I stood on my PHD once to give downpressure. It was an incredibly stupid thing to do. I have very hard clay topsoil. If it is damp, a standard auger will drill, but if dry and hard, forget it. Beneath the clay is duripan, a very hard hardpan that is silica cemented from ancient volcanic ash. It is as hard as concrete and almost water impervious. That "almost" makes a big difference.
Recently I made some modifications to my PHD to allow it to drill in the hardpan. There is a machinist/welder down the road who does good work for a fraction of the cost of most shops. I picked up some scrap steel at a steel yard. From that, using the design I created, the machinist made the ballast support sub-frame you see below. He also welded the bar to the sub-soiler you will see in the later pics. Cost from machinist-$40 for frame, $10 for weld.
The steel yard also had an old barbell bar with two 50 lb. disc weights that I got for $25. I picked up the other weights you will see for $0.33/lb. at a used sports equipment store, along with the locking collars for $5/ea, and the spring collar on the sub-soiler for $2.50. Nuts and bolts were about $9.
I cut a short piece of the barbell bar to insert through the PHD ballast frame. Another piece got welded to the sub-soiler. I have a third piece extra. Total cost for ballast system on PHD $117. Spent $22.50 more for small discs and collar for sub-soiler ballast.
I also went to the Kubota dealer and got a new Pengo 6" dia. 42" long auger with carbide teeth and a Tri-Flow tip. They had 4 versions of the Tri-Flow tip: std., carbide tipped, hard faced, and all carbide-which has carbide studs up the side of the tip. I got the all carbide.
Now with 260 lbs. of ballast on the PHD and this all carbide tip, the auger still simply spun around when it hit the hardpan. I do have a neighbor with a Bobcat skid-steer and front mount downpressure 12" dia. auger/carbide tip that slices through this stuff like butter. I was astounded when mine still just spun round and round.
I then decided to water saturate a place where the pan was exposed and keep it wet for a couple of weeks. Finally, the thing did dig-5 min. for a 30" hole. With my first hole, the 3-ph on the Kubota
BX2200 did not have the strength to pull the auger, 260 lb. of ballast, and mucked on tailings out of the muck hole. I put the lift lever in up position and had to use a lot of strength to "assist" the PHD main frame. Finally I settled on 200 lb. of ballast. It still takes around 5 min. per hole if the pan has been saturated for many days. The 3-ph has just enough lift to the auger out of the mucky hole. A BX can lift a half ton @ 2' from the 3ph, but this is a full sized PHD and that ballast is a long way from the lift arms.
Most PHDs that fit a subCUT take a 30" auger. I did some mods on the 4ph bh subframe and got a full sized PHD on. This Pengo auger is 42" long with 19 1/2" clearance @ full 3ph lift. I have an 18" auger extender on order, which will put me at 60" total. Hopefully that will get me a 48"-50" deep hole.
The same weights can be used as ballast on my sub-soiler, as shown in the last photo. This gives a good bite in the clay when dry and hard, and also enables it to rip about an inch into the hardpan, although that wears off the standard steel tooth at an amazingly fast rate.
Edit: This post is at the end of p.5; there are 6 more pics on the next page.
