drilling tempered steel

P

Phatz

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Jul 8, 2006
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Can anyone advise how to drill a 7/64 (1/4 deep) hole in heat treated VG1?

I'm seeing various types of bits..... solid carbide etc, but I'm not sure what to use.

I'm willing to go through a few bits if need be.

Also, is there a method used to prevent the bit from skating?

thanks
 
Carbide or diamond.
Center punch the work before drilling to keep the bit steady.
 
Diamond is not a good option for steel. You should be fine with a solid carbide spade drill. There is a synthetic diamond called CBN (cubic boron nitride) that would probably work, but they are very expensive. Regular diamond should never be used on steel, since the diamond is composed of carbon and there is carbon in the steel, when heated such as by drilling, etc. the carbon will migrate and destroy the drill quickly.
 
Thanks for the input guys.

When I saw the variety of bits said to be for drilling heat treated steel I figured that I had better ask.


In the past, when I've tried a center punch it just rang off of the blade - leaving no mark whatsoever.
It was a typical punch that would be used on mild steel.

I thought that there might be different punches used by machinists that are harder?


Last night, I tested a small diamond engraving tool (in a dremel) on a Buck knife that I had laying around.

It was easy enough to position precisely. It managed a small dimple that would guide whatever bit might work.

I'm willing to buy a few bits if needed. i just don't want to buy bits that won't cut the steel at all.

Richard....have you done this with a carbide or diamond bit? If so, were they the type of bits that would be found in a large hardware store?

I ask, because as a carpenter I'm aware that there's a BIG difference in the quality of diamond cutting tools. I used diamond circular saw blades, and they vary in price from $25.00 (junk) to several hundred dollars. And I learned a while back that you get what you pay for.

eKretz....Like this?:

http://www.fastenal.com/web/products/detail.ex?sku=0357314&ucst=t

Thanks again,
Mike
 
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your diamond bits will be toast after the first 50/60 rotations. carbide bits with oil or water as a lube. and if you have a drill press run it slow. also can you heat the spot with a torch to anneal it so it doesnt become "work hardened"? if you anneal it you soften the metal. if its in the handle section its not a problem. just dont mess with the hardness of the cutting edge.you can anneal it by getting the spot you want to drill cherry red and letting it air cool. concerntrate the heat in the spot you want to drill. when it gets a reddish/yellow color, your done. let it cool,than drill away. that much heat applied to the tang of the blade will not affect the tempering of the cutting edge.
 
This has been an ongoing question for me. Carbide bits are the only sure way I know of. BTW, vg1 will likely air harden if heated red and allowed to air cool. It could end up harder than you started.
 
It looks like the general consensus is solid carbide.

I'll pick 2 up and report back.

I'll be drilling the spine, so I'm afraid to try any heat.

It was mentioned by someone that there's a chance of snapping the bit off in the blade.

Now *that* would be a kick in the oblongs.


We shall see.......
thanks,
mike
 
Brownells sells top quality carbide bits. They also sell a product called 'Heat Stop.' It comes in a lidded can and has the look/feel of window putty. You can mark your future hole locations with a Dremel grinding burr, diamond punch, whatever, then form a small mound of the Heat Stop around the location with the marked area in the center of the 'putty volcano.' Heat just that area with a small tip flame from an oxy/acetelene or propane torch. Watch for color change and you may have to shine the area first so you can see it. When it blues you've removed the temper from just that small area. The Heat Stop will harden as it absorbs the heat around the hole area and can then be brushed off. Next step is a carbide bit. In the gun trade we use Heat Stop to drill and tap scope mounting holes in rifles, usually old military ones, that have hardened receivers. If you try this, experiment on another piece of hardened steel first to get a feel for it. BTW, a gunsmith's horror is to break a tap in one of those 'hard to bore' holes. Been there, done that. It does turn one into a cautious and careful workman.....
 
Heating air-hardening steel makes it harder! This only works with carbon steels, as a rule.
I don't know if VG! is air hardening, or not.
 
Mike, the drill you linked is exactly right for the job, just what I was meaning. Run the drill at about 120-150 surface feet per minute. In case you don't know, your rpm can be calculated using the formula:

SFMx3.82
----------- = RPM
tool diam.

Tool diameter needs to be in decimal inches ie .25"
It's very important not to run the drill too fast or you will burn up the cutting edge.
 
You plan on tackling this with a cordless drill or what? :D


You need a rigid set-up and the danger lies upon break through/exit.
That's when the bit will snap and you'll be hating life. :o


..avoid that by clamping (tightly!) a piece of steel to the backside of the blade.
 
Diamond carving bit sets are cheap and drill perfect holes, no water or oil needed for hardened steel.can use drill press but don't use pressure, go slow and let the bit slowly cut. Be patient! Makes perfect hole without heating up blade.
 
I read this thread with great interest. I’ve always wanted to try to make an acetylene key hole in a bottle opener blade. But never knew how to proceed. These diamond bits may be the way to go.
 
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eveled said:
View attachment 1459291 I read this thread with great interest. I’ve always wanted to try to make an acetylene key hole in a bottle opener blade. But never knew how to proceed. These diamond bits may be the way to go.
Click to expand...
I'd recommend a carbide bit to drill the initial hole, then diamond files to convert the round hole into a square.

I've drilled more holes than I can remember in hardened steel and always used/use carbide bits, either solid carbide or carbide-tipped (which is cheaper). And of course a drill press.

I get my carbide bits from McMaster-Carr.com. Inexpensive sets of diamond files can be found on Amazon. I've purchased several from there.
 
Cheapest source for solid carbide bits is packs of 10 bits from the electronics suppliers in the usual chineese suspects. They seem to be used to drill through circuit boards (the glass fiber reinforcement eats up HSS bits I guess). I buy them in 2, 2.5 and 3mm mainly for drilling spearfishing shafts (which are hardened) and I have use them a few times for cutlery hardened steel. They work fine, but as stated above, they snap on exit, so back it up with another piece of steel. The funny thing is that they even when the tip is thrased, they still cut! Don't expect long curly chips like when you drill mild steel or stainless... it will be more powdery, ala cast iron.

Mikel
 
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