18" PHD Auger on B7800

[RickHouTX]

18\" PHD Auger on B7800

Does anyone think I can successfully dig 18" holes with a 30 HP (~22 at PTO) compact tractor? I want to drill several 18" holes for 6 X 6 posts for a barn, but don't want to buy a PHD big enough to do it if my tractor doesn't have the capacity. Will be drilling in what we call "Black Gumbo" (dark soil with lots of clay in it) down here.

Rick in Houston, TX

 

[Henro]

Re: 18\" PHD Auger on B7800

I would imagine that 18" holes would be no problem with the B7800. I do know for sure that 14" holes are not an issue at all with my B2910, which is the same tractor for all practical purposes.

Side note: I used my 14" auger to drill holes for 6x6 posts supporting my shed. I dropped in 12" round concrete stones to set the posts on. This worked well. Can we assume that local codes require a larger hole in your case?

Anyway, my bet is the B7800 will power an 18" auger just fine.

Frankly, I would not hesitate to buy a 24 inch auger for mine if I had the need. I currently have 9 and 14 inch augers, so the logical progression would be to something larger than 18" I think, in my case. My gut tells me that the B7800/B2910 could handle a 24" without much if any problem.

 

[RickHouTX]

Re: 18\" PHD Auger on B7800

I am not sure if the local codes require it, but I thought the bigger the better. Slabs are typically designed to float here because of the drastic soil moisture changes we experience.

I see so many PHDs that are recommended for augers 6, 9 and 12" The ones that are rated for 18 and 24" are usually a little more HD and more $. It is conceivable that I could get away with using a lighter duty model to bore the 50 or so 18" holes that I plan to use it for. That is not how I usually buy tools however, so hence all the research.

Here is a little pic of the barn I want to tear down and replace. The B7800 in the background needs a home...

Thanks for the reply,
Rick

 

[john_bud]

Re: 18\" PHD Auger on B7800

Only problem may be in popping the shear bolts in the pto driveline. The HD units have slip clutches. Just get a pocket full of bolts and you should be fine.

Don't forget that a PHD is more dangerous that a one legged drunk with a chain saw on ice trying to pee.

jb

 

[bota7800]

Re: 18\" PHD Auger on B7800

On the same topic so I will post here:

Doesn't it depend upon the soil conditions? I am in Colorado foothills, former cow pasture. There is a lot of rock on the surface so I expect some underground, too.

I was planning to drill 4-500 12" holes for fence posts with my B7800. I was in the market for a PHD but a neighbor said they had a lot of trouble drilling 6 (9")holes for a 3-sided run-in. She said they had to soak the holes and it took a long time. They are experienced, having put in 300 posts at their last place.

Am I missing something? Their experience concerned me. I don't want to spend all summer digging post holes and ruin my tractor in the process.

 

[Henro]

Re: 18\" PHD Auger on B7800

<font color="blue"> Am I missing something? </font>

No, not at all. Soil conditions are key. The original poster menioned he had dark soil with lots of clay. We have lots of clay here as well. But it never seems to dry out and turn concrete-like.

No doubt that if one were drilling holes in rock, it would take a special auger with special teeth, etc, and maybe even down pressure.

I know when I posted my reply, after reading the description of black gumbo, the soil type I was thinking of was something similar to what we have here, clay that seems to stay damp year round, even in dry summer(once you get down a few inches).

Your neighbor's experience would be most likey what yours will be when you dig your holes. Some members here have reported terrible times trying to dig post holes in soil that sounded like it may be very similar to yours.

 

[firemanpat2910]

Re: 18\" PHD Auger on B7800

This may be a dumb question but.... Can you pre drill a 6"
or 9" hole and then use the big bit ? it might be easier on the gear box, If you can keep the hole straight.

 

[RickHouTX]

Re: 18\" PHD Auger on B7800

"This may be a dumb question but.... Can you pre drill a 6"
or 9" hole and then use the big bit ? it might be easier on the gear box, If you can keep the hole straight. "

There are augers that are made stepped, that is they have a smaller pilot size such as 6" or 9" and then step up to 18" or 24" respectively, for example.

You would not be able to easily bore a larger hold concentric with the smaller hole without such a pilot. It would be similar to trying to use a hole saw to drill a 2-1/2" hole where you already have a 1" hole. You might be able to get the hole saw started without the pilot drill, but it would not be centered on the 1" hole.

Thanks again for the equipment specific experience Henro.

Rick

 

[MadDog]

Re: 18\" PHD Auger on B7800

Rick: I share the question expressed earlier as to why you want to drill 18" holes for a 6x6 post. The diagonal of a 6x6 timber would be a shade under 8 1/2" or, if nominal 6x6 and actually 5 1/2" square, would be a bit over 7 3/4". Either way, you'd want a bit of room to get the post in, make adjustments to set it vertical, and have enough room to tamp your backfill down around it or pour concrete, whichever you are planning on.

I think you could do all that pretty easily with a 12" diam hole or even, perhaps, 10". Why do you want to go so much wider"? Maybe I'm missing something.

 

[GabeTX]

Re: 18\" PHD Auger on B7800

Rick, I faced a very similar problem while building a fence recently.

I too have black "gumbo" clay, with lots of rocks. I also have a solid layer of limestone 1.5-3 ft below the surface--do you know how deep your soil is?

Here's a thread where several different options were discussed.

Ultimately, I ended up paying $110/hour for a truck-mounted pier drilling rig. Give some serious thought to that option. It's pretty much gauranteed to give you good results quickly and inexpensively regardless of your soil (or solid rock...) conditions.

I just mention that as it may not be an option you'd thought of (I hadn't, until Harvey suggested it--pay lots of attention to his posts if you read that thread).

If you must go with a 3-pt PHD... Check out www.danuser.com