Drilling in rock-bit type?

[cwii]

I am trying to drill 5/16 holes in a rock wall for mounting conduit. Using a 1/2 in. hammer drill, tried a couple types of masonry bits but no luck. I get about 1/4inch deep and it is extremely slow. Any ideas on the type of bit or procedure I should be using?

Thanks,
Chuck

 

[Jeff Ivers]

What kind of rock is the wall made of? May need some type of diamond bit.

 

[cwii]

I don't know anything about rock or how to ID it, all I can say it is a dark red color and really tough to drill. It does seem to be fairly common in this area.(el paso tx)

 

[manwithtools]

Get a SDS drill and associated bits, way better than the typical hammer drill. You can probably rent for one time use. I'd buy a new bit though.

Since I got an SDS hammer drill, I now buy the non-hammer version of other drills as I think they drill more accurately. Just my opinion however...

 

[timgunn1962]

SDS drill is the way to go. They turn slowly, but hit much harder than an a conventional old-style hammer drill. The difference is almost unbelievable the first time you use one.

For 5/16 holes, any SDS drill will be fine. If you drill bricks, going for an overpowered SDS drill will tend to cause problems with knocking the back out of the brick when part-way through: a problem with brick-built houses here in the UK, but maybe less of a problem if that's not a construction method you encounter. I find anything over about 2J of impact energy is too much for brick, but for drilling bigger holes in concrete, more impact energy is good.

The cheapest import SDS will drill stone/brick/concrete much better than even the most expensive combi drill, so if you are not going to use it much, buy a cheap corded one under 2J.

 

[Copymutt]

I’ve had great success w/ diamond hole saw drills. Around $30.00 for your size @HD. Keep the water to em.

 

[LXCam]

Like mwt n timgun said. Go rent a sds hammer drill and buy a new bit. Anything else on stucco, brick and block is fine but on dense material is worthless.

 

[dcg9381]

Interesting. Drilling in limestone, A typical masonry bit and a hammer drill do it all day long...

 

[theoldwizard1]

Interesting. Drilling in limestone, A typical masonry bit and a hammer drill do it all day long...

Limestone is a fairly "soft" rock.

 

[nadogail]

I have found that Hilti brand drills and bits work best for me. My experience has been limited to drilling in concrete.

 

[cwii]

The SDS drill with new bit did the trick. I bought the least expensive one on Amazon and it drilled the holes very quickly. For a limited homeowner use it will probably be all I ever need.
ENEACRO 1-1/4 Inch SDS-Plus 12.5 Amp Heavy Duty Rotary Hammer Drill, Safety Clutch 3 Functions with Vibration Control Including Grease, Chisels and Dr.

Thanks

 

[50pascals]

Technically the SDS style drills are considered "rotary hammers." because they have an actual hammer mechanism, and generally drill through rock and concrete like butter.

Other hammer drills have a ratcheting mechanism. They can be frustrating just putting a hole for a moly anchor in concrete block!

 

[hefnerconstructionlc]

Squirt bottle with water. You may be overheating the bit. Drill and spray to cool the bit. Don't push to hard allow hammer action to work.

 

[mkef]

Technically the SDS style drills are considered "rotary hammers." because they have an actual hammer mechanism, and generally drill through rock and concrete like butter.

Other hammer drills have a ratcheting mechanism. They can be frustrating just putting a hole for a moly anchor in concrete block!

Not to mention the annoying sound haha. Sds+ all day

 

[CJDave]

Is there a difference between masonry bits and percussion bits? My 40+ year old Bosch Hornet 3/8" hammer drill is killer on concrete and brick and block. The Bosch bits that I bought with the hammer drill came in cardboard tubes. The lettering on the tubes is all worn away now but I recall them being labeled "percussion" not masonry. CJDave.

 

[kaymccampbell]

I use a HF rotary hammer with SDS bits. Goes through rock easily.

 

[Gummi Bear]

I have found that Hilti brand drills and bits work best for me. My experience has been limited to drilling in concrete.

Hilti makes terrific bits. We buy a bunch of them


If you don’t have a Hilti store nearby, for just a few holes, I like Bosch and Milwaukee bits pretty good in the smaller sizes (¾” and smaller)



I went to the woods because I wished to live deliberately...

Henry David Thoreau

 

[NUTTSGT]

The SDS drill with new bit did the trick. I bought the least expensive one on Amazon and it drilled the holes very quickly. For a limited homeowner use it will probably be all I ever need.
ENEACRO 1-1/4 Inch SDS-Plus 12.5 Amp Heavy Duty Rotary Hammer Drill, Safety Clutch 3 Functions with Vibration Control Including Grease, Chisels and Dr.

Thanks

So you got a new tool out of this project ? awesome