I have table saw runout...now what?

[Zach England]

I bought my first serious table saw--a used jet a few weeks ago. I had never checked the runout before as I don't have a dial indicator. I hadn't worries about it too much until I got a zero-clearance insert. I noticed that the blade was rubbing against a side of the insert because I could hear it, so I turned the blade manually and determined the two teeth that were touching, marked them, then rotated the blade 180 degrees and the rubbing is now on the opposite side of the blade. I'll order a dial indicator so I can do a more precise test, but I have to assume that it will fall into the "intolerable" range. What do I do then? I see a lot of info about checking the runout, but none about what to do when it is off. What's the worst consequence of using the saw as-is? It seems to work beautifully to me, but I don't really have a basis of comparison.

[Jeff Miller]

Try a different blade before you do anything....................just my thoughts:D




JEFF:)

[joe milana]

It could just be the blade. Might want to try a different blade. It also doesn't take much to get rubbing on a ZCI. It could be just a few thousands off and be rubbing. You may be just fine.

[David DeCristoforo]

What you are doing can not be used to accurately asses arbor runout. It could easily be the blade that is "out". Furthermore, many blades will measure a few thousandths off when "static" but will "flatten out" at running speed. So you need to measure at the arbor flange or with a reference plate.

[Zach England]

I understand that this is not accurate, but if it is the blade why would the difference be reflected on the opposite side of the blade when I rotate it?

I'll get a dial indicator and see what I find.

[Floyd Mah]

http://www.woodgears.ca/saw_arbor/index.html
Check out this webpage if you want to learn how to intelligently correct runout. Someone posted a link to his stuff last week. He's an incredible engineer.

[Cliff Rohrabacher]

I understand that this is not accurate, but if it is the blade why would the difference be reflected on the opposite side of the blade when I rotate it?

I'll get a dial indicator and see what I find.
Hypoid parabaloid warp of the blade will affect all of the blade.

[Zach England]

Thanks. I ordered the dial indicator and magnetic base from lee valley, so hopefully I will know more in a few days. The blade was a forrest, so I assumed it would not have any problems. I tried all the other blades I have and could not duplicate the problem, but the original forrest is about 1/32 wider kerf than any of the others.

[Larry Browning]

Until your dial indicator arrives, couldn't you loosen the blade and rotate it a quarter turn or so, retighten and see if a different tooth is out of whack. If it is the same tooth, then it is probably the blade. If it is a different tooth, then it is probably the arbor.

does that make since? I only say this because I have never done this, it just makes logical since to me.

[Larry Browning]

Hypoid parabaloid warp of the blade will affect all of the blade.

You made those words up didn't you? Or did you hear them on Star Trek?:D

Of course the other option is that you know way more about this than I, and I am just showing my own ignorance. (most likely of all possibilities)

[Thomas S Stockton]

First thing to do is try another blade as others have suggested. The second thing is to look closley at the flange on the arbor that the blade sits against and the large washer, a little spot of rust or a raised burr will cause run out.
Tom

[Zach England]

Until your dial indicator arrives, couldn't you loosen the blade and rotate it a quarter turn or so, retighten and see if a different tooth is out of whack. If it is the same tooth, then it is probably the blade. If it is a different tooth, then it is probably the arbor.

does that make since? I only say this because I have never done this, it just makes logical since to me.

This is what I did--I think i just didn't explain it very well. Your explanation is much better. I also cleaned off the arbor with steel wool and wd-40. I'll just have to wait for the indicator and try to resist the urge to take it apart anymore.

[Brad Wood]

what is runout?

sorry for the newb question

thanks

[Wes Grass]

You could see obvious runout at the teeth if the flange is out a half thou'. And there's basically nothing you can do about it. And since it "works beautifully" for you why worry about it?

More than that? That's another matter.

I'd go over the flange with a small stone to check for, and eliminate, any burrs or dings before checking anything else. And while you have the indicator in there check for radial runout of the spindle journal as well.

[Chip Lindley]

By definition, a Zero Clearance insert has NO Clearance! Something is bound to RUB somewhere! And, what is to say that the insert did not shift slightly within the TS throat?

IF the saw works beautifully, and cuts as you wish it to--straight, without burning--If it Ain't Broke, Don't be Fixing on It!

[Billy Chambless]

You could see obvious runout at the teeth if the flange is out a half thou'. And there's basically nothing you can do about it. And since it "works beautifully" for you why worry about it?


That was my thought, as well. If it ain't broke...

[James MacArthur]

I don't know if this is of any help to you but WoodWorking Online's latest video is on Table Saw tuning:

http://www.woodworkingonline.com/category/podcast/

[Josiah Bartlett]

http://www.woodgears.ca/saw_arbor/index.html
Check out this webpage if you want to learn how to intelligently correct runout. Someone posted a link to his stuff last week. He's an incredible engineer.

I did that procedure when I bought a used unisaw and found the arbor out of true. It was pretty bad, and I found that using a stone was painfully slow. I used a running angle grinder clamped to the fence instead (along with the running saw) - it didn't load up with metal and it was much quicker. It worked like a charm.

The first thing you should do, though, is make sure the blade, arbor, and arbor washer are clean and free of sap or sawdust. It doesn't take much gunk to throw it out.

[Narayan Nayar]

What's the worst consequence of using the saw as-is? It seems to work beautifully to me, but I don't really have a basis of comparison.

Zach, if the saw is working beautifully and is cutting accurately, it really doesn't matter what a dial indicator tells you. There all sorts of cut-based tests you can perform to test your saw, and these are much more practical reflections of how accurate the saw is.

You can spend a lot of time worrying about getting it right with feeler gauges and dial indicators. That's certainly one way to set up a shop, and for some, the only way. You could also judge your tools' performance by using them to cut wood. Novel idea, I know. :)

I do agree with others, though--the way you've tested it won't tell you anything useful. Runout happens at the arbor, not at the blade.

A more useful measurement for you would be squareness of the blade to the miter slot, and squareness (and adjustment) of the rip fence to the blade. If those things are good and you're not having any difficulty moving wood through the blade, you're all set.

[Zach England]

I'd like to thank everyone for the advice. I got the dial indicator (after fedex somehow managed to lose the box for a week) and it turns out my runout at the arbor is within the margin of error of the indicator (less than .0005 in) but on all of my blades, even my two Forest $100+ blades, I have runout between .003 and .006 in. I realize we are talking about woodworking and not silicon chip manufacturing, but my OCD tendancies get the best of me. Is this acceptable? It seems to me it should be negligible all things considered, but I want to make sure.

[Ken Fitzgerald]

Zack,

In my shop 3-6 thousands on the circular blade would be fine.

Wood is not metal. The wood will expand and contract that much due to changes in humidy and temperature.


That's my opinion....

[Todd Miranda]

I'd like to thank everyone for the advice. I got the dial indicator (after fedex somehow managed to lose the box for a week) and it turns out my runout at the arbor is within the margin of error of the indicator (less than .0005 in) but on all of my blades, even my two Forest $100+ blades, I have runout between .003 and .006 in. I realize we are talking about woodworking and not silicon chip manufacturing, but my OCD tendancies get the best of me. Is this acceptable? It seems to me it should be negligible all things considered, but I want to make sure.

IMHO tighten the arbor nut and move on! If your T.I.R (total indicator reading) is .0005" on your arbor flange, your not going to get any better. As far as your blades go are you measuring on the carbide teeth or just below them? Either way the blades manufacturing process can account for a couple of those thousands of an inch and 4-5" out from your arbor would account for a few more.

I've got 20+ years in the metal working industry and can relate to your desire for perfection. However I really don't think the average table saws are manufactured with perfection in mind.

[Floyd Mah]

I would like to point out that run-out of 0.0005 inch across the arbor flange is entirely consistent with run-out of 0.003 inch at the teeth since the flange spans about two inches and the blade diameter is five times larger at 10 inches. So, if you were able to correct the unmeasureable error in your arbor, you would have zero run-out at the teeth. I think that this is a worthwhile goal and you should devote at least five hours of your time to fix it.