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Table Saw Blade comes loose after using Incra Miter Express for a While

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Forum topic by NeophyteGrant posted 03-26-2019 01:20 AM 913 views 0 times favorited 12 replies Add to Favorites Watch
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NeophyteGrant

102 posts in 837 days


03-26-2019 01:20 AM

Topic tags/keywords: table saw loose blade miter sled

I’ve had this happen twice now. Both after prolonged 30 minute sessions. It wobbles a bit out of round, then the brake doesn’t engage, and it takes a while to slow down. It doesn’t visibly wobble UNTIL AFTER it starts powering down. Upon inspection the nut has come loose off the flange.

I have a thin kerf 80T cutoff blade on a Grizzly 771Z. I have a 5” Forrest blade stabilizer installed that has helped immensely with burning and such on rip cuts. Seem to get less fuzz and no marks, even on the 24T blade (not the 30T) with it.

I’m wondering whether the perpetual contact (there is some slight runout, but less than .003 if I remember from calibration when I last did maintenance about a year ago) from the cutoff side of the sled and the main sled is causing it to loosen. During long sessions I will start it up and power down a couple times before it happens. Runout on slow down could be an issue? NOTE: I did an hour long rip session today and didn’t not have any loosening issues.

Thoughts appreciated.


12 replies so far

View Woodknack's profile

Woodknack

12726 posts in 2708 days


#1 posted 03-26-2019 01:34 AM

That doesn’t seem possible, arbor nuts are self tightening.

-- Rick M, http://thewoodknack.blogspot.com/

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NeophyteGrant

102 posts in 837 days


#2 posted 03-26-2019 04:07 PM

It looks like a possible culprit may being a flange (or my stabilizer) slipping when the break engages—havent read the full thread yet, but something similar described here:https://familywoodworking.org/forums/showthread.php?1330-Tablesaw-arbor-nut-comes-loose-and-I-know-why/page2&s=f3bb0c343f3f8774093e2070cd43d359

That would make sense since it only loosens on power down. Miter sled looks to have nothing to do with it. Probably some dust and debris got onto the blade stack.

View Andybb's profile

Andybb

1856 posts in 931 days


#3 posted 03-28-2019 12:00 AM

I think I remember someone else having that issue too. The problem was the flange. Try making slower cuts without the flange. Do you really need a thin kerf blade?? Maybe try a different brand regular kerf blade or one with a few more teeth. Combination, cross cut or rip??

-- Andy - Seattle USA

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runswithscissors

3006 posts in 2353 days


#4 posted 03-28-2019 03:30 AM

The blade stabilizer has quite a bit of mass. When you put the brake on, the inertia causes the flange, and therefore the arbor nut, to unwind. You might be better off not using the brake (is it automatic?), and let it power down at its own pace.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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MrUnix

7301 posts in 2527 days


#5 posted 03-28-2019 05:39 AM

It wobbles a bit out of round, then the brake doesn’t engage, and it takes a while to slow down.
-NeophyteGrant

AFAIK, that saw does not have any sort of braking system… how old is the saw, how much use has it seen, and when did this problem start?

I’m wondering whether the perpetual contact (there is some slight runout, but less than .003 if I remember from calibration when I last did maintenance about a year ago) from the cutoff side of the sled and the main sled is causing it to loosen.

Not possible… you would have to have the blade speed up (relative to arbor) to loosen the nut. Resistance due to contact with the sled (or anything actually) is basically the same direction of force as cutting wood, which would cause the arbor nut to tighten, not loosen.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View therealSteveN's profile

therealSteveN

2357 posts in 902 days


#6 posted 03-28-2019 06:02 AM

Loose the stabilizer, and keep the sled, is it still happening? Run the saw exactly as you have been doing, just without the disc.

If not loose the stabilizer forever, and just work on getting a better blade used, versus feed rate. I suppose there are times a thin kerf blade is helpful, I guess I have never had them though.

One thing is for certain if you are spinning the TK blade, PLUS the mass of that disc, your saw can handle a full kerf blade, at which point the disc is redundant.

-- Think safe, be safe

View unclearthur's profile

unclearthur

238 posts in 2116 days


#7 posted 03-28-2019 06:26 AM

If the blade is coming loose only when you power down, then it is possibly due to a bad bearing, causing the blade to stop too fast and loosening the arbor nut due to the inertia. This happened on my Grizzly TS, as discussed in real time on this thread.

I’d suggest timing how long it takes the blade to stop after closing power – if it is too fast then that is maybe the problem. Mine was stopping in 3-4 seconds, and once I posted a video of it, some LJs immediately identified the problem. You may also notice a slow or shakey start-up.

Dado blades seem to make the nut loosening problem worse, I guess due to the higher mass, so you may want to be careful with those.

Grizzly BTW were no help whatsoever, despite it being a brand new saw. Had to return it at my own time and cost. Something I keep whining about whenever given the chance.

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MrRon

5386 posts in 3571 days


#8 posted 03-28-2019 05:59 PM

The arbor nut may not be tightened sufficiently.

View Woodknack's profile

Woodknack

12726 posts in 2708 days


#9 posted 03-28-2019 07:43 PM

The arbor washer on my Delta was so closely machined it was difficult to put on or remove from the saw and sometimes it would go on cattywhampus and seem like it was tight against the blade but it wasn’t. So when the blade spun up the washer would spin free and leave the nut a tiny bit loose but you could see the run out in the blade. I fixed it by carefully filing the inside of the washer until it could slide on and off smoothly.

-- Rick M, http://thewoodknack.blogspot.com/

View therealSteveN's profile

therealSteveN

2357 posts in 902 days


#10 posted 03-28-2019 09:09 PM



The arbor washer on my Delta was so closely machined it was difficult to put on or remove from the saw and sometimes it would go on cattywhampus and seem like it was tight against the blade but it wasn t. So when the blade spun up the washer would spin free and leave the nut a tiny bit loose but you could see the run out in the blade. I fixed it by carefully filing the inside of the washer until it could slide on and off smoothly.

- Woodknack

What you are describing isn’t rare at all. Probably the number one reason blades come loose. No matter what saw you have you need to put the washer on flat, and after feeling it, visual inspection to assure you felt it right. Probably no one will get hit by a blade, but it’s a high risk you may get a big kickback if a wobbling blade pinches wood between the fence, and the tilted blade.

-- Think safe, be safe

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NeophyteGrant

102 posts in 837 days


#11 posted 04-01-2019 02:48 AM

Hi All:

I think I had some contact issues with the nut or stabilizer, as several of you have described. I appreciate it, and sorry for the delay. I carefully examined it per everyone’s suggestions, and wiped some debris off—haven’t had any issues in three days of use since.

And to answer another question: good point on the stabilizer. I had bought into the talk about going thin-kerf with my underpowered saw after some burning, but it seems the mass of the stabilizer would negate any weight gains from thin-kerf. It has cut more cleanly. I have some slight arbor runout and it seems to help with fluttering, if that makes sense. But again, seems like I could get by with full-kerf. I’m a bit down the creek because I got good results and went with thin-kerf blades, so I’m bought into that now V_V .

Thanks again, everyone!

View runswithscissors's profile

runswithscissors

3006 posts in 2353 days


#12 posted 04-01-2019 04:16 AM

I think the use of a TK blade for a low powered saw is not for weight saving, but rather that the saw doesn’t have to work so hard because the TK removes less wood per cut. I often use a TK blade on a 3 hp saw because you don’t turn so much expensive wood into sawdust. The stabilizer (which I don’t use) is to tame blade wobble.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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