dickfoster
Elite Member
A Drill Doctor will pay for itself in short order. Maybe you can get Santa to bring you one, he brought me mine.
Drill bit sharpening
- Thread starter JRobyn
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dickfoster
Elite Member
What?! Tungsten carbide takes diamond tooling to do anything with it.
thompsonseatgrinder
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The Drill Doctor 750 comes standard with a diamond wheel and will sharpen anything up to cobalt and carbide. Most concrete bits are carbide. The green wheels on the bench will also work as CalG mentioned.
Wagtail
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Sucking at something is the first step to being sorta good at something.
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Not really. I do use a diamond hone to touch up carbide tooling ocassionally when running a multi station CNC in the shop but most of my tooling is now ceramic.
Creamer
Elite Member
When I used to have the tool shop I found I could pay a machinist to stand at a grinder and sharpen drill bits or buy a Drill Doctor and have a flunky do it at a lot lower rate. The bottom line was that the Drill Doctor did it as well and more consistently than a machinist on a bench grinder and a lot quicker at a lot less cost. At first the machinists laughed but soon the machinists were just using the drill doctor if we did not have a sharp drill available.
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In drillspeak, you have the lands, the heel, the point and the relief and all must work together to cut a cylindrical hole. I would suggest (if you offhand sharpen) getting a drill point gage.
The true test of a properly sharpened drill bit is you get equal swarf from both cutting edges when you feed the drill into the work with the drill secured in a drill chuck, affixed to an accurate spindle, such as a good drill press, a vertical mill or a lathe tailstock. Half arsed sharpening will suffice for cutting purposes, but the drill won't drill an accurate hole because the cut action is lopsided and that causes the drill point to run out and drill a non-concentric hole. In the shop, to offset that, we use chucking reamers to make oval holes concentric.
When both sides (heel and cutting edge) is sharpened properly and correctly, the line (center point) of the bit will be perpendicular to each side. That applies to ordinary split point drills and parabolic drills as well.
On drills over 1/4" 0.250, I always relieve the heel as well as relieving the heel allows easier drilling and also allows lubricant/coolant to reach the cutting edge easier.
I used to sharpen all my mills, I own a cutter grinder but it's actually cheaper to toss them unless it's a very large cutter, than sharpen them.
Offhand sharpening accurately and consistently is an acquired skill, just like playing a Guitar or TIG welding. Just because you do it correctly one time, don't mean you can repeat it. Takes practice and lots of it.
I don't throw any twist drill away until it's too short to work. For me, it's so easy to resharpen one, if a drill isn't cutting properly, I pull it out of the chuck and over to the Milwaukee bench grinder for a touch up and back to the machine... maybe a 45 second job.
The true test of a properly sharpened drill bit is you get equal swarf from both cutting edges when you feed the drill into the work with the drill secured in a drill chuck, affixed to an accurate spindle, such as a good drill press, a vertical mill or a lathe tailstock. Half arsed sharpening will suffice for cutting purposes, but the drill won't drill an accurate hole because the cut action is lopsided and that causes the drill point to run out and drill a non-concentric hole. In the shop, to offset that, we use chucking reamers to make oval holes concentric.
When both sides (heel and cutting edge) is sharpened properly and correctly, the line (center point) of the bit will be perpendicular to each side. That applies to ordinary split point drills and parabolic drills as well.
On drills over 1/4" 0.250, I always relieve the heel as well as relieving the heel allows easier drilling and also allows lubricant/coolant to reach the cutting edge easier.
I used to sharpen all my mills, I own a cutter grinder but it's actually cheaper to toss them unless it's a very large cutter, than sharpen them.
Offhand sharpening accurately and consistently is an acquired skill, just like playing a Guitar or TIG welding. Just because you do it correctly one time, don't mean you can repeat it. Takes practice and lots of it.
I don't throw any twist drill away until it's too short to work. For me, it's so easy to resharpen one, if a drill isn't cutting properly, I pull it out of the chuck and over to the Milwaukee bench grinder for a touch up and back to the machine... maybe a 45 second job.
pmsmechanic
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CalG
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I'm with 5030
if I don't like the way the drill is cutting, out it come, over to the grinder for a "dusting off".
I've been known to watch the chip formation and touch up the lip that needs attention. Somewhat easier on the lathe than the drill, as the bit isn't turning in the tailstock chuck.
if I don't like the way the drill is cutting, out it come, over to the grinder for a "dusting off".
I've been known to watch the chip formation and touch up the lip that needs attention. Somewhat easier on the lathe than the drill, as the bit isn't turning in the tailstock chuck.
