School me on Hammer-Drills / Roto-Hammers

Need to drill some holes in concrete (to mount my bender), and I figured on installing a few extra holes, in a few alternate locations, in case I want to move the bender. Never know what'll be in the garage, so versitility is a benefit.

Anyhow, since I couldn't find one to borrow, my options are either
A) Rent one
B) Buy new
C) Buy used from sources like Craigslist.

However there seems to be a huge difference in values on Hammer Drills, from what I can observe. So, those who've used these tools post up some ideas about what to look for. I've noticed both corded and cordless versions, some with brand names I'm familiar with, others I've never heard.

So school me on drilling holes in concrete! Need to drill a dozen or twenty holes, about 7/8ths diameter.

Ive used both Bosche and Milwaukee corded ones. Both worked great. 7/8 is a serious concrete anchor! Ive done 1" with the milwaukee and it wasnt anything difficult. If your're just mounting a bender stand id just use 3/8" or 1/2" anchors but thats up to you.

You need a roto-hammer, not a "hammer drill". Hammer drills are things like an 18V Dewalt cordless that has a hammer setting to do small holes in masonry or the like.

A Roto-Hammer is like a Bocsh, Makita or Hilti special purpose tool specifically designed for drilling holes in concrete and other hard surfaces. Same hammer and rotation as a hammer drill, but more powerful and better at the job.

The most common (and cheapest) roto-hammer is the smaller "7/8" ones, Bocsh Bulldog is a very common and popular model. They say they are good to 7/8" diameter, but really up to 1/2" with any regularity. For a 7/8" I'd go up a size. Bigger tool, better at the job.

Easiest is to just rent one from HomeDepot or the like, with the correct sized bit. Have everything laid out and ready, pick it up, drill your holes and get it back in the 4-hr minimum.

For anchors, sounds like you already have them in mind but get the "drop-in and set" kind. Not as cheap and you'll have to get a setting tool as well, but will leave you a nice, flush floor. Over time they will fill up with dust and crap, but just use a screwdriver and shop vac, then shop air to blow them out.

Where are you located?

mark said:

For anchors, sounds like you already have them in mind but get the "drop-in and set" kind. Not as cheap and you'll have to get a setting tool as well, but will leave you a nice, flush floor. Over time they will fill up with dust and crap, but just use a screwdriver and shop vac, then shop air to blow them out.

Where are you located?

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Bremerton, Gig Harbor area.

I've already bought the "drop in and set" anchors, and I bought 5/8ths threaded, full stainless anchors (as I'm intending to use pressure washer to keep floor clean). These anchors use a 7/8ths hole and are set at 2" depth. I'm also going to install allen headed set screws to keep debris out of the holes.

Thanks for the clarification on roto-hammers -v- hammer-drills. That's the knowledge I'm lacking.

Tony, Buy the 7/8s SDS type bit and you can borrow my large roto hammer or I can come out on tuesday or wed eveing and do it for you.

Don't know where you are, but I'm in Burien, if you would like to borrow mine.. You would need to buy a bit for it. Probably thru Grainger. Its a Hitachi DH 40 FR.

pokey said:

Tony, Buy the 7/8s SDS type bit and you can borrow my large roto hammer or I can come out on tuesday or wed eveing and do it for you.

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Jim,

does yours take "SDS" or SDS-Max ??

Strait SDS is the small bit, SDS-Max seems to be the standard for the "Big" hammers. He'll need to know that.

mark said:

Jim,

does yours take "SDS" or SDS-Max ??

Strait SDS is the small bit, SDS-Max seems to be the standard for the "Big" hammers. He'll need to know that.

Click to expand...

SDS, I have bits up to 3/4 but havent had a need to go bigger so I dont know if theres a sds bit in 7/8. I also have a adapter to use a tapered bit so that might be a option.

Lowes doesn't have bits that big. I'll look at Tacoma Screw tomorrow.

I have a Bosch SDS roto-hammer and a 3/4" sds bit. You can get different anchors and use what I have, or get a bit and borrow my hammer. I am in Steilacoom.

TreeClimber said:

Lowes doesn't have bits that big. I'll look at Tacoma Screw tomorrow.

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I picked one up at HD this morning. Tried your cell but no answer and no damned voice mail either :looser: Give me a call.

pokey said:

I picked one up at HD this morning. Tried your cell but no answer and no damned voice mail either :looser: Give me a call.

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See you tomorrow.

personally I would buy a used one that seems to not have been ran hard. you really have to beat on a rotohammer to kill it. I have one of the smaller bosch rotohammers and have put large bits on it and just leaned on it until it was super hot a bunch of times. If you watch craigslist for a bit to figure out what rotohammers go for you can buy one then sell it for the same money if you find yourself never using it.

the other option is to buy diamond holesaws and you can run those in a regular power drill although they may not go deep enough. they should be enough for wedge anchors or allthread/epoxy though.

i've used bosch, milwaukee, makita, dewalt and metabo in corded and cordless varieties, all very good units. IMO if you aren't going to use it much but do want to buy it, go corded, that way you don't have to worry about batteries goin tits up.