tentman Posted April 30, 2017 Report Share Posted April 30, 2017 Gidday Guys I'm wondering if there's any rule of thumb for selecting an auger size to predrill post holes in hard clay, posts driven down the hole after pre-drilling. Working in fairly tough clay, currently lots of (good) posts getting smashed with a 340 kg monkey. I was hoping to get away with buying one 100mm flight but do you use a different size for strainers?? Thanks Link to comment Share on other sites More sharing options...
Green Man Posted April 30, 2017 Report Share Posted April 30, 2017 I would guess at 75% of the size of the post you are going to drive so 200mm post 150mm auger or 100mm post 75mm auger. Link to comment Share on other sites More sharing options...
tepapa Posted April 30, 2017 Report Share Posted April 30, 2017 Really you need different sizes for different scenarios and different types of ground. If your drilling really hard ground or rock you might want auger just slightly smaller than the post. If your just using a 4" you've only got the benefit a rockspike could do. Link to comment Share on other sites More sharing options...
Matt on the Moors Posted April 30, 2017 Report Share Posted April 30, 2017 A 4 inch auger will be more beneficial than a rockspike because it actually removes the material from the hole- a spike will just compact the side of the hole further- this is why in my opinion augers are better for hard/compacted ground and spikes are better when things need shattering- i.e. Rocks and concrete/tracks etc. I tend to use an auger 2 inches smaller than the post if it's hard ground. I have a 4" 6" and 12" which covers most scenarios. Link to comment Share on other sites More sharing options...
Matt on the Moors Posted April 30, 2017 Report Share Posted April 30, 2017 A 4 inch auger will be more beneficial than a rockspike because it actually removes the material from the hole- a spike will just compact the side of the hole further- this is why in my opinion augers are better for hard/compacted ground and spikes are better when things need shattering- i.e. Rocks and concrete/tracks etc. I tend to use an auger 2 inches smaller than the post if it's hard ground. I have a 4" 6" and 12" which covers most scenarios. Link to comment Share on other sites More sharing options...
Goaty Posted April 30, 2017 Report Share Posted April 30, 2017 I would agree with using a narrower auger in clay. As mentioned in another thread dug in posts are not as secure and need little effort to pull out. Whereas driven posts require alot more force to extract. In clay which expands and shrinks with water content a tight fit is required. A pre drilled hole the force of going in should compact the sides for a snug fit. Link to comment Share on other sites More sharing options...
Matt on the Moors Posted April 30, 2017 Report Share Posted April 30, 2017 I also think it's far better to get a post deep by pre drilling with an auger than to get a post not so deep but no predrill. When I started I only had a 100kg monkey on my post driver- on its own it was pretty **** in hard ground but if I predrilled with an auger 2" narrower it was surprising how deep I could a big post in even pretty hard ground. Link to comment Share on other sites More sharing options...
Folly Fencing Posted July 19, 2017 Report Share Posted July 19, 2017 What augers are you guys using? Hand held or machine mounted? Link to comment Share on other sites More sharing options...
tepapa Posted July 19, 2017 Report Share Posted July 19, 2017 Machine mounted, auger torque. Link to comment Share on other sites More sharing options...
tepapa Posted July 19, 2017 Report Share Posted July 19, 2017 Machine mounted, auger torque. Link to comment Share on other sites More sharing options...
Markhibberdfencing Posted July 20, 2017 Report Share Posted July 20, 2017 Auger torque,also use mine for winding wire up with home made fabrication goes well. Link to comment Share on other sites More sharing options...
tentman Posted July 21, 2017 Author Report Share Posted July 21, 2017 Mine is an augertorue as well. Has anyone tried a cone type wood-splitter on their Auger . . . results?? Link to comment Share on other sites More sharing options...
Ajmoore1 Posted August 28, 2017 Report Share Posted August 28, 2017 What size augertorque are people using. Looking at mounting one on my a p230 protech. Also have a Takeuchi 1.5 ton mini digger so want one that will fit on that as well. Also what augers are best to get. Are there different types or just different screw on cutters? Link to comment Share on other sites More sharing options...
Matt on the Moors Posted August 29, 2017 Report Share Posted August 29, 2017 I had a x2000 augertorque on my old Tak tb016. It worked well up to 12". Both by augers have tungsten tip- not really sure there is any advantage to having a lesser tip other than a minimal cost saving Link to comment Share on other sites More sharing options...
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