WoodNet Forums: How I Fixed my TS Arbor Flange Runout

Hopefully this might be of use to some of you looking to reduce the arbor flange runout on your table saw. You don't need fancy tools, honing jigs, and you certainly don't need to send your arbor to a machine shop. You will need some patience, a fine touch with your hands, and some basic tools shown below (plus masking tape, and minus the lamp). I'll say up front that I don't trust jigs or hand held stones/files to be rigid enough to perform a live touchup to the flange - I find they hop or just follow the existing contour, removing material but leaving the same runout on the flange.

Before we get too far along, a brief overview of what I'm going to accomplish today. My table saw arbor flange has excessive runout at a hair over .0015 inches FIM - remember that runout at the flange needs to be multiplied by ~4.5 to predict the runout at the blade rim. This causes my blade to wobble at the rim by over .014 inches, and generates rough cuts, or rougher than I would like. Some of the wobble is due to the blade, some is due to the arbor flange. I can't fix blade runout, so I will do my best to reduce the arbor flange runout to minimize the problem.

The basic idea is to find the hi and low zones on the arbor flange, file the hi zones in progressive steps, finally honing the flange with a stone to less than .0005 inches. This is part of the reason why I feel >.0005 runout is excessive - because I'm going to hand file my arbor to less, and the manufacturer should be using a side grinder capable of better than .0002 runout all day every day.

Tools (minus masking tape) are shown below. Nothing fancy. A sharpie (or machinists' blue), dial indicator with magnetic stand, fine file about 6" long (I use a double cut file, single would work too), and a honing stone (I use a brown india stone).

Next step, I jack the motor or remove the belt...whatever it takes to unload the arbor. This is so I can easily rotate the arbor shaft while taking measurements, as I'm going to be measuring down into the tenths of thousandths of runout on the flange.

That done, I stone the arbor flange to remove any burrs, clean the arbor flange with mineral spirits, and tape off the arbor where the blade mounts (in order to protect it).

I mount the dial indicator to the mag stand and snake the arms down beneath the table. Leaving the arm above the table will get in the way when filing and runout magnitudes wil not be accurate if the dial indicator is at an angle - I need magnitudes to know when it's OK to stop (i.e. when runout is < .0005, you may have your own goal).

I slowly rotate the arbor while watching the dial indicator and get a feel for the runout pattern. First check is to make sure it repeats. If it does not, then the flange might be dirty. I then mark the hi and low zones with a sharpie marker. Typically, the flange does not have a single sharp peak causing runout. The proud material is typically spread over a significant portion of the flange, and the dial indicator needle stays pegged high over a zone of the flange circumference. This is what I call the hi zone. The very first time you mark the flange, you may find a single defined hi point instead of a zone. In addition to the hi and low zones, I mark the half way points between them. This gives me a rework map for the flange.

Note that a single mark at the hi spot (center of the hi zone) is very difficult starting point for rework. It would be like someone handing you a belt sander and a cutting board with a pencil dot marking the highest point and saying "sand it flat." You need to know the contour in order to file the proud flange material only, and feather it into the low zone.

My hi zone is solid black, between the intermediate points and the hi zone is cross hatched, low zone is unmarked.

I hold the file against the arbor flange, spanning the as wide a gap as possible (for stability). I use finger pressure from the index finger to apply cutting pressure to the far edge of the flange on the forward stroke. Make sure to hold the file against the flange - if it rocks, you'll crown the face of the flange (not a good thing).

I work around the flange by rotating it slightly with each stroke. The sharpie marks are my guide - when the sharpie mark is removed, I move on to the next section. I hog out the solid marks first (the hi zone) and feather it from the hi zone to the intermediate zone. The action is a bit more continuous than it sounds, as I take overlapping passes and rotate the arbor.

The following photos are a mid way progress shot, followed by the finished progress shot (for this iteration at least).

I stone the face, clean with a blast of air, then measure runout. You should see about .0001 to .0003 difference with light file pressure and just barely removing the sharpy mark. Re-marking the hi zone over successive iterations should show the zone increasing in size, and harder to define. At some point, you'll find the runout is below your acceptance limit, and it's time to move on to the blade runout check. Ideally, the runout will be noise, and hi and low spots won't be 180 degrees out when you're done.

This is the stopping point. If you find blade runout (i.e. runout at the blade rim) isn't acceptable, you need to re-check your flange measurements and use some standard clocking methods to determine if it's the blade runout that is excessive. How to tell? If I've achieved my goal, the contribution from flange runout is much, much less than the blade runout itself. If this is the case, then I should see the hi and low spots on the blade rim runout traces clustered in the same locations no matter how it's clocked on the arbor.

Mount the blade and dial indicator above the table. Make a match mark between the flange and blade. Measure blade rim runout and mark a "+1" at the high spot on the blade and a "-1" at the low spot. Next, turn the blade 90 degrees and re-tighten. Perform the same runout measurement and place "+2" and "-2" marks on the blade. Rotate the blade 90 degrees and take measurements / place marks twice more. My results are shown below.

My + and - marks clearly follow the blade and not the arbor. This means the contribution from arbor flange runout is much less than the blade runout. I stopped after 3 marks because it was clear they were clustered. Note my measurements on the paper show ~.001 flange runout contribution AT THE BLADE which means less than ~.0003 at the flange...pretty good for a quick filing. Notice my blade runout is ~.005...I wish it was a bit better, but beggars can't be choosers.

If your + and - marks are 90 degrees apart, then it's the arbor flange runout that is causing the blade runout, and it's time to try filing again.

I wrote this in the hope that it might help someone correct TS arbor flange runout without the need to spend money at a machine shop or wait for replacement parts from the manufacturer. It's a relatively simple process, and I think even a novice can master the technique after a few passes with the file. If all goes wrong, you remove the arbor and have it machined, or call the manufacturer.

If anyone has any suggestions for improvement, please feel free to share them.

Edited slightly for clarity and spelling.