Post Hole Auger Parts

[Anonymous-0]

I'm putting in some fencing for a horse pasture and I've been using a tractor mounted (3 pt hitch) post hole digger. The problem is that I hit rock anywhere from 12 - 24 inches below the surface. I'm trying to go down 36 inches.

The rock itself is not particularly hard as I can put some moderate weight on the auger and grind through. Unfortunately the wear on the auger knives is tremendous and I've only gotten 5 or 6 holes before the knives are ground away.

The auger has a replaceable spiral point, and while this gets quite hot, so far its holding up. The knives however appear to be cast metal and can't take the punishment.

My first question is, what do professionals do when having to auger down into "sandy" rock?

Are there replacement knives that are made of harder material (i.e. hardened steel) that might hold up better?

The auger diameter is 6 inches with one knife on each auger edge (2 knives total).

Suggestions?

John

 

[Anonymous-0]

People who do lots of holes weld hard surfacing on the auger flighting. If the teeth are forged steel they could be hard faced as well or you can get carbide teeth for very hard digging. Dave

 

[Anonymous-0]

I would rig up a water barrel and wet things down. That will give your cutting edge some lubricity and cooling, helping it last longer.

 

[Anonymous-0]

i have a post hole digger that has been used until all the bearings and the u-joints were gone. I can tell you that i've never replaced the auger knives, in actuality, it still works.

 

[Anonymous-0]

The clay here in Michigan is notoriously tough on post hole augers, not to mention the chunks of granite mixed in with the clay. The local rental shops use a carbide cutter that looks like a big arrowhead on the end of the auger.

The link below shows the carbide point and some other specialized blades. These are for the Little Beaver brand, but might work for your application.
<ul><li><a href="http://www.littlebeaver.com/prod_augers.php">Little Beaver augers</a></ul>

 

[Anonymous-0]

I would strongly suggest you use steel weight and not human weight as I have a friend with one arm because the auger bounced. If we do use human weight we wedge a six foot bar in and bear down on it from a distance, also you can perhaps tripple the down pressure with the same amound of weight. It did happen fast and at a slow idle with the operator having his hand on the pto lever.

 

[Anonymous-0]

Mark,

Thanks for the link. I noticed that the carbide points actually mount in the middle of the auger and extend to the full diameter of the auger. This makes sense when drilling the really hard stuff.

I think I can adapt this to my auger. I've got an old center point that I can make into an adapter that should fit one of their carbide tips.

The auger is made by Dale Phillips Co. I'll probably give them a call to see what they recommend.

Unfortunately there is lots of big rock in this field, but as long as I can keep good knives and tips on the auger, my old John Deere model 50 tractor has enough torque to spin the bit slowly and not blink an eye.

Thanks again,
John

 

[Anonymous-0]

A little water is a good idea. I can tell you that after a few minutes of drilling that the spiral point gets very very hot. Hot enough to cause discoloration. The ground up grit is also very warm indicating a lot of generated heat.

Thanks for the suggestion,
John

 

[Anonymous-0]

Dave,

You make an excellent point. I weigh about 220 and standing on the 3 point hitch arm does not make much difference. When I need down force I like to borrow my neighbors John Deere compact tractor which has a front mounted bucket. I simply center the bucket over the post hole digger frame and lower the bucket enough to just raise the front wheels on the little John Deere. It appears that if the auger is going to drill the hole it will do so with that much weight. I doubt that adding more weight than that would be either productive or sensable.

My tractor that drives the post hole digger is an old John Deere model 50. One of the old two cylinder models. It has all sorts of torque at low engine speeds, which makes it ideal for spinning the auger slowly.

Regards,
John

 

[Anonymous-0]

Dave,

Thanks for the post. The flighting on this auger is pretty good and appears to be able to take the added weight I put on it. The tip and knives appear to be cast, possibly forged. I don't know enough about metalurigy to know if I can harden the cast knives but its an idea. The alternative is to replace the knives every 5 or 6 holes. I estimate something like 180 holes to drill in this field and while I COULD buy 30 sets of knives I'd rather not.

Regards,
John

 

[Anonymous-0]

Why not just dig two foot holes? I have an equine operation (50 horses) with lots of fence and cross fence, most posts are buried 2 ft with no problems. That would save your auger knives and avoid the possibility of an accident trying to weight the auger to get those last few inches.

 

[Anonymous-0]

I had considered setting the posts a little more shallow. Problem is that in places I run into the rock before I even get to 2 feet.

The posts I'm burying at the moment are corner posts and gate posts so I'd really like to get them down 3 feet. I've got some smaller posts around the property buried at 2 feet, but the soil is such that they didn't anchor well.

I may end up having to concrete some of the posts.

I've been doing a bit more research since my original post. The original auger manufacturer does have some hardened knives and is sending me a pair. If I can get 15 or 20 posts with a set of hardened knives, and if they are not too expensive it might work out okay.

There also are augers that are specifically made for digging into rock. I found one of these for around $400. Thats a little on the high side for my budget, but still cheaper than having to pay someone to come in a drill the holes for me. I've estimated something like 180 holes for the upper pasture.

Thanks for the reply,
John