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Thread: I need Miter Gauge/Sled help **pics added**

  1. #1
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    I need Miter Gauge/Sled help **pics added**

    I have the Jointech SmartMiter (which I love) but I need help with something.

    Is there a good way to test that it is at 90, in a video they give they show cutting a squared up 6" wide piece of wood, then flipping one half one way and one half the other (or something like that) and if there is a gap is should clearly show, maybe even double. If the gap is at the top you move the sled one direction, at the bottom you move it the other.

    I originally set this up and I have never any problems that I know of, BUT know that I am trying to make a picture frame the 45's are not coming our right which to me means that its not 90 when I think it is.

    They send a "wedge" that you can use when cutting 45 when you rotate the fence the opposite direction and it is cut at 45, it looks good on my combination square. I rotated the fence and raised the blade high and put this wedge in there until it didn't wiggle between the two.

    To get it not to wiggle (which would be 45) I had to have the fence at 45 1/4, then the picture frame came out pretty good.

    I know something is messed up, what is a good way to test for 90 & even 45. I am mostly worried about 90 because if you get that set up right then 45 should follow without any adjustments. Tips, Tricks?

    Thanks
    Last edited by Aaron Beaver; 11-09-2008 at 01:06 PM.
    Rise above the rest

  2. #2
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    Quote Originally Posted by Aaron Beaver View Post
    They send a "wedge" that you can use when cutting 45 when you rotate the fence the opposite direction and it is cut at 45, it looks good on my combination square. I rotated the fence and raised the blade high and put this wedge in there until it didn't wiggle between the two.

    To get it not to wiggle (which would be 45) I had to have the fence at 45 1/4, then the picture frame came out pretty good.
    Thanks
    When I read this, I can only think of one answer. If you are setting up the jig using the wedge and getting a good tight picture frame, then your angles at that setup are correct. This must mean that you are set right at 45'. The conclusion I draw is that your initial adjustment is out by 1/4' and it's the scale that is reading wrong.

    cheers

    John

  3. #3
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    You could try the 5 sided cut test. I do this a few times a year to re-certify my sleds. For my miter gauge I just clamp the miter bar in the vise with the head hanging toward the floor and use my Wixey to confirm 90* but the 5 sided method can certify gauges as well.

    Example here, scroll down to the section just above "Calibrating Crosscut Fixtures/Sliding Tables" and click the word next by the picture:
    http://www.thewoodshop.20m.com/howto_crosscut.htm

    Another description:
    http://benchmark.20m.com/articles/Th...eSidedCut.html

    and another:
    http://www.thewoodshop.20m.com/five_cut_method_swf.htm

    This method uses the actual cut as opposed to a measuring tool. No matter how good your triangle or square may be, as you hold it up against a surface and try to sight long the blade, too many elements come into play to make it easy to get into the thousandths for accuracy. By using the cut result to test, adjust, test, adjust; you end up with the actual result from your saw cut.
    Last edited by glenn bradley; 11-05-2008 at 02:43 PM.
    Any sufficiently advanced technology is indistinguishable from magic.
    - Arthur C. Clarke

  4. #4
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    It is good to have some tools just for setting up other tools. The least expensive and the most deadly accurate ones in my shop include plastic drafting triangles from the office supply store. For setting up my saw I use the largest ones I can get. The biggest one I have is a 12" 'er 45-45-90. I also have an 8" adjustable triangle and it is great for all those other angles and fractions of an angle.

    Combination squares are rarely ever "square". To check your, tape a piece of paper on the edge of your bench, so it doesn't move. Place your square against the bench edge and draw a line, the longer the better. Now flip your square to the opposite side of the line, bring the square up to the line and drawing another. If those two lines diverge even a little, your square ain't.

  5. #5
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    I had a problem on an old saw I had where the blade wasn't parallel to the miter slots. I had a heck of a time trying to make picture frames. I tried several times to adjust the trunnions but they wouldn't hold (very cheap saw) and finally sold it and got a new one.
    Aloha,

    What goes around, comes around.

  6. #6
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    Like Glen said, the 5-sided cut is the sure method. My sliding tablesaw has something not found on regular tablesaws ---- a 64" crosscut fence. If not precisely at 90 to the blade, all the cuts coming off the table are out of plumb.

    In Europe, where these saws were invented, instructions for making a five-sided test cut are included with the equipment. They are valid for your Jointech, or for a humble Miter Gauge.

    Start with a hefty square piece of wood measuring at least 18-24" on a side.
    Cut a narrow strip of one edge to get true edge. Rotate the board clockwise so the true edge is against your fence on the Jointech. Make another narrow cut. Repeat 4 more times. Save the last offcut and carefully label the near and far ends. Measure with a micrometer or digital caliper.

    Assuming your board at the start was 24", a difference on your last offcut of 1/16" would mean that if you were to cut a 4x8' sheet of ply lengthwise, you would be off 1/4". Bad.

    So, you adjust and test, and adjust and test, and adjust and test until you get your final test offcut down to a front/rear difference of say .002" of an inch. Your equipment is capable of such accuracy.

    Gary Curtis

  7. #7
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    Hi Aaron

    The test with the 6" wide board is good but, the test piece MUST have a very consistent width all along the board.
    Any deviation from perfect width consistency will show as a gap when you turn the pieces.

    When I check my sleds and sliding table, first I check the blade / miter slot alignment first, with the simple method of checking the distances front and back of the blade (same tooth) but then, I "fine tune" it by "Dynamic check" i.e. - while the blade is running at normal speed (that includes all the "run-outs" and blade flattering).

    All the miter gauges, sleds and sliding table fences, should be set to run parallel to the miter slot or in other words, the fence should be at 90 to the miter slot...personally, I never use the blade as reference line...

    After adjusting and testing the blade alignment, I set the Rip Fence parallel to the miter slot and make a test cut and then, I'm using the rip fence as a reference line to set the miter gauge, sled or sliding table fence by using a 12" plastic drawing triangle (that I find to be very accurate).

    You can see an animated "5 cut test" here
    http://www.thewoodshop.20m.com/five_cut_method_swf.htm

    You can use the same triangle to set the miter gauge fence to 45 again, using the rip fence as a reference line.

    As for cutting at 45 (for picture frames), I prefer to use a sled and the "Left - Right" cutting method because it will automatically compensate even for very, very small deviations from 45 and also, if the blade is not at perfect 90, the final result will be perfect....I did not cut many frames with the sled (maybe 15) but all of them were "from the saw to the gluing station" with perfect result.

    The 45 cutting sled, also lets you to put the stops at the front and not 5' far behind so you don't need "fence extensions" to set your stops.

    Regards
    niki

  8. #8
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    Thanks for all the replies, when I get home tonight I will look at those links you provided and try the 5 cut method. I was using a 4" Lee Valley square to check the 90 because I know the square is machined to tight tolerances, BUT I do not think 4" leg is long enough to check for square.

    I will try the 5 cut and see what happens.
    Rise above the rest

  9. #9
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    Aaron, if you choose a 24" board for the 5-cut method, you are in effect using a square with a 8-foot arms to check the squareness. It is hard to beat that for precision.

    Us woodworkers get all goofy and slaphappy when we buy a Starret 6" square. The reality is that we typically are working with material sizes that would leave a machinist gasping in shock. I don't know what's in your woodrack, but mine is stocked with many sheets of 4x8 plywood.

    Gary Curtis

  10. #10
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    Here the results after many hours of testing, tweaking, setting up the sled from scratch, testing, tweaking, moving the sled the wrong way , then having to do more test.

    If I ever do it again I know it will not take as long because I have an understanding of the process now, I think my biggest problem was moving the sled, in that its supposed to be as close the the blade as possible but when I adjust one end the other end would hit the blade so I had to try and move the WHOLE sled over so I could adjust more and not hit the blade.

    I am happy with the end result, I started out with a 20" square of MDF and ended up with something that was 9 1/2x13, so you can see I did a lot of testing since the most I took off was 1/2" and that was usually the last cut.

    Here is the end result.

    End A


    This is end B


    I will say this, I am still worried about the 45 cuts. I know 90 is fine but I am not positive 45 is 45 on the sled reading. The sled has little indents in it that stop it every 1/2 so I know I am on 45. When using that wedge against the blade fence there seems to be some play.

    Maybe the scale is wrong and that's fine if it is because I can mark on it, guess I just machine some pieces and see how they fit together. Unless there is some other test to check for 45?
    Rise above the rest

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