Bad mishap with the drill press, could have been worse, more precautions needed?

jonnymac44

jonnymac44

Joined
Sep 27, 2007
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Well, I'm very careful to securely clamp my work when drilling holes, use plenty of cutting fluid, and I've had a great track record with the drill press, but am a bit shaken by what could have been a whole lot worse if my heavy duty Kant-Twist brand clamp hadn't done it's job:eek:

I had been thinking that it was about time to pick up a fresh couple of 3/8" bits for drilling tangs. I use the ti coated bits from Dewalt with the little starter point and I've always been happy with them. Started to drill through some .144" CPM-154 today and was already thinking that it wasn't cutting as smooth as I'd like and that yes, I definitely should get some new bits soon. Right at the end, with the hole on the backside about 1/4" just ready for final breakthrough everything went bad. The bit somehow snagged in the hole and with a whole bunch of force drove the half of the blade that wasn't clamped down up the bit about an inch!! At that point the bit seized up and stopped the motor in it's tracks. I ended up with a severely bent blade with somewhere near a 140 degree angle. Thank god that Kant-twist held firm because I don't want to know what would have happened if that blade had been shot right into my stomach!

That one scared me a bit, so I immediately added a second clamp to hold down the opposite side when possible, and did a quick setup of a barrier with some clamps and a piece of 1 inch oak to block any projectiles. Is this a little better? Am I being a little too paranoid? Does anybody know if there's anything I did wrong to cause that to happen that I can change in the future? If it was an operator error, trust me I don't want it to happen again.

Here is how I changed the setup.
Drillingsetup.jpg


Drillingsetup1.jpg
 
On thicker material, with a large hole, you should ramp off the pressure on the tail end right before you break though. FYI Most of the time a blade will not be thrown, it will just turn into a helicopter rotor.
 
No you're not being too paranoid. When I work on anything that requires cutting, grinding, drilling I always take the utmost precautions. You're right, that blade could have easily flung straight into your stomach and your story would be on Spike's "1000 ways to die".
 
Yeah that's scary! Just today I had a cut off disc in the dremel break and hit me in the chest, left a good little welt, good thing it wasn't my face!


When you think you should replace something, chances are it needs to be replaced.



-Xander
 
I would clamp closer to the hole being drilled and add a clamp or bolt of some type in the direction of rotation that can stop the blank from rotating at all if it comes loose from the clamps.

I've had a similar experience with drilling flat stock. It'll definitely make you check your drawers, afterward!
 
Buy yourself some regular cobalt bits, and learn to sharpen them. Those pilot drills are cool for the first few holes, but they are a pain to sharpen.
Many poeple find drill sharpening daunting, however if you can grind bevels, you can sharpen drills. I have sharpened .040" drills by hand on my belt sander.
Drill doctors are for sissys.
Oh and lay off the pressure near the end of the hole.

Spike's "1000 ways to die". One of my favorite programs, natural selection in progress.

Del
 
In addition to clamping securely,I added a footswitch to my d-press,so if anything happened,there's no fumbling for the switch,I just lift my foot...This also works well drilling hard material,you just jog the motor while drilling---and yep I almost wrapped my finger around the chuck only once :) before adding the switch--Regards Butch
 
I was a bit surprised to read that you are using those "starter point" drill bits for steel....especially for drilling something like 154. After viewing the first image, and seeing the size of the "chips", my opinion is that using those bits is asking for trouble. Chips of that size are normally what you would see coming off of mild or wrought, and only then if your really over pressuring the bit.

I would recommend staying away from those bits for anything other than very soft materials such as wood, plastics, Micarta, etc. Get yourself some good 135 degree split points, and back off on the pressure. The best safety feature that I have ever come up with for drill presses is a momentary foot switch (Linemaster/Clipper switch). That way IF something goes wrong, you simply step back and everything shuts down.
 
Jon,

Glad that was all that bent. I like pilot holes for anything that size. Little pressure is needed for the second bit and they don't tend to dig in.
 
Get a #3 or #4 Carbide center drill center drill until the drill portion clears the bottom. Without moving the piece hit it with your 3/8" cobalt drill and you will fly through those blades.
 
Lots of good info guys. Footswitch is a great idea and is now definitely on my list for the press.
I don't have any problem with sharpening normal drill bits, I've done it many times. I've just had really good experiences with these bits and still in the past. Ed, maybe you're right and they're not the best for this. The bit that did this today had drilled hundreds of holes perfectly up until this morning, and although the chips you saw were large, there usually weren't many at all, just nice big solid curly cues all the way through.

I'll pick up some more cobalts.

Thanks guys
 
With anything that heavy and spinning that fast I don't blame you for putting up that little barrier... glad you're ok, fast spinning shop equipment is scary stuff when anything gets snagged or caught on them:eek:

Worst I've done so far is send pieces of wood flying with belt sanders and table saws... and find them embedded in the walls 10 feet away.

On a side note.. that clamp is pretty snazzy! Would you recommend it? Currently looking for something to replace using c-clamps
 
Jonathan, definitely would recommend the Kant Twist clamp! It's really helped me to keep my holes true and applies really solid pressure. Can't say enough good about it, but last time I looked for another one, they were scarce. Good luck!
 
As a machinist I would recommend getting some good quality cobalt drills from MSC or Grainger for drilling steel and like everyone else said lighten up when you break through
 
In my opinion, your setup looks okay. Also, it is okay to use a fair bit of pressure when drilling a hole. It is counter intuitive, but underfeeding a cutter can wear it out due to excessive rubbing.

You have to let up once the web penetrates the back of the work piece. The high force needed to feed a dull drill can cause these problems once the point starts to exit the back of the work piece and the high pressure being used to feed the drill turns into overfeeding. A small pilot hole the size of your web thickness can help prevent this by reducing feed pressure.

If you're getting hundreds of holes in knife steel out of consumer quality drills, you're doing it right, and your set up looks okay. I think you may have simply got sloppy with your technique.

A low helix drill would work well in this application and is less grabby.
 
I step up through bits when I drill larger holes.... Center punch, .125", .250", .312" then .375". It makes the big expensive bits last a lot longer and are a lot less likely to snag. Definitely get some 135 degree split point cobalt bits. I use carbide .125" bits as I use that one a lot.
 
No real recommendations that haven't already been mentioned, I'm just glad you weren't hurt. IMO, the drill press is more dangerous than the buffer in my shop. Why, because we tend to become complacent with the thing that can spin a blade at high speed, not just throw it at our foot! I've had more "close calls" with the drill press than I've had with any other tool in my shop...

Charlie
 
Glad you weren't hurt. Alot of good suggestions here. I usually use a small vice to hold the steel and a couple of c-clamps to hold it to the table. It hasn't spun on me yet. I have had a few spin on me and scare the crap out of me too.
 
Ed Caffrey said:
I was a bit surprised to read that you are using those "starter point" drill bits for steel....especially for drilling something like 154. After viewing the first image, and seeing the size of the "chips", my opinion is that using those bits is asking for trouble.
Click to expand...

Yeah, that's not what those are meant for at all. I think I'd rather pop a zit with a drill than make a 3/8" hole in tool steel without an actual pilot hole first, even with the proper bit. That's a heckuva lot of tough steel to be cutting all at once.

The foot-switch sounds like a good idea for any power tool. Just remember unless there's a true E-stop with a brake, it's going to keep spinning for a while. The printing presses I used to run had them, they're hard on bearings but saved my fingers more than once. Some table saws have them too, I hear they'll pretty much destroy a blade but hey...
 
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