Posthole Digger Post Hole Augers - Breaking Shear Bolts

[TTTTTT]

For all the 3ph post hole auger experts, I need a little direction/assurance. Just picked up and older auger with a 12" bit I was doing a few test holes in cottage country type earth (a few small rocks and small tree roots). I know it is a good thing to break shear bolts rather than your tractor pto or auger gears, but I was snapping off 3/8" #8 bolts what I thought was a little to frequently. Not being pristine farm field with few rocks etc, is this par for augers running a 12" bit. Had the pto on 540 rpm and idle revs (800). Is the torque that great? Guess it is.

Thanks Dave

 

[art]

When a machine shears bolts it will move a little metal until the hole gets elongated and then they shear quite regular!

I've always perfered hydraulic drive in our area do to the stones. You can just back them out!

 

[2fast2]

I use the same size auger, same RPM or maybe 1000, 540 pto. I haven't broken a single shear bolt, ever (knock on wood) so maybe there is more to it. Check the gear case lube, make sure it is good and turns freely. Also, check your power take off shaft u joints to make sure they're not binding and in some way contributing to this (though I doubt it.) The other question is whether you're going down too quickly and maybe loading things too much. I drill down some, lift and empty the hole, go down farther, lift again, etc.
We plant all our trees this way, put in split rail fence, and it sure beats digging by hand!

 

[tjc1989]

The other question is whether you're going down too quickly and maybe loading things too much. I drill down some, lift and empty the hole, go down farther, lift again, etc.
quote]

This is the way I do it, too, and I have dug through some really thick tough clay this way. Patience is the key, and not expect to dig the hole in 10 seconds. I do this procedure even with a 6 inch auger, let alone a 12 inch. I also bring my auger up near the top to spin off the accumulated soil before going back down into the hole. I have never broken a sheer bolt or damaged a driveline.

 

[TTTTTT]

When a machine shears bolts it will move a little metal until the hole gets elongated and then they shear quite regular!

I've always perfered hydraulic drive in our area do to the stones. You can just back them out!

Good point!

Thanks for the quick comments. Shaft, u joints and auger gears are smooth. I am going down slow and coming up and down. I was down about 3 ' , this auger is a 48". Maybe just hitting something further down.

Dave

 

[MtnViewRanch]

For all the 3ph post hole auger experts, I need a little direction/assurance. Just picked up and older auger with a 12" bit I was doing a few test holes in cottage country type earth (a few small rocks and small tree roots). I know it is a good thing to break shear bolts rather than your tractor pto or auger gears, but I was snapping off 3/8" #8 bolts what I thought was a little to frequently. Not being pristine farm field with few rocks etc, is this par for augers running a 12" bit. Had the pto on 540 rpm and idle revs (800). Is the torque that great? Guess it is.

Thanks Dave

Typically grade 8 bolts are considered a no no. Grade 5 or less is the norm. Something else that you might try, give the tractor no throttle, just let it idle when you are digging. While digging, only dig down 12" at a time, then lift and clear the auger every 12".

Hope that some of these suggestions might help you out.

 

[tjc1989]

Something else that you might try, give the tractor no throttle, just let it idle when you are digging.

Good point. I always just stand beside my tractor with my hand on the lift lever, and at idle. I feel I have better control, plus I more readily hear when the motor and PTO is loading up.

 

[TTTTTT]

Typically grade 8 bolts are considered a no no. Grade 5 or less is the norm. Something else that you might try, give the tractor no throttle, just let it idle when you are digging. While digging, only dig down 12" at a time, then lift and clear the auger every 12".

Hope that some of these suggestions might help you out.

Thanks

That is the way I was doing it other than to clear the bit and hole, I would up the revs just a little. I was using #5's and #8's, they both seemed to shear under a similar load. I guess you are saying before a #8 will go something else will!

Dave

 

[MtnViewRanch]

Dave, just a question on your phd, does it take 1 or 2 shear bolts? I'm asking because I think that most phds only take 1, but mine takes 2.

Just curious :confused3:

 

[sweettractors]

Good point. I always just stand beside my tractor with my hand on the lift lever, and at idle. I feel I have better control, plus I more readily hear when the motor and PTO is loading up.

I had rather be in the tractor seat. I have been on the ground, like you describe and the PHD sheared a pin and it hit me in the chest and stung pretty good. If it had hit me in the eye, it would have put it out for sure. In the seat puts you above the "throw plane" when a bolt shears. Be careful !!-- Ken Sweet