miter saw whirring sound, blade vibration, and loosening arbor nut

[Bob Riefer]

Hello,
Looking for confirmation or new ideas..

Delta 12" miter saw has served me well for 20 years with basically zero maintenance ever.

Recently, swapped in a new blade (same brand/style as the blade that it replaced) and began noticing that during braking there was a "whirring" sound that was new, and the braking happened more slowly than before. Blade used to spin to a stop in (say) 2-3 seconds, and this was now (approx) 5-6 seconds. Enough to notice, but not cuts were good so I didn't give it much thought.

Flash forward a few weeks and several hundred cuts and the blade got stuck in piece of 3/4" pine. That was surprising. The arbor nut had loosened. Weird.

I figured perhaps I hadn't tightened it well enough, so I went to tighten it. The arbor nut was hot to touch. Snugged very tight, I made a few more cuts and was able to complete the task but can noticeably see vibration and the whirring sound is still present. Luckily that task was a carpentry task and the cut was sufficient, but time to fix this.

My research tells me I ought to:
1. Ensure arbor shaft and washers are all nice and clean, and try another know-successful blade (e.g. the blade I just recently used)... perhaps the replacement blade is just defective and a bit too thin or is warped, or some dirt/grime is the culprit.

2. If easy fix above doesn't resolve, replacing the arbor bearing seems the next logical step. Appears from quick research that doing so is far easier on a miter saw than my previous experience on cabinet saw.

3. Some have mentioned that brushes could be part of issue in some cases, but I think arbor bearing seems more likely for these symptoms.

What say you SMC gurus?

[Mike Kees]

Bob I think you will find that it is the bearings. The 20 years of use is a big clue,hot shaft and vibration seals the deal.

[Bob Riefer]

Thanks Mike! I think you're right. Going to dig out the owner's manual today and figure out how to remove/replace. Some youtubing shows me this shouldn't be terribly difficult as compared to recent table saw and jointer sagas lol

[Bob Riefer]

Very strange.... I entirely disassembled the miter saw, cleaning it out as I went. Played with all the bearings and they were smooth as can be, not the slightest hint of resistance or crunch etc. The brushes are near-new looking too.

It seemed senseless to pull the bearings off (turns out not an easy task on every miter saw) so I tried reassembling, putting a known good blade on, and giving it another go. Sounds fine again. Vibration gone. If I make a cut, let the saw cycle down, the blade is perfectly against the piece with zero gap even when rotating the blade 360 degrees. Blade braking has returned to the performance I've always had until recently. Shrug.

Fool's gold? Or do you think that simply cleaning and showing the tool some love was enough to resolve?

If it gives me more grief, I would be willing to purchase another miter saw as I only have $150 into this one and it's given me 20 years of service already... I prefer non-slider (less moving parts, more accurate, smaller footprint) and 12" (I use for home carpentry as well as stock break down for furniture)... current recommended models in the reasonable $$ range? I try to use table saw for cross cuts for furniture, but admit that the miter saw gets the job at times when it makes sense.

[Ron Selzer]

"current recommended models in the reasonable $$ range?"
I hav been very happy buying from
https://bigskytool.com/tools/saws/corded-tools-miter-saws.html
have bought numerous items, some sold as renewed C all look and perform as new
good luck
Ron

[Rick Potter]

One thought.

Are you using a saw with a 5/8 arbor and a thin kerf blade with a one inch hole and a bushing? If so, and the bushing is thicker than the blade, it could be possible you are not getting the blade tight.

If you don't have an arbor washer with a depression in it to take up the gap between a thick bushing on a thin blade, it may not tighten properly.

[Lee Schierer]

Blade braking has returned to the performance I've always had until recently. Shrug.

Fool's gold? Or do you think that simply cleaning and showing the tool some love was enough to resolve?.

I've found that 90% of what is wrong with most mechanical things is dirt.

[Mike Kees]

Bob,from your original description it seemed bearings were obviously suspect. Well it is not the first time ,I have been wrong before...:D.

[Bob Riefer]

"current recommended models in the reasonable $$ range?"
I hav been very happy buying from
https://bigskytool.com/tools/saws/corded-tools-miter-saws.html
have bought numerous items, some sold as renewed C all look and perform as new
good luck
Ron



Great tip, thanks Ron! Bookmarked that for future use :-)

[Bob Riefer]

One thought.

Are you using a saw with a 5/8 arbor and a thin kerf blade with a one inch hole and a bushing? If so, and the bushing is thicker than the blade, it could be possible you are not getting the blade tight.

If you don't have an arbor washer with a depression in it to take up the gap between a thick bushing on a thin blade, it may not tighten properly.

Good thought but not the issue in this case I don't think. 1" arbor on the miter saw and all the blades as well. The only difference I can see is that the blade that was used when having the problems was 80 tooth vs. the usual 40 or 60 that I had been using up until then. All blades are diablo, but perhaps the 80 toot version has some difference I didn't notice... perhaps thinner or thicker? I'll try to find specs...

More likely, perhaps I had the blade installed with some "gook" keeping it from tightening securely

[Bob Riefer]

I've found that 90% of what is wrong with most mechanical things is dirt.

It seems that could very well be the case this time around (and I'm hoping so! this saw has been just fine and I have no interest in a new "toy" when this one has always done what I asked of it)

[Bob Riefer]

Bob,from your original description it seemed bearings were obviously suspect. Well it is not the first time ,I have been wrong before...:D.

I was right there with you... and I'm somewhat holding my breath to see if the issues return before too long. Fingers crossed it was a simple, and long lasting, fix!

[Bob Riefer]

Good thought but not the issue in this case I don't think. 1" arbor on the miter saw and all the blades as well. The only difference I can see is that the blade that was used when having the problems was 80 tooth vs. the usual 40 or 60 that I had been using up until then. All blades are diablo, but perhaps the 80 toot version has some difference I didn't notice... perhaps thinner or thicker? I'll try to find specs...

More likely, perhaps I had the blade installed with some "gook" keeping it from tightening securely

Found the specs...

The 80 tooth blade has a plate measurement of .087" whereas the 60 tooth blade measures .071"... any perspective on whether that could have potentially been part of the issue?

[Mark W Pugh]

Wow, this is amazing. I've had this happen on my Dewalt 12" slider a few times. it's really freaky, especially at the end of a cut. Then, to find out the arbor nut loosened. I guess a good cleaning is in order.
Thanks for your problem, uhh posting your problem.

[Rick Potter]

No, I don't see the thickness of the blade being an issue here.

[Larry Edgerton]

Get into the habit of only using the Brake when you need it instead of an automatic reaction if that is possible on your saw. The nut loosening is most likely from braking and those older Deltas had a very strong brake. If the blade spins on the arbor enough saw is useless as the cost of repair is too high to justify. Saws with brakes require a very tight arbor nut as the braking forces want to make the nut back off.

[Brian Tymchak]

The nut loosening is most likely from braking and those older Deltas had a very strong brake. .. Saws with brakes require a very tight arbor nut as the braking forces want to make the nut back off.

+1. I had the same experience when I changed to WoodWorker II on my Makita a few years ago. I could not find any reason ( dirt, dust, etc) that would have been the cause. I tightened the arbor bolt tighter than I did the first time, and it has held since. I think I tightened that bolt the first time thinking along the lines of tightening the arbor nut on the table saw, where you don't want to crank down on it as the rotation will serve to tighten the nut. Did not consider the blade brake was working against the bolt.

[Larry Edgerton]

Also, check your brushes. a brush past its service life will get to the holder and if run unchecked it gars the armature. A brush in that condition can make a whiring noise like a card in the bicycle spokes.