table saw arbor nut loosened during use

[Bob Riefer]

I made several sliver cuts the other day on my table saw to bring a stack of parts down to a specific dimension. The offcut in each case was about 1/8" wide x 3/4" thick x 14" long...

Despite my best efforts, one or two of the offcuts got pulled down into the saw cabinet as I went along. Otherwise, business as usual, cuts going fine.

After one of the cuts, I powered down the saw to take a phone call and noticed out of the corner of my eye that it took much longer for the blade to stop spinning than usual, so I took the insert out (not a zero clearance insert) to take a look, and found the arbor nut had loosened considerably.

My diagnosis at the time was that one of the offcuts that got pulled down into the saw may have momentarily jammed, causing a "brake" type of action when I shut the saw down, thereby loosening the nut.

After re-tightening the nut, I have made many more cuts, pausing regularly to remove the insert and double check that it's staying tight (it is).

So, would you agree with my "offcut jamming/braking" theory? And, is this finally enough reason for me to buy/build a zero clearance insert?

[Jim Dwight]

Before my SawStop PCS I used a Ryobi BT3100 table saw. I lost both it's belts early in my usage when a thin offset dropped down and trashed them. I have used zero clearance inserts since that experience. I don't keep them pristine, the kerf opens up a little over time, but I use them.

I don't know about your theory. I guess it is possible. Seems more likely the blade cocked a little fooling you into thinking the nut was tight the last time you had it off, however. Maybe.

But I think zero clearance inserts are definitely worthwhile. I use a Colliflower on my PCS.

[Lee Schierer]

On a table saw where the blade slides on the arbor from right to left, the cutting action should tend to tighten the nut. Likewise any scrap trying to act as a brake should also tend to tighten the nut. Most likely the blade wasn't seated properly against the flange resulting in it not being properly tightened.

I would strongly suggest getting a zero clearance insert to prevent thin cut offs from going down next to the blade. Bad things can happen when this occurs.