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Finished My Finger Grinding Fixture....... Finally !

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  • Finished My Finger Grinding Fixture....... Finally !

    Yesterday I completed this fixture for milling and grinding the 45 deg. faces of the fingers for my 24" finger brake.

    I milled a couple slots on each end so I can clamp it to the mill. I probably will have to remove about .006 - .010 to completely clean them up. I'll have to see how it all plays out.
    I'll probably mill a few thou off all of them and finish up on the grinder. The final amount of material removal will determined by what it takes to clean the one up that has the deepest imperfections.
    So I may have to do a little back and forth till I see where that actually is. Some may have deeper dings than others, it's hard to tell exactly. I'll do the worst one first. That should give me an approximate stopping point.

    Click image for larger version

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    It's a masterpiece in flatness and squareness. Best I can indicate with the primitive tools I have is it's overall flat and square to .00015.

    Click image for larger version

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    This is the position where I will mill and grind the 45 deg. faces of all the fingers. the fixture is 6 1/2" long. I have 24" worth of fingers to do. Two at 6" in length which will be done individually,
    two at 3" in length that will be done together and two at 1 1/4", 1" and 3/4" that total 6" in will be done as a group.

    Click image for larger version

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    The final clean up of the front edge will be done on the grinder with the fixture in the vertical position. All will be done equally. I think the edge is supposed to be about .020 in width.

    Click image for larger version

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    Hope you enjoyed the show !!

    JL...............



  • #2
    I always enjoy seeing interesting and new-to-me things!
    Location: Saskatoon, Saskatchewan, Canada

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    • #3
      Nice fixture Joe. I may have to rent if off you when/if I ever get around to restoring my brake.

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      • #4
        Thanks for the compliments guys. One thing that I don't particularly like is that the width of the 45 deg. base is 1" in width. the T-slots on my mill are about 5/8" wide. I have to straddle the slot in order to come straight in with the clamp. That leaves about 1/8" of fixture sitting on either side of the slot. It'll be OK as I'm only going to be taking a couple thou at a time so I don't expect it to move.
        But I would feel more comfortable if the fixture was setting between the slot rather than over it but then I can't grab it with a clamp.
        So I'm wondering if there is anyone that makes some type of "straddle type" clamp that allows for this type of set up.

        I'd hate to spend a few more days making something special for a basically one time deal.

        JL................

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        • #5
          Hi JoeLee,

          I'm only a HSM but one thing that I have done before and worked for the situation that I was in is, I lay parallels on there side over the T-slot and then mount the part. I have found that the parallel set I have they are ground flat on the side too, so it makes for a good base for what your talking about.
          Just another way to get it done !

          TX
          Mr fixit for the family
          Chris

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          • #6
            When I first saw the title of the thread I wondered why you'd want to grind your fingers, much less make a fixture for it. Most people spend their live trying to avoid grinding their fingers, or any other part of their anatomy. Then I realised you were talking about the fingers for your brake. Duh!
            'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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            • #7
              Originally posted by Mr Fixit View Post
              Hi JoeLee,

              I'm only a HSM but one thing that I have done before and worked for the situation that I was in is, I lay parallels on there side over the T-slot and then mount the part. I have found that the parallel set I have they are ground flat on the side too, so it makes for a good base for what your talking about.
              Just another way to get it done !

              TX
              Mr fixit for the family
              Chris
              Yes, I was thinking of doing that but for the light milling I figured it would be OK.

              JL.................

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              • #8
                I got all the 45 deg. faces milled. First pass I took .0025 off, they cleaned up nice. Lastly I grouped all the small fingers in the fixture and there were a couple fingers that the cutter didn't touch.
                I had to take an extra .002 to clean those up. So as to keep everything equal I had to mill the other again. I had planed on something like that happening. The job went pretty quickly without any issues.
                The weld dabs were hard and I had some sparks flying off my inserts. that's the problem with quick little TIG dabs. They end up being hard spots.

                The clamps are there for extra support because I can't tighten up the set screws too much as that starts to spread the fixture. I won't worry about it on the grinder.

                JL.................

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                Last edited by JoeLee; 02-06-2021, 05:21 PM.

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                • #9
                  Once you grind the first ones on the grinder, you might want to set up a surface gauge and DTI to record the height from your mag chuck, just in case you don't get through all the others without the need to dress the wheel.
                  Peter - novice home machinist, modern motorcycle enthusiast.

                  Denford Viceroy 280 Synchro (11 x 24)
                  Herbert 0V adapted to R8 by 'Sir John'.
                  Monarch 10EE 1942

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                  • #10
                    I'm sorry. I must be feeling a bit cynical today. When I saw the title of the post my first reaction was that I'm going to see pictures of a hand covered with bandages. Grinding your fingers?.......

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                    • #11
                      Originally posted by tom_d View Post
                      I'm sorry. I must be feeling a bit cynical today. When I saw the title of the post my first reaction was that I'm going to see pictures of a hand covered with bandages. Grinding your fingers?.......
                      Well, good for a laugh anyway, but this forum software doesn't let you edit titles. The older version did. I guess that's what these software nerds call progress.

                      JL.............

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                      • #12
                        Originally posted by Peter. View Post
                        Once you grind the first ones on the grinder, you might want to set up a surface gauge and DTI to record the height from your mag chuck, just in case you don't get through all the others without the need to dress the wheel.
                        I have thought about that as I'll never do all that grinding without a few wheel dressings.
                        I figure the way I'll do it is when I get all of them where I want I'll dress the wheel one last time and take a light cut across all of them with out moving the head.

                        I still have to figure out how much of a flat to put on the edge, I'll go about that the same way.

                        JL.............

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                        • #13
                          When you get done with all this work are you going to use the brake or is it just an exercise of OCD?

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                          • #14
                            Originally posted by J.Ramsey View Post
                            When you get done with all this work are you going to use the brake or is it just an exercise of OCD?
                            What's OCD ???

                            This summer I'm going to tear it down, paint it and hot blue the hardware. This is just the machine work part of the restoration.

                            JL............

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