I know this has been covered in other threads, I did a search through the archives. I'm looking at Hilti demolition hammers, but would really prefer a combo unit in case I want to core or drill. For the price of these ($1200-$1450) I'd like it to do more than pound ground rods.
The soil around here (swampland, Illinois) is better than Arizona. I can get a ground rod in with a 4 lb. hammer in about 30 minutes when it's tough. I don't know how anyone uses a sledge. I'd probably miss the rod & hit my leg. I may also opt for the cheap pipe with sledge head welded on.
So the question is what model do you have, how is it holding it 8' up with ground rods? If you use it for drilling or coring, what size holes, etc.? Any info would be greatly appreciated.
I've never used these before & its about triple what I usually spend on tools. I want to make sure it will be my new best friend.
I have a TE76 and use it mostly for ground rods but do blast holes in foundations with it as well. When I install a rod strait down I drill down 1st with my long bit then start the rod by hand then just put the Hilti on it and shoot it in. Only takes a few seconds or a minute at best if it it tough.
#43797 - 10/23/0412:36 AMRe: Hilti Ground Rod Driver
Hi Dave, I use a Dewalt DW541K Rotary Hammer Drill. 3/4" ground rods are no problem for it. It will take a 1 1/2" bit and I have dry cored 4" holes for Wiremold poke thur floor boxes. I also use it as a chipping gun. The company I work for has about 50 large hammer drills. A combination of Dewalt and Bosch. They used to buy Hilti but don't anymore. I believe the reason is price.
#43802 - 10/23/0412:19 PMRe: Hilti Ground Rod Driver
I use a 32oz cup full of water. I start the ground rod by simply pushing it as far as I can get it and still withdraw it. Withdraw the rod, fill the hole with water, replace the rod, and shove the rod down HARD, as far as it will go and still pull out partially. Pull up on the rod two feet or so, but not completely out this time. And repeat. Trickle water down the rod to wash off the resistance of the mud on the rod each time you pull the rod back up, enough to wash off the rod mostly, but no more is needed. The water also will run down into the ground along the rod, and as you shove the rod down again, the water provides hydraulic pressure by being compressed in the hole by the rod, and this shoves dirt out if the way.
If you've ever watched an older well drilling rig, they use the same method to drive a casing to some pretty good depths.
Of course, this works best in morain soils, since really sandy soils won't contain the water in the pounded hole long enough to create the pressure needed, and rocky soils will cause the same problems AND the rocks themself block the rod. Clay soils can be worked if you find some sand to help loosen the grip of the wet clay, but it's a job.
Now, there were a couple of inspectors who didn't like us "drilling" with water, but none could ever cite a Code violation. If you wait a while for the ground to drain, you can't pull the rod back out, so the one concern of a "loose ground" seems groundless!
#43803 - 10/23/0412:35 PMRe: Hilti Ground Rod Driver
I have tried using my rotary hammer to drive ground rods but it is too slow for me. I use a Bosch demolition hammer which works great. Hilti makes great tools but since it sound like you’re not going to be using this tool that frequently you might want to consider getting both a rotary hammer and 20-30lb demolition hammer from another manufacture for about the same price. I haven’t priced these tools recently but I would guess you could get the demolition hammer for around $800 and a decent rotary hammer for $400. The demolition hammer will work much better for the ground rods, breaking concrete and trenching with a clay spade. The large rotary hammers can do pretty well for all of these things but they are very heavy to use for drilling.