Stuck Arbor Nut

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Forum topic by Will posted 07-11-2012 09:04 PM 13200 views 0 times favorited 53 replies Add to Favorites Watch
View Will's profile


8 posts in 2186 days

07-11-2012 09:04 PM

Topic tags/keywords: tablesaw unisaw arbor nut

So, I bought a used Unisaw that came with a Diablo 80t blade, which was nice, except that I cannot for the life of me loosen the arbor nut to change blades. The guy that owned it previously did a lot of mechanical work, and I think he may have overtorqued it when putting it on.

It’s a right-tilt saw, so the threads are left hand. I managed to rig up a way to hold the blade still, but turning the wrench with considerable force turns the nut and the arbor (I guess spinning it within the bearing?). Do I need to try an impact wrench? What about using penetrating oil?

Any thoughts?


53 replies so far

View MonteCristo's profile


2099 posts in 2213 days

#1 posted 07-11-2012 09:49 PM

My Unisaw has opposing flat spots on the arbor shaft for a second wrench. Your saw most likely does too. It sounds like it is LH thread but that should be clear just by looking ciosely at the end of the arbor shaft.

When you spun the whole deal, all that was doing was making everything (motor, belts etc) except the blade turn. No big deal.

BTW, using the blade that way is frowned on as there is the possibility of blade damage . . .

Putting a little penetrating oil on the nut/shaft is likely a good idea too, especially if it looks rusty.

Finally, overtorquing this nut is a poor idea. The big arbor washers are supposed to be compressed slightly, not flattened !

Good luck.

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

View knotscott's profile


8056 posts in 3400 days

#2 posted 07-11-2012 10:53 PM

Be sure you pull towards the front of the saw to loosen it.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View IrreverentJack's profile


727 posts in 2867 days

#3 posted 07-11-2012 11:33 PM

pull towards the front of the saw to loosen

Right-tilt with left handed thread = pull towards front to loosen.
Left-tilt with right handed thread = pull towards front to loosen.

I had to stare at my saw a while before I wrote that. Thanks Scott. -Jack

View Dusty56's profile


11819 posts in 3712 days

#4 posted 07-11-2012 11:42 PM

I was also going to ask about the wrench flats on the inside of the blade arbor.

-- I'm absolutely positive that I couldn't be more uncertain!

View MonteCristo's profile


2099 posts in 2213 days

#5 posted 07-12-2012 02:54 AM

I like knotscott’s tip ! Takes the clockwise vs counterclockwise thinking out of it . . .

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

View lumberjoe's profile


2899 posts in 2273 days

#6 posted 07-12-2012 03:42 PM

You are using two wrenches, right? You need to lock the arbor to loosen the nut. I am not familair with Unisaws, but every table saw I have changed a blade on required two wrenches; one on each side of the blade. One loosens the nut, one keeps the arbor from spinning. My miter saw and circular saw have arbor lock buttons.


View Will's profile


8 posts in 2186 days

#7 posted 07-12-2012 06:25 PM

I didn’t see any flats for a second wrench. The Unisaw manual from around the time of my saw actually instructs you to stick a piece of wood under the blade to hold it while you turn the nut towards the front of the saw, which is what I initially tried.

This is the arbor and arbor nut:

And this is the backside (don’t see anywhere for there to even be any flats):

That sucker is on there tight, though. I can’t get back to it until this weekend. I am going to get some impact sockets and try to take it off that way, though I am hesitant, lest I make the situation worse.

View helluvawreck's profile


31378 posts in 2891 days

#8 posted 07-12-2012 06:41 PM

If all else fails you can always split the nut in a couple of places with a small grinder. go almost to the threads but not close enough to touch or damage them. It will probable come off with a wrench after that but if it doesn’t you can then put a cold chisel in the groove and tap it a little but don’t hit hard. If it still won’t budge soak it a little more and try again. We’ve gotten a lot of nuts off of old machinery this way at the plant. Hopefully your threads are ok.


-- helluvawreck aka Charles,

View MonteCristo's profile


2099 posts in 2213 days

#9 posted 07-12-2012 06:50 PM

Must be a pretty old saw. Any idea of its vintage ?

Another idea would be to somehow jam the drive pulley and belt(s) so that you don’t turn the whole deal when the blade slips. Maybe attach a clamp that swings up and jams against the frame when you turn the nut ? Things don’t look rusty so it must just be tight. As helluvawreck says, if all else fails . . .

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

View Enoelf's profile


192 posts in 2288 days

#10 posted 07-12-2012 06:51 PM

It is a reverse thread, so it is clockwise to loosen, just keep that in mind before you hit it with an impact wrench. I have seen some saws (not necessarily a unisaw) that have a detent that locks the spindle shaft in place.
Splitting the nut isn’t a bad idea, but before I tried that, I would try to secure the backside of that arbor with a hefty pair of vice-grips, and remember that the nut needs to turn clockwise to loosen.

-- Central Ohio, Still got 9 and 15/16 fingers!

View teejk's profile


1215 posts in 2709 days

#11 posted 07-12-2012 06:55 PM

think Delta has a “fixed” big flange on the “non-nut” side. that should have 2 flat sides behind it that accept an open end wrench (the Delta stock wrench is actually just a piece of heavy gauge steel with a slight bend in it). It looks like you have that but it was painted (perhaps lipstick on the pig?).

your arbor nut looks pretty rough (as does the outer flange). but before I did “impact”, I’d go liguid wrench followed by a propane/MAAP torch if needed (the combination can be pretty effective).

the nut should heat up pretty fast (expand) and give you a chance. and I think most saws violate the “tighty/righty” rule…designed so rotation (top of the blade always coming toward you) will not spin the nut free, only tend to tighten it.

View Will's profile


8 posts in 2186 days

#12 posted 07-12-2012 06:57 PM

I think it’s from 1966 but have not been able to verify that other than checking on

I’ve definitely been trying to turn the nut clockwise but with a constant force from me and a wrench instead of the taps of an impact wrench.

Funny though, I had to get a regular bolt out of junk box and hold it up next to the arbor to see the opposite threads and make sure I wasn’t crazy.

View dlmckirdy's profile


199 posts in 3158 days

#13 posted 07-12-2012 07:00 PM

After soaking some penetrating oil on the threads, try TIGHTENING it even the very slightest amount of movement. Sometimes you can break the friction lock on the threads this way with less torque than loosening. Use the oil on the nut/threads, and nut/washer interface only. Do not oil the washer/blade interface – you will want that friction surface with the new blade!

-- Doug, Bakersfield, CA - I measured twice, cut it twice, and it is still too short!

View Will's profile


8 posts in 2186 days

#14 posted 07-12-2012 07:01 PM

I’ll definitely check behind the flange. I spun the arbor last night and looked at the fixed flange but saw no flats. I don’t think there would be any room to get a wrench in there if the flats are behind the flange; maybe the reason for the “bent” wrench.

I appreciate all of the input, as I really want to get this nut off so that I can get my new combination blade on, get everything ali

View dbhost's profile


5725 posts in 3256 days

#15 posted 07-12-2012 07:08 PM

There has to be some way to lock the arbor. Either a push button mechanism, or a couple of flats on the inside of the arbor for an arbor wrench. Because if there wasn’t some way to hold the arbor still, the nut wrench would just spin the arbor…

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