w/t on masonry drill bits

amakarevic

i got some expensive masonry drill bit set, supposedly german-made, called MEGA. i was just drilling some holes for anchors in my 100-yr old foundation (many pebbles), heavy drilling. however, i did not expect to wear the bit down all the way through the tread and it got so hot that the tip was literally GLOWING RED. i did keep drilling about 15 min non-stop.

is this a crappy bit or was i working it too hard ?

Ron6519

When I drill through exceptionally hard concrete I will spray water on the bit to keep it cool and reduce the pressure a bit. Are you using a hammer drill? These are much better for drilling into concrete. I use Bosch bits, and on occasion have destroyed the tips. It happens.
Ron

Sammy

Not familiar with that brand but most will get hot.

We use carbide bits for punchin holes in safe doors and most bits will come out looking pretty mangled.

Most of the time you can resharpen them on a green wheel grinder and get some more life out of them.

Hammer drill does make it easier when going thru crete..

Remember when drilling in somethig hard like that, bits are expendable.

terri_and_jj

100 year old concrete is going to be HARD, and if lots of aggregate (stones) you will really need to hammer drill for large holes.

does the bit you are talking about look like a standard steel drill bit ( slow spiral) or does it have lots of flutes ( fast spiral)? Fast spiral are made for light duty stuff, like brick and block. slow spiral are better for concrete, but you are going to wear these out on old, stone filled concrete like you are decribing. i wouldn't waste my time with these on holes larger than 1/4"

you can get carbide tipped ones for a non-hammer drill, this might work better if the ones you have aren't carbide tipped

wire_twister

If you use water on them, use it from the start, if you get the bit hot then spray the carbide with water it could fracture.

__________________
Jimmy

Life is tough, Life is tougher when you are stupid.

amakarevic

absolutely.

terri_and_jj

since you are using a hammer drill, you might want to make sure that the bits are in fact hammer bits. did the package specify "hammer" or "percussion" on them? if not, this could very well be the problem!!!

if they are percussion bits make sure your drill is set to the hammer drill setting (the one with the pict of the drill bit AND the hammer) and DON'T put a lot of force on the drill when drilling, let the tool do the work. Don't mean to insult you, but I've talked to a lot of people who don't know this

Chris Johnson

What size hole are you drilling, and how many?

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Chris

amakarevic

7/16 bores * maybe 2-3 in deep. was drilling about 4 at a time non-stop before the incident, now i rest after each bore.

thanks,

- a -

Chris Johnson

If this is a one shot deal for you, and if you have a Harbor Frieght near you (I don't recommend their tools by the way) but if it is for only a bit of household work, they sell a SDS plus drill, $ 49.00, and the bits, you will have more success with this as opposed to what you are doing.

One of my guys was proud to show me the tool he bought one day, 250 holes later it died. That is why I don't recommend their tools for professional use, but for DIY once in a while I am sure it is fine

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Chris

terri_and_jj

you could probably rent a nice Bosch or Hilti SDS hammer for about $15 a day

End Grain

I have a compact corded Bosch hammer drill that I use with SDS bits and I have no problem whatsoever drilling into concrete or stone. At times, its drilling capabilities astound me. Totally effortless.

FWIW, using a cordless impact drill with masonry bits - no matter how good or expensive they may be - to drill into concrete is a waste of time and drill bits. Not enough ooomph or constant speed and BPM's to get the job done. For those reasons, I never regretted selling my DeWalt 18V impact drill or buying my corded Bosch to replace it.

But everyone's different and some may have good success with cordless impact drills.