Recommendation? Carbide drill bit

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AbLonewolf

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Jan 30, 2020
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How well do carbide (glass/ceramic) drill bits work on hardened steel?

If they do, recommended drill press speed?

Thanx
 
Some masonry bits work but not all, home depot brand wouldn't drill 61rc D2, bosch made it 2 holes and lost the carbide, Irwin made it 28 holes, and still seems like it has some life. the Irwin are cheap and will eventually break buy 2 or 3. I run them like 1000 rpm but honestly, I am just too lazy to change speeds. I have no idea what the ideal speed for a masonry bit on hard steel is, I would assume high rpms.

How well do they work? lol, they will make a hole but that's about it. Not very fun.
 
I've never tried those carbide tipped drills, but a full carbide drill bit goes through hardened steel like a hot knife through butter. Worth paying more for one or 2 in your most common sizes. Think of them like concrete though, they do well with slow steady pressure, but not sudden impact or chattering, so they need to be used firmly locked in place in a drill press (ideally a full size mill) and run at high RPM.
 
All the questions here on carbide drills, i thought people were so stupid for not just drilling first.

But then I did it too.
It's easy to do.

Solid carbide spade bit drills do work like a charm.
Stupid expensive here in Canada because shipping, import and exchange easily double the price of everything.

They are brittle, have the work clamped, or any movement will break a carbide drill.
(waiting 4 weeks for a $40 drill, then breaking it in the first hour)

If you're drilling a letter or number size for pin clearance, you won't find them easily or cheaply
go standard size and clearance with a carbide burr, or dremel stone, or abrasive cloth on a stick in a drill.



Carbide tipped masonry drills have the carbide soldered in but the grind is not for steel.
You can sharpen them in a Drill Dr - diamond wheel.
Keep the speed down.
If you generate enough heat the soldered tips come out.
(but that's idgaf red hot heat)



Carbide scrap pays well, so it may be hard to get for free; but broken carbide endmills still drill a hole in blade steel as is
If you know someone with a D bit grinder - you can get a D bit ground out of the shank end.

Even paying for a new one is cheaper than the drills.



Carbide burrs don't shatter like a drill does.
 
AbLonewolf said:
How well do carbide (glass/ceramic) drill bits work on hardened steel?

If they do, recommended drill press speed?

Thanx
Click to expand...
I just drilled this hole in hardened T3 HSS steel, 3mm ...............800 or it was 900 RPM I don t remember.
Dukeq1F.jpg

0qYBOI9.jpg

And this is 67 HRC M35 steel ....................
 
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AbLonewolf said:
Thanx for the tips.

Natlek...I see you did not use oil to keep everything cool?
Click to expand...
I never use any oil ,seems to me counterproductive... to lube place where I want friction.If carbide drill bits is sharp job was done fast , very little temperature there.
 
Thanx for the replies boys and girls...appreciate it.

Suppose the best way to do this is simply "normalize" before you drill...hehe
 
Natlek said:
I just drilled this hole in hardened T3 HSS steel, 3mm ...............800 or it was 900 RPM I don t remember.
Dukeq1F.jpg

0qYBOI9.jpg

And this is 67 HRC M35 steel ....................
Click to expand...
What drill bit are you using? I use 65hrc rated carbide bit. 14c28n at 61/62 hrc is no problem. But RWL-34 at 64 is very very tough
 
I have used expensive full carbide drill bits and they crumpled with my crappy drill press and practices.

Best luck as been Black and Decker spade bits for glass and tile. Have drilled quite a few holes in power hack saw blades which are at 64-65 Rc and most likely M2 steel.

Last purchase was a 10 pack of carbide spade bits off of Amazon for 10 bucks. Yes they are cheap and only last for a few holes but price is right.
 
The Milwaukee White tip natural stone carbide bits do pretty well in hardened steel, but not as good as solid carbide. The Triangle pointy glass spade type bits work well, especially to enlarge an existing hole. Some of the 4 edge work better than the 2 edge ones I tried a while back. Some of the 2 edge ones wouldn't even make a hole on their own.

I found having the blade clamped down well makes a big difference in carbide bits lasting longer, less chatter. I will often get a 5/32" carbide bit and then use the Milwaukee or spade type glass bits to open up the holes if needed instead of getting solid carbide bits in each diameter I use. I drill my tang holes oversized to let epoxy get in there, so 5/32" works well for me and I can open it up more if needed.
 
I have a couple carbide tipped jobber drill bits I bought on amazon, they seem to actually work pretty well. They're basically the same as a regular drill bit, with a piece of brazed carbide at the tip rather than steel. Same geometry as normal metal cutting bits. I believe the name of them was super tool.

I tried using a carbide tipped masonry bit, it shattered on me. It was probably my fault though. I do recommend giving these a shot, if you dont want to pay for a full carbide bits.
 
My experience is with masonry bits and glass bits. Both sharpened with diamond Dremel disc. For me it was very hard to make the masonry bits cut steel. The glass bits needed just a little bit of sharpening and tweaking the angle. But sometimes additional sharpening was needed to finish the hole. A friend of mine has proper solid carbide bits for metal and they are much better, but I can't find where they sell them in my country (and honestly I don't think I need them since I have to drill hardened steel very rarely.
 
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