Table saw tune up question

[Harry Myers]

I have a table saw setup problem that is baffling me.

I've had a Bosch 4000 table saw for 7 years. It has always been very accurate. Now, all of a sudden my rip cuts aren't square (instead of 90 degrees I get about 89.5 degrees). It doesn't sound like much, but when you stand a board on the cut edge, it's very noticeable (1/4" of lean with a 24" wide board).

I’ve verified the blade is perpendicular to the table with both a machinist’s square and a wixie angle meter. The wixie shows the error is less than .1 degree, yet my cuts are off by .5 degrees. The metal throat plate is straight, and flush with the table. I’ve tried a Freud 50T combination blade, and a Freud 30T Glue Line rip blade. Both gave the same result. The runout at the blade measures 0.002”.

What I’m beginning to suspect is that under load, the entire blade mechanism tilts slightly to the left. I flipped the saw over to look for something loose, but everything is tight. Any ideas what this could be? Again, this is new behavior. The saw did not used to cut this way.

[Jim Fay]

Hi Harry
I had a similar problem. Mine was simply an outfeed roller stand issue. Took a awhile to figure it out though. Turned out my young son had knocked it over and it no longer turned at the same rate throughout the rotation of the roller. The problem only showed up, of course, on long rips (imagine that lol). I wasn't clear in your post if this was on any length rips or all ripping. Anyway, hope you get to the bottom of it.
Jim

[Harry Myers]

That was a great idea Jim. I checked the outfeed support (built into the saw), and it's just below the table, so that's not it.

[Lee Schierer]

Is this a direct drive saw? If the blade mounts on the motor shaft you could have worn bearings. With the power off and the blade removed, check for side play in the motor shaft.

Also check that the leading edge and trailing edge of the blade, with the blade fully raised, are still aligned with the miter slot and the fence is aligned with the same miter slot. Check this alignment using the flat part of the blade behind a tooth not the edge of a tooth as Freud blade teeth have angled sides.

[Harry Myers]

Great idea Lee! It is a direct drive saw. There doesn't feel like there's any play in the shaft, but if I place a dial indicator against the flange, I can measure about .005" of play. I have to apply about 10 lbs of force to measure this. Does this sound like a bad bearing, or am I pushing too hard for this to be legitimate?

Looking at the exploded parts diagram, there are no less than 4 bearings at different points along the shaft. I'm assuming I would only replace the outermost bearing. If not, then I probably need to take the saw to Bosch.