SMT alignment

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  • Skip C
    Forum Newbie
    • Jan 2004
    • 84
    • Rowley, MA.

    SMT alignment

    Before I attempted a new project recently, I decided to check and realign the SMT assembly and fence. I ended up making everything even worse - so worse, that I borrowed my son's smt and used it for my project.

    This week I got around to reading all the info on this forum that I could find and with that info and the manual, I spend a few hours adjusting everything and I thought I had everything back to specs. At least it checked out that way before i turned on the saw! When I did the 5 cut test of a 12" square (which I found on this website), I ended up with the last cut having a difference of 0.050" (or about 3/64") between the widths of the top and bottom of the last slice. That seems a little too large. What is tolerable? The author states it would be that difference over the distance of a 46" board.

    Also (of more certain, I think), the corners of the square that I cut have angles of 89 and 91 degrees. As I mentioned, it seemed that all the individual alignments were spot on but obviously not! I will check everything out again before making any adjustments. Do my results indicate whether it is the fence or the table or the rails that are the culprit?

    Thanks for any help.

    Skip
  • Black wallnut
    cycling to health
    • Jan 2003
    • 4715
    • Ellensburg, Wa, USA.
    • BT3k 1999

    #2
    There can be a number of causes, including technique. Guides not quite tight enough can also have an effect.
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    marK in WA and Ryobi Fanatic Association State President ©

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    • Skip C
      Forum Newbie
      • Jan 2004
      • 84
      • Rowley, MA.

      #3
      Techinque is always a possibility!! And I did have to repalce one of the guides which broke; but if anything, I believe that the guides are tight and maybe too tight.

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      • mpc
        Senior Member
        • Feb 2005
        • 979
        • Cypress, CA, USA.
        • BT3000 orig 13amp model

        #4
        A few "technique" tips some folks aren't aware of or forget about in the heat of the moment when doing the alignments:

        With the saw unplugged, verify the arbor itself isn't the problem - if the whole arbor+motor assembly is loose/worn on the shims the blade can wander a bit during the cut. When the shims are worn/loose the blade will "rest" at one angle when the saw is off (i.e. when you are adjusting the SMT and rip fence to the blade)... then when dealing with the aft pressure of a workpiece the blade might be angled a little differently.

        Also, when doing the SMT & rip fence alignments, are you using one saw blade tooth or the whole blade? Use one tooth in case the blade itself is warped a little. Mark one tooth with a Sharpie or something, then rotate the blade by hand so that tooth is at the front of the saw. Check your measurements, rotate the blade to put that tooth at the rear, and re-measure and compare measurements.

        Check the rails for parallelism; you may find one (or both) are slightly bent. If the front rail is banana shaped the rip fence to blade angle will change depending on where it's clamped down; it'll only be "correct" when clamped down at the spot you used when doing the alignment in the first place. Folks that use the rails as wheelbarrow handles when moving the saw dramatically increase the risk of non-parallel rails. Especially if they've added weight to the saw/stand by adding storage or work surface extensions, routers, etc.

        One last "gotcha" is the floor itself. The BT3 stands aren't the most rigid things in the world so if your floor is uneven the saw may be twisting differently each time you move the saw. Some folks have put marks on the floor so they know just where to put the saw each time they get it out of its "storage" parking spot when they use it... just to avoid this issue.

        mpc

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        • Lonnie in Orlando
          Senior Member
          • May 2003
          • 649
          • Orlando, FL, USA.
          • BT3000

          #5
          Another improvement to cross cut accuracy: Use the adjusting knob and support to push the SMT through the blade instead of pushing on one end of the cross cut fence.

          - Lonnie
          Last edited by Lonnie in Orlando; 02-24-2012, 09:16 AM.
          OLD STUFF ... houses, furniture, cars, wine ... I love it all

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