I have just bought a 72cc post hole digger with the goal of boring 300mm holes in clay. It’s a one person machine with multiple augurs. Do I drill a pilot hole first or just go for it?
paulie12,
Apr 1, 6:53pm
No go straight to the 300 mm auger
wembley1,
Apr 1, 8:01pm
Good luck with the clay. I was helping a mate dig post holes in Wellington clay using a two man post hole digger. The auger caught and threw my mate off. According to the womenfolk watching, and after they had finished wetting themselves with laughter, I went around at least twice before I let go.
l8apex,
Apr 1, 8:35pm
Thanks. I’ll get the missus to record video for fail army
krames,
Apr 2, 2:05pm
2 men and brace yourself, lift out often and clear the blade
mark_g,
Apr 2, 6:33pm
^^^ That.
Unlikely you can do it on your own. Even with two people, lifting the auger often to clear the blade (necessary) is difficult with a 300mm auger.
grrrahaaam,
Apr 2, 6:57pm
If you are not use to it or unfit might be a problem. But some fencers/farmers use them solo all the time, often with an extension to dig strainer holes around 4 feet deep. I have about a 150m fence line involving 2 strainers an angle and 30 odd posts to do. Plan on hiring a post hole borer for a day from the local Kennards Hire. Is clay, might be some tree roots in places which can be a hassle. Probably use a smaller auger for the posts.
5425,
Apr 2, 7:19pm
Seriously , when would a fencer/farmer need a 300mm hole .? for 150m of fence?.
5425,
Apr 2, 7:21pm
4+strong men and a keg should do the job. The depth and number of holes needed may require backups/strong men.
oliver6,
Apr 2, 9:44pm
Don't drill a pilot hole. If you are digging a 2 metre deep hole, best not to put all the required extensions on first. If you do you will need to stand on a ladder and it is illegal to work off a ladder.
pauldw,
Apr 2, 11:14pm
Why would anyone want to go 2m deep with only 300mm?
I think OP needs to find a spare patch of ground and try a few test holes starting with smaller augers.
nzjay,
Apr 2, 11:24pm
It's all in the way you hold it. Holding it away from your body gives little control of the twisting forces. A good grip, in close to your body with your wrists and arms locked to your torso or hips. Legs spread a little for stability. No loose clothing that may catch. Bend your legs rather than alter your close grip as the auger is going down and working hard. Straighten your legs to start the lift out to clear. Do smaller bites and clear rather than trying to go down a long way in one hit. As soon as your wrists and arms become extended away from your body, you are in trouble, as they just can't control the twisting forces in that position. Always be ready to throttle off, as you never know what root or big stone is down there. when they grab, they grab big!
nzjay,
Apr 2, 11:37pm
It would be a lot quicker, safer to get a small bob-cat operator with augers in to dig these quite large diameter holes for a one man borer in clay. There's skidder types of bob-cats, but also smaller walk behind types as well that may be able to be hired. I'd pay a bit extra and let an operator do it. they really are quick.
wind.turbine,
Apr 3, 5:43am
For the end strainers, cant go sticking a 200mm strainer in a 150 hole and still have room around it to ram. I am a fencer :)
l8apex,
Apr 5, 6:31pm
Thanks for all of the replies. I have to drill six 350mm holes to a depth of 1.6m so I can put 175 sed poles into fix a leaning section of retaining wall. The area is at the back of my house and inaccessible to machinery so it’s either dig it out by hand or use the borer. I chose the borer. Even with the biggest augur I have I will still be enlarging the holes. Fun. Now I just need to find a time when one or more sons is out of bed in daylight to help.
mtbotrev,
Apr 5, 8:56pm
That is a mission. Could u get one of these down the back or have I misinterpreted the job?.
Just a comment that may help ya inaccessible to machinery? reality is little dingos are the go for re piling houses that have been resited/shifted small as buggery and can easily drill the holes ya need
pauldw,
Apr 5, 9:20pm
If you're going to hand finish the holes I'd go smaller, maybe even 2 or 3 smaller holes close together.
Are you rebuilding a section or adding poles? Sounds messy.
sqidlie,
Apr 6, 7:20am
And of course the OP will check for buried cables and pipe first right?
91zero,
Apr 6, 1:06pm
Na just get stuck in.
I recently used a post hole borer for going into clay - tough work.
What I found really handy (and fully recommend) was using it in conjunction with a heavy digging bar to loosen/split the clay (made life a HEAP easier). I found the borer useful, but the drill bit got clogged quickly so needed constant cleaning.
harm_less,
Apr 6, 2:27pm
The auger will lift the dirt out of the hole while it is the same diameter as the auger but not after you've enlarged the hole. Getting the 'trimmings' out of the 1.6m larger hole will be a problem I think. Just a thought.
mrcat1,
Apr 9, 8:08pm
I've drilled 9 meters deep with a 200mm auger.
nzdoug,
Apr 9, 8:11pm
fat lady to sit on it
mrcat1,
Apr 9, 8:12pm
With a pendulum type auger like a one man or digger/ bobcat unit you will find they will all run into each other unless you have a good gap between the holes. If he runs the auger down and then uses a good fencing spade to open up the diameter of the hole and then clean the loose out of the hole, it will work out not to bad.
grrrahaaam,
Apr 9, 9:40pm
Wow.
The local hire out fit would only give me a 200mm and 150mm auger with there one man borer. There two man borer has a 250mm. I would guess it is to reduce the demand on the gear and probably safety considerations. Hire was about $110/day.
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