Drill Bit Sharpening
Hello Everyone
Over the years I have sharpened several wood boring bits, but I have never successfully sharpened a metal boring bit, that is until today. Many years ago, I picked up a drill bit sharpener from someplace. This sharpener was all rusty and inoperable. Recently I decided to revamp the sharpener and make it operational. And today I made a temporary setup for a grinder and the drill sharpening tool. For a trial run, I did not pick just any old bit. I picked one of the largest and dullest bits that I had. My selection was a 7/16" 135 degree bit, that was so dull, it probably would have struggled going through a piece of paper. After a few setbacks of learning how to properly use the drill bit sharpener, I finally finished up with the 7/16" bit. Most of the bit looked old and weathered, but the tip looked pretty good, and of course, you know I had to test it's ability to drill metal. Once again, I did not just pick a random piece of metal, instead I chose the thickest piece of aluminum that I had available, which was 1" thick. To quickly sum it up, it drilled right through it, like a hot knife slicing through butter.
Needless to say that tomorrow will be a long and boring day, but when it is over, I will be a happy guy. However, I now kick myself for all the bits that went in the trash
Even though my drill grinding attachment is probably 30 years old, they are still available through Sears. If anyone is interested, here is a link: http://www.sears.com/general-drill-grinding-attachment/p-00925444000P?prdNo=1&blockNo=1&blockType=G1
I give this tool the thumbs up
Bruce
Over the years I have sharpened several wood boring bits, but I have never successfully sharpened a metal boring bit, that is until today. Many years ago, I picked up a drill bit sharpener from someplace. This sharpener was all rusty and inoperable. Recently I decided to revamp the sharpener and make it operational. And today I made a temporary setup for a grinder and the drill sharpening tool. For a trial run, I did not pick just any old bit. I picked one of the largest and dullest bits that I had. My selection was a 7/16" 135 degree bit, that was so dull, it probably would have struggled going through a piece of paper. After a few setbacks of learning how to properly use the drill bit sharpener, I finally finished up with the 7/16" bit. Most of the bit looked old and weathered, but the tip looked pretty good, and of course, you know I had to test it's ability to drill metal. Once again, I did not just pick a random piece of metal, instead I chose the thickest piece of aluminum that I had available, which was 1" thick. To quickly sum it up, it drilled right through it, like a hot knife slicing through butter.
Needless to say that tomorrow will be a long and boring day, but when it is over, I will be a happy guy. However, I now kick myself for all the bits that went in the trash
Even though my drill grinding attachment is probably 30 years old, they are still available through Sears. If anyone is interested, here is a link: http://www.sears.com/general-drill-grinding-attachment/p-00925444000P?prdNo=1&blockNo=1&blockType=G1
I give this tool the thumbs up
Bruce
Comments
Very nice. Now I wish I had one of those.
The tool I have is pretty time consuming, and now, I don't believe I have the patience to do this all day. I think I will have to sharpen them as I use them. I imagine with proper upkeep of the bits that it would probably amount to about a minute a bit, but some of my bits are in horrible shape.
Anyhow, thanks for the link and video.
Bruce
For larger bits, even at $140 for the Drill Doctor, that's overall cheaper than buying bits with fancy coatings. The coating will grind off anyway when resharpened, so you might as well get a cheaper set of steel bits, and sharpen as needed. Depending on the amount of drilling you do, the grinder will pay for itself in a year or so.
-- Gordon
Yea that is a wonderful thought, a new set of numbered, lettered, and fractional bits, would be great. However my money is very tight until the patent sells. But once it sells, tool sales will sky rocket
In my opinion, I drill a lot of holes, in comparison to the normal guy or gal. Honestly, I am tired of drilling holes
Bruce
Which tool do you hate?
BTW, before I bought a Drill Doctor, I bought a cheapo sharpener from Harbor Freight - it was pathetic!! Got my money back at least.
@lardom- Good luck to you as well.
I'm not paid by the hour, but by project, so the only way I can give myself a raise is to work more efficiently and get more done. The replacement bits end up costing a dollar or two per month, and I treat it as a business expense. (In fact, it's one of the least costly expenses in my business!) If I heavily used 1/4" or larger bits I'm sure I'd sharpen them rather than replace.
I drill a lot of holes, too, but on a CNC router that uses mill bits (and of course this is all with plastic, not metal). It's not a tool-changing rig, so one bit does all the holes. I replace it far more often than I'd like.
-- Gordon
I have given up on the current resharpening method, because in my opinion, it is unreliable. Drill bits naturally get dull from repeated drilling. In some cases, it certainly would be more beneficial to just buy new bits,especially the smaller ones, but when you start talking about buying larger bits in individual quantites, well that can get expensive, and it is not always convenient. Over the last three years, I have replaced my bits when they got dull, but enough is enough. I just need a nice resharpening tool. I use a lot of numbered and lettered drill bits, which most stores don't carry. Luckily for me, local suppliers have at least started to stock a limited supply of the numbered drill bits, but the lettered drill bits are much harder to obtain. My current situation requires a letter B machine screw drill bit, and of course, I will have to wait until at least tomorrow to order it, and then it could take anywhere from a day to a week until it is delivered.
I will eventually purchase a drill doctor and some new bits and sharpen as required. However, for the smaller bits, that will always be a replacement.
Bruce
Just a thought.
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I can hand sharping a drill-bit to factor specs.;Re-tempering not so much.One can quench grind past the Burt-up tip of a tool bit, But its very time consuming.
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A good understanding of a speeds & feeds chart will prolong tool life tremendously.
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Hand grinding works very well once you understand the cut angles and the relief angles. And the chiseling edged.
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http://www.winsloweng.com/articles/drillChart_content.htm
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http://www.cuttingtoolexpress.com/html/speeds_and_feeds_-_drilling.html
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http://www.youtube.com/watch?v=pW7kGFcM2sc
-Phil
Right now my friend and I put up a building at his farm and have a few mills, a couple of drill presses, three lathes, a lookalike Bridgeport, a surface grinder and some odds and ends attachments we bought to help out local farmers and make a couple of bucks. The only problem is that farmers hammer, weld, shim and altercate everything they own till it is so far out of shape that it cannot be repaired. I just go up a couple of times a week mostly to play and make attachments for my garden tractor or my grill.
Seriously though, when a bit gets to the point where it doesn't cut through metal anymore I just dress it up a bit on the grinder, and it works fine enough for my purposes. Of course I don't do detailed machining like some of you guys. If it was me, I would just use new bits for the precision work, and throw the dull bits in a drawer to be sharpened and used for projects that don't require high precision. Come to think of it, I do have a lot of old miscellaneous bits filling up a drawer in my garage.
Simply drill a pilot hole with a much smaller and sharper bit.
I have done this to get through 1/2" or so of mild steel with ease. First I would use a 1/8th drill bit, then follow up with the appropriate size - often quite large, like 1/2" diameter.
How does it work? Well the tip of the bit dulls first. So by drilling the pilot hole, the larger bit doesn't bounce off a dull point. And there are added benefits in using a small pilot hole. First, the drill bit stays centered on the pilot hole - no drift. And second, the two-step process is much faster and easier than sitting on a big drill bit and pushing with all your might.
In a pinch, emery cloth can sharpen smaller bits by hand if they are not it really bad shape. I've used a belt sander with 220 grit. You don't have to have a stone wheel.
What do you do if your 1/8 drill bit gets dull? Do you predrill with a 1/32 drill? I know drilling with a 1/2 inch drill is hard with a hand drill and I generally use a 3/16 drill first to make it easier but we are talking about dull cutting edges. Tools cut better with sharp cutting edges!!! Drills are easy to sharpen. Take a little bit of time and look at what you have started out with. These are generally called twist drills so most people thin you have to twist them to sharpen them. They are absolutely wrong. If you take a drill and hold it about the same angle on a grinding wheel ( or even a belt sander ) and roll it down you will get some relief. It has to be negative relief or it will not cut. DO NOT TWIST. DO NOT TAKE BIG CUTS. Take a small amount from one side and keeping your hand in the same position take another small amount from the opposite side. Keep this up until the angle is around 59 degrees and both sides look even. ( I am old so in my case I need magnifying glasses attached to my glasses ) Take your time, I found out early in my apprenticeship that if you keep your tools sharp you will wind up with a correct part which was done with little effort that was done in a small amount of time.
As a carpenter, I would carry at least a dozen freshly sharpened circular saw blades for finish work and I would regularly have the crosscut and rip handsaws sharpened. Carbide blades are nice, but tend to be run until teeth are chipped and missing. Wood spade bits would be sharpened by hand with a file.
But there are those days when someone has a piece of steel that needs a bolt hole and out comes a set a rather neglected twist drills. 3/16 or 1/8 doesn't make much differences to me in a pilot hole - just the fast that the bit is small, good steel, and sharp.
When you carry around $1000 to $1500USD of tools to just stay employed, you tend to not want more weight and more costs.
I did mention that we'd use a belt sander to sharpen twist drills.