I've watched your videos at work when one break but never got around to testing them when I got home. I spoke on the phone with Inventables and with belts they just said "when you pluck them they should make a note/sound, and not just flap around". So I adjusted belts until they were above flapping and 'sang' a note.
I just went and got my fish scale out of my tackle box and did your test.. my belts were at 1lb! So I bumped them up to albs and below is the result.
SOOOOO much better! There are a few spots where the bit starts/ends the circles that don't seem perfect, but when measuring the circle with calipers it seems pretty good on as far as the circles being... round. The end depth looks a little deeper than the start (can really see in left circle). is that likely my clamping, work surface, or wood imperfection?
@Inventables, @RobertA_Rieke's method works great! Time to start selling fish scales on the website!
Do you think @RobertA_Rieke I need to do the POT test if these are my results? Or are those imperfections of the start/end of the bit expected?
I did wire brush and hit with 80 sandpaper real quick to get the fuzzies so you could see the circle better