Damn I love the smell of burning HSS in the evening.

GRX · Jan 28, 2012

Love the smell of burning HSS in the evening / drill bit sharpening

Sparks .... from dull red to bright & bushy.

Just spent a couple hours at the bench grinder sharpening drill bits and chisels. To make a long story short, a friend got a large coffee can full of used drill bits at an estate sale & gave them to me, no charge. All sizes from 1/16" to 3/4" with some letter sizes mixed in. Many are HSS (high speed steel) too

. Most were broken at the tip, had a galled shank, or were otherwise butchered by someone who had no idea how to sharpen them. And while I was at it, decided to sharpen and de-mushroom all my chisels too.

Anyone else love the smell of burning steel in the evening?

napaAl · Jan 29, 2012

Positively. I bought a Drill Doctor for the smaller bits. I use an HF wet wheel for chisels and garden tools. Assorted stones and leather strop for the knives.

ndnchf · Jan 29, 2012

Indeed a very satisfying endeavor. I got a top of the line Drill Doctor for Christmas and sharpened about 50 old bits I had been collecting for years. No more dull bits in my garage!

djb2 · Jan 29, 2012

Hmmm, if the sparks fly and the tip glows red... hasn't the steel (even HSS) lost its temper?

Addrock · Jan 29, 2012

I also use a bench grinder for drill bit sharpening and love the smell of HSS any time of the day!

OccupantRJ · Jan 29, 2012

djb2 said:
Hmmm, if the sparks fly and the tip glows red... hasn't the steel (even HSS) lost its temper?

He was describing the sparks produced. The shape and color of the sparks can be used as an indicator of the type and quality of the steel. Sharpening a drill bit offhand is quickly becoming a lost art, although I consider it one of the required basic skills needed in a workshop.

sdguy55 · Jan 29, 2012

OccupantRJ said:
He was describing the sparks produced. The shape and color of the sparks can be used as an indicator of the type and quality of the steel. Sharpening a drill bit offhand is quickly becoming a lost art, although I consider it one of the required basic skills needed in a workshop.

here here! The tech school i went to actually required us for an entire day to learn what the different angles for the bits did for you and how to sharpen them. And the instructor was no slouch either. If you didnt sharpen the bit at the right angle, you did it again, and again, and again.

GRX · Jan 29, 2012

Thinking about the sparks again, seems many of these bits are Cobalt steel not HSS. Even better! It is gratifying drilling steel watching your newly hand-sharpened drill bit produce nice curly chips from both cutting edges equally. Ahhh, the little things in life.

GRX · Jan 29, 2012

djb2 said:
Hmmm, if the sparks fly and the tip glows red... hasn't the steel (even HSS) lost its temper?

Great question and RJ answered it admirably. Keeping it cool is essential. Which is why you should always have some water around to dip the bit periodically. Note the Dole can in my image. Blue is bad, glowing red even worse.

OccupantRJ said:
He was describing the sparks produced. The shape and color of the sparks can be used as an indicator of the type and quality of the steel. Sharpening a drill bit offhand is quickly becoming a lost art, although I consider it one of the required basic skills needed in a workshop.

Great post x2. :thumbup:

Couldn't have said it better myself. I was trained tool & die by an old WW2 era Navy machinist. We could not even start until we knew how to sharpen our own bits & cutters. And assessing what metal you are working with through a spark test was machine shop 101. This is how one determines proper cutter type, well as tool & feed speed for the required task. Pains me to see how many so called machinists that lack those essential skills these days. Machine operators I call them.

A_Pmech · Jan 29, 2012

GRX said:
It is gratifying drilling steel watching your newly hand-sharpened drill bit produce nice curly chips from both cutting edges equally.

Yup.

chickenfarmer · Jan 29, 2012

OccupantRJ said:
Sharpening a drill bit offhand is quickly becoming a lost art, although I consider it one of the required basic skills needed in a workshop.

I can do it, but for some reason the sharp edge only last through one or two holes

GRX · Jan 29, 2012

Just for the heck of it here are a couple images. A good way to observe the various spark effects is to grind a standard nail compared to a chisel. When you get up to the harder high alloy metals like Cobalt or Tungsten steel the sparks are very small, short, dark red with little to no forking at the ends.

kc-steve · Jan 29, 2012

Here's my preferred method of avoiding bench grinder and Drill Doctor time . . . it's called an oil can.

Steve

jhelrey · Jan 29, 2012

and how do you go about sharpening a drill bit?!?!

A_Pmech · Jan 29, 2012

kc-steve said:
here's my preferred method of avoiding bench grinder and drill doctor time . . . It's called an oil can. :d

steve

rofl

GRX · Jan 29, 2012

kc-steve said:
Here's my preferred method of avoiding bench grinder and Drill Doctor time . . . it's called an oil can.

Steve

What is this lube & coolant stuff of which you speak? Well played. lol

I keep one of those around filled with kerosene for cutting aluminum. This stuff is great also, especially for carbide burrs. Hard waxy consistency.

GRX · Jan 29, 2012

chickenfarmer said:
I can do it, but for some reason the sharp edge only last through one or two holes

Assuming you have good quality drill bits, perhaps your RPM's are too high. Remember, the larger diameter the bit the slower the RPM. Could also be your angle or amount of relief behind the cutting edge is the cause. Here is a simplistic image from the net. There are any number of angle gauges available to check your work.

GRX · Jan 29, 2012

jhelrey said:
and how do you go about sharpening a drill bit?!?!

Here are a couple videos.

The basics:

More detailed:

Hammer1963 · Jan 29, 2012

I'm kind of like you. I do really enjoy grinding my chisels and drill bits. I sharpen all of my HSS & Cobalt by hand. It was a required skill for the Machining trade and one that has saved me many a dollar and many an hour on the job.

Now granted, my eyes are nowhere near what they once were, so anything under 3/16" is a **** shoot. I've just realized that I will just keep buying double ended 1/8" bits from now on and of course anything smaller than that.

I'm sure it's an odd thing for people who have not aquired the skill. A nice bench grinder and smooth belt grinder like a Multitool sure does help.

geologist · Jan 29, 2012

Being that I use a cutting torch frequently, I love just about every part of burning or melting HSS or any other metal.

GRX · Jan 30, 2012

I am right there with you on the eyes thing Hammer1963. ***** getting old. Bi-focal safety glasses are great! And it helps having a clamp-on fluorescent swing arm magnifier lamp around the shop too.

Trucky · Jan 30, 2012

I took a much different approach than most of the other kids at school (in machine shop) when it came to making and grinding bits. I used to do it all day, for fun, because it was something I wanted to learn how to do. I can usually hand grind a bit in one or two tries with a basic gage, and it's kinda fun. As far as lathe bits go, I've probably done well over 100 or so of those, and still have most of them. The rest (the junk ones) got lent to people who should have learned to grind their own. It's a skill I find rather valuable when you dont have a dedicated sharpening rig to do it with.

OccupantRJ · Jan 30, 2012

GRX said:
Thinking about the sparks again, seems many of these bits are Cobalt steel not HSS. Even better! It is gratifying drilling steel watching your newly hand-sharpened drill bit produce nice curly chips from both cutting edges equally. Ahhh, the little things in life.

Something a lot of people do not realize is that a drill can be sharpened purposely off center to produce a hole slightly larger than the drill itself, when needed. The off center grind forces the bit off center, making it act somewhat like a boring bar. Thought I would throw that out there for the drill bit newbies, to give them something else to research.

OccupantRJ · Jan 30, 2012

chickenfarmer said:
I can do it, but for some reason the sharp edge only last through one or two holes

Keep in mind that a drill is generally not going to last as long in a hand drill due to all the banging around while drilling. Machine tools offer much more control in many ways. It shocks people that I machine mostly dry, unless getting down to a level requiring more precision, like reaming. I prototype a lot of heating elements and devices, and the last thing you want is oil cooking out of the metal after heat up, as this will ruin the element. If one has the feed and speeds correct, a lot of the heat will be absorbed by the chip or curl generated. Since I sharpen my own drills, I could care less if one gets dull, as I sharpen them as I use them. Production machining is another ball game, as far as coolants and drill life. We even use a cutting oil that we have custom blended per our recipe. Sorry for rambling, but hey, I was on a roll.

GRX · Jan 30, 2012

Yes, you were on a roll RJ. Thanks for sharing your knowledge. Hopefully some who read this thread will feel encouraged to attempt re-sharpening their own dull or broken bits instead of simply grabbing a new one off the shelf.

chickenfarmer · Jan 31, 2012

GRX said:
Yes, you were on a roll RJ. Thanks for sharing your knowledge. Hopefully some who read this thread will feel encouraged to attempt re-sharpening their own dull or broken bits instead of simply grabbing a new one off the shelf.

Don't get me wrong, I attempt to resharpen them all the time, I'm just not good at it. My junk Taiwan grinder probably doesn't hep either...

Jolomite · Jan 31, 2012

GRX said:
Assuming you have good quality drill bits, perhaps your RPM's are too high. Remember, the larger diameter the bit the slower the RPM. Could also be your angle or amount of relief behind the cutting edge is the cause. Here is a simplistic image from the net. There are any number of angle gauges available to check your work.

Thanks for the diagram! I've been dabbling in sharpening some flea market bits and your edge angle description makes all the sense in the world. Now- more practice!

OccupantRJ · Jan 31, 2012

chickenfarmer said:
Don't get me wrong, I attempt to resharpen them all the time, I'm just not good at it. My junk Taiwan grinder probably doesn't hep either...

Your grinder is fine for sharpening drill bits, but the type of stone and it's grit are the real factors, mechanically. A wheel dresser is needed to keep the stone in proper condition, and to keep the loaded metal out of the pores so the stone will cut, not rub. I don't even try to sharpen anything on an abrasive belt, as I feel that a stone will attain a sharper edge. I have an import grinder along with an old school 60's Craftsman at home and which one I choose to use is a matter of which type stone I happen to need. Not much special about bench grinders for the home shop, as long as they rotate.

GRX · Jan 31, 2012

chickenfarmer said:
Don't get me wrong, I attempt to resharpen them all the time, I'm just not good at it. My junk Taiwan grinder probably doesn't hep either...

In addition to what RJ said, the important thing is you gave it a shot. May take more practice. Some people are better at some things than others. Everyone is different. That's what makes life interesting!

Jolomite said:
Thanks for the diagram! I've been dabbling in sharpening some flea market bits and your edge angle description makes all the sense in the world. Now- more practice!

Slaman37 · Jan 31, 2012

Thanks for the info guys, I've tried sharpinging them before but never knew the theory of the proper way to sharpen them. Now once I get my new bench built and I get my bench gringer I can start sharpinging that drawer full of bits I have.

chickenfarmer · Feb 1, 2012

Alright cool, is a finer or courser grit better?

bad_idea · Feb 3, 2012

can you resharpen a drill bit with a chipped tip?

GRX · Feb 3, 2012

chickenfarmer said:
Alright cool, is a finer or courser grit better?

Depends on what you are doing. As for myself, I like to have both on my grinder. Course for faster removal on larger bits, then fine for finishing those up, and also for grinding small bits.

bad_idea said:
can you resharpen a drill bit with a chipped tip?

Yes. You may be able to see the broken Cobalt bit in post #1. There were several like that. Usually I grind the end flat, then work the correct angle back into the tip from there. And of course, be sure to prevent the bit from getting hot by dipping into water frequently. Discoloration of the metal should be avoided.

OccupantRJ · Feb 3, 2013

Reading back through this thread this morning, I though I would make another input for people just getting into drilling. For those people who may not know why a pilot hole is needed for proper and easier drilling, take the largest drill bit you have and look straight on at the center web of the cutting end. See the small straight portion in the middle? Now imagine a round rod of that same diameter spinning. This is essentially the size of rod you are trying to push through a piece of metal during the drilling operation. With that in mind, imagine how much easier the drilling would be if that center was not in play. The lack of material in the center of the intended drilling location after pilot drilling allows the cutting edges of a larger drill to get a bite in order to auger it's way into the hole, and tends to keep the hole in the intended location. Get yourself a bright finish stubby drill in the 3/32" to 5/32" range to use as a pilot. Use a fairly high speed and more importantly, pull the drill out of the metal often while drilling to clear the chips out of the flutes. Drills snap when flutes jam full of material. Hold the drill motor with two hands while drilling. Back off pressure when you feel the drill exiting the other side. Watch the chips produced to tell what the bit is doing, and also how much pressure to apply. A fluid such as rapid tap or cool tool will also help the endeavor.

Schurkey · Aug 11, 2015

GRX said:
What is this lube & coolant stuff of which you speak? Well played. lol I keep one of those around filled with kerosene for cutting aluminum. This stuff is great also, especially for carbide burrs. Hard waxy consistency.

At home, I'm using some freaky liquid tap lube which evaporates too quickly and probably causes herpes or brain rot or some-such. (I think it's "TapFree 2", but it's been awhile since I looked at the bottle.)

When I was working on a so-called production line, we were given a product that was hard 'n' waxy, greenish color. Came in a round cardboard container, and the tool room would cut four inches off of a perhaps one-foot tube for an individual's use.

The stuff was "Do-All Tool Saver". I'd like to find a tube of the stuff, but I come up empty on Amazon and my web searches. I did buy a tube of a similar product--Blair Rotabroach stick lube. Castrol, CRC, and others also make stick lubes.

http://www.amazon.com/dp/B002YKH8L8/?tag=atomicindus08-20

uart · Aug 11, 2015

bad_idea said:
can you resharpen a drill bit with a chipped tip?

Yes definitely. You can grind them back to flat and totally reshape even very damaged bits.

I grabbed this old 3/8" HSS bit from scrap a few weeks ago just to practice sharpening. The end was amazingly worn, like almost completely rounded. It looked like it had been abused drilling something extremely abrasive. I sharpened it until the end looked good, but it still wouldn't drill holes for ****. Then I realized that the flutes themselves were completely worn for about the first 1/2 to 3/4 inch of the drills length.

So I cut clean though it with an angle grinder and lopped about 1/2" off the tip. Then I ground it back flat for another 1/8" or so on the grinder (to remove anything the might have been overheated by angle grinder) and sharpened it to a nice little stub bit. It drills absolutely fine now, I used it just today to put a couple of holes in some 1/2" steel plate.

You might notice that I ground the heel back a fair bit to thin the web on this one. So it's got what I think they call a high tensile notch ground into it.

Dennis Leigh Henry · Aug 11, 2015

I've found using a drill point gage useful. It helps you to know that the angle is correct, that the point is centered, and if you rotate the drill in the gage well, you can also evaluate your tip / relief.. This webpage appears to be full of good sharpening stuff...including the snip of the drill gage I used..

http://www.tpub.com/steelworker2/121.htm

uart · Aug 12, 2015

chickenfarmer said:
I can do it, but for some reason the sharp edge only last through one or two holes

Are you starting with quality HSS bits, or are they cheap imports. I've found that cheap "gold" coated Chinese bits don't really hold an edge very well once you grind them.

If you're starting with good quality bits, and assuming they held their edge ok initially (when new), then the most likely thing you're getting wrong is the relief angle. Getting the correct relief angle seems to be one of the things that gives people the most trouble when they're learning.

If there is not enough relief angle then the heel will just rub and the drill wont cut.

If there is too much relief angle then the cutting edge is weak and will flex or chip instead of cutting properly in hard materials (but will cut like crazy in soft materials).

I guess the other issue you might have is if you're sharping the drills down crazy short or something by doing too many repeated attempts. I know that when I was learning to sharpen I'd sometimes think to myself that all my bits will be machine screw length by the time I get this right.

If you sharpen a jobber length bit too short the web gets thicker (so it cuts less effectively) and the steel get softer if you get too close to the shank. You'd have to be grinding the heck out of them to do that though.

OutsideMachinist · Aug 12, 2015

Schurkey said:
At home, I'm using some freaky liquid tap lube which evaporates too quickly and probably causes herpes or brain rot or some-such. (I think it's "TapFree 2", but it's been awhile since I looked at the bottle.)

When I was working on a so-called production line, we were given a product that was hard 'n' waxy, greenish color. Came in a round cardboard container, and the tool room would cut four inches off of a perhaps one-foot tube for an individual's use.

The stuff was "Do-All Tool Saver". I'd like to find a tube of the stuff, but I come up empty on Amazon and my web searches. I did buy a tube of a similar product--Blair Rotabroach stick lube. Castrol, CRC, and others also make stick lubes.

http://www.amazon.com/dp/B002YKH8L8/?tag=atomicindus08-20

Yep I like both. Good cutting oil works fine most of the time. Do-All makes good stuff. The paste is good, especially if you are drilling around electrical components or something you don't want oil getting into.

2oolhound · Aug 12, 2015

I always pick up cans of drills when I see them cheap although I've got so many now they have to be real cheap. I toss them in a pile when they get dull. When it's late and I don't want to make a lot of noise but I don't want to shut down, I'll sharpen the drills.

Another thing that prolongs the the life of the tip is drilling pilot holes. If i have to drill a 3/4" hole I'll do 2-3 steps to get there. It may seen slow but every step cuts like butter and the 3/4" doesn't heat up from all that friction it would make.

Damn I love the smell of burning HSS in the evening.

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