21829 had a kick back, did I bend my arbor? Any way to check or for accuracy? W/video

[SilentSam]

First sorry but I haven't been around at all for a year. Living in Richmond, VA and working during the week in Baltimore for a new job, free time is rare these days.

So last spring I was cross cutting directly against the fence. I know I should not have and all the risks in it, but I obviously had a severe attack of the stupid and lazy. the moments that followed I became ever more angry with myself and the dozen ways I should have cut the stick. No humans were injured, lessons were learned, and I revived my respect for spinning sharp things. Not running the guard either.

The blade grabbed the off cut and jammed it between the fence & the blade. The fence stayed put and the blade bent over and actually kissed the left side of the metal throat plate. It actually took some metal with it. So the blade is done for in my book at this point. So I put on another blade and got out the dial indicator just to see. The following video shows how that turned out.

http://youtu.be/0LtwGVokpEU

The indicator was new and I had not used it prior. So I do not have a base line to go on & compare to.

So tonight I'm about to order a new arbor but I decided to get it out and see if I could get a dial indicator on the shaft to confirm my suspicion that I bent it. The arbor had the milled flats all the way up to the bearing & elevation housing.

Any way to check the arbor for accuracy with out a blade on it?
Is that "run out" normal?
Anything else I should check? replace? I'm already ordering parts.
Any advice or am I worrying too much?

As possible I will take more pictures and/or video if you guys tell me what to focus on. The arbor is $11 plus shipping and I'm ordering other parts anyway. Its not a bank breaker. Changing it might make me want to go buy a new saw.

Thanks!

SS

[jussi]

Put a dial indicator on a magnetic base.

[SilentSam]

Put a dial indicator on a magnetic base.

That is what I intended to do tonight but the shaft has milled flats all the way up to the bearing housing.

[jdon]

One thing that might work: mark the "high" spots on the blade with a Sharpie. Then, loosen the arbor nut a turn or so, like you're going to change blades. Rotate the blade 90 degrees or more while keeping the arbor shaft fixed with the wrench that fits the flats on the arbor.

Retighten, and recheck runout on the blade. If the high spots are in the same places on the blade, the blade isn't true; if the high spots are now 90 degrees (or whatever you rotated) from the marks, it's the arbor.

BTW, the runout on the youtube seems a bit high, IMHO- and without any specs to draw on. With respect to using a magnetic base, the big problem is finding a piece of steel in this saw! Good luck. Aren't those "Doh!" moments great? SWMBO calls them "teachable moments"

[RAV2]

Some notes:

Using the method in the video, mark the blade 'high side' - then remove the blade, install it backwards, and measure it again. If the high side becomes a 'low side' the blade is bent.

Grab a metal switch box cover and some double sided tape. Tape the plate to the saw surface and try the indicator again.

You are going to have to get the indicator on the shaft and mark a high spot. Using the jam nut, tap the high spot with a sledge hammer - working in small increments - and see if you can true up the shaft. You may be able to recover the arbor in place.

[woodturner]

Is that "run out" normal?

Short answer, yes, it's fine.

I assume your dial indicator is measuring thousandths? So your runout is about .010" on the blade? That's really pretty good for a saw, typically less than .020" is considered very good.

As a practical matter, the runout could be mostly in the blade. Blades are intentionally made not flat, so that when they are running at full speed they flatten out. In addition, you are measuring the runout at the blade, which will magnify any runout on the arbor because it is offset from the actual arbor flange. Think of a wobble dado blade - the further out you go on the blade diameter, the more the wobble.

If you are really concerned, take off the blade and measure the runout on the arbor flange and the arbor shaft directly. Clamp the base to the table and use a couple of extension arms to position the indicator plunger perpendicular to the flange, and then perpendicular to the shaft.

Personally, I would just adjust the saw to make sure the blade is parallel to the sliding table and perpendicular to the miter fence. Crosscut a wider board, 6" or so, and check the quality of cut. If the cut is not straight or burns, there could be a problem, or it could just be out of adjustment.

[toolguy1000]

here's how a-line-it suggests checking the arbor flange for runout:

http://www.in-lineindustries.com/alineit-test2.html

they also have a suggestion about checking the arbor for run out. to my way of thinking, leaving a blade on the arbor and trying to test it for runout adds a variable (the blade and where it meets the flange) that you don't want to have to consider.

[cabinetman]

If you check for run out, the base of the gauge must be fixed to the table so as to eliminate any movement by hand holding. Make sure the projection arm and sensor button indicator is 90° to the face of the blade, just below the gullets. Check against the arbor stop washer, and the arbor itself.

.

[capncarl]

At least you did not loose a hunk of hide. I would put on a fresh new blade or a good flat one and measure from the sides of the blade against the rip fence. You can back the fence off and clamp the indicator to it and measure blade run out. It would take a lot to bend that short of shaft, and would possibly stripped out the drive belts before it bent.
capncarl