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Squaring my Incra Miter Gauge with a Micro Adjust Jig

7914 Views 9 Replies 6 Participants Last post by  Hard_as_Wood
I just bought an Incra Miter gauge because my miter gauge is "wobbly" in the miter slot and has not adjustments to make the miter bar fit better. So I had hoped that it'd be square right out the box, but no such luck. Not a big deal, I'm sure such an object bouncing around in shipping and so forth it would be unreasonable to expect it to be but I can always hope right?

The miter gauge has 4 mounting screwed for the front bracket to allow you to adjust it to be perfectly square at the 0 mark on the gauge. I used an aluminum square to square the miter gauge to my miter slot as recommended by

After that I checked it using the 5 cut method a lot of people use for cross cut sleds it it was really close, but 3/128th's after 4 cuts seemed like a bit high (I know it gets divided by 4 so the error is less than 1/128ths but I felt I could do better).

For a while I had all the screwed loose except the 2 edge screws which I would use the adjust the sides to try and get closer to square. I'd unscrew one side, tap it lightly and all it all that sucked. It just wasn't predictable enough, what I needed was a micro adjustment type system.

So I made one!
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The jig is just a piece of purple heart scrap that I drilled 2 holes into. One to mount the wood to the miter gauge and another for a t-nut that I put a t-bolt through with 2 normal nuts tightened together at the end.

First I tapped the right side of the miter gauge so that it was too close to me, then I used the micro adjust to slowly creap up on a square. It took a while and a lot of patience but I slowly crept up on it and got it about as close to perfect as I'm going to get.

I used the 5 cut method, with an 8'' piece of MDF and the 5th piece was less than 1/128th of an inch difference (my fractional digital caliper only goes to 1/128ths difference). So that means that over 32'' the error is less than 1/512th's of an inch.

That's close enough for me :)



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Jeremy -
Having a perfectly square "root" is pointless if your fence is off by a bit. You need to set up your miter gauge as you plan to use it and make your adjustments from there.

If you're under .007" at the "root", take it and run. Put on your sacrificial fence and square up on it. Keep in mind that you're working with wood. Just changing the way you grip your workpiece will change the perfection of your cuts.
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