Drilling heat treated blades

does anyone have any suggestions on how to drill a heat treated blade

Two "C" words come to mind, carbide and careful. Carbide bits are necessary and great care is needed.

I agree with Doug, and I'd even go farther, and say that you might be better off to start that particular job over.

Sometimes that just isn't feasible, but drilling hardened steel is problematic. Also, carbide drills at $15 to $25 a whack (and they shatter easily) can run up the cost of producing a blade in a big hurry.

There is a way called spot annealing.Turn the spot red hot and drill it while it is RED.
It is a pain to do esspecially on s/s.Dangerous,too!
You can drill with carbide but BE CAREFUL.-(either way)

I drill a lot of holes in heat treated blades. Certainly care must be taken but it can be done with sucsess. If the hole does not have to be accurate a good masonary bit can be used. Your drill should be run slow. Some cutting fluids don't do much but get in the way. A product called Anchorlube probable works the best and is very good for unhardened stainless steels as well as other hard metals. I have also used S.T.P. oil treatment and it will help. For accurate holes Use silicon carbide spade bits which can be purchased from a lot of tool suppliers.If the bit gets dull you must sharpen or of course you will try to over work it and it will probably break. Care of course when you are just going through the far side .Hope this helps some. The masonary bits can be the easiest way to go. Frank.

As stated above, both methods work. As far as the carbide drill bits, they are very brittle. I have bought 3/32 or #41 bits from Wholesale Tool for a very economical price. They were a couple of bucks. My suggestion is that if you find that you have to do it, buy at least three bits of the same size. It is inevitable that you will break one on a Sunday afternoon or late evening when all the places that sell them are closed.

Geno's method of "spot annealing" works very well.

The only time that I have ever had to do this was after I forgot to drill the hole before heat treat, go figure......I suppose some folks may have a need if they want to add a bolster or something to a kit blade.

C Wilkins

Use a carbide spade drill and a lot of fluid.

A.T.
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Chris, ask my left thumb. When I first got started making knives got in a big hurry. Tried horsing the bit, got to relax in the emergency room while getting stiched up. Be careful and use your head at all times. Like Don said, sometimes its better to start all over instead of taking a chance. Ray

I routinely drill a counter sink for the screw that holds my thumb studs after my BG-42 or D2 blades are hardened to Rc 61 (which allows me to make a last minute decision as to whether this blade will be left handed or right handed). For that, I use a #28 Hi Roc carbide drill bit.

The hi roc bits are more expensive (most of the smaller ones are in the $10 - $15 range) but I have yet to break one. They are much more durable than spade bits and are easier to use at depths greater than the drill diameter (a stated but often ignored limitation for spade bits). I use these bits in sizes from #44 to 3/8" (that one was $45) and they seem to me to be the best for the purpose. As stated above, use a good cutting fluid and go slow.

Hi Roc bits are available from MSC in any size a knife maker is likely to want...

One method which seems to work after a fashion is spot-annealing with a difference. I can't remember who put me onto this idea but I've tried it and had some success:

Take a nail, as thick or thicker than you need your hole.
Cut off the head and the point, make one of the ends square. Stick the nail in your drill and put it on high speed.
Drill with this flat-ended thing on your hardened steel until it anneals the spot.......
Don't use fluid, it takes away some heat and defeats the object.
Keep the nail in a box marked 'might come in useful one day'
Then drill slowly and with fluid as normal.

No guarantees!

Roger

Guys,
Oftentimes in diemaking it is necessary to relocate a bolt hole in a hardened block of tool steel for various reasons. In most cases the block is at a hardness of around 60 Rc. I have found that by using a carbide ball end mill, running at 600 to 750 RPMs (use LOTS of coolant,i.e. water, or dilling fluid, etc.) it is completely possible to cut through the hardened block. The steel will heat up to a dull red glow sometimes, but don't worry about that, just be sure to keep the end mill flooded with coolant. I realize that most knifemakers probably wouldn't use, or maybe even wouldn't have a ball end mill, but it is one option that works. I have used this method many times when doing a die modification. It is possble to cut all the way through a 1" thick hardened block if you have that much flute on your end mill. This should also work in a drill press. Just be sure that the knife is clamped securely in a vise so that it won't move. My 2 cents.
Larry