I consider my 3 point auger to be one of the most useful attachments that I have. I couldn't imagine having a farm and not having an auger.
When I bought mine, I knew nothing about them. My dealer sold it to me for a good price when I bought my 37 hp tractor from him. I think it was $400 back in 2003.
Over the years, and hundreds of fence posts, wood posts and trees planted, I've learned that the most important thing with a 3 point auger is the cutting teeth of the auger.
I'm on my third auger. The original one had a plate that you could grind to sharpen, but it never did very well in dry clay. I upgraded that to a Speeco auger that had replaceable teeth that was a lot better, but very hard to find the replicable teeth.
One day, when I was desperate to find replaceable teeth that would fit the Speeco auger, I decided to buy a Countryline auger from Tractor Supply. That's when I learned that there is a difference in cutting teeth. The Countryline auger drilled a lot better than the Speeco.
It drilled so well that I now had a new problem of burying the auger in the ground and not being able to get it out. The two solutions to this was a large pipe wrench to unscrew the auger from the ground or using my backhoe to pull it out and create a much bigger hole. Eventually I built a wood bridge to go across the hole that would let the auger bury itself that worked well, but it also increased what I had to do to drill a hole.
Two years ago I got a bigger John Deere 5065 tractor. 65 hp over 37 hp solved the burying issue with the auger. It turns out that with more horse power, you can control how fast it digs and pull it back up when it starts to bury itself.
In August and September, my ground becomes like concrete. I still find spots where I just cant drill into the clay with the auger, so I use my SDS Max Rotary Hammer with a Spade Bit to break through the ground and dig down about six inches. Then I fill the hole with water and let it soak into the ground. I add water to the hole during the week, and by the next weekend, I can drill it easily.
My auger is 12 inches, and I think that's the perfect size for everything that I do. I bought a 6 inch auger for some metal pipe that I was going to use, but I couldn't control how quickly it dug down and decided to give up on using it. It's been sitting there ever since. I took the teeth off of it and used them on my 12 inch auger, so it wasn't a total waste, but overall, it was a mistake to buy the smaller auger.
When not in use, I hang it from a wooden frame. This makes it easy to connect it. But it also keeps it off of the ground, which I think is important.
