Ways to sharpen a core drill bit when no other method seems to work.
Though a Core drill bit is suppose to be self sharpening. If you are a core drill operator then you have been here.
You push, and push as hard as you can but the core drill bit just does not seem to be cutting.
Here is what we sometimes do with older core drill bits (in a pinch) to get them sharpened and cutting like new. We do NOT suggest using this method except as a last resort
A) Take a good roofing hammer and use the claw side of the hammer to gently tap the top edges of the core drill bit.
Don't beat the heck out of your core drill bit just a little tappping with the claw hammer end of the hammer will make your core drill bit cut faster through concrete or rebar.
try not to break off the teeth using this way of sharpening your core drill bit.
B) Use a hand held 4" grinder with a cutting rock to score the edges of the diamond teeth.
C) Last choice? Find a Way to roughen up the edges of your bit without bending or destroying your core drill bit is the gist of what you need to do.
One traditional way is to use good silcate sand and throw it in your concrete hole every once in while to deglaze the diamonds in the bit.
Turn the water supply all the way off and run the core drill bit dry for just a bit, then slowly add water. Repeat until the core drill bit starts cutting the concrete.
Onother traditional way is to use a concrete block (ie: also known as bessa block, besser block, cement block, etc.) and core drill through it several times and that will sharpen your core drill bit.
But honestly if your on a 25 story condo in the middle of even a mid size city, how many sand bags and concrete blocks do you expect to be laying around. A claw hammer or grinder may be
easier to find.
Questions you may have about sharpening core drill bits
If I break a tooth somehow can I still use the bit?
In most cases if its only one tooth lost on a bit 3" diameter and larger then yes, if more than one then maybe not
What is the theory behind a core drill bit being self sharpening?
Contrary to popular belief that the softer a material is then the easier it is to core drill. It actually works the other way.
A core drill bit sharpens by being slightly softer than the material that is being cored.
When used properly and the core drill bit grade matches the hardness of the material to be cored then the softer metal tubular casing wears away exposing new diamonds that in
turn cut the material which continues to wear (i.e.; grind?) away the soft metal to expose new diamonds to drill with.
Concrete core drilling with a diamond bit is the process of which one uses a
large high speed drill to drill Clean, Non-destructive holes in concrete. The drill bit used
to drill is hollow, which is where the core part comes in because
instead of a regular hole like you get with a solid steel drill bit the
center is left to be knocked out later after the desired core drilling depth is
reached.
10 inch core drill hole shown.
Core Drilling can be either wet or
dry.
Normally we in Charlotte, NC wet core drill most materials, and
use a SDS roatary hammer drill when dry drilling.
Wet core drilling involves using water as a cooling agent as the
core drill bit cuts a hole the material. Most core drill bits are
embedded with bits of diamonds (in the teeth of the bit only) for
cutting steel and other hard substances that may be in the
concrete, brick or block you are drilling.
