TS Runout. How much is too much?

[Eric Haycraft]

I have a dewalt 746 and after installing a Wixey on it, I noticed that I was having a horrible time getting results to match the Wixey readout. I also noticed that the width of the cut was noticably wider than the blade kerf. Long story short, I finally broke out the robocator and took a peek. I came up with .0075 of variance when I rotated the blade 360 degrees measuring at the teeth. Flipped the blade 180 degrees and got the same results in relation to the arbor and not the blade telling me that the variation came from the arbor. Also checked with another blade, found the same thing. This seems like a lot to me and has me concerned. I also suspect that it is causing blade lines to be left when I crosscut hardwoods or cut plywood. My cuts appear to be coming out .015 wider than the kerf of the blade, so I have the feeling that this runout gets worse once the blade spins up.

So..How much axial runout is too much and what can I do to fix it? I looked in the dewalt manual, and it didn't have any specs so I don't know if this is normal or not for the machine.

Thanks,
Eric

[Mike Marcade]

I would take the blade off and check the arbors runout to take that variable out. THe runout on the arbor should only be around .001 - .002" at the most.

[Eric Haycraft]

I checked the axial runout with three different blades. Two of them very high quality that are perfectly flat and the runout always matches the same point on the arbor in the same direction for every blade and even if I rotate the blade in relation to the arbor. I also checked the arbor and it was very clean with no dust or rough spots.
Regardless, I only have the Robocator on hand and would have to pick up another gauge to measure at the arbor.

[David Weaver]

I have a dewalt 746 and after installing a Wixey on it, I noticed that I was having a horrible time getting results to match the Wixey readout. I also noticed that the width of the cut was noticably wider than the blade kerf. Long story short, I finally broke out the robocator and took a peek. I came up with .0075 of variance when I rotated the blade 360 degrees measuring at the teeth. Flipped the blade 180 degrees and got the same results in relation to the arbor and not the blade telling me that the variation came from the arbor. Also checked with another blade, found the same thing. This seems like a lot to me and has me concerned. I also suspect that it is causing blade lines to be left when I crosscut hardwoods or cut plywood. My cuts appear to be coming out .015 wider than the kerf of the blade, so I have the feeling that this runout gets worse once the blade spins up.

So..How much axial runout is too much and what can I do to fix it? I looked in the dewalt manual, and it didn't have any specs so I don't know if this is normal or not for the machine.

Thanks,
Eric

Eric - I have a delta hybrid saw - 36-717, and have almost the exact same amount of runout. At the arbor flange, that equates to about 0.002". Delta's spec is 0.0025", so what you're seeing isn't out of the ordinary, and not out of spec.

Try calling customer service. I found out the delta spec by talking to a tech rep. I think the table tops and runout specs have gotten looser over the years. The only saw that I've seen that has runout that can't be measured is one powermatic 66 that's about 8-10 years old now, and from what I've read from others on here, that's not common, even on a powermatic.

Your only way to guarantee runout lower than what you're seeing is to get a saw that has a runout spec less than that, and I think that's going to cost you some serious $$. Either that, or you can hawk around craigslist for used saws and take a dial indicator and miter bar setup to check the used saws, and take one that doesn't have much runout.

By the way, I get along using my saw just fine with that amount of runout. You can minimize what that does to your performance with a quality sawblade that has a guaranteed level of flatness.

Also, as an alternative, when I brought my topic up, same as you have, someone suggested figuring out what side of the arbor flange the runout was on (yours is likely similar to mine) and shimming that side 1/2 of the runout amount (since the effect is doubled by a full rotation going through the high and low spots). That would require finding something 0.001" thick to shim, though, and the only thing I've seen that's that thin and common is a handplane shaving from a well-tuned plane.

I've just never felt the reason to dicker with mine - once you set the saw up, it shouldn't make much of a difference.

[CPeter James]

LEE Valley sells a large washer with set screws in it that allows you to fine tune out the runout. I used to have one on another saw that I had and it does work.

CPeter