Interesting to better understand piles as explained in SG's second link. Struck a chord with me because of a fascination with building the Brooklyn Bridge, no less. Why? Built in the days of horse & rope tackle, and ultimately strung with inferior steel cables (excess sulphur in steel way back when ring a bell, or unscrupulous inspectors?) there was concern when digging the piles. Here's the bit: One dig found bedrock at a convenient depth (end friction) but not so the other, where side friction is relied on to support the deeper pile and all substructure on a questionably-stable river bottom. btw: Neither Robeling or government officials would have bet their bones that this American icon would be standing today, but it is. :thumbsup:
Can't imagine drilling with the PHD and not working the throttle continuously, backing off a bit (rpm) when lifting to clear each 'peck' or givin' 'er more when going in to prevent stalling as needed. I've 'drilled' dozens with an 'Earthquake' hand-held auger for every one done with tractor power, and obviously a helper to muscle auger & extension when pecking-in/out. If we get a rhythm going, 3 rotations then lift a foot or so, seems to clear best in all soils (sand or clay here, pick one, plenty of rocks everywhere in the GL basin) without rattling loose soil to fall back or over-widening the top of the hole. I'm convinced that moderation will allow some compaction in the sides vs wobbling a crater, and bet the OP got a feel for that by the 3rd or 4th hole.
Sleuth, I'd also bet the next six holes you dig take half the effort of the first few. (You go, man!) btw, guys: I never asked my 'rebar' guy about heavy mesh like that. Is that where to look for it, or is it 'ag' stuff that TSC or someone would offer?