Dull drill bits - throw them out
 

I figured I'd share this quick story to perhaps help prevent someone else from doing what I accidentally did. I've drilled thousands of holes over the last 10 years, but until last night, not a one of them was drilled through my hand.

A student was drilling a 3/16" hole in a piece, and having some trouble with the drill bit not cutting very well. Wondering what was up, I said "here, let me see it" and took over the job. Indeed the drill bit was dull. Thinking it would still work fine, I pushed a bit harder (big mistake). Drill bit snapped, and drill slipped, shifted over and punched right into my hand between the thumb and index finger. About a 3/8" deep torn-up puncture wound, requiring stitches. I was lucky it hit an area without any bones or tendons.

Now, when I find a dull drill bit, I throw it out. It's not something I will allow in my shop anymore. Drill bits are cheap. Using a dull one simply isn't worth the risk of snapping it.

So, as a reminder to all teams, keep your tools and equipment in good and safe operating condition. And any time you apply a significant force to something (by hand or any other means), think of what would happen if the opposing force suddenly disappeared.

I've operated a lot of large and dangerous machinery over the years, and sometimes its the simple things you do every day that will end up hurting you.

Re: Dull drill bits - throw them out
 

Nasty story.

You could also buy a drill doctor at OSH, they are around $200. Makes sharpening all those old drill bits easy.

Re: Dull drill bits - throw them out
 

Doctor the drill, or doctor your hand. Easy choice. Let's all make the right one.

Re: Dull drill bits - throw them out
 

Drill bits are so cheap that I don't even find it worth it to sharpen anything under 3/8" really. Anyhow, kind of interesting how the dull tool becomes the dangerous tool. Not what you might think at first.

Re: Dull drill bits - throw them out
 

FTFY.

It's still sharp. Just not as sharp. Fortunately, I've never dealt with any sort of injury resulting a dull tool. I have, however, cut my index finger from handling a recently sharpened tool like it hadn't been sharpened.

Re: Dull drill bits - throw them out
 

Sanddrag, sorry to hear about your accident but in light of the situation, I'm glad it sounds like you will make a full recovery - hopefully it's a speedy one!

One thing I have noticed while working in shops (and many other areas in life, in fact) is that when you are operating big tools or doing dangerous things, or at least tasks perceived as dangerous, you get your "guard up", and begin to really think each task through and just generally be very careful. It's when doing those mundane tasks that we've done a thousand times, like drilling holes, that we're actually more likely to get hurt! It's because of the simple fact that when doing mundane tasks, we don't have our guard up because the task is perceived as easy or simple because we've done it so frequently. We must try to keep our guard up at all times, thinking about how to prevent injury, or what would happen if x-y-or-z happened, or consider plan B, or have an "out route".

Sadly, it often takes an accident or injury such as yours to reminds ourselves and others that a "simple" task such as drilling a hole can quickly turn into a very dangerous situation. So, hopefully your accident can be a lesson to others on your team and here on Chief Delphi. Again, hope you experience a complete and speedy recovery!

Re: Dull drill bits - throw them out
 

Quoted for truth.

When the job at hand gets to be more of a habit than safety on the job, thats when people get hurt.

Make safety a habit.

//Sandrag, Glad to hear that your 'learning experiance' was fairly minor. //

Re: Dull drill bits - throw them out
 

Sandrag, I'm glad you were not mangled too much :D

Soemthimes I ask the students what is more dangerous, a sharp knife or a dull one? The dull one is more dangerous as you have to put more effort into using it :ahh:

Re: Dull drill bits - throw them out
 

When we've done things hundreds of times, we get complacent. Complacency is one of the biggest things that flies in the face of safety. We must be vigilant.

It is also 100% true that a less-than-stellarly maintained tool (a less-than sharp drill bit, knife, whatever) is FAR less safe than a sharp one.

You're alot more likely to complete the job safely if you're not putting alot of load on the tool.

Re: Dull drill bits - throw them out
 

Sorry to here about you getting hurt. At the same time if you learn how to sharpen them. By hand on a fine belt sander it is a live learn skill. And Any live learn skill is worth the time. I agree that at somepoint it is cheaper to get new. Somewhere down where I can't see the tip.

Re: Dull drill bits - throw them out
 

In thin gauge Al, I start every hole with a #40. This is not only the smallest practical bit in my opinion, it is also the hole size for a 3/32 rivet (and the associated cleco clamp).

The middle of your standard 118° chisel point twist drill does not so much cut, as mush metal out of the way. The chisel point is also the first part of the bit to dull. The only bit that has to do difficult center cutting is the pilot, so you might as well use a small one to limit the force required. After that you can generally chase the hole with your desired drill. If you are drilling a particularly big hole, measure the web thickness of your finish bit, and select an intermediate bit that is larger. This wil ensure that only the best cutting geometry of your bit is put into service. This can be a little chattery with a hand drill, but takes less dangerous effort.

Drill sets are a waste of money and space (I bet you use that M bit 50 times a day). If you design your own robot, you can keep fastener type count down, and only need a few bit sizes.

My bit of choice for hand drilling Al is jobber's length, 135° split point, HSS, bright finish. HSS is less brittle than cobalt and plenty hard and heat resistant for Al. Bright finish (no coating, just polished) is fine at preventing chip welding in Al, much better than any import-grade coating. The split point helps with wandering, but if you start with a #40, you almost don't even need to center punch. That configuration is also about the cheapest there is, so buy from a nice name brand made in USA/Switzerland company and get a zillion #40s. Good tooling doesn't cost money, it makes money (and prevents doctor visits).

If you are still breaking bits, get a faster drill, like a <=3/8 chuck air drill, which is also lighter and easier to control. The recommended RPM for drilling an 1/8" hole in Al is about 12KRPM, or around 5 times faster than your average battery powered drill. Screw length bits are about half as long as jobbers, and thus less likely to snap in twain.

travis "drillbit" taylor

Re: Dull drill bits - throw them out
 

The same thing is true for kitchen cutlery. A sharp knife easy cuts onions, carrots, etc. A dull knife cuts fingers.

Re: Dull drill bits - throw them out
 

Good to hear you didn't get permanent damage to your hand, but still, OUCH!

I don't quite know whether the dull bit, or the practice of holding your hand near where the drill is operating, was major contributor to the accident?

Re: Dull drill bits - throw them out
 

I definitely should have been using a drill press and a vise. And a quality US-made screw-length bit would have been nice (love those things). My hand was about 2-3 inches away from the drilling location, and not anywhere near the path of the drill, but the manner in which it broke/slipped caused it to go over sideways right into me. It's the things we've done thousands of times over for years and years without incident, that we tend to get sloppy about, and eventually it hurts us.

Well said travis. Cheap tools make for expensive injuries.

Re: Dull drill bits - throw them out
 

Why throw them away when you can quickly and easily sharpen them? Seems like a big waste of money to me. Especially with number drills in large sets.

Re: Dull drill bits - throw them out
 

We toss all small drills (ie: any number drills). We can buy them for $0.40-$0.60 ea. It's not worth the time it takes to sharpen it to save 60 cents.

Re: Dull drill bits - throw them out
 

Dull drill bits are not worth keeping around. Replacements are cheap and dull tooling will reflect itself in the quality of your finished pieces.

As for regrinding, in my limited experience its not worth it for small bits. A drill bit requires precise geometry which varies significant among different styles, manufacturers, sizes, purposes etc. A harbor freight sharpener or even a $1500 sharpener just isn't going to cut it.

Re: Dull drill bits - throw them out
 

I'll agree with Mr. Howard here. You can easily resharpen them at any stationary grinder. Grind it according to its structure to get the best drilling out of the bit. And if you throw it out, just make sure you recycle it or use it as recycled parts. Just be careful on sharpening.