Hammer drill for drilling in concrete
I’ve got about six 5/8″ holes to drill in the foundation of my garage so I can add some hold downs, as well as redoing some mudsill ties.
After completing one hole, I’ve apparently discovered the aggregate stones are actually industrial diamonds… OK, maybe that is a slight exaggeration.
I hoped to go cheap and easy with my initial buy (I don’t drill a lot of rock). I got the Ryobi 18v cordless hammer drill (to go with the rest of my set) and a Vermont masonry bit. Three battery packs to get one hole 4.5″ deep. Back to the store for a better hammerdrill. I picked up the Rigid – 9 amps, more BPM than the competition, lots of adjustability. But on my second hole I hit a rock that I just can’t seem to drill though. After about 30 minutes of drilling – stopping periodically to cool the bit, stopping again to go buy a Bosch Blue Granite bit because the first one chipped on the rock. Even the new bit is going sideways rather than down into the rock.
Do I just have the wrong tools for the job here? Would a different hammerdrill or bit go though this better, or do I just have unreasonable expectations. An hour of drilling per hole seems excessive.
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Replies
Rotary Hammer. I have a hilti and the difference between it and a hammer drill is nite and day. Ask how to use it. You push hard enough to engage the bit, you don't put your back into it. Let the bit and tool do the work.
Rent it along with the bit.
You may have hit a pc of rebar which you won't drill through with a mas. bit.
A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
Quittin' Time
I thought it might be rebar too, but it is close enough to the surface I could get a look. No shine, just a lead like blue grey stone.
Rotary hammer, eh? OK, looks like I'm off to Harbor Freight tomorrow morning. I just hope it is thin enough to fit beween the stucco wall intrusion and where I need to drill the hole.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Discussed a lot in the past.
Did a similar query 2 years ago for needing to drill 50 9 inch deep 3/4 holes in a 4000 psi concrete pad at the Haleakala peak observatory.
bought the recommended Bosch at the time, a coworker actually went to Maui to drillthe holes and do the install of equipment. He's a 6'6' 220# guy, compalined about the drill overheating. Another board member in a follow on thread (cannot recall who, live in the rockies) commented that it overheated not due to the 10,000 ft altitude but to the operator -- pay attention to the previous post on pressure!.
This summer got a Bosch 611 with a 3/4" bit at a garage sale for a really good price and (beat up but working, engraved iden of the seller, so no, to you garage sale phobics, it was not stolen goods). My oh my, does that baby drill holes, did a 3/4" dia 8" hole thru the foundation for a copper water pipe in less than one minute.
Reminded me of "how dumb I am' for not having similar ephimamuy years ago. (aka, so dumb manual used a car lug wrench vs. air impact up till early 80's!
Thanks for the reminder about pressure. After 15 minutes of no forward progress, I figured I wasn't helping that bit get enough bite! I will be careful with the rotary hammer.
Say, what is a 1/2" hammer drill good for anyway? Does it top out at 1/4" holes or what?Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Say, what is a 1/2" hammer drill good for anyway? Does it top out at 1/4" holes or what?
Lots of stuff!
Drilling Tapcon holes is what I use my hammer drills for the most and I've done way too many of those.
For whatever the reason I bought a 24V DeWalt hammer drill a number of years back and it's come in very handy many times especially when the AC power is a long way off. It sure beats unrolling a 100' cord. Heck, I even use it in low gear to mix up small batches of Durabond. Even in low it spins a little too fast for that but still works OK.
They'll also shake your fillings loose pretty nicely as well if that's ever needed.
Yeah, for efficiency and much less strain I use my rotary hammer for anything over 1/4" in concrete. IIRC many 1/2" HD's have a max recommened 1/2" for concrete.But it is better to fail in originality than to succeed in imitation. - Herman Melville
I have two of them and they will throw you off a ladder. I usually grab the Bosch Bulldog to drill concrete though. For just a few holes that would require a a cord I grab one of the 24v's. The reason I have two is I thought the transmission had shelled out on the first one and bought a brand new shelf model for $100 instead of having the other one fixed. Turns out it was really ok.
I have the Milwaukee 18V hammer drill and no, it doesn't top out at 1/4". The SRS would definitely get the job done, but if the holes are as shallow as what is being drilled in this case, going in with a thin rod, then hitting it with a hammer should fracture the stone. If it's a rebar, the stone dust may be obscuring any shine that would normally be seen. If a magnetic pickup tool is inserted, metal shavings will come out if it's steel or iron.
"I cut this piece four times and it's still too short."
Paul, get yourself a Bosch Bulldog & you won't look back.
SDS is a whole nuther deal.
Joe H
While i would love to get a top name brand tool for this, I really can't justify spending over $200 for a tool I'll only need for 5 holes this year. $30 daily rental is OK too (for a Makita), but bang for the buck it looks like the junk tool from Harbor Freight wins this round. Less than $80 buys a 1" rotary hammer plus some bits. Granded, it may only drill a lifetime of 100 holes... but then again I may only need to drill 25 with it!
Thanks everyone for giving me some clarity on this!Rebuilding my home in Cypress, CA
Also a CRX fanatic!
I have a 12 YO Mil hammer drill and, about 2 years ago got a Hitachi rotary hammer. Since I got the rotary hammer I have never used the hammer drill to drill concrete/masonry. It's just not an option if you have a choice.
Since I got the rotary hammer I have never used the hammer drill to drill concrete/masonry.
Same here, except I bought a Hilti. Felt a little guilty when I sold my Bosch hammerdrill for $25 at a yard sale. At least I threw in all the crappy bits. After all the trouble I had drilling hundreds of Tapcon holes in our concrete house, I could hardly believe the ease of a rotary hammer. And how long the bits last.PAHS Designer/Builder- Bury it!
If thats all you got to drill and you dont really need the tool. Go rent a good rotary hammer. I think the HD has one for rent. A lot cheaper than buying one and having it sit around for ever.
Yes, it is a pretty close call either way... for something you will use rarely: rent a good tool or buy a crappy one? Since I never know when I will have uninterupted time, I think buying this one will be better. Plus it's not too big to store.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Paul,Sancho is right, you know. Drill your 5 holes quickly with a good tool and bit, then return them and save $50. Bonus is you don't have to store the thing, and it can't be stolen from you after you return it.Bill
the7/8" are going for about $199 at HD now. They are replacing them with this one:
View Image
11255VSR
BULLDOG Xtreme™ 1" SDS-plus¯ Rotary Hammer
The 7/8 have worked great when I rented them in the past. Hoping to catch one on clearance sale soon.
"All men's miseries derive from not being able to sit in a quiet room alone." Pascal
Well, after taking back the two hammer drills that I had previously purchased, I realized that to keep the $100 off I got for opening a comercial accout I would HAVE to buy the new rotary hammer there.
So the Bulldog Extreme it was! Just used it for two holes... it workes just like I expected it to - Thanks for the tips everyone!Rebuilding my home in Cypress, CA
Also a CRX fanatic!
It's a bargain in the long run.
Congrats!
"All men's miseries derive from not being able to sit in a quiet room alone." Pascal
I think you're probably better off to own than rent. As you work on your house, you'll discover surprises. I'd be surprised if the rotary hammer never helps solve any of those problems.
-- J.S.
Bosch 11203 (my sweet little chipping hammer). Takes standard splined bits (I like Makita bits) for drilling mode, and is a nice mini-jackhammer when you need it. I just drilled six holes (5/8 x 3 inches deep) in a block of New Hampshire granite for lag shields. Took about a minute per hole. I haven't seen a VA bit yet that can drill though much more than brick or a mortar joint. One little piece of quartz or steel and it's toast. Usually they heat up after about 30 seconds on something hard then one of the carbide inserts fall into the hole. Try drilling through one of those buggers!
I've been interested in the bosch line and went to Lowes today to check them out. They carry the #11224VSR 7/8" 6.9amp., the Bulldog Extreme 11255 1" 7.2 amp., and the #11236VS 1 1/8" 7.5 amp. which has the motor 90 degrees to the shaft and looks to be heavier duty.
In checking the Bosch site I found that the "optimal" drill size for each tool is about 1/4' dia. less than the stated size. I want to drill some rocks for anchor rings for a dock and think I'll want at least 3/4" .
Is the 1 1/8" #11236VS a lot more rugged? Slower rpm (0 - 850) so I assume it's geared lower.
Worth the extra $80?
pros? cons?
Thanks
oldfred
Oldfred,I have not used the 11236, but in general the bigger the diameter rating, the slower the rotational speed, and the hits are both less frequent and harder to fracture bigger chunks of what you are drilling. For what you propose, the bigger tool is worth the extra $80. The motor at 90 degrees to the spindle shaft makes for a more compact, easier handling tool. I have a D-handled Bulldog, and it is annoying how long that tool is. Hilti makes even nicer rotohammers, but mucho bucks.Bill
Bill,
Thanks for the reply. The 1 1/8" 11236vs is just about as long as the Bulldog but may be balanced better - don't know. I'd consider the Hilti but this is already a stretch in price.
I have the 11236, it's nice for working in the crawl space because the motor is set 90 degrees to the working axis, making it shorter. For 3/4" holes, it'll do OK. I ended up having to pop for a Bosch 11245 for larger holes, like 2 1/2", but it gets inconveniently long, over 4 ft. with that size Relton bit. Now I grab the big one when it'll fit and the little one or the Milwaukee Hole Hawg when access dictates the choice.
-- J.S.
Actually, I'll use it more for setting lags in brick and concrete walls and just now and then the rock work. Just don't want to burn it out when I do the occaisional rock. Might even make sense to buy the 1" bulldog and rent the heavier one when I need it.
Don't know if you saw this on JLC or not. They had a good article on Combi-hammers. These are bigger than the bulldog.
They highly recommended the Hitachi:
Hitachi DH40MR View Image Rpm: 240-480 Blows per minute: 1,320-2,650 Maximum impact energy: 7.4 foot-pounds Weight (with handle but no cord): 16 pounds Street price: $449 Hitachi Power Tools, 800/829-4752, http://www.hitachipowertools.com Pro: The DH40MR is simple and compact, and drills faster than any other model. It's quiet, smooth-running, and less expensive than most hammers in this category. The side handle is very rigid because it's attached with a steel bracket. Con: This tool lacks a service indicator light, and theall-metal housing makes it heavier than other 1 9/16-inch hammers.
http://www.jlconline.com/cgi-bin/jlconline.storefront/4398994f001b069627177f000001056f/UserTemplate/82?s=4398994f001b069627177f000001056f&c=4a4a6b19e40e8e50ac564ae5f220364a&p=1"All men's miseries derive from not being able to sit in a quiet room alone." Pascal
5/8 diamond core cutting bit and some water?
don't use in hammer mode. should cut thru steel ( slowly ) and even the hardest stone.
james
Just because it doesn't look like rebar doesn't mean it isn't. Stick a magnet down in there and see for sure if it is rock or steel.
I was just thinking to myself today, as I used my Milwaukee 3/4" Falcon Rotary Hammer to drill another of the thousands (literally) of holes I've drilled with it, what an amazing old workhorse it has been. I've had it for around 9 or 10 years, it has been in the shop once, and makes me smile as much today as it did the day I bought it to replace a worthless #^%&@*!! Dewalt. I gave away both of my Ramsets many years ago, and I used my Falcon and TapCons anytime I need to fasten to concrete. Even with anchor bolts, I like to use the TapComs to pull it down tight on the adhesive.
Allen in Boulder Creek
I have the Bosch bulldog but the Hilti is very nice. You need a rotary hammer, not a hammer drill.
As someone once said on this forum "A rotary hammer is for drilling holes in concrete and a hammer drill is for playing jokes on your helper." great quote.
Billy
Yep, I gotta say I felt like the butt of something!Rebuilding my home in Cypress, CA
Also a CRX fanatic!
I've got the Harbor Freight SDS rotary hammer that I bought for $69 a couple years ago. Has worked fine for the occasional use I've given it. Would get a name brand if I was using it all the time.
As suggested, if you can do them all at the same time (should only take a couple minutes per hole), then renting a good unit for a few hours is probably the way to go.
Don