Posthole Digger How well should 3pt post hole digger handle rocks?

[MarkLeininger]

We live in an area that has about 12" of nice topsoil on top of very rocky, sandy soil. It's a moraine if you're into geology. The rocks vary in size, most ranging in size from apples to large grapefruits, densely packed together in sandy soil. Great for septic systems, not so great for post hole diggers. My question is what should my expectation be for a 3pt PHD in this kind of soil? Mine is breaking off shear bolts on the driveline at least once per hole, and I have to finish each hole by hand using large cheater bars and sledge hammer. Some of the rocks are flat and rough, but most are very smooth, so sometimes the PHD just gets on top of one and spins without engaging. Fortunately about half the time the hole goes right into clean sand without the rocks so it's like butter. Are there any tricks to dealing with the rocks? If I bought the mother of all post hole diggers could it go through rocks like this?

 

[beenthere]

I think digging the rocks out by hand is the only way.
Unless the PHD auger can crunch up the rocks (which I don't thing any can because they roll around to easily) or get under them, you will just 'spin your wheels'. I live on a terminal moraine of the glacier and know (I think) exactly of which you speak. I have to dig post holes by hand almost every time. Mine get to be every size, eggs, grapefruit, watermelon, beach ball, ............up to the size of my tractors. I wish I had more sand. If anything other than glacial till, I get into red clay.
PS You have about 9 more inches of topsoil than I do /forums/images/graemlins/tongue.gif

 

[lmiller]

I went with a 9" auger to help me slip between the rocks /forums/images/graemlins/grin.gif

As for the Mother of all post hole diggers, when we first put up our cabin I hired a guy with a rig to sink telephone poles. He had a 12" auger with its own 8 cyl engine mounted on an old 6 wheel drive dodge power wagon. The auger shaft was about 2-1/2" square steel and the rig had so much power the shaft had a twist to it from hitting rocks.
In the western catskills most of the rock is bluestone ledges. When the auger hit the rock the hydraulic down feed on the rig would lift the back of the truck (about 4 tons) and then the auger would go thru the rock /forums/images/graemlins/cool.gif

I haven't hit any big rocks yet with the phd on my tractor but I'm sure my loaded tires help. Have you looked into different styles of auger? Some have carbide teeth and some have a floating tip.

Lou