Hammerdrill vs demolition hammer questions

[jim_wilson]

My current project is running some conduits and a water line thru the foundation wall of my house to supply a detached garage I will be building in the spring. I rented a core drill with a 3" bit to drill the holes for the conduit and then I bought a 1" Bosch hammer drill bit for my Dewalt hammerdrill to put in the hole for the water line. Problem is that when I went to put the 1" hole in last night it was real bear to get the hole in - I ended up getting in about 5 inches or so (in an 8" wall) before it seemed like it just didn't want to go any more. A few weeks back I had the plumber here moving my gas meter from inside the house to outside the house - he had to drill a 1 1/4" hole for the iron pipe and he used a Hilti demolition hammer style drill. If I remember correctly it probably took him about 10 minutes to get thru the wall. The hammerdrill I am using is a Dewalt 1/2" drill/hammerdrill. I have had this problem before drilling other holes in concrete - it just seems like the Dewalt doesn't cut it for some reason. So my question(s) are - what makes a demolition hammer different from a hammerdrill? And if I was looking to buy one what should I look for? I did some quick searching on different products and noticed there are demolition hammers (mucho $$) and then there are cheaper demo hammer / drills. I could also rent something locally just to get this job done but I know I will have other uses for one in the future and am trying to weigh buying vs renting also.

 

[timb]

Hammer drills like yours (I have a similar Milwaukee) with a good bit are great for the occasional anchor hole or small pass through hole in concrete or block but they don't do the job of the big Hilti's. I think the major difference is in rate (hammers/second) and stroke length. Worst job I've done with mine was drilling around 100-150 consectutive and adjacent 3/8" holes through 2-3" concrete to break out a section of floor where I couldn't fit a saw into that location. Drill was pretty warm after that workout. A 1" hole is a pretty big hole for a hammerdrill to tackle.

 

[Freds]

The Hilti rep told me that a Hilti hammer drill is the only hammer drill with a true hammering action. I didn't get into the technical aspect at the time, but they sure do drill a hole in concrete easier than any of the other brands I've used (Bosch, Metabo, Hornet...). I would venture a guess that a demo hammer drill, what we always called a macho, has this "true" hammering action, also.
I would get the best one you can afford. They come in handy for breaking out concrete pads and all kinds of stuff. Compare the price and availabilty of the bits too. The last one I purchased was a Bosch. It had a nice amp to weight ratio.

 

[jim_wilson]

I am pretty up on most tools but demolition hammers are one thing I know pretty much nothing about. I know the name Hilti simply because it is what I see all the contractors using. Bosch seems to be popular in that they are available a number of places. Bosch makes good tools in my experience but if you had to choose would you go with a Bosch or a Hilti? I checked the Hilti website and am going to try and find a dealer in my area.

 

[Freds]

Hilti is definitely the Cadillac, but the money you'll save buying a comparable Bosch you can pick up a few extra bits. I had to choose spending someone else's money and went with a Bosch, plus the bits are more readily available if you run into a situation where you need one that day, at least where I live. You'll see lots of contractors with Dewalt, too...
I expect any name brand macho you get will last a DIY homeowner many generations. Look for the best kit at the best price.

 

[GaryM]

There's a difference between "hammer drills" and "rotary hammers".

Hammer drills, and I've owned several, just rotate and vibrate at the same time. Not too bad for light work.

A rotary hammer, like the Hilti or Bosch, there are others too, actually drive the bit with a electro-pneumatic impact unit, and of course rotate at the same time.

All the good units will take the spline drive bits. They won't have a regular drill chuck. Of couse you can get an adapter chuck for use with regular drill bits so you don't have to carry two tools if you need to drill into wood or steel rather than masonary.

I have a Bosch 7/8" SDS rotary hammer and it does a fine job. I can drill a 3/4" hole trough a normal foundation in a few minutes.

For anything bigger, hit the rental yard.

 

[turnkey4099]

Having been down the 'drill concrete' route several times I learned my lesson. Hammer drills (used both 3/8 and 1/2") aren't worth spit when doing that job. Cost of a real rotary hammer is too steep for occasional use. My solution is to make the 30 mile round trip and rent one. Cost is reasonable, goes through hard concrete like butter and hitting agregate doesn't stop it.

Harry K

 

[jim_wilson]

Sounds like I am looking for a rotary hammer. I have the Dewalt 1/2" hammer drill and that does work pretty good for smaller holes in concrete - apparently 1" is too much for it though.

I stopped at Home Depot this morning and they have a 1 7/8" Bosch rotary hammer unit that looks like what I would need. It takes SDS Max splined bits and can take other tools like chisels and points. I already have the Dewalt if I need something with a chuck so the spline only is fine.

Another question - is "SDS Max" some type of industry standard? I looked at the BoschTools site and the Dewalt website and they both list rotary hammers as being SDS Max compatible. Drilling a hole in " a few minutes" would be what I am looking for - my hand is still hurting from the hour and a half I spent on the Dewalt last night.

If Hilti is the Cadillac is Bosch at least pretty good? The Bosch stuff seems pretty easy to get - Home Depot and a number of other places carry them and the bits. The Hilti stuff appears harder to get - but if Hilti makes units that are "SDS Max" then I would consider a Hilti hammer and still be able to use commonly available bits.

 

[Freds]

One thing nice about Hilti is the local rep. They have a guy around here that drives a van with various stuff in it. I knew him from my former job, but it's not like the company I worked for was purchasing a lot of Hilti tools or fasteners.... still, when I bought 1000 shot and nails from him for a remodeling project I had, he let me use the powder accuated gun. If a tool breaks down he will let you use a loaner until it gets fixed, but he can fix some tools himself. You may want to call Hilti just to see if you can strike up any kind of deal with them. Nowadays it seems like "contractor only" is a thing of the past. It's also nice having the stuff delivered.

 

[GaryM]

I have the Bosch 7/8" Rotary Hammer. I believe the hole size is limited to 7/8". Not sure they make a 1 7/8",. Need to look at their website or Amazon Tools. My 7/8" was about $160 or so if I'm remembering correctly. I belive this is it SDS Rotary Hammer

The SDS is the type of bit holder(chuck). You can get points and chisels as you mentioned. I used mine with a point a while back to break up some concrete muffins left by the concrete truck.