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Egg Spurt
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Discussion Starter · #1 ·
I used to put them on just a tightish snug, but twice now I've had things come lose. First time was just a free spinning blade and I tightened down a bit more..no problems, but today the entire nut and washer went flying to parts unknown for awhile and a dado blade got destroyed. I had to take the dust collection hose and the impeller cover off just to find the washer and luckily it stopped right before hitting the impeller. I'm surprised that heavy washer got sucked that far up the hose.
I don't really enjoy having to muscle every blade change, but apparently that's what I'm going to have to do from now on. This was never really an issue until today, but @ at least $100 a pop not counting brake cartridges I'm cranking those nuts down good and tight every time.
How I avoided tripping the brake this time I'll never know, but I did get smacked with a piece of flying carbide from the destroyed blade..
Oh well..yet another lesson learned the hard way. At least I now have a nice sharp dado stack. The old one was getting a bit too dull..
I had been thinking about replacing it and now it's replaced..
 

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today the entire nut and washer went flying to parts unknown for awhile and a dado blade got destroyed.
:eek: That was with your new SawStop? Any damage to the arbor, throat plate etc? I used my new SS Contractor for a while without touching the arbor nut. When I put on a SS 60t blade I was surprised how easy it was to take the nut off, I put it back tighter. Wish we had something more precise than "tightish snug" etc. Back in the day I'd use a torque wrench for axle nuts on sport bikes.

Seems possible it had something to do with the dado stack, if you had tightened a normal blade to the same feel it would have been less likely to come loose.
 

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Really like to know why. The rotation of the blade SHOULD be working against the nut to tighten it. All these years I just give it a little tug on the wrench and let it run.
 

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I used to put them on just a tightish snug, but twice now I've had things come lose. First time was just a free spinning blade and I tightened down a bit more..no problems, but today the entire nut and washer went flying to parts unknown for awhile and a dado blade got destroyed. I had to take the dust collection hose and the impeller cover off just to find the washer and luckily it stopped right before hitting the impeller. I'm surprised that heavy washer got sucked that far up the hose.
I don't really enjoy having to muscle every blade change, but apparently that's what I'm going to have to do from now on. This was never really an issue until today, but @ at least $100 a pop not counting brake cartridges I'm cranking those nuts down good and tight every time.
How I avoided tripping the brake this time I'll never know, but I did get smacked with a piece of flying carbide from the destroyed blade..
Oh well..yet another lesson learned the hard way. At least I now have a nice sharp dado stack. The old one was getting a bit too dull..
I had been thinking about replacing it and now it's replaced..
I've never had a sawstop before. Sometimes I just tighten the nut finger tight and I've never had one come loose. The nut is threaded to where it should tighten when running. The only time I've ever seen a nut come loose is when something goes wrong with the electricity and it causes the saw to stop running suddenly.
 

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Egg Spurt
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Discussion Starter · #5 ·
I have no idea what's going on, but I ain't taking no more chances with tightening even if it means the end of my knuckles.. lol
First time it happened was a new ripping blade and it just kept spinning after I hit the kill switch the way my old saw took forever to stop..
This time things went haywire.. The washer had a good size ding in it so I had to file that down then hone it flat.it's alright, but no longer has the layer of paint to keep the rust off, but oh well..I honed my craftsman washer flat periodically anyway ..
The only thing that even comes to mind is possibly one of the shims i used didn't seat properly all the way up against the chipper? That might have shifted while I was cutting. At least I was testing the cut with scrap and not a finished piece so I had that much go right..
 
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Does the the Sawstop saw blade normally coast to a stop or does it's motor have a fast stop? If the blade is not coasting to a stop, the motor braking action could be loosening the blades.
 

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Same thing happened to my Laguna Fusion 2 Table Saw. Here is what they said...........

"What appears to have happened is that the arbor shaft was not tighten down with enough torque from the factory. You never want to over tighten so moderate pressure or slightly more than moderate pressure should be sufficient. I suggest you take a flashlight and look for cracks, fissures and other anomalies. I will send a replacement blade your warranty is current."

BTW. my blade coasts to a stop. The nut and washer did not come completely. It made this really loud screeching sound when it happened and my blade got destroyed.
 

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I called SawStop technical support. My primary motive was to learn if they have a torque spec for the arbor nut. They do not. I highly recommend that @allpurpose call SawStop technical support at (503) 582-9934 and discuss what happened.

Q: Did the first event (with the free spinning blade) happen with a standard 10 inch blade or the dado stack?

The SawStop technical person told me that when the blade spins up, it tightens the arbor nut further and should not come off. He said that even if you just finger tighten the arbor nut, it should get tighter, not loosen as described.

IMPORTANT:
-> The technical support person warned me to avoid overtightening the arbor nut. He said that many customers habitually overtighten the arbor nut. The extra pressure stretches the threads on the arbor nut, and eventually blades stop fitting on the arbor because it has been distorted from the overpressure.

He said to snug the arbor nut with the wrench, but not more. I asked him for the torque spec, but he said that they don't have one.

He also asked about which dado stack came loose. He mentioned the Oshlun dado stack can cause problems because it has too much mass - full body chippers. Which dado stack had the problem? Could it have been a heavy dado stack? He mentioned that the DeWalt 7670 stack was lightweight and ideal for SawStop. I asked about the Ridge Carbide set that I just bought, and he said it was good.

We also talked briefly about the Freud SD208S dado stack. SawStop specifies an 8 inch dado stack, and he told me that the Freud blades are not standard, they are metric. He said that the Freud SD208S dado stack is 200 mm, not exactly 8 inches. The owners of the contractor and cabinet saws have a brake position adjustment screw, but the jobsite saws do not. Jobsite saw owners complain that the SD208S dado stack does not fit their saw. SawStop says, "Yeah, it is not 8 inches."

As stated above, I think that @allpurpose should call SawStop technical support and discuss what happened, and learn the root cause of his issue. I hope he shares it with us.

One important lesson: Don't overtighten your arbor nut, or eventually you will damage your arbor threads.
 

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One important lesson: Don't overtighten your arbor nut, or eventually you will damage your arbor threads.
Thanks for looking into and reporting that. Really bugs me when a torque like that is by feel. And I gotta say, what happened to @allpurpose is scarier to me than a stretched arbor in 5 years lol.

Haven't used it yet, but I did end up getting the DeWalt 7670. After our convo about which dado set has the smallest bat ears etc, I decided my ww skills don't justify a more expensive set, and ears from a $$$ set would bug me more than from a medium priced set lol.
 

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Saw a video on YouTube recently on this topic. Apparently dado sets are banned in Europe since most saws there have a braking system and as others have mentioned the inertia of the dado stack will try to unwind the arbor nut. My TS doesn’t have a brake and I’ve never had this problem in many years of dado blade use.
 

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Saw a video on YouTube recently on this topic. Apparently dado sets are banned in Europe since most saws there have a braking system and as others have mentioned the inertia of the dado stack will try to unwind the arbor nut. My TS doesn’t have a brake and I’ve never had this problem in many years of dado blade use.
Referenced video:
(I recently saw it too)
 

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I hope that @allpurpose shares more details about the incidents with us.

-> Was the first incident with the spinning blade a regular blade or a dado stack?
-> Which brand dado stack came off the arbor the second incident? Was it Oshlun? Some other brand?
-> How wide was the dado stack? 3/4 inch? Something else?

Here is additional info for allpurpose and others:

According to SawStop, their table saws do not have electronic braking from the motor in ordinary use. When you press the paddle switch to OFF, the blade simply coasts to a stop. The motor does not apply any "back pressure" to slow the blade. The only forces that slow the blade's inertia are ordinary friction in the bearings, air friction, etc.
 

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I called SawStop technical support. My primary motive was to learn if they have a torque spec for the arbor nut. They do not. I highly recommend that @allpurpose call SawStop technical support at (503) 582-9934 and discuss what happened.

Q: Did the first event (with the free spinning blade) happen with a standard 10 inch blade or the dado stack?

The SawStop technical person told me that when the blade spins up, it tightens the arbor nut further and should not come off. He said that even if you just finger tighten the arbor nut, it should get tighter, not loosen as described.

IMPORTANT:
-> The technical support person warned me to avoid overtightening the arbor nut. He said that many customers habitually overtighten the arbor nut. The extra pressure stretches the threads on the arbor nut, and eventually blades stop fitting on the arbor because it has been distorted from the overpressure.

He said to snug the arbor nut with the wrench, but not more. I asked him for the torque spec, but he said that they don't have one.

He also asked about which dado stack came loose. He mentioned the Oshlun dado stack can cause problems because it has too much mass - full body chippers. Which dado stack had the problem? Could it have been a heavy dado stack? He mentioned that the DeWalt 7670 stack was lightweight and ideal for SawStop. I asked about the Ridge Carbide set that I just bought, and he said it was good.

We also talked briefly about the Freud SD208S dado stack. SawStop specifies an 8 inch dado stack, and he told me that the Freud blades are not standard, they are metric. He said that the Freud SD208S dado stack is 200 mm, not exactly 8 inches. The owners of the contractor and cabinet saws have a brake position adjustment screw, but the jobsite saws do not. Jobsite saw owners complain that the SD208S dado stack does not fit their saw. SawStop says, "Yeah, it is not 8 inches."

As stated above, I think that @allpurpose should call SawStop technical support and discuss what happened, and learn the root cause of his issue. I hope he shares it with us.

One important lesson: Don't overtighten your arbor nut, or eventually you will damage your arbor threads.
What the technician described you could apply that to any brand of saw, not just sawstop.
 

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Termite
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I've never had a problem on any table saw. I know when I came on woodworking forums there was a lot about how tight to get a nut on a saw.
 

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Here's what I do. Finger tighten the nut, then using the wrench, tighten it 1/4 turn more. If I recall, I hand hold the blade or jam a piece of scrap into the teeth to secure it. FYI, I also had a dado set come loose and it scared the bejesus out of me. Luckily, I had a scrap piece of wood handy to jam into the spinning blades ..... AFTER I had turned the saw OFF. I can't remember if I had shut the saw down and then this happened, but most likely:

Rick C said;
When you shut the motor down, the inertia of the stacked dado keeps going and unscrews the nut. It will happen with any saw.
 

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If I had realized how many people weren't aware of this situation, I would have elaborated more in my original response. I took it for granted that it was common knowledge.

It can happen with any blade on (nearly) any saw, and will depend on the circumstances. One of the biggest criteria is how much cutting you've done before shutting the saw down. The worst case is when you start the saw, but immediately shut it back down without any cutting yet. The initial start-up torque of the motor will put a fairly good torque on the nut due to inertia, but if the nut was very loose in the first place, this may not be enough. However, with a dado blade, even this startup torque is not enough, and the likelihood of it coming loose on shut-down is high.

Another thing to look out for with dado blades is whether shims are used or not, especially if you put the shims against the outside blade. A shim can get hung up in the acme thread of the arbor and make it appear that the nut is tight, but the nut is tightening against only the outer blade and the shim, and the rest of the chippers and inner blade is not tight. To prevent this, I used to blue-tape the shims to the inner blade to ensure they were centered on the arbor when the nut was tightened.

There is also the alternate problem on some saws with brakes, such as miter saws. The Festool Kapex saw is an example. On a Kapex saw, blade friction will NOT tighten the arbor bolt. This is because the arbor flange is keyed to the arbor, and does not spin, even if the blade spins. So for saws like the Kapex, you need to tighten the arbor bolt as much as necessary to hold the blade, and not rely on friction to make it tighter.

Festool Kapex Arbor Flanges:
429382
 

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I would like to add... Make it a habit to dust down all the surfaces (flanges blades and shims) prior to installing the dado set ... and be sure the carbide teeth in all the blades DO NOT TOUCH each other before you tighten the arbor nut. The carbide teeth extend beyond the width if the disk of the blade and can prevent the disks from properly tightening in the first place.

On another note: I have seen where someone turned a router on (that had a loose collet, with no bit installed)... and the collet nut spun tight from centrifugal force, and it ruined the collet.
 

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Since this thread began, @allpurpose started two more threads and responded to others.

I had hoped that he would share more information about when the arbor nut came off, so we could learn how to avoid the same issue and understand it better. Here are my unanswered questions:

-> Was the first incident with the spinning blade a regular blade or a dado stack?
-> Which brand of dado stack came off the arbor the second incident?
-> How wide was the dado stack? 3/4 inch? Something else?

@allpurpose?
 
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