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I recently purchased the XtremepowerUS 2200Watt Heavy Duty Electric Demolition Jack hammer Concrete Breaker. With it I am trying to punch a hole through the concrete to replace an iron shower drain with a PVC one.

It's amazingly hard work, so much so I think I am doing it wrong. Most of the videos about how to use a jack hammer, involve breaking up slab by attacking it from one side and working to the other. They don't talk about punching a hole through the foundation. This tool comes with 16" bull point chisel and a 16" flat chisel. The flat chisel made it really easy to chip the top of the concrete into an almost perfect square by digging holes first and then going back and fracturing around them. But now it's really hard to actually dig with the demolition hammer. My concrete foundation has rocks in it. Is there anyway to make actually getting to the grade easier. I've spend 5 hours on this and I'm probably 10 inches down near the drain and I still haven't hit the dirt.

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    Hint 1: do not push on it, let it freely vibrate. Drill holes all the way few inches appart, that will weaken the concrete.
    – Traveler
    Jun 25, 2023 at 4:59
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    Step 0: recognize that a "real" jackhammer is typically powered by a large diesel engine driving a huge air compressor. Step 1: recognize that a device which claims it's 2200 Watt while having an input of 15A at 115 V (so, 1725W at 100% efficiency, and it's not 100% efficient) is lying to you.
    – Ecnerwal
    Jun 25, 2023 at 11:22
  • Consider renting a bigger hammer from a tool rental place...
    – FreeMan
    Jul 3, 2023 at 14:34

4 Answers 4

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If you have a suitable masonry drill, I would suggest drilling a pattern of holes. It's easier to break out chunks between holes than to break chunks out of an unblemished solid.

Rocks are a normal part of concrete, which is a mixture of cement and aggregate, where "aggregate" is a blend of rocks and sand, or various sizes of rock and crushed rock, depending on locale.

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    And depending on the size of the hole needed, the OP might be better off just using a concrete saw.
    – Huesmann
    Jun 25, 2023 at 13:08
  • Those are difficult to use when the hole you have made is 10 inches down, unless it's a very large hole.
    – Ecnerwal
    Jun 25, 2023 at 15:15
  • Like I said, depending on the side of the hole needed...
    – Huesmann
    Jun 26, 2023 at 11:23
  • I tried this, I'm not sure what happened there but even with the holes a mere couple of inches apart my demo hammer wasn't enough to break this concrete. This concrete is just incredibly strong. Nothing like any video I've seen online. I just don't understand why this is so difficult to break through a 10+ inch slab of concrete with rocks. I drilled holes. I put my demo hammer next to the hole it slipped into the hole, I like it rattle around in the hole until it got stuck in the hole. Then I did the same thing 3 more times. Total waste of an hour. Jul 2, 2023 at 23:16
  • Hard work incoming: with the hammer at about a 45° angle, slip the tip into a hole and hammer at the side of the hole. This will break up the "web" left between the holes. You may have to repeat this action on every hole, and you may have to pause (your body will thank you), once you've reached the bottom of the holes to drill them deeper.
    – FreeMan
    Jul 3, 2023 at 14:32
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That jack hammer doesn't look great for the job - at $150 you get what you pay for.

I have a bosch brute 65# demo hammer - $2k. The weight helps it get through concrete.

A 10" thick slab is crazy. I've used the 65# to break through 1960 8" concrete wall. I also have a 21# dewalt jack hammer $1k which is closer to what you have. I'll only use it for vertical work where I can't dolly the 65# one around. An hour on the 21# hammer is about 5 minutes on the 65# hammer. I've also used the 65# hammer to break a bolder apart ( tried drilling but kept breaking the carbide teeth - rock was hard ! ).

I also have the Makita HR4013C 1 9/16" SDS Max Rotary Hammer - load that thing up with a 2" quad cutting bit and it plows through concrete. The nice thing about the rotary hammer is the bit doesn't get stuck and you don't have to man handle it.

Now if all I had was that thing and I was intent on doing the job then I'd use the flat chisel to create a line in the concrete and I'd use the jackhammer on an angle and keep making the line deeper focusing on not getting the bit stuck. Once you are down a little bit I'd move an inch to the side and break the edge into the line (making the line wider) before making it too deep and getting my bit stuck. If you get the bit stuck a sledge hammer can help free it or you put in another bit and make a relief hole beside it (again focusing on not getting it stuck). 10" is quite thick so you'll be working on this for hours. You can still get the bits stuck on the larger jack hammers though so you need to work on the technique of not getting them stuck.

The other affordable option is to get a diamond blade and a 7 1/4" circ saw. You can then cut kerf lines, 2-3" apart into the concrete in a row that are ~3" deep. Do several of these cuts and then use the jack hammer to help clear out the areas between the kerf lines.

Good luck !

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The problem is not your demo hammer, but that concrete that thick is not going to give way from the top, as it's being supported by more concrete from all sides.

You have two alternatives:

  1. Use a 1" masonry bit and make a hole that goes all the way through the concrete, then use your demo hammer to chip away, towards the inside of the hole. You might have to clean the hole several times, to make space for new chips to fall in. Once you enlarge the hole, you keep chipping towards the hole.
  2. Use small masonry bits (say 1/4") and drill many holes outlining the outside perimeter of the hole you are trying to make. It's going to be a lot of holes and it will take a really long time. Then hit the center with a sledge hammer.
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Future readers might perhaps take into consideration to rent a diamond core drill.

Fast, quieter than a jackhammer, gentle to the foundation, dust free (the watercooled one)

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