Drilling and WD40 vs. Cutting fluid

Jun 7, 2013
I'm new to knife making with only a couple of knives or so under the belt and I use WD40 for drilling holes because I have it around the garage, but it seems I can't keep drill bits sharp for anything. Correlation or coincidence? Should I get cutting fluid? What's the difference?
I've had no experience from using Wd40 where it helped with cutting. Actual cutting oil is much more effective.
WD-40 is a pretty poor lubricant in my opinion, get some real cutting fluid and you'll be happier for it.
You don't want a lubricant for cutting. Get some cutting fluid.

That said, I don't use any fluid. Just good drill bits. ;)
WD40 is mostly kerosene, a bit of alcohol and some other stuff.

It's good for thawing a frozen lock, or drying out a wet distributor, or cutting fluid on aluminum

It's a pretty useless cutting lube on steel

You can get real cutting fluid at home depot as pipe tapping fluid in the steel water pipe section
However it's not really needed

first make sure your steel is annealed, HRA not just hot rolled

turn the speed down, it's probably too high.

make sure the drill is sharp, feed it fast enough to cut
Last edited:
"cutting fluid" doesn't do a whole in this application, so it is unlikely the fluid you chose will have much effect on anything. The primary thing is feeding hard enough to keep the drill cutting, but not so hard that you break down the cutting edge. Rubbing=wear. Overfeeding when the web exits the back of the work piece causes problems.

WD40 is useful on aluminum because it reduces built up edge, but doesn't do a whole lot on steel. It's function in this role is mostly as a coolant.
What type of drill bits? Hss, cobalt, unknown?
What brand of drill is it?
How many holes are you getting from a new bit?
What size hole are you drilling?
What is your rpm?
What is your feed rate?

Can you post a vid of you drilling some steel? I think we would solve your problem immediately if we could see what's going on.
WD-40 is basically a cleaner. its actually a DE-greaser. it burns up and smokes when you use it for lubricating drill bits. the only time WD-40 is used as an actual lubricant is on the micro-scale.
"WD" is short for "Water Dispersing" lubricant. WD-40 was not designed to be a cutting fluid. It displaces water, and is supposed to replace it with a fine barrier of lubricating film.

PT Doc is on the right path by asking you about your drill bit material, drill point angle, rpm (cutting speed), feed rate and pressure, etc. A quality cobalt drill bit should serve you well, if it is fed without too much force or rpm.

Most likely, your drill is rotating too quickly. Ideal rpm's for drilling common hole sizes through blade steels will rarely exceed 600 rpm.

Still, . . . As a matter of habit, I drill my holes through blade steel with a few drops of Tap-Magic from the 1990's applied to the tip of my bits. It smokes a bit but may reduce friction or heat while drilling. At least I feel good about it. :)

On the drill press the fist thing you want to do is slow things down. if you are cutting steel at wood speeds you will dull the drill bits quickly. I use 3 in 1 oil, cause I have it around and it works, Most cutting oils have sulfur in them, avoid these if you can, you want 700 rpms or less depending on what you are doing? Carbon steel Stainless?

I have no machinist training, but google it. Speeds for drilling steel etc and you will get reems of info.

When I am drilling hardened steel I slow down the press to 210 RPMs give it a lite drop of 3 in one and take my time drilling. Like anything else there is a sweet spot in applied pressure. You will feel when it's cutting properly.
WD-40 is as good a cutting oil for manual drilling of holes as anything else. Tapmatic Steel Cutting Fluid is essentially pure kerosene. WD-40 is kerosene and fish oil. The only real benefit of cutting oil in this application is to prevent chips from sticking to and building up on the cutting edge and in the flutes of the drill. Many modern coatings on drills negate the use of lubricants. Many cheaper drills that have high-tech coatings are not properly surface finished before application of the coating so it doesn't matter. Black oxide coated drills are actually supposed to hold cutting oil in the coating to aid in chip evacuation.

As others have pointed out, buy quality drills and run them at proper speed and you will have much less trouble.

Cutting fluid if you must but I usually go at it dry, it makes for easier clean up. LOL
I try to keep enough pressure and adjust my speed to send nice pretty spirals everywhere. (DONT GRAB ONE!) Best thing I've found as far as drilling goes is that when drilling my holes in the tang I use short drill bits. They flex less and cut longer for me. Some steels from some places I cut to length and then anneal before any other work. The high temp and slow cooling rate means I get more holes drilled and less of that OM*G squeal of a dull bit that just work hardened your hole, er well, your attempt at drilling a hole.
Being new to drilling hard steels, annealed or hardened and working w/ a HF 5 speed drill press that even at it's slowest setting is a little faster than ideal for steel I've found that starting with a good drill bit and using Rapid Tap and taking it slow works well so far. I've only drilled mild steel and 1080 but the difference without the oil vs. with the oil is like night and day. It only takes a drop or two for a 1/4" hole or smaller and my bits seem to be holding their edge well so far. I think I bought it at more of a specialty hardware store nearby because HD and Lowes didn't have any real cutting oil. Had a couple employees try to convince me that WD-40 was just as good as a cutting oil but I've compared them side by side and there's a HUGE difference (I even tried PB Blaster, Deep Creep and another I can't recall at the moment and none compared to the cutting oil)! I think I got a 4 or 8 ounce bottle for about $6 and I think it's going to be lasting me for quite a while. Well worth it in my experience so far! :) Good luck!
I second what Nathan says. In the shop I routinely use WD40 on aluminum for drilling, tapping, and reaming but use a coolant mix we have here on all steel while drilling or while milling with a rougher. I only use cutting oil when reaming and tapping steel.

You could pick up a small bottle of cutting fluid. Shouldn't cost you too much. If you are just using it to drill holes, a small bottle will last a long time.

I am still using a bottle of TapMatic cutting fluid that I got several years ago.

I have had good result with Oatey dark cutting fluid that can be gotten from Home Depot.
Grab a few cobalt bits and you should be good to go. I have had good luck with the DeWalt sets that Lowes carries. 15n20 can be a pain sometimes but the cobalt bits go through it like butter.