couple of those mini-mag holders and have used them a lot with good results. The old South bends had a factory holder that worked well. If you are not confident with the magnets a holder that clamps to the ways will be more secure. A micrometer type carriage stop like this is hard to beat in some instances.


          this shows the basic clamp.
          Byron Boucher
          Burnet, TX

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          • #6
            Good idea Bryon,

            I have seen those before in fact I have one that came with my lathe. It would make a much more stable mount than the magnets.

            I wonder if I could make one with a lever lock and an indicator mount

            Tim

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            • #7
              The Southbend indicator holder had a lock screw. The whole thing kind of stowed on the left end and just slid out and locked in place when you wanted to use the indicator.
              Byron Boucher
              Burnet, TX

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              • #8
                The one that came with my lathe has the cap screws on the bottom, so you have to stand on your head to clamp it down. It is a pain in the A$$.

                I see that yours has the cap screw heads on top where they are easily accessible.

                Since it will probably be awhile before I can get a real DRO (I will get one for the lathe and one for the mill) I think I will go ahead and make a couple of way clamps like that so I can mount my indicators more solidly.

                I guess the magnets will work ok until I get them built.

                Tim

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                • #9
                  I have watched the guys cutting the tapered threads on drill collars. When they get close they screw on a gage and measure the gap with a feeler gage and then plop a magnetic base indicator on the ways and use that to make the cut. They do it enough that there is nothing tentative in their approach.

                  When you make yours consider not cutting a pocket for the screw head. It is easier to take on and off if you can turn the screws with your fingers. The screws on top are better and I would rather have them sticking up than down flush.
                  Byron Boucher
                  Burnet, TX

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                  • #10
                    Good idea, maybe some thumbscrews

                    Tim

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                    • #11
                      I was trying to read the X axis DRO and my chair fell over. If you would clamp web cams pointing at both you could email yourself the output.

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                      • #12
                        Originally posted by GKman
                        I was trying to read the X axis DRO and my chair fell over. If you would clamp web cams pointing at both you could email yourself the output.
                        Reposition chair?

                        Tim

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                        • #13
                          OK, here's my implementation of the "poor man's DRO". It's a small scale, designed in Illustrator, printed out on a laser printer, and glued to a strip of 1" flexible magnet. (I picked up a roll of 1" flex magnet at my local OSH; it even came with adhesive on one side!) It's graduated in 1/10 inch, which will get you within range, so you can make final adjustments with the graduated dial on the hand wheel to .001 or better. To reset your PMDRO, just scootch the magnet strip (or adjust the pointer, which sits on a magnet). I don't lose track of hand wheel turns anymore.





                          Before magnet epoxied into place:

                          Last edited by Bolster; 11-05-2010, 02:28 AM.

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                          • #14


                            My implementation of the PMDRO, cables operated for lathe X and Y travel.

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                            • #15
                              That's very nice; I'm not sure it qualifies for poor, does it?

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