checking blade parallel to miter slot

[Brian Runau]

Checking my tolerance before beginning a new project. Measures 006 difference between the front end and the back end. This is too much correct? I think it should be @ .003?

Thanks.

Brian

[Dan Friedrichs]

Are you marking a spot on the blade with a marker and rotating the blade so that you're measuring at the same spot? If so, then yes, 0.006" is high, but it will certainly cut and may even give acceptable results.

[Brian Runau]

I was just moving the measuring device in the slot from front to back. Got it down to .001. Should be OK. thanks brian

[glenn bradley]

Well done. .001" is my target. Mostly I hit it, on some tools I stop when I get within reason if they are erratic while aligning.

[Bill Dufour]

Unclear if you are measuring the same spot on the blade or randomly measuring along a line on the blade.
Bill D.

[Brian Runau]

I have a digital gauge that mounts on a slider that fits in the miter slot. I raise the blade as high as it will go and measure the front of the blade and then slide the point of the digital gauge to the back of the blade and measure there. Probably not a true 180 degrees, but I think close enough for the girls I know! thanks brian

[Doug Garson]

I have a digital gauge that mounts on a slider that fits in the miter slot. I raise the blade as high as it will go and measure the front of the blade and then slide the point of the digital gauge to the back of the blade and measure there. Probably not a true 180 degrees, but I think close enough for the girls I know! thanks brian
As others have said, you need rotate the blade and measure to the same spot front and back (I mark a spot with a sharpie near a tooth) otherwise you could be fooled by a warped blade.

[Brian Runau]

As others have said, you need rotate the blade and measure to the same spot front and back (I mark a spot with a sharpie near a tooth) otherwise you could be fooled by a warped blade.


It's a newer Forest blade not warped. thanks brian

[Andrew Seemann]

I was just moving the measuring device in the slot from front to back. Got it down to .001. Should be OK. thanks brian

0.001" is closer than any other tolerance on a table saw. Plenty good. Even 0.006" isn't that far off. Heck, on my old 1968 Unisaw, the miter slots were worn more than 0.006" in the center, probably closer to 0.150" and the top had a dip in it close to 1/16". Setting that up was a matter of averaging things out. Even good old 'arn wears down over time:)

Remember for many decades, most people set their blade parallelness with nothing more than a combination square, and typically a Craftsman. Affordable dial indicators are something that only started when cheap machine tools became available from Taiwan in the late 80s/early 90s.

[Bill Space]

It's a newer Forest blade not warped. thanks brian

It does not really matter what one might think of the condition of his blade.

Best practice is to use the same point on the blade when taking both measurements. This eliminates the unknown...that being how much out of wack the blade may be...or not be.

Not doing this gives results that are questionable and not easily defended. Your results could be right on, or in error. Better just to eliminate the question, and use the same point on the blade for both measurements.

[Michael Drew]

I bought a 1/8" X 10" disk that I use for this. Don't remember where I got it, but it makes checking the table alignment a piece of cake. It's basically a saw blade blank without the teeth. I built a Tee out of red oak that I mount a dial indicator to that slides in the miter slot.

[Doug Garson]

It does not really matter what one might think of the condition of his blade.

Best practice is to use the same point on the blade when taking both measurements. This eliminates the unknown...that being how much out of wack the blade may be...or not be.

Not doing this gives results that are questionable and not easily defended. Your results could be right on, or in error. Better just to eliminate the question, and use the same point on the blade for both measurements.
Plus it takes almost no effort to rotate the blade and eliminate the blade as the cause of the error.

[Andrew Seemann]

Plus it takes almost no effort to rotate the blade and eliminate the blade as the cause of the error.

But then are you confounding the out of flat on the blade with the runout on the arbor:)? What about the parellelness of the blade raising arm, do you need to average it top and bottom? What about the other miter slot, is it within 0.001" of the other slot? Are all the parts the same temperature? If you move the saw, do you average the measurements in the two places you use the saw the most?

This is all in jest of course:), but you do hit a point of diminishing returns when setting things up, and at some point you begin chasing the tolerance of the individual components, not to mention their interaction with each other.

[Anuj Prateek]

Checking my tolerance before beginning a new project. Measures 006 difference between the front end and the back end. This is too much correct? I think it should be @ .003?

Thanks.

Brian

When I was setting up my Sawstop, I took tolerance numbers from Sawstop specifications. Every measurement turned to few factor better than listed. I stopped at that point.

So far cuts are all good. Try cutting, and fine tune more only if results are not good.

[Peter Mich]

I found Steven Woodward’s video very helpful for checking and aligning the table top and fence.

https://youtu.be/tOHy69VmNwk

[Bill Dufour]

Best is too measure from the same spot(s) on the blade then do a test cut. If it fails then it is time to consider the blade, bearings, arbor, flange, arbor trunnions etc. There are so many things affecting blade motion it is best to eliminate them as problems only when needed.
Bill D

[Lee Schierer]

But then are you confounding the out of flat on the blade with the runout on the arbor:)? What about the parellelness of the blade raising arm, do you need to average it top and bottom? What about the other miter slot, is it within 0.001" of the other slot? Are all the parts the same temperature? If you move the saw, do you average the measurements in the two places you use the saw the most?

This is all in jest of course:), but you do hit a point of diminishing returns when setting things up, and at some point you begin chasing the tolerance of the individual components, not to mention their interaction with each other.

Since the blade is firmly attached to the arbor, rotating the blade so your measuring spot goes from front to rear of the table, I don't think the flatness of the blade, flange run out or a bent arbor even come into play. Only worn or loose bearings would come into play.