All of Those Scrap Drill Bits!

[Frank S]

Am I the only one on this planet who doesn't use a drill doctor or a jig to sharpen my drills? For my drills larger than 3/4" I use my 118° drill gauge but for the smaller ones I find I can get a twin curl chip without it easy enough I hate those bench grinders with the v groove notch in them because I like to use the whole face of the wheel.
I would like to have another drill doctor if they would make one out of anything but plastic

[olderdan]

Am I the only one on this planet who doesn't use a drill doctor or a jig to sharpen my drills? For my drills larger than 3/4" I use my 118° drill gauge but for the smaller ones I find I can get a twin curl chip without it easy enough I hate those bench grinders with the v groove notch in them because I like to use the whole face of the wheel.
I would like to have another drill doctor if they would make one out of anything but plastic

I have never used any form of drill sharpening jig, all done by hand/eye, CBN wheel for small ones.

[DrByte]

I have a Drill Doc and use it often. I like sharp bits. I just want a better lasting bit. Thanks for the input Frank S!

[Ed Weldon]

I gave up on the drill doctor except for badly broken drills. I even bought a brand new spare dirt cheap at an estate sale and have yet to take it out of the box. That's because it doesn't easily produce a clearance angle. I've learned to eyeball the correct drill position and give it a finger twist of the shank to get a good clearance angle behind the 118 degree chisel edge.

[pfredX1]

Years ago on a lark I bought a 115 piece drill index set off Harbor Freight for $29.95 because it was just so damn cheap. It came with Chinese black oxide twist drills in it. So not really the best bits known to Man. But I regularly drill mild steel with them. They work fine in my home shop too, because I'm not doing high production, or working with exotic materials. I also calculate the optimal speed to run them at too. Most folks simply drill too high RPM and end up burning their bits up that way. I also use a drop of cutting oil when I drill steel too. I use Rapid Tap. Now the question is what is the right speed? I use 50 surface feet per minute for good sized drills, and a bit faster for smaller diameter bits. This is the formula to calculate surface speed SFPM=(PI*DIA*RPM)/12 DIA (Diameter of the bit) is in inches. PI=3.14159

So let's say you want to drill a 1/8" diameter hole. 1/8=0.125 So (3.14159*0.125*1500)/12=49 SFPM Running at 1,500 RPM you will get good results. Now your typical pistol hand drill runs anywhere from 2,500-3000 RPM. So a tad too fast. Though theoretically High Speed Steel should be able to handle 100 SFPM cutting mild steel. I find that twist drills seem to work better at half that speed for me. I run mill cutters at 100 SFPM though.

I should also add that if I think a bit is dull I'll sharpen it before I use it. Sharp tools work better. Being able to sharpen twist drill bits is a useful skill. It is worth practicing some until you get good at it. Understanding the geometry in your mind is a large part of the process. Your clearance, and what have you. Though if you are using a poor wheel your odds of success are nil. It is all fundamentals really. One thing builds on the next.

[Ed Weldon]

Good info, pfred. Thanks for the short course. I think Chinese metallurgists have pretty well dialed in the making and heat treating of ordinary steel alloys. Wasn't always that way. They have come a long way in the 40 years since their cultural revolution threw away 5000 years of Chinese science. From my own personal work experience I came to believe that the Taiwan scientists helped in preserving that culture. But it takes time to bring up the tribal knowledge of a culture whose old knowledge was systematically destroyed by politicians with their heads off in another world.

[pfredX1]

I have worse drill bits, that's for sure. I bought an old corded drill kit with a bunch of bits in it, and the whole package looks circa the 60s to me. There's Japanese bits in there that barely drill wood. They're bad.

[Frank S]

I was once on a job in a small town and my drill motor burned out mid job so I bought one at the only store in town that had tools the only drill motor I could find was a Wenn brand 1/4" chuck ultra cheap and with an even cheaper bit set that came along with it So I tossed them in the tool box and forgot about them. Finished the job then sometime later I tried to use one of the twist drills basically that is all they were just soft metal twisted to resemble a drill bit but they would drill in wood or did until I hit a knot in the board the bit wasn't even hard enough to break it just hung then twisted in the opposite direction. I kept it for years and would tell everyone the way to make a left hand drill was to find a knot in a piece of wood.

[Ed Weldon]

Frank S - Your story prompts mine. In recent years everyone is giving up on corded drills and going over to cordless. So perfectly good corded drills sell for next to nothing at estate and garage sales. Often at the next garage sale or flea market space there will be a complete cordless set with aged out batteries for which there are no usable replacements available at any price. Worthless, but there maybe a $30-$40 price tag on it. Go figure.....
Some time back I bought a good sized inverter to use in my truck for various stuff I use on long camping trips. When confronted later with a $5 used 1/4" corded drill I realized the inverter would drive it. It sits behind the seat of my truck with a bag of common resharpened drills. It's been useful more than once. One of these days I'll add some hex bits and wood spade drills to the bag. 5/8 spade drill is easy to resharpen and can drill a hole in a piece of wood for an emergency repair big enough to pass a rope through.

[pfredX1]

Ah yes, the Wen will it work brand of tools. I am familiar with them.