Drill your holes

[Nathan the Machinist]

The topic of how to drill a hole comes up a lot here. A lot of people have problems drilling holes. I believe the problem is people aren't feeding hard enough. A lot of the advice, such as run as slow as possible and use lots of oil aren't really necessary. I think 90% of the problem is people aren't feeding correctly. So I've made this thread to illustrate that fancy cutters, fancy coatings, lube and slow speeds aren't necessary.

I'll start off with this old clapped out drill. No special coating, just an old American made HSS drill. It is already fairly dull.

I'm gonna drill a bunch of holes in D2 at 660 RPM without coolant or oil.

Wow. Looky there, no problems.

Movie of the cut:

[video=youtube_share;vAy11Fv4N7s]http://youtu.be/vAy11Fv4N7s[/video]


Technique is a little off because I'm drilling by hand and filming at the same time. You want to feed it moderately to get it started. Lift. feed it hard to cut. peck. feed it a little lighter as it exits the back of the hole. Once the web of the drill pokes through the back it is real easy to over feed and wipe out your corners. Blue chips aren't a good thing with HSS, but they aren't the end of the world either.

drill is fine.

okay, lets try this again with a cheapass POS made in China drill. These are garbage. You would be hard pressed to find cheaper crap at wallmart. Don't be fulled by the gold colored titanium nitride coating, it is just for looks, it does absolutely nothing on drills of this quality in applications like this.

oops, overdid it and cooked it. cheap drill. :thumbdn:

That's okay, three seconds on the grinder and it is better than new.

seriously folks. Three seconds. This is not rocket science. Anyone who can grind a knife can do this.

And done. This entire thing didn't take ten minutes

You'll notice the hole quality from the old used worn American made drill is much better than even the first hole drilled with the new China drill. Round holes, smooth bores, very little burr. But that was not the purpose of this exercise. It was to illustrate that even less than optimal drills can cut D2 just fine without all the slow speeds and oil if you'll just feed it correctly.

I recommend quality HSS made in USA drills. They last for hundreds of holes. In fact, in a machining center with controlled optimized speeds and feeds and flood coolant they can last thousands of holes. Slower speeds won't hurt you, but when running coolant I regularly drill 3/8" holes in D2 at 1000 RPM. Light cutting pressure and drilling so slow that the cutter just sits there spinning in its own fines work hardening the work piece is what is killing your drill bits.


edit: Just a sub note: Don't get me wrong, there is nothing wrong with using slower speeds and oil. You'll probably get better results. But they won't fix your problem if you're not feeding it correctly.

 

[Patrice Lemée]

Thanks, great post Nathan. I do ok but still I'll try a faster feed.
First found out that going faster worked better when parting in the lathe. But that is just scary.

 

[DCL Knives]

Thanks for the tips but the problem I'm having is that my bit is slipping up in the chuck of my skil drill press, I'm using cheap bits and do think good bits will help solve the problem or do you think I need a new chuck. Thanks

 

[daizee]

Thanks, Nathan!

-Daizee

 

[Brian Ayres]

Thanks Nathan. I was drilling a bunch of holes in some bel grinder parts the other day and increased my feed pressure/speed after the first hole and noticed a much better result.
I appreciate the advice. Machining/drilling and tapping are all something I am learning to do well and this helps.

 

[severtecher]

Thank you Nathan. There are a lot of these simple tutorials you could do. ( I'm looking for more ;-) I find people have trouble with the simplest things just because a knowledgable person never showed the how to do it correctly. A good tool, an interest,and a little time and it's all done.
I was always asked to extract screws by my fellow aircraft mechanics because they were never shown how to do it right. PASS ON YOUR KNOWLEDGE gentlemen. Slipping off a screw and dragging a steel tip across aluminum was not a pretty sight. First thing I did was to keep a spare Phillips Apex tip that had 40 or 50 thousandths ground off the tip. This grabbed the screw higher in the slot where someone else had not yet messed it up. 90% of the screws I encountered could be removed with this and a little muscle. Well , I gotta give credit to gravity too. Having 250+ pounds to bear down with helped. I told them to tighten the screw first to break it loose, then crank it out like normal. Most guys went and made the special Apex right away.
Drilling out screwswas the same story. No need for a brand new tip. Prep it, drill it, and patiently remove it. This worked on the difficult 10%.

Thanks again Nathan. Hope to see more with the good pictures. A good machinist is a great friend to have. kevin

 

[P. McKinley]

Nathan - thanks for the tutorial.

The issue I often encounter, and did this morning, is drilling into forged, annealed blade tangs. I use good HSS bits in a cheapo drill press, but it seems I get just through the layer of scale before the bit just stops biting... no matter how much pressure I apply, or speed I run the drill.

Not properly annealed??
Dull bits?
Work hardening from the drill bit and pressure?

Any thoughts??

Thanks again,
Peter

 

[amamachinist]

Nathan - thanks for the tutorial.

The issue I often encounter, and did this morning, is drilling into forged, annealed blade tangs. I use good HSS bits in a cheapo drill press, but it seems I get just through the layer of scale before the bit just stops biting... no matter how much pressure I apply, or speed I run the drill.

Not properly annealed??
Dull bits?
Work hardening from the drill bit and pressure?

Any thoughts??

Thanks again,
Peter

Peter,

Are you spotting your holes before you drill? A 90deg. Spot tool or center drill will often get you thru half of the thickness of a knife. These are only fluted a short distance which prevents any flex so you immediately get a nice centered hole. As for the pressure or feed rate to use with the drill it should be very high. On large drills maybe .400 or bigger I usually need to give it everything I have to get it to drill correctly I'm literally pulling down on my quill feed as hard as I can. But it's a varied pressure. I don't slam the drill into the work. I gently touch the drill to the piece and then steadily apply more pressure until I've drilled maybe .175-.200 deep after that I retract spread a little oil in the hole and start my next peck. This is for drilling thru thick material though. Yesterday I drilled six holes thru 4140 plate 2.0 thick with one drill no problem the drill is still perfect. When drilling thin material like a knife and the holes are pre-spotted you should be able to slam right thru one shot as hard as possible.

 

[JBS TOOLMAKER]

Good thread Nathan.

 

[Charlie_K]

I tried to do the fast feed on a piece of mild steel once and wound up burning off the tip of the drill bit. After that I've gone with slow but steady pressure and a generous bit of oil for lubrication and cooling of the metal.

 

[Fiddleback]

Nice post Nathan. Thanks. Can you show how you sharpened the bit?

 

[P. McKinley]

Amamachinist - Thanks for the reply.
No, I have neither a spot tool nor center drill. I'll pick one up and see what happens though.
From your description, its likely I'm not applying nearly enough pressure. I'm a bit skeptical that my $149.00 drill press can handle that stress though, as the table rest bends under just moderate pressure.
Possibly time for a better machine me thinks.

Thanks again,

Peter

 

[Mudbug007]

Thanks for the info Nathan! For all you that are drill press challenged, here's a few more tips for drilling holes. Just read through the tutorial for some golden nuggets of info.

 

[sunshadow]

If you are "annealing" your tangs by doing the "heat it red hot and cool it really slowly in the insulating material of your choice" method, especially if you are using a hypereutechtoid steel you may be precipitating pearlite which is essentially little microscopic flat carbides in soft iron matrix. Those carbides will quickly ruin a drill because they are extremely hard even though they are surrounded by soft iron. Spheroidize your tangs and you should be fine. I have a cheapie drillpress in my basement and I have no problem drilling steel with it, also centerpunch your holes to start so that the bit has something to start on, it makes a huge difference

-Page

 

[Daniel Fairly Knives]

Great information!

When I first started I couldn't make a bit last for one knife, I would say I get 50 knives per bit now and I use a lot of thick steel and Ti.

 

[Nathan the Machinist]

Nathan - thanks for the tutorial.

The issue I often encounter, and did this morning, is drilling into forged, annealed blade tangs. I use good HSS bits in a cheapo drill press, but it seems I get just through the layer of scale before the bit just stops biting... no matter how much pressure I apply, or speed I run the drill.

Not properly annealed??
Dull bits?
Work hardening from the drill bit and pressure?

Any thoughts??

Thanks again,
Peter

You need a sharp drill and high feed rate. This is a good application for a 130 degree split point. High carbon, high carbide work piece material will resist penetration by the drill web.

Once the drill isn't cutting freely, stop right there and sharpen it. Lean into it if you have to but keep that drill cutting, don't let it just rub. Once it stops cutting, the carbides in your work piece that had just been moving out of the way will start to seriously cut into your tool. A dull cutter is a waste of time in this application, so once it isn't cutting freely you need to stop and sharpen it.

If your material isn't spheroidized you may only get a couple holes between sharpenings, but any steel softer than about HRC 40 will cut.

 

[Nathan the Machinist]

Nice post Nathan. Thanks. Can you show how you sharpened the bit?

Andy,

I'm not coordinated enough to grind and film at the same time, so I'd probably need a camera girl...

I'm not sure you'd learn much by watching me anyway without a full on tutorial explanation. This is something you could learn in two minutes if I were in your shop with you, but it is kinda hard to explain over the internet.

I'll try and do a real tutorial when I get a little more time.

 

[12345678910]

That's good info.


The HF drill press speeds are listed as

Spindle Speeds: 250, 340, 390, 510, 600, 650, 990, 1550, 1620, 1900, 2620, 3100 RPM

so 660 rpm is quite slow compared to 3100

 

[Nathan the Machinist]

That's good info.


The HF drill press speeds are listed as

Spindle Speeds: 250, 340, 390, 510, 600, 650, 990, 1550, 1620, 1900, 2620, 3100 RPM

so 660 rpm is quite slow compared to 3100

Yes that's true. Everything is relative. I'd run it at 1200 RPM if it were wet. I'd run it at 300 RPM if it were a 1/2" in D2 without coolant. I'd run it a 2400 RPM if it were 1/8" and wet etc.

Nothing bad happens if you run it at 200 RPM, other than you spend a lit of time.

I'd run it at 4,300 RPM and feed it at 43 IPM if it were wet and we were drilling aluminum. So, everything is relative.

 

[P. McKinley]

Page - Thanks for the reply. I think you may have hit on my problem.

Can you describe the process used to "spheroidize" the tang? Is this just a matter of heating to 1200F or so and holding at temp for a period of time(??), then slow cooling?

Thanks for help guys.

Peter