Thread: Drilling holes in hard steel?

Can you do it with ordinary HSS drill bits? I have a folding knife I'd like to add a thumb-stud to. In the past, I have repaired razors with out-of-round pin holes by filling with epoxy, rather than drilling & installing a sleeve, because I was afraid to try to drill into the hardened steel.

Knowing what kind of knife/brand might help answer the question a little better, as far as the type of steel and perhaps heat treatment. But, that may be only a need to satisfy curiosity as most folding knife blades will be through hardened to make sure the tang is hardened as well.

Then, it will depend on whether you have a flat spot to drill into. Drilling on an angle is a nightmare. And, will the blade be willing to take a divot from a center punch to give you a place for the drill bit to bite. Other than those concerns to start with, a carbide drill bit will usually do the job on all but the most exotic steels. Sometimes you can sneak by with a cobalt drill bit, but if you buy the best you only cry once.

I like the idea of using epoxy and redrilling. Some tangs are thick enough that they don't get as hard as the edge and might respond well to a drill bit. The problem is trying to keep the drill bit from walking around the sloppy hole you want to fix. But, using the epoxy to fill, then drilling undersize and then drilling to a size you wish sort of forms a nice drill guide to solve that problem, as long as your drilling time doesn't generate enough heat to melt the epoxy...

Actually what I did was simpler than that. I filled with epoxy, then drilled a 1/16" hole through the epoxy & used it that way. The epoxy became the sleeve.

i wonder if you could spot anneal by heating up an old fashioned soldering iron red hot and then putting the tip right on the place where you want to drill. i've done it when making a bow saw using old bandsaw blades.

Here are a couple of things that can make life easier. A decent machinist's vise to hold the work safely and position it precisely. Center drills have a heavy shank and their sole purpose is to mark the work for drilling precisely. Much more effective than a center punch IME. As the photo shows they are available in different sizes.

The vise cost me about $250 maybe 10 years ago and has paid for itself many times over. The press cost the same from a local machine shop where I saw it standing in a corner. Probably from the 1930s but still works great. One advantage of being divorced is I can have a workshop in a walk in closet in a bedroom.

Originally Posted by JimmyHAD

One advantage of being divorced is I can have a workshop in a walk in closet in a bedroom.

Oh you lucky man!

I knew I could have found a better place to put my buffer! (Actually, my basement is warmer in the winter... Maybe I should live down there and have the workshop in my entire apartment.....)

Lubrication is also important, and a low-speed setting on your drill press is also a good idea. If you heat up your bits too quickly, you can kill their temper and they will become soft and basically turn to mush. Cobalt bits are recommended, as well.

I have just begun doing some drilling of steel while I have been putting together my new 2x72 grinder... if you take your time and have the right tools, its a breeze.. if you don't have the right tools it can be bad.

For instance, I only have a 8" swing bench drill press.. and I have a piece of steel longer than 8" that I need to drill a few holes in.. I decided I'd free hand it with an electric drill since they weren't really important holes... well, long story short I busted my cobalt bit off in the piece of steel..... sigh

JimmyHAD gave some great advise about holding that sucker still while trying to drill it and about center drills. It is definitely worth having a set of center drills around.

You might also look into carbide center drills. I know McMaster Carr sells them. Other places a bound to be a bit cheaper but this will let you know what to look for.

McMaster-Carr

They are not cheap, but sometimes they are just the ticket to get 'er done. Just remember to have your rpm going slow and use a light feed (pressure on the handle of the drill press or mill) and use a pecking feed. Pressure then release then pressure and so on and so forth. This is to clear chips so they do not pack the flutes of the cutter. It also helps keep you from drilling crooked holes (wandering) which is easy to do when you get into micro sized drills.

As far as cutting lubricant, I have had good luck with mistic metal mover. A local industrial supply house sells it where I live.

Here is an oldtime recipe for homemade cutting oil............

Motor oil [new or used] mixed 50/50 with turpentine. It works in a pinch.