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Truing a table saw arbor to perfection

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Blog entry by vipond33 posted 08-29-2012 04:55 AM 3255 reads 6 times favorited 11 comments Add to Favorites Watch

Following up on a post by MrRon concerning “Concerns regarding saw cutting accuracy” I thought I would show anyone interested how to achieve pretty close to zero run-out on any table saw equipped with a pressed on or integrally machined flange.

It’s worth doing. For this is the tool that for most of us makes or breaks the accuracy and satisfaction in our machining. If you run high quality blades (from any manufacturer) then this simple operation will enable you to get the best out of your saw.

It was taught to me by Rockwell service technicians in 1981 when they owned and made the Unisaw and others in the then and now Delta line. I don’t know if it was a technique they used to cure rotten quality control or maybe just the odd flier (if you’re a target shooter) that somehow slipped through their lines.

It was easy. You simply mounted a 3/4”, 1/4” shank coarse grinding wheel to your router and then offered it up to the inner flange of your saw while both were running. Both rotations work in the same direction so it is sort of a climb cutting with no digging in. With a light and careful touch you can machine in place using the dynamics of tools you already own and enjoy great results. I have done this trick on almost a dozen saws with tight readings resulting and much cleaner cuts.

Procedure:

Clean out your base and internals of all sawdust. Have a fire extinguisher handy. Keep an eye on the area for an hour afterwards.
Having said that there is very little danger here, but there is also real profit in careful and safe working. Sparks are tiny fires.

To begin you may use a dial indicator if you wish to check on your current state, or just a careful eyeballing will do and will tell you if there’s run-out.

So then:

Raise the arbor to maximum height,

Remove insert, nut, outer flange and blade.

Tilt arbor to 1 degree. The aim is to make the flange ever so slightly concave so that the pressure on the blade is at the outer edge at first, much like a well tuned vise.

Set the router depth with grinding wheel to fully contact the face of the flange.

Turn on saw and router with wheel away from the flange.
Slowly bring the grinding wheel into contact with the centre of the flange and tightly hold that position till it sparks out.

Always do a very light first pass, stop both machines and inspect your flange. It will probably show fresh grinding marks at points and arcs. Make another light pass, inspect again. Three grindings will usually do it for an average condition, giving a perfectly uniform scratch pattern. Stop and re-test your blade or use an indicator. I always black colour the flange with a Sharpie before grinding starts so as to easily show fresh metal.

Notes:

It is helpful to position the fence near the insert opening so that you may rest your right hand against it and pivot the router into position.

This type of small wheel is rated for 25,000 rpm so there are no concerns about disintegration but I would pay attention to the quality on the shank seeing as it’s being used in a collet.

To complete, pass your outer flange over a diamond or coarse stone by hand till it shows the same effect.

gene

-- gene@toronto.ontario.canada : dovetail free since '53, critiques always welcome.



11 comments so far

View shipwright's profile

shipwright

4979 posts in 1454 days


#1 posted 08-29-2012 05:15 AM

Thanks for this one Gene.
It never hurts to start out with the best chance for success. There are enough places to lose a little without staring behind the 8 ball.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View Sylvain's profile

Sylvain

553 posts in 1156 days


#2 posted 08-29-2012 10:18 AM

Matthias Wandel did it slightly differently

see :
http://woodgears.ca/saw_arbor/index.html

Do you see a benefit in using a router?

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

View Roger's profile

Roger

14601 posts in 1461 days


#3 posted 08-29-2012 10:44 AM

Very interesting. My old Craftsman cuts really good, but, just fer the hay of it, I may check the arbor and washer out. Thnx fer posting, and thnx Sylvain for your link also

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View chopnhack's profile

chopnhack

368 posts in 1051 days


#4 posted 08-29-2012 11:48 AM

Wow, good info Gene! My dad and I were just talking yesterday about how we are losing the ability to machine / make things and the tips and tricks that go with it! Thanks for passing this one down : -)

-- Sneaking up on the line....

View MedicKen's profile

MedicKen

1599 posts in 2119 days


#5 posted 08-29-2012 12:07 PM

I have also done a similar thing to the arbor on both unisaws and Powermatic 66’s but using a waterstone. Set the stone up on a block of wood clamped to 90 degrees and run the saw and using very LIGHT pressure allow the stone to true the arbor.

-- My job is to give my kids things to discuss with their therapist....medic20447@gmail.com

View Philip's profile

Philip

1114 posts in 1195 days


#6 posted 08-29-2012 02:28 PM

Very interesting…I will have to keep this one for future reference…

-- If you can dream it, I can do it!

View rance's profile

rance

4132 posts in 1817 days


#7 posted 08-29-2012 03:11 PM

This is GREAT information. Thanks for sharing it. It is something that any DIY person could do. And its not rocket science. Even Steve could do this. :D

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View mafe's profile

mafe

9547 posts in 1746 days


#8 posted 08-29-2012 08:10 PM

Really cool trick, this I will remember.
Thank you.
Best thoughts,
Mads

-- Mad F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View Karson's profile

Karson

34876 posts in 3057 days


#9 posted 08-29-2012 11:44 PM

I thank you for this suggestion.

I own a Fay-Egan 16” table saw that has a 013” wobble at the blade. I’m assuming that this 50 year old saw had a 4X4 or larger piece of wood dropped on top of the blade.

The saw arbor is the motor shaft. It’s a direct drive. It has a machined flange by the motor and then 3 spacers about 1/2” thick that are machined. The blade then rests against the spacers. I’m guessing that you take out the spacers and could have at least a 2” dado cut blade installed. I’ve put some masking tape on one side of the spacers to make a gap on one side. I might try a piece of soda can (aluminum) as a one sided spacer.

I think my problem is the shaft wobbles and not an alignment on the flange.

But I’ll give it another go. It would be nice to cut out some of the play.

I get great cuts though. The alignment seems to be various, because when that chunk of steel called a blade probably takes out some of the wobble when at speed. I measure the thickness of the cut by getting the width of a board before cutting and then ripping it in two and then measuring the width of the two pieces. The difference is the thickness of the saw cut. Then I measure the width of the cutting tooth and find the difference. That is my in use wobble factor.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View LittlePaw's profile

LittlePaw

1571 posts in 1735 days


#10 posted 08-30-2012 12:17 AM

Maybe that’s the problem with my table saw; I sure will give it a go ! ! THANX!

-- LittlePAW - The sweetest sound in my shop, next to Mozart, is what a hand plane makes slicing a ribbon.

View vipond33's profile

vipond33

1405 posts in 1154 days


#11 posted 09-16-2012 07:56 PM

I was not aware of Matthias’s method but I assume it would work after a fashion. The only problem with it as I see would be that any flutter in the flange would vibrate the stone away. A better method using just a stone as he did would be to clamp the stone to a long heavy bar of wood and clamp that bar to the saw top. Tilt the saw to 45 and then ever so carefully raise it to the stone as per his photo. Let it spark out and inspect.
I believe the router method to be a bit better as the is no clogging, it is done in seconds and the combination of two moving surfaces yields perfect results.
gene

-- gene@toronto.ontario.canada : dovetail free since '53, critiques always welcome.

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