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Discussion Starter · #1 ·
I got a new Incra for Christmas, and was very excited to add the sort of accuracy they are known for to my shop. I quickly got it close enough to square just to try it out, but hadn't used it much until last night.

I made a cut and checked it with my machinist square, showing that it was off. I went back through the instructions, and set it up again using my machinist square flush to the fence of the Incra, and flush to the body of my blade. Initially the far end of the square showed a gap of about 1/32" or so. I made another cut, and got the exact same results, if not worse!

square plywood.jpg

I checked it with my machinist square and my framing square. I checked both squares against a stock edge of plywood to ensure their squareness and both appeared to be dead on. I even recheck the gauge to the blade once all the bolts on the Incra are fully tightened and it still lines up.

I kept the blade raised a lot higher and made some more cuts which made it a little better, but not much. I have a Ridgid R4512 which I've heard are notorious for going out of square at different heights, but I hadn't found that to be true on mine as of yet. I also set the blade parallel to the miter slots with a dial indicator.

What could I be missing here? Is it my square? Is it my table saw? Is it the Incra? Is it just Murphy teaching me a frustrating lesson?!?!?!?!

Sean
 

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Are you speaking of the miter gauge INCRA Miter 1000HD?

Have you attempted to adjust the 1/10th Degrees Vernier Cursor? It could be that it may need to be adjusted one way or the other.

I have the Incra 1000SE, and it has been dead on accurate since the day I began using it 7 years ago.

I am not an expert on either miter gauges, but just a thought as to that one adjustment.
 

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Discussion Starter · #3 ·
Are you speaking of the miter gauge INCRA Miter 1000HD?

Have you attempted to adjust the 1/10th Degrees Vernier Cursor? It could be that it may need to be adjusted one way or the other.

I have the Incra 1000SE, and it has been dead on accurate since the day I began using it 7 years ago.

I am not an expert on either miter gauges, but just a thought as to that one adjustment.
Yes, I forgot a 0 it is the 1000HD. I have not adjusted that, but I don't think that would be the issue. All of the checking I'm doing is telling me that the fence is already square to the blade, but the cut is telling me otherwise.
 

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Your blade is terrible, so start with that. The picture shows evidence that the miter gauge is not running parallel to the blade. A dull blade or incorrect type of blade can pull the work piece. If you are using a bare metal face to hold the work to, the work can slip. A dial indicator only measures the width of the blade which isn't much and a slight variation may not show easily. I use a long straight edge against the blade body and measure to the miter ways from that. When you make the cut, don't back up afterwards. With the saw off, hold the square on the miter fence so it touches the blade body, then push the miter gauge ahead. Watch for the square blade staying tight to the saw blade all the way. If it pushes against the blade or the gap opens, your miter ways are not square to the blade. The miter bar also has to fit the ways so there is no side to side slop. You have to do that fitting before anything else.
 

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Yeah that cut clearly isnt straight. Id correct that problem first and then worry about square.
 

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Discussion Starter · #6 ·
Your blade is terrible, so start with that. The picture shows evidence that the miter gauge is not running parallel to the blade. A dull blade or incorrect type of blade can pull the work piece. If you are using a bare metal face to hold the work to, the work can slip. A dial indicator only measures the width of the blade which isn't much and a slight variation may not show easily. I use a long straight edge against the blade body and measure to the miter ways from that. When you make the cut, don't back up afterwards. With the saw off, hold the square on the miter fence so it touches the blade body, then push the miter gauge ahead. Watch for the square blade staying tight to the saw blade all the way. If it pushes against the blade or the gap opens, your miter ways are not square to the blade. The miter bar also has to fit the ways so there is no side to side slop. You have to do that fitting before anything else.
It's a Forrest WWII and if you are referring to all of the tearout on the ply, I'd say it was from having the blade raised up much higher than needed. The cuts are normally much cleaner.

I just realized that I've only ever checked the miter slot to the right of the blade, and I wouldn't be surprised if the miter slots weren't perfectly parallel. I'll check the other side tonight. I don't think I have a straight edge long enough to use your other method, but I'll see if I can figure something out as that seems like a much more accurate method.

I'll try some sticky back sandpaper on the front of the gauge to prevent the workpiece from slipping. There is no slop with the bar in the miter slot. I spent a while tweaking each adjuster to make sure that didn't happen before I tried squaring.

Yeah that cut clearly isnt straight. Id correct that problem first and then worry about square.
Thanks, hopefully I have some answers to post up here tomorrow.
 

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The best blades get dull. Another issue can be making skim cuts, where you only take 1/8" or so off. Blades, especially thin kerfs, can wobble a little when not supported equally on both sides. Skim cuts can also result in a rough cut. Like I said earlier, hold the square on the miter fence and push it along, looking to see if it stays tight to the blade body. Don't know how you adjust your particular saw but just tightening up can cause things to move a touch. I can't comment on the accuracy of your saw. You didn't say if you are using a guard, splitter or riving knife. Alignment with those can play a part, too.
 

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Discussion Starter · #8 ·
The best blades get dull. Another issue can be making skim cuts, where you only take 1/8" or so off. Blades, especially thin kerfs, can wobble a little when not supported equally on both sides. Skim cuts can also result in a rough cut. Like I said earlier, hold the square on the miter fence and push it along, looking to see if it stays tight to the blade body. Don't know how you adjust your particular saw but just tightening up can cause things to move a touch. I can't comment on the accuracy of your saw. You didn't say if you are using a guard, splitter or riving knife. Alignment with those can play a part, too.
Gentlemen, I thank you very much for your responses. I went out to the shop last night and decided to double check that my miter slots were parallel to the blade..... and they were NOT. I had re checked it after we moved to the new house, and it either was bumped out of alignment after that, or I didn't read the gauge correctly.

Either way, I spent a good hour or so pulling the back off the saw and realigning the blade. Unfortunately I found that even after I get it to within .001 of perfect and fully tightened down, just setting something down on the saw top a little rough will know it back out of alignment a bit. I figured I was tightening it down with a little bit of memory left in the trunnion mounts or something. I did this a few times and ended up setting it out of square in the other direction, and then bumping the saw top until the gauge read square. Hopefully doing it this way will make it stay true for longer.

Anyway, I re squared the miter gauge and here are the results.
actually square plywood.jpg

It cut much smoother, and dead on square! Thanks again y'all for the advice. I would have continued to be stubborn and not checked my alignment if both of y'all hadn't chimed in with the same observation.

Sean
 

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Andthe cut is straight!! Looks much better.:thumbsup:
 
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