OT: Holes in Stainless



#2

Someone here should be able to help . . .

I'm trying to drill a small hole in the blade of a (Victorinox) Swiss Army Knife. That stuff is tough! Can someone suggest the right kind of drill bit to use?

The backstory:

My favorite pocket knife has been a SAK "Tinker", and lately a slightly enhanced model (the name of which escapes me) that's basically a Tinker with a saw. I'm using that thing ALL the time. (No, I don't want a multi-tool -- tried 'em and never made the switch.)

Anyway, the one missing feature on Swiss Army Knives until lately has been one-hand opening. It seems I'm always wanting to open a blade while holding something else in my left hand. So I took to carrying a simple, one-blade pocket knife with a locking, one-hand-opening blade.

So then I had two knives in my pocket. But just lately I looked, and lo & behold, Victorinox now offers one-hand blades. So I bought a "One Hand Trekker". Way cool, but a bit larger than I'd like.

Only then does it occur to me that I could probably add a lug (or whatever it's called) to the large blade on my old Tinker and open it with one hand. So, I've ground out an opening in the side edge (aluminum & plastic) next to the large blade on my Tinker, and started to drill a ~1/16" hole for some sort of projecting lug with which to deploy the blade.

Buuuuut, none of my drill bits will touch the blade. My pseudo-Dremel tool's cutting disk grinds nicely into it, so I made two shallow cross-cuts in the surface to locate the drill bit. But despite that, I can't get a bit to bite. It's pretty amazing stuff!

Anyway, if anyone's got any ideas, I'm all eyes.


#3

Ask a dentist!

#4

Yes, it's very difficult to machine hardened steel. It's normally machine first then hardened. You probably need a diamond drill bit, or cubic boron nitride, and it still won't be easy.

#5

You also risk cracking the whole blade.


#6

No, thats (nearly) not possible.
Michael


#7

And how is it that you think that? I have a cracked Spyderco. Cracked at the thumb hole.

What is the ductility of hardened tool steel? Not much. What is the difference between brittle ceramics and tough metal? Ductility--of which tool steel is closer to ceramics. What causes ceramics or any brittle material to fail? Cracks. What causes cracks? Well, drilling holes for one.

#8

Why not etch the surface, and then adhesively bond a lug? There are super adhesives for metal bonding. Used in aerospace.

#9

As you've discovered grinding is almost the only way to get through hard steel. Depending on how hard it is carbide drills might work but an EDM machine will "burn" it's way through hard material with ease.

If you have a buddy with a machine shop and an EDM that would be the way to go.

#10

Hi!

Superglue or laser drilling. Or both.

Greetings, Max


#11

Laser would be okay. The CA (Superglue) is a very poor choice as it is excellent in tension but its' sheer strength is a joke. If you're going to use an adhesive use some form of epoxy.


#12

For laser you probably need a "fiber laser". The more common CO2 laser doesn't work well on metals, though it can be used to etch the surface of anodized metals.

#13

Harbor Freight Tools sells sets of diamond-coated bits to work in Dremel-like tools. They are cheap, and I suspect they might wear out pretty quick. Real diamond bits probably cost more than the knife.

You could keep wearing out the regular reddish-brown Dremel grinding bits until you get through.

Have you tried solid carbide bits?


#14

Solid carbide bits would be my suggestion. Buy a few of them, though, in case you wear them out.

-Tim


#15

I used to be a machine tool designer. Solid Carbide is generally the best but I suspect that your hole will be small and so the drill will be small as well and break very easily if not used properly. If you try to use a small solid carbide bit in a hand tool you will likely break at least a few getting through the blade.

For the best chance of success, everything should be fixtured and as rigid as possible. You should use a real drill press or at least the Dremel version. If possible, the drill should be guided by a bushing and a continuous stream of coolant should be used. See this page for more information on drilling with a bushing. This may be overkill but definitely helps.

Having the proper drill RPM and feed rate is also important for doing the least damage to the metal. If I am right that the hole is small, then faster will be better. Wear Eye Protection! That is so important, I'm going to say it again Wear Eye Protection!

If you know someone with a machine shop, they will know the right RPM and feed rate. A high speed steel (HSS) drill could also be used but you will get a better hole with the solid carbide if used right.


#16

Quote:
Having the proper drill RPM and feed rate is also important for doing the least damage to the metal. If I am right that the hole is small, then faster will be better. Wear Eye Protection! That is so important, I'm going to say it again Wear Eye Protection!

Good advice, there. Recently, I bought a pair of safety goggles for drilling a 3mm hole in a dense metal assembly to remove an ignition-key cylinder. I ended up breaking the bit in two places, but nothing hit me. Later, I decided to wear those goggles while pushing a sharp-edged lockwasher onto a steering shaft against a strong spring. The washer shot out and hit my lips once, without injury.

-- KS


#17

Quote:
I bought a pair of safety goggles for drilling a 3mm hole in a dense metal assembly to remove an ignition-key cylinder

Just remember Karl: Crime doesn't pay!! But while you're at it, I'd suggest making yourself less visible by wearing dark safety googles to match your dark clothes (please don't tell me you're doing these jobs in the daytime). 8-)

Edited: 17 Dec 2009, 1:43 p.m.


#18

...

#19

One learns something new everyday here. Some forum members seem to have even stranger hobbies / jobs (please check) than I imagined d;-)


#20

How do you think he can pay for those @#%$ calculators?!

#21

Hi, Matt --

Ha, ha! I was going to leave the OT post for several days, then remove it, not really expecting any responses. I hadn't even considered the car-theft angle...

The "dense metal assembly" in one of my 1980's cars had three stripped holes for the screws that hold switches in place, and had to be replaced. The attempt to remove the lock cylinder by drilling was prescribed procedure, as no accessible release pin was provided. My objective to transfer the cylinder to the new assembly was not met, and I had to buy another cylinder, as well. The lockwasher and spring had to be removed in order to remove the assembly.

The price of parts wasn't too bad, and all's well that ends well -- successful repair with no injuries. However, it took a fair amount of time and trouble that would not have been necessary with better quality and design of several parts -- something Spice-series restorers can certainly relate to.

As for "those @#%$ (mostly-1980's) calculators", I've spent more acquiring much of my limited collection than that car is worth now. But, 1980's stuff is generally good stuff; that's why I still have it, or bought it later...

-- KS


Edited: 18 Dec 2009, 2:00 a.m.

#22

Matt & Karl,

Ignition key problems reminds me of my solution a few years ago. I had bought a car that had a really bad ignition key cylinder. For a few weeks I just hot-wired it. Then I found a complete steering wheel assembly from a junk yard that had a good cylinder but no key for it. To get a new key made, I just hot wired the car drove it to a lock smith, took the junk yard steering wheel assembly in and requested that a key be made. They made a couple of keys for me, and then in front of the shop, I swapped out the steering columns, connected the ignition wires to the cylinder, used my new key to start the car and drove away. During all of this, several people walked by and never questioned what I was doing. Amazing!

Bill

#23

Hello,
my english is verry bad - so please ask!!

When i remember back to my time at University....
Usually a knife blade has HRC(Rockwell) of 55-60. Your Schweizer Taschenmesser has HRC 56.(http://en.wikipedia.org/wiki/Swiss_Army_knife)
You need something to drill over the HRC of your blade, in Germany this material is standard for drilling and its called HSS(High Speed Steel (EN ISO 4957 HS)). You have to be careful because the blade would not look nice when the heat raises too high!

Michael W


#24

...and the heat destroys the temper of the steel.


#25

Maybe quench it with a continuous flow of water while drilling?

-Tim

#26

I don't know if U.S. HSS is the same as German, but it would be way too soft for this task.

#27

I'm a bit late getting back.

"Case hardened", eh? I thought the dig on Swiss Army Knives is that it's hard to get a good edge on stainless. I'm certainly a babe in the woods re: metallurgy, but it never had occurred to me that stainless steel could be tempered. It's obviously plenty hard, alright -- certainly harder than the "316" stainless used for the deck fastenings on my sailboat! (I guess that's what I'd been expecting -- what a surprise!)

The Super Glue suggestion isn't realistic, is it? I'd say that Super Glue stuff has never lived up to its hype, as far as I'm concerned -- but perhaps I've misused it.

I trust there are metal bonding adhesives that would work with proper etching, etc., but I'm not sure I'm up to that. I may look around some more.

Carbide bits sure are spendy, and the cautions re: eye protection are well taken.

Actually, I'm liking my "One Hand Trekker" so much, I doubt I'll be following through on this little idea. But a big thanks to all who contributed. One can always count on the MoHPC Forum for an informed discussion of . . . whatever!


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