I'm looking at the drill doctors and notice they list drill angle from 115-140 and 118-135, or something like that. What is the "predominant" angle of what most of us hobbist use? Would either work in most cases. I have a friend that works at grainger and can get me a nice discount right now and I've wanted a drill doctor for sometime. What say the pros....that know!
Last edited by Peggy M; 07/23/20245:00 PM. Reason: added more info to the title
"Standard" jobber-length drill bits uaually have a 118 degree included angle between the flutes. They're good for drilling plain steel and some alloys that are harder than normal. The 135 degree bits have a little more aggressive cut in softer metals such as aluminum or brass, and don't do well with tough alloys. As the angle gets flatter and the speed is slowed down, harder metals can be drilled more efficiently. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Thanks Jerry. I think I'm going to buy me one 118-135 and sharpens up to a 1/2". I can't go wrong on the price my friend can get me one for....doing his brake job has benefits!!
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
Hey Alvin - a Drill Doctor is a good investment. Jerry is correct on the angles. Nothing can be more frustrating than a durn dull drill (and dangerous because you will try to force the drill to cut and possibly break the bit). We have a Drill Doctor in our shop and they work great.
I bought a drill doctor after years of sharpening by hand. I now think, "Why didn't I just buy one of these years ago?" I showed my neighbor mine and how it worked, and he went and bought one too.
I like them for general-purpose drilling. If I've got a special job to do, such as drilling very tough steel, I'll hand-sharpen a bit to a very flat angle, slow the lathe or drill press way down, and use a lot of lubricant like Rapid Tap. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
...I got tired of "trying" to use dull bits and I'd end up driving up to Ace Hardware and getting a new one. Now they are closing and its time to get on with the program. I probably spent enough for bits to pay for one....I just did it $3-$4 at a time. Trying to drill a hole with a bad bit is like trying to cut with a dull chain saw blade....... I just ain't gonna do it. It wears me out about as much as the bit or chain!!
Thanks for all the comments guys. I do appreciate it. I'll get mine next week. (it'll be happy EARLY birthday to me)
Jerry, My eye sight went south a few years ago...but then I never was GOOD at sharpening my own.
Here is a way to check your angle on your drill bits. Take to nuts American made and stick them together and you have 118 degrees I keep them in my tool box for refrence. My nuts happen to be 5/8" Dia. size just lay them flat and tack them together works great. 62Blue Don
62Blue 62Chevy in progress You've never been lost until you've been lost at Mach3" Paul F Crichmore (Test Pilot)
"Standard" jobber-length drill bits uaually have a 118 degree included angle between the flutes. They're good for drilling plain steel and some alloys that are harder than normal. The 135 degree bits have a little more aggressive cut in softer metals such as aluminum or brass, and don't do well with tough alloys. As the angle gets flatter and the speed is slowed down, harder metals can be drilled more efficiently. Jerry
It's the other way around...135-140 degree drill points are what is used for tougher materials. Here’s a good article on drill point geometry:
have the drill doctor, love it for smaller bits but have not had such good luck with the bigger ones. maybe its just me its kind of a new tool in the shop but its saved me a few times working late at night when the hardware store is closed. i still like a new bit when drilling precise holes. also as hot rod said i go slow even pulse the trigger on my drill seams to cut way better. as far as the drill press i have that set at the slowest speed all the time. drill bits are always frustrating even with the drill doctor seems your always missing the right one. maybe some day i will figure out how this happens. good luck with your new tool later MO
Isn't the angle made by tacking two hex nuts together actually 120 degrees, not 118? Close enough, I guess! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Mo, as my eyesight went south I decided to get me a drill doctor. It took a little "practice" but I think I've got it figured out. The one thing I found out is to not be afraid to sharpen and sharpen and sharpen..until the bit is done right. I torture bits myself and it takes more than a "pass" on the doctor to get them back in good shape. I've reset and re-sharpen many to get it right. I can't remember which angle drills the best but the doctor is set up at 118 and 130 if my memory is correct. Heck, once I got all my bits sharpened up, including the split bits, I may not ever need the doctor again in my life time!! Stay at it. You'll get the hang of it.
I have a drill doctor. I've noticed that if the drill is abused, so that the rise along the flute edge is ground down. Darn bed angle. The drill has to be sharpened down enough to get a clean edge on the flute. That can take sometime even in a DD. Grinding off the the tip is an option, but I can't hand sharpen to begin with. That's why I bought the DD. I don't abuse my drills anymore, if I have any doubt about it's cutting, I put it in the drill doctor.
Larry
I don't own a vehicle that isn't old enough to drink.
If you have a bit that's in really sad shape take it to the bench grinder, belt sander, or even start with a cutoff wheel. Do the best you can approximating the angle and relief but don't worry about being perfect. Stop when you have it back to clean full diameter at the corners. Then take it to the doctor for the final cleanup. Faster that way and avoids some wear on the wheel in the doctor.
I saw this on Youtube the other day and thought he did a fair job of demonstrating the technique for dressing up a twist drill. But I think I'd try a smaller stone for smaller bits
i do the same as you do chipmunk i keep turning that thing until my wrist is sore then i switch hands. maybe my probsbly with the bigger bits is the diameter thing next time i will grind it done on the bench grinder first. easy enough now that the company i work for threw out my new dewalt bench grinder. something about osha. so they bought a 1500 dollar disc/belt sander for us to use. all i had to do is pickit up out of the garbage can. great deal for me as it was only 6 months old. later MO
Grigg, I've tried that several times so far with a grinding wheel, so far hasn't worked out. I'll try a cutoff blade next time.
btw there are fine and coarse wheels for the DD.
Larry
I was suggesting cutting off a 1/4" or 1/2" or whatever part of the drill is bad with the cutoff wheel to save time. Then still use the grinder to get it back in approximate shape before truing it nicely in the doctor.
I have a fancy version of the Drill Doctor at work, a Darex V390
It's a great machine but still more efficient to rough out nasty chipped or burned ones on the belt sander or grinder first.
i use several drills larger than my drill doctor will handle. i have drills in 64ths up to 2" and 16ths from 2 to 3". a lot of these i bought used and use once and a while. i can usually get them better with the grinding wheel but they never seem to cut as good as a new one. even with the drill dr on the smaller ones, they never seem to do quite as good a a new one, but it's prob just me.
Drill doctor has a plastic 'V' representation for 118 and another for 135 so its real easy to see what angle your bit is right on the outside of the unit. This is one of the most awesome tools in the shop. Whats so nice about it is, you can purchase the HF 115 pc drill bit set for $50 or so and never look back. I have drilled about 100 1/2" holes before needing to resharpen. Worth every penny. And my unit is 10 years old!
