I checked with a dial gauge the blade vs the miter slots - only about 0.002's off from one side of the blade to the other against the same point on the blade. The dial gauge is a home made thing bolted to a bar run in the miter slot (good quality). So, I think that means the trunnion positions are OK.
Then I checked for wobble in the blade. It seems to be about 0.01 inch. I'm not certain that I'm doing that measurement correctly but rotating the blade by hand with the dial gauge against the blade (slightly "inside" the carbide) can exceed 0.01 from one side of the blade to 180 degrees. It returns cleanly to 0.000 after 360. Looking carefully, I can actually see it wobble.
I checked more than one blade, cleaned and checked the arbor, nut and washer. No effect.
So, I take it all apart. The tilt lock bolt is bent and the bushing like thing on the side wall supporting the tilt knob is pushed out the saw side wall at least a 1/4 inch (a design problem there). I don't know how this happened. My only guess is somehow the lock bolt binds and it slowly bends when you tilt the blade over and over.
I bend all that back and the blade still has wobble even without the belt tension and yet the arbor spins freely and seems to have no play. There is a ground area between the threads and where the blade normally sits that looks a bit too deep but seems to be original.
Ridgid's phone support was some help suggesting the arbor bearing and they supplied a local repair shop and parts supply numbers.
So, finally my questions:
- I have seen plates for sale to use rather than a saw blade to check the runout and alignment. Are these worth the dollars?
- More importantly, what should be the maximum "wobble" you measure with a good blade, aligned saw, bearings in good condition, etc ? I found one comment at Rockler that suggested 0.005" on a 10" diameter. I find the "arbor runout" term confusing. I would think there are at least three items: || to miter slot, vertical translation square to table face, wobble in the arbor bearings, blade flatness, maybe others.
Any suggestions would be appreciated. I don't want to use the saw in this condition and I'm really don't care for the idea of someone else working on it.