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Micro positioner, low profile design

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  • Micro positioner, low profile design

    Inspired by the several designs offered by others (hats off to Rod Kirby and JimD), I thought I would have a go at building a micro-adjuster. Glad that I did – the rip fence moves so easily, it takes the hassle out of that last bit of adjustment.

    http://www.bt3central.com/attachment...1&d=1317782989

    If you have an Ace Hardware nearby that has a “parts playground” you're in luck. That's where I got most of the pieces for this design.

    2 – elevator bolts 1/4x20 1”
    2 – mylar washers 3/8” opening
    2 – 1/4” steel washers
    2 – 1/4x20 wing nuts
    1 - #10x32 2” cap bolt
    1 – two-armed knob made to fit the head of the cap bolt
    1 - #10x32 lock nut (nylon insert)
    1 – 1/2” dia. “supermagnet” (NIB)
    2 – small wood screws
    2 – 3/16” x 1” x 1-1/2” steel coupons
    1 – hardwood block 1/2” x 1-1/2” x

    I wanted to keep the overall profile low and easy to set up. The assembly should be clear from the photos. Some notes on construction:

    Elevator bolts have a thin, circular plate for a head. These needed flats filed on the sides to fit in the width of the slot. The mylar washers are there because I don't like steel in contact with aluminum. They are about the thickness of an index card.

    http://www.bt3central.com/attachment...1&d=1317782989

    The supermagnet idea works great! The adjuster can pull just as easily as it pushes. One steel plate is epoxied to the end of the rip fence handle and the magnet is just stuck to it. Makes it easy to pull off when not in use.

    I had to route a recess in the top of the hardwood block to allow the arms of the cap to rotate but keeping the profile low means it doesn't catch sleeves and stays below the table of the saw. Having the red armed cap isn't a necessity but it does make a good reference point for quarter-turns. I never imagined I could adjust a cut by 1/128th of an inch (~0.008”) but the performance is pretty close to that.

    http://www.bt3central.com/attachment...1&d=1317782989

    When drilling for the #10x32 tap, I used a #21 bit. Many charts call out #18 as the bit but a test showed that in the 3/16” thick steel, there was enough play in the threads cut to a #18 bit that the cap bolt could wiggle side to side and had a bit of lash when reversing direction. Using a #21 bit, you may have to run the cap bolt back and forth a time or two in the newly tapped hole before it gets loose enough to turn by hand. Also, make sure the nylon insert nut is steel not brass. Besides staying put, this type of nut rises to a small crown. I chucked this one in the drill press and sanded a nice, flat surface on the crown.

    Sure is nice to be able to set the approximate width of a cut, make a test cut, measure it and consistently “dial-in” the exact width in one trial. Hats off again to all the great info shared on this forum.
    Attached Files
    “It is not necessary to change. Survival is not mandatory.” ~W. Edwards Deming

  • #2
    What a gem of a first post! Sorry it took so long for approval.
    Donate to my Tour de Cure


    marK in WA and Ryobi Fanatic Association State President ©

    Head servant of the forum

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    • #3
      Likewise... That looks fantastic!
      Please like and subscribe to my YouTube channel. Please check out and subscribe to my Workshop Blog.

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      • #4
        Nicely done!

        I agree about the utility of a micro-positioner. Mine is "store bought", but surely not better than yours in any way. I use it very requently in my box making, assuring a nice match on tight fitting pieces.

        JR
        JR

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        • #5
          Lookin' good.
          Downunder ... 1" = 25.4mm

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