Reply by gauntlet21

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Posted on Miter Saw Tolerances

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69 posts in 633 days

#1 posted 11-05-2018 02:20 PM

Thanks, I was aligning the blade using my Starrett 12” combination square when I thought about a different way to adjust my saw. The manual (as almost all do) mention to adjust your bevel to the bed of the saw and then adjust your blade to the fence or your fence to the blade depending on the model and design. I’ve got the Woodpeckers One Time Tool 26” Precision Woodworking Square (amazing tool) and was using the square to measure the deviation of my cuts. I then remembered that I had seen a YouTube video that mentioned a better tool than even a Starrett combination square for aligning miter guages on the table saw. I figured I could use the same principles in that setup on my miter saw. Here’s a link to the tool: (I am in no way affiliated to any Amazon sales, the manufacturer of the triangle, etc. Just sharing a cheap but great tool for setting up long range cuts).

As I was using the Starrett and algining the blade to the fence, I got out the feeler gauges to see where I was off. I was able to get the Starrett to reject the 0.0015” feeler gauge along the short handle of the 12” version. (I had the 12” rule against the fence and the handle against the blade as the manual instructed). When I went to make a cut, I was getting the error that I mentioned in my first post. I was frustrated because even though there’s flexing in the blade and the sliding components, I was thinking there had to be a better way. I took out my dial indicator and mount to measure the blade for unevenness. Initially, I got 0.0065” which wasn’t scary bad but I thought I would take out the blade and give it a quick cleaning. I also removed the aftermarket bushing and laser guide that I had installed and replaced it with the OEM bushing and my aftermarket blade. The blade is a 12” Amana A.G.E. Thin Kerf 72 Tooth Blade and is about 8 months old. I got the dial indicator to read less than 0.0025” all the way out to the edge of the blade just before the gullets and teeth begin.

With that information, I knew the blade was straight and not the issue. I then used the large Alvin drafting triangle and aligned everything to be square with the miter saw in the down and not extended position. Side note: I aligned the square to the edges of the two carbide teeth (near and far) as the body of the blade cannot be accessed when using such a large straight edge. I then slid the blade toward me to the extended position while listening for the subtle scraping noise of the carbide teeth making contact with the PLASTIC triangle. I am aware that the carbide teeth are precious and losing one would be bad for the blade but its a piece of plastic with no pressure pressing against the tooth. Just a gentle glide. I made minute adjustments until there was contact then entire range of the sliding mechanism on BOTH SIDES of the saw blade.

I then tested the cut and I had a much closer square cut than when I used the combination square. This also incorporated the sliding mechanism. To take things further, I then looking at which side of the cut was short/long and determined if the angle was just over or under 90 degrees. Considering I make almost all of my cuts from the left side of the blade, I made microscopic adjustments to the blade angle until I got a 23.5” x 5” board to reject the 0.0015” feeler gauge. And now, my saw is awesome. I’ve got a shooting board and hand planes but I wanted to know the capabilities of my saw. I asked the question and despite the variables that DO make a sliding miter saw less accurate than a non-sliding one, I’m very pleased with the accuracy of my saw. Cuts from the right side of the saw are just as accurate. I did reach a point where I was plenty pleased with the results but I just kept going to see if consisitent “nearly perfect” cuts could be obtained. I know that cutting boards changes the grain forces, and not to get boggled down by trying to make it perfect but I just needed to see. So I recommend if anyone is having a problem similar to mine, try using a long range square/triangle to magnify the error. I also performed the 5 cut test and that provided consistent and identical results.

Thanks again,


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