On Thursday, September 24, 2020 at 11:20:48 AM UTC-4, Andrew M wrote:
On Thursday, September 24, 2020 at 6:47:03 AM UTC-7, dpb wrote:
On 9/24/2020 8:00 AM, Leon wrote:
...
Yes most circular saws have arbor locks.
I've yet to see one... ???

A flat maybe, a lock is pretty rare.

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So an update--the sanding solution worked initially, however once I swapped back to the dado stack and then tried to reinstall the single blade, I had the slippage occur again...Frustrating.

Fortunately, the thin wrench set I ordered from amazon arrived and I was able to use the 7/8" thin wrench on the arbor which held the arbor in place while I tightened the 1-1/16" arbor nut.
This is what I ordered: https://www.amazon.com/Grip-Super-Th.../dp/B001HZQW0Y

Is it possible that you have an issue with the arbor itself? I can't explain why, but before I changed the arbor on my 70's vintage Craftsman TS (due to a chunky bearing) I used to get some slippage while tightening with the blade held still with a piece of wood. It wasn't slippage like it was still loose, it was more like soft jerk after it was tight like something was turning inside the arbor. (There is no provision for a second wrench on my saw.)

I had a spare arbor, so I decided to change the whole thing instead of just the bearings. Now when I tighten the arbor nut nothing slips and I feel that I could tighten it way more than I need to (but I don't).