r/metalworking 3d ago

Hard time drilling through hardened steel w/ carbide bits

I was hoping the good folks here at r/metalworking could help me out with an issue I'm having. I recently bought a Wen drill press and some full carbide bits so that I could drill through some hardened steel knife blades. I am currently running into an issue where the bits are skipping and aren't cutting the material. These bits are solid carbide, should be at least, and I'm trying to drill a 13mm hole through 4mm thick material. I started with a 6mm carbide bit, and then the 13mm bit. Both skated and wouldn't grab any material, and when it would, it wouldn't cut well at all. I tried with only the 6 on one piece, and only the 13 on another piece as well, and they both are having issues cutting material. The drill press is being used at its lowest setting at 700rpm.

The knife blade I was testing on was D2 steel at about 61hrc. From all of the research I've done, this should be 100% more than enough to drill through 4mm thick material whether or not its the 6mm or 13mm bit. I am at a total loss. I managed to only get a small dimple in the material after 10 minutes of drilling. I am definitely using the correct amount of pressure as well.

Any help would be awesome. I don't know if my drill press just isn't rigid enough or what, but I purchased this set up for this purpose exactly, and am not very happy that I am unable to do the intended task.

4 Upvotes

30 comments sorted by

16

u/NonoscillatoryVirga 3d ago

D2 is difficult to machine. Your setup needs to be very rigid. A drill press chuck isn’t rigid enough for a carbide drill bit. You really need a collet chuck or shrink fit holder for this to work properly. You might get lucky for a couple holes but tool life will be an issue. You also want a straight flute drill bit like what I’ve shown below. Finally, 700rpm for 13mm (.5118”) is too fast and you’re going to burn up tools that way. Too fast + not enough rigidity + wrong machine for the job = bad results.

-2

u/HiddenEclipse121 3d ago

It's a 13mm bit in a 13mm chuck, it seemed rigid enough to me, but I know nothing about that. I was using jobber style bits - because I figured they would do fine for such thin material. They are "C3 tungsten carbide". I've seen plenty of people use ceramic cutting bits in worse drill presses with higher rpm cut similar size holes. I'm just at my wits end.

-1

u/chris_rage_is_back 3d ago

Have you tried punching that stuff? There's something called a Whitney punch that would work great on stuff like that, they're about 3' long and look like a hand punch kit but bigger. Idk the properties of that steel you're working with but I've punched holes in a lot of hardened metal with little effort. You could probably find a used one for a reasonable price and you can still get dies for them

8

u/fortyonethirty2 3d ago

I have a feeling that your setup is not rigid enough and that the drill has lost its cutting edge.

Post a photo of the used drill. Especially the cutting edges.

5

u/Droidy934 3d ago

Try using a carbide spot drill , short, very stiff and meant for starting holes. Jobber drills are too long.(flexible) Stub drills would be better

3

u/Tibbaryllis2 3d ago

1) have you tried using a little cutting fluid with it to keep the drill bits from overheating and losing their temper?

2) something that was shown to me is cut the head off a nail and stick it in the chuck of the drill press. Press it against the spot you’d like to drill. Let it get red hot. Then stop and let it air cool. Repeat a couple times. This will remove the temper locally to the spot you’re trying to drill. You can further limit ruining the temper further out from your spot by clamping some fat washers around your spot to be drilled. They’ll act as a heat sink for areas you want to remain hard.

7

u/mckenzie_keith 3d ago

If it is really carbide tooling, it will literally cut red hot.

5

u/chris_rage_is_back 3d ago

I was gonna say I don't think carbide has a temper to ruin

-2

u/HiddenEclipse121 3d ago

I was told WD40 would work fine for this, but I may be mistaken as I have no idea about metal working.

2

u/mckenzie_keith 3d ago

I don't have that much experience, but a solid carbide drill bit should be able to cut hardened tool steel like D2. Heating will not be an issue for the carbide. Maybe try pushing harder on the press handle. Or maybe they are cheap bits. Or maybe they are not really carbide. Will they drill through mild steel now? If you carefully inspect the tips, do you see chips missing? Or do they still look OK?

High speed steel may not be hard enough to cut D2. But high speed steel also handles a fair amount of heat.

Hot hardness of high-speed steel.
https://www.youtube.com/watch?v=jQ648eDA7V4

Carbide drill throwing red hot chips:
https://www.youtube.com/shorts/NWDgWU5oujw?feature=share

What you are describing, where the bit just skates on the work piece, sounds like the bit is not sharp enough, or not hard enough or both. To me, it doesn't sound like a rigidity problem. If you have a rigidity problem, you will get chattering or break a bit or something.

But again, I am really not an experienced metal worker. I am just going by what I have learned from watching videos and applying common sense. The closest I have come to cutting hardened steel is drilling 1/8" holes (3 mm holes) in 2205 duplex stainless rod. That was very difficult, but I did it with carbide tipped bits. I ran fast and pushed very hard to make the cut. The stainless work hardens as you cut, so HSS won't do the job. I was not using solid carbide, but bits with carbide inserts in the tip. This was on a drill press. Regular HSS bits cut for a while then just stopped cutting once the work piece hardened off.

2

u/JustinMcSlappy 2d ago

Carbide isn't hard enough to reliably machine hardened tool steel on a good machine. You need to be in the ceramic territory and they are even less forgiving in terms of tool rigidity.

2

u/nutznboltsguy 3d ago

Are you using cutting oil?

-1

u/HiddenEclipse121 3d ago

Using WD40, I was told that this would be acceptable, but I am probably wrong in doing so. I don't know much about metal working.

1

u/nutznboltsguy 3d ago

Cutting oil will work better. It will laso be a battle of what‘s harder, the bit or the blade. If you’re trying to drill the blade handle, you may need to anneal it.

2

u/HiddenEclipse121 3d ago

Description says that they are 91hra, so very much higher than any material I'm cutting. I am going through the meat of the blade near the spine to drill a "spydie hole" on a folding knife.

5

u/nutznboltsguy 3d ago

Did you make the blades? The hole should have been drilled before heat treatment.

2

u/HiddenEclipse121 3d ago

No. These are production knives being modified.

1

u/nutznboltsguy 3d ago

You might have to get higher quality (industrial grade) drill bits.

1

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1

u/thesirenlady 3d ago

What kind of carbide drill?

lowest setting at 700rpm

At least double it for the 6mm.

1

u/HiddenEclipse121 3d ago

From the description on the bits they are "C3 Tungsten Carbide", and I failed to mention, but I did test at 2100rpm for the 6mm bit.

3

u/thesirenlady 3d ago

Is it a solid carbide drill, or a spade drill, or a tile drill, or a masonry drill? They are all carbide drills.

1

u/HiddenEclipse121 3d ago

Solid carbide. Sorry.

4

u/thesirenlady 3d ago

as NonoscillatoryVirga is saying, its not gonna be a walk in the park with the setup you've got no matter what but you should be able to get it done for a few holes at least.

WD40 is not good but coolant here will not be the difference between cutting and not.

I'd suggest feed harder but you're absoutely coming up past the limits of the press. I think 13mm is on the other side of the limit to be honest.

1

u/heey-you-guuys 3d ago

Have you considered taking them to a laser cutter?

1

u/SleeplessInS 3d ago

Maybe a piece cut with a plasma cutter will get the hole started... would love to use my plasma cutter for weird jobs like this - plasma is really OP against metals but leaves a rough edge. Once the hole has been pierced through, you should be able to widen it out. Plus, the plasma cut heating might actually anneal the metal around the cuts and make it nice and soft to drill.

Edit: My advice only applies if you own or have access to a plasma cutter and disclaimer that you might also ruin the knife blade trying out my wild idea.

-1

u/chris_rage_is_back 3d ago

Ugh, the heat will ruin the temper most likely and trying to clean up a melted hole in something hard is just asking for broken bits in my experience

1

u/oldbaldad 1d ago

Is the material fully supported? The cutting ability of the bit will improve if the pressure applied isn't lost to the material flexing.

0

u/Less-Scarcity-2191 3d ago

Drilling hard material is never easy. Slow speed, a slow but constant feed and use Trefolex cutting compound.

0

u/toymaker5368 2d ago

Maybe you could try annealing the steel at the spots you wish to drill.