Bit or auger type for post hole digger

[Mossy dell]

I'm looking at post hole diggers (PHDs) and Danuser is the only one I've come across that offers auger bits for different types of soils. That makes sense to me. Does it matter? I don't know, but it seems weird that all economy and most other post hole diggers seem to offer basically the same plain augers, just in different widths.

My tractor is a 25.5 hp Kubota B2601, so compact. Our soil here is tight clay full of shale. I mean all sizes of shale, which is formed from compressed clay. And then there are solid shale shelfs. Now nothing I can use will go through a shelf of rock. But I need something to deal with small, medium, and big rocks above those solid shelves. Realistically I guess it would wallow them out. Trying to dig footings here, you are not going to have a nice straight trench. When you hit the edge of a big rock, it gets pulled into the trench and leaves a big hole in the trench's side.

My past experience was with an old PHD, unknown brand but sturdy, and a 33 hp JD970. It did great but our soil was not rocky. I also had a post pounder that worked well. Here, it takes some kind of pre-drilling to drive a post, from what I've been told. The rocks are unreal. To plant a small tree or bush, I have learned to bring a pick as well as a shovel.

So . . . is finding an auger made for such soil important? Does anyone offer this besides Danuser?

Here are the choices for Danuser's 20/40 PHD from their web site; the Hole Digger Head mentions shale:

Plain Edge
For digging in dirt, clay, sod, and other light-duty conditions.

Features:
Available in 40”, 52”, and 72” lengths for PTO diggers, and Models 8300, 8800, and 8900 hydraulic drives.
(click to see available auger bits)

Serrated Edge
For digging in compact soils, light tree roots, and dry soil.

Features:
Available in 40”, 52”, and 72” lengths for PTO diggers, and Models 8300, 8800, and 8900 hydraulic drives.
(click to see available auger bits)

Hole Digger Head
For digging in clay, caliche, shale, mixed limestone, frozen ground, and light rock. The most aggressive design offered.

Features:
Available in 40”, 52”, and 72” lengths for PTO diggers, and Models 8300, 8800, and 8900 hydraulic drives.
(click to see available auger bits)

Stepped (plain and serrated edges)
Stepped tree planting auger for bulb type trees.

Features:
Available in 33” and 40” lengths for PTO diggers, and Models 8300, 8800, and 8900 hydraulic drives.

 

[ctfjr]

I can only offer my experiences here in CT. The soil is very rocky but where we are at least there is no clay. 5 miles from here in our old house we had loads of 'redstone' (we were on the corner of Redstone Dr). Using a phd in both places taught me to try to avoid the rocks as a 1st choice. You could go through the redstone usually but it was hard drilling.

You can really beat the crap out of your machine bouncing off buried rocks. I just finished drilling 23 holes for 4X4's to support my driveway lights. The spacing wasn't critical between them - good thing. I was shooting for 14' spacing but every once in a while I'd get down 18" or so and hit a rock to big to auger out. I don't know what different heads would have done but unless you have a rock drilling tool I don't think it would make a difference.
The auger often would try to side step the rock by sliding off of it. Not a good solution if you are looking for a straight hole. It made sense to just move 6-8" and try again.

 

[Mossy dell]

Thanks, ctfjr. I do a lot of dodging rocks here too. Not sure how much the bit type would matter. But I think it might help with some issues.

This video mentions using water and Bentonite. That's a natural volcanic clay sometimes used to seal pond bottoms. I guess it melds with the existing soil or something.

 

[JimmyJazz]

I would pay a guy with a backhoe.

 

[Njtool]

I have a Digga post hole digger that I purchased from EverythingAttachments. They have a standard bit and a rock bit. I purchased the rock bit and I’ve been happy with it so far

check them out

 

[ctfjr]

now that's a serous phd!

 

[Mossy dell]

I would pay a guy with a backhoe.

Good point! I'll have to get my act together and figure out all the holes. Not sure how many I actually need—post holes here and there for gates and grape trellises. Small job but might get someone to do it. And MIGHT be less than an auger.

 

[Mossy dell]

NJtool, I like the front mount. And I have a front remote on my B2601. But the video I've seen of them in action on compact tractors made them look painfully slow.

Could you address the speed issue. My old digger really spun. I think our tractor's have about the same horsepower but yours is about a frame larger and I imagine has much great hydraulic flow.

P.S.-Just checked and mine is rated at 8.3 gpm hydraulic flow. Don't know how much/if that's reduced in the front remote.

 

[Njtool]

NJtool, I like the front mount. And I have a front remote on my B2601. But the video I've seen of them in action on compact tractors made them look painfully slow.

Could you address the speed issue. My old digger really spun. I think our tractor's have about the same horsepower but yours is about a frame larger and I imagine has much great hydraulic flow.

P.S.-Just checked and mine is rated at 8.3 gpm hydraulic flow. Don't know how much/if that's reduced in the front remote.

We have about the same oil flow. From my understanding, a portion of that is used for power steering etc. so the available flow to attachments is less.
I haven’t clocked the rpm on my bit, but it digs holes very well. I can put down pressure on the auger if needed. But I usually put the loader in float so it digs at a constant speed.
I will try to clock it next time it’s on. I can tell you that I would buy it again without hesitation. I’m very happy with what it does and how it digs.
Next time it’s on, I will count the rpm

 

[Mossy dell]

Thank you, NJtool. I got the gpm from my owner's manual, no actual measure. I would love to know what yours is rated at. But this is really reassuring so far. I think I could use it alone a lot better if it were out front!

By the way I am interested in a 12" and in the same rock auger you got. What is the diameter of yours? I might be better to get a 6" or 9" and drill two holes for big posts.

 

[racerboy]

Thank you, NJtool. I got the gpm from my owner's manual, no actual measure. I would love to know what yours is rated at. But this is really reassuring so far. I think I could use it alone a lot better if it were out front!

By the way I am interested in a 12" and in the same rock auger you got. What is the diameter of yours? I might be better to get a 6" or 9" and drill two holes for big posts.

Mossy dell, I'm curious which route you ultimately chose. I'm considering doing a fencing job at home that will require about 50 post holes dug, and was wondering if I could justify to myself buying an attachment for the B2601.

NJtool - not sure where in NJ you are, but I'm up north in Sussex County and my soil is all rock, so the Digga tool you showed looks like the right tool for my spoil, but I don't if the holes it digs are too big (wide) for chain link posts. This is my first time to do a fencing job, so I am still learning all the details on how to do it correctly.

 

[mcmxi]

I have a Digga post hole digger that I purchased from EverythingAttachments. They have a standard bit and a rock bit. I purchased the rock bit and I’ve been happy with it so far

check them out
View attachment 64969 View attachment 64970

That rock/earth combo auger is wicked. I have a Land Pride HD25 SSQA PHD with 9" and 12" bits but it's so rocky up here, and not fracturable rock like that Digga auger is designed for. At around $1k for those augers it's risky to invest in something that might not work for me. How is the rock in NJ?

 

[Tim Horton]

The first PHD I owned was a well used Speeco.. It cleaned up, tightened up from about 7/8 worn out to about 1/2 wore out... It came with a 9 and a 12" augers.. All for cheap.. Of course the teeth were wore out but the center drills were OK.. At the time I just made replacement teeth out of mild steel and sharpened every 2-4 holes as needed... The teeth didn't need to be razor sharp, just not fully rounded dull... I wore out 2 sets of soft teeth to finish that job..

The soft steel teeth were good enough to finish the job until I could get new hardened teeth for the augers... Depending on the job needed done things don't need to be perfect to get by until you have time to do something different..

 

[Mossy dell]

Mossy dell, I'm curious which route you ultimately chose. I'm considering doing a fencing job at home that will require about 50 post holes dug, and was wondering if I could justify to myself buying an attachment for the B2601.

Racerboy, I ended up hiring it done! For the number of posts, I couldn't justify an attachment.