Drill bits

tusker

Well-Known Member
Hi guys, can any one recommend a drill bit that will drill carbon steel. I am having trouble finding one and have ruined 3 bits this weekend.
Thanks, Tusker
 

hybridfiat

Well-Known Member
Depends how big and how deep you want to go. I used to do a lot of scope mounts, occasionally a hardened receiver or slide would cause problems. I bought straight flute tungsten bits from Brownells (expensive) and away I went. Another way is to spot soften the area to be drilled using a fine tip oxy torch and lots of heat sink where you don't want the heat to go. Is the area case hardened or tough all the way?
 

Loki

Well-Known Member
Hi
I would suggest a flick through a Screwfix catalogue - they have a range of drill bits for different materials including ones to last longer.
Cheers
L
 
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lochty

Well-Known Member
You might want to try some cutting fluid as well, something like Rocol will help to take some of the heat away from the drill. Never mind the smoke, it does that ;)
 

Legolas

Well-Known Member
Agreed on the cobalt drill bits. I bought a load of cobalt bits from this place http://www.ukdrills.com/ for a project recently. They are good value and easy to deal with. Do tick the no emails box if you do use them though, they are very keen about letting you know of their latset offers!!
 

tusker

Well-Known Member
Depends how big and how deep you want to go. I used to do a lot of scope mounts, occasionally a hardened receiver or slide would cause problems. I bought straight flute tungsten bits from Brownells (expensive) and away I went. Another way is to spot soften the area to be drilled using a fine tip oxy torch and lots of heat sink where you don't want the heat to go. Is the area case hardened or tough all the way?
3-5 mil wide and no more than 4 mil deep. Its for my knife making and the steel is hard all the way through.
Tusker
 

Whitebeard

Well-Known Member
Any decent make HSS drill should do the job, the key is to keep your RPM low, the commonest killer of drills in the workshop is to much RPM.

Ian.
 

Hornet 6

Well-Known Member
Any decent make HSS drill should do the job, the key is to keep your RPM low, the commonest killer of drills in the workshop is to much RPM.

Ian.
As above, also note if you get high carbon steel too hot while drilling you will spot harden it.
If the steel is already hardened then probably best to let the area to be drilled down by spot
heat treating.
If you really must make a hole in hardened steel then find a local engineering shop with a spark eroder.

Neil. :)
 

bewsher500

Well-Known Member
I find cobalt drills crap personally, or at least the ones I had (pretty sure the type I had were bosch and Piranha)

Tungsten Carbide bits I have in both drill and die grinder are awesome
cut through most things like chocolate
will work at higher rpm too

if using low speed HSS then cutting oil is an absolute must
 

ejg

Well-Known Member
At a push one can re-shape a masonry Tungsten tipped drill to cut hardened steel. Cheap too. To shape a diamond grinding disk is an advantage.

edi
 
Have drilled cultivating discs in past by spot softening them using a broken drill/nail. Loads of speed, loads of pressure and get it blue. Let it cool slowly and then drill the soft spot you made.
 

CCB

Well-Known Member
Presto bits for me, Simple! old school! pay attention to the speed and dont over heat the drills! try and make use of a pillar drill where possible! :thumb:
 

hybridfiat

Well-Known Member
I second the masonry bit idea. I'd forgotten that one. You may have to resharpen an couple of times but they do work. Heat will not be your friend when drilling hardening steel.
Use a diamond file or hone.
 

Muir

Well-Known Member
The big problem with most drill bits you buy at hardware stores is that while they are sharp, they had the edge in what amounts to the wrong place. The cutting geometry is wrong to do much more than make a dent in the metal before burning up: In other words, the sharp edge doesn't make correct contact with the metal being cut. Also, they are often unevenly ground which causes tolerance issues. Buy drills from industrial machinery supply houses and you get a better product.

As to cutting oils, a good and inexpensive general cutting lube is 50/50 lard oil and kerosene. It's an old time thing but I used it one afternoon then I ran out of commercial Boe-Lube (Used for drilling titanium) and was very pleased with the results. Don't drill dry, lube, and keep pressure on the cutting edge lest you burn it off.~Muir
 

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