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Testing table saw arbor runout

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Forum topic by Furnitude posted 02-26-2011 01:18 AM 4397 views 4 times favorited 14 replies Add to Favorites Watch
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Furnitude

346 posts in 2232 days


02-26-2011 01:18 AM

I’m a little concerned that I may have some arbor wobble going on, so I wanted to show what I’ve done and get your feedback on the results. I’m using an a-line-ment set with a dial indicator. The first photo is lousy, but shows the pin touching the surface of the arbor.

arbortest1

As I turned the shaft, I got a measurement of a little less than a 1/1000th. I’ve always read that if you get any measurement at all, it’s too much.

arbortest2

I then put on a blade (a good Forrest, so I’m almost certain it isn’t warped) and set the dial indicator to touch about in the middle of the blade. When I turn the blade, I get play of over 4/1000th!

arbortest3

My main question, gulp, is if this means I have a wobbly arbor. Once I establish that, I’ll figure out what comes next. Thanks for any and all feedback.
Mitch

-- Mitch, http://furnitude.blogspot.com Also blog at http://www.craftsy.com/blog/author/mitch-roberson/


14 replies so far

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Furnitude

346 posts in 2232 days


#1 posted 02-26-2011 01:53 AM

Actually, I need to clarify my terms. In the top photo, the tip of the plunger is touching the surface of the inner arbor flange.

I also tested the arbor shaft and that was dead on. So perhaps the arbor flange isn’t flat and that is the problem.

-- Mitch, http://furnitude.blogspot.com Also blog at http://www.craftsy.com/blog/author/mitch-roberson/

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Fuzzy

293 posts in 2713 days


#2 posted 02-26-2011 02:18 AM

Here’s a link to a GREAT tutorial on your topic.

http://www.forums.woodnet.net/ubbthreads/showflat.php?Cat=&Number=3395953&page=7&view=collapsed&sb=7&o=&fpart=all&vc=1

I followed his method(s) and, in the end, I had to use a dial indicator that read to 1/10th of one thousandth to see the runout. The needle on a standard indicator barely wiggled.

-- - dabbling in sarcasm is foolish … if you’re not proficient at it, you end up looking stupid … ... ...

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ajosephg

1857 posts in 2286 days


#3 posted 02-26-2011 02:37 AM

You should be putting the indicator close to the edge of the arbor, because that is what will have the most influence on blade run out. It appears that you are quite a ways in.

Likewise, you should measure blade run out just below the teeth to get the worst case number.

-- Joe

View TLE's profile

TLE

25 posts in 2173 days


#4 posted 02-26-2011 02:52 AM

Runout on the flange face should be almost undetectable. If you are reading .001” runout with the indicator at a 45 degree angle it means that the actual displacement is .0014” – which extends to well over .005” at the tooth tip on a 10 inch blade (depending on the flange diameter, of course).

I had this problem with my saw when it was new years ago. A machinist friend mounted the flanges on the lathe and machined the faces flat and planar with the base surface. My blade runout is now just about perfectly true to the blade manufacturer’s specs (well, make sure that there is no sawdust on the flange face when you mount the blade.

I’m sure that getting the flanges trued up will really high-grade your saw. Good luck.

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Furnitude

346 posts in 2232 days


#5 posted 02-28-2011 07:13 PM

I’m looking at ideas for truing the flange. The post from Fuzzy looks interesting, but I’m hesitant to take a file to anything for fear of making it worse. Here’s my question. Instead of taking a bit off of the flange to true it up, how about adding a bit on? what if I carefully measured the runout and found the places on the flange that are too low and then made some tiny shims? I imagine I could make shims out of either paper or aluminum foil, adding them layer by layer and checking the runout until it is improved. If I arrived at a good solution, I could mark the arbor somehow to show where the shims need to go in the future. Yes, I would have to do this everytime I change the blade, but if you factor out that aggravation, would this work?

I may end up doing what Fuzzy recommended, but it seems to me that adding a bit is worth a try.

-- Mitch, http://furnitude.blogspot.com Also blog at http://www.craftsy.com/blog/author/mitch-roberson/

View EEngineer's profile

EEngineer

906 posts in 2338 days


#6 posted 02-28-2011 08:03 PM

And another source here

I’d recommend against shimming. You would have to repeat the shimming process every time you switch blades. True the arbor up once and it should be good for every blade.

-- "Find out what you cannot do and then go do it!"

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Furnitude

346 posts in 2232 days


#7 posted 02-28-2011 08:09 PM

Aside from the inconvenience, is there any other downside to shimming?

-- Mitch, http://furnitude.blogspot.com Also blog at http://www.craftsy.com/blog/author/mitch-roberson/

View Loren's profile

Loren

7809 posts in 2372 days


#8 posted 02-28-2011 08:13 PM

I think flange-facing is best done by a machine shop.

-- http://lawoodworking.com

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JJohnston

1590 posts in 2016 days


#9 posted 02-28-2011 08:14 PM

I shimmed the arbor on a cheap contractor’s saw with Scotch packaging tape (0.002”). I had about 0.0015” runout at the edge of the flange, which produced about 0.01” at the teeth. The 0.002” on the low spot gave me a correction of about 0.013” at the teeth, for a net runout of 0.003”. The tape stayed right where I put it, and was still there when I sold the saw.

-- "Sometimes even now, when I'm feeling lonely and beat, I drift back in time, and I find my feet...Down on Main Street." - Bob Seger

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rogerw

262 posts in 1414 days


#10 posted 03-01-2011 12:57 AM

would aluminum tape work? just a thought

-- >> my shop teacher used to say "do the best at everything you make for your mom because you're going to see it for the rest of your life!" <<

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1yeldud1

297 posts in 1767 days


#11 posted 03-01-2011 01:34 AM

Honestly as a tool and die maker for more that 35 years I’d have to say that – .004 runout close to the major diameter of the saw blade – that isnt that bad. If your saw blades “curf” was designed to be .125 – that means that means that the actual saw “curf” would be very close to .133 wide. Unless you are splitting hairs with your table saw I’d saw that this would be acceptiable. I would NOT try to shim that flange – If it was bothering me THAT bad I have the flange ground on a cylinderical grinder (If it was permantly attached to the shaft)or surface ground (if it is removeable) – Just my two cents worth.

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Furnitude

346 posts in 2232 days


#12 posted 03-01-2011 08:11 PM

I wish someone would take this dial indicator away from me! Actually, I will surrender it back to my friend probably tomorrow. Last night I was pursuing the angle of adding tape. I measured some Scotch tape (that was fun!) to be about 2/1000th. So I put a little piece on the flange, put on a blade and gave it a go. There was still quite a bit of wobble. Maybe even more. Frustrated, I put on my friend’s Forrest cross cut blade and cut some walnut. the finish was like glass. I think I’m inclined to go with what 1yeldud1 said above. I took off the tape shim. I’m going to get my own high-quality saw blade and see how it goes. Sometimes I lose sight of the most important goal. My goal is to make quality cuts, not to be within a certain measurement on a dial indicator. I’m going to concentrate on aligning the blade well (haven’t managed that yet) and then if I notice the blade making a bad surface, I’ll address it later.
Thanks all for your comments.
Mitch

-- Mitch, http://furnitude.blogspot.com Also blog at http://www.craftsy.com/blog/author/mitch-roberson/

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1yeldud1

297 posts in 1767 days


#13 posted 03-01-2011 08:38 PM

I most definatly would align the blade with the fence—get that done and have fun designing and building projects !!!!!!!

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SouthpawCA

254 posts in 1958 days


#14 posted 03-02-2011 05:51 AM

After reading this forum topic, I thought I’d see if there was any runout on my arbor. I had tested it a year or so ago and at that time I thought what I had was OK and I’d deal with it later. Well it was someplace between 1/1000 and 2/1000 off. I tediously marked where the highest part was and carefully used a fine metal file on the area. It was fairly easy, the area did loose some of it’s height (of that’s the word) compared to the low spot. I thought about adding, but figured it wasn’t all that hard removing – just took time.

After about 2 hours of meticulous filing and marking and remarking after every filing I got my arbor runout almost completely removed. There is still a very slight difference from the high to the low but the needle now hardly moves. I purchased a tune up your table saw magazine awhile back and they said that manufacturers strive for a 1/1000 or less of runout. I am now definitely within those standards.

Thanks for posting this topic and thanks to Fuzzy for the link.

-- Don

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