I need to either buy a drill doctor and keep sharpening my high speed steel bits or buy some expensive cobalt bits for drilling steel. Any advise appreciated. I see a 29 piece cobalt drill bit set at Harbor Freight that looks interesting. Anyone own that and want to comment on the quality?
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Drill Doctor or cobalt bits
- Thread starter diamond
- Start date
Larry DeCamp
Well Known Member
Fastenal drill bits
Diamond, fastenal outlets keep good qulity industrial bits in a case at the front counter. You jus open the lid and pick what you need. They will drill stainless ( @ slow rpm with pressure and cutting lube)
Diamond, fastenal outlets keep good qulity industrial bits in a case at the front counter. You jus open the lid and pick what you need. They will drill stainless ( @ slow rpm with pressure and cutting lube)
Isaac
Well Known Member
Drill Doctor
I have a Drill Doctor in my shop that is collecting dust. I was never able to make it work (or felt that it worked) well enough to justify buying it.
I would suggest getting the common drill bit sizes that are used in a RV project
#40 and a #30 for 3/32" and 1/8" rivets
#28 (or #27) for size 6 screw
#19 for size 8 screws
#12 for size 10 screws and AN3 bolts
1/4" for AN4 bolts
A package of 10 of each sizes listed above are probably all you will need to do an entire build for any of the RV types. As you get further into it, you may find you need something else.
For larger holes invest in a reamer or the cheaper alternative a "step" drill. Large drill bits don't work well in thin aluminum or (4130 steel or SS), they tend to rip holes rather than cut.
Personally, I like the piloted double margin drill bits that Pan American tool sells. The hole quality they produce is on par with what you get with a reamer. The drill bits and reamers that Pan American sells are high quality. My only complaint with Pan American is their shipping charges tend to be higher than other tool providers like Brown, Avery and Cleveland.
I have a Drill Doctor in my shop that is collecting dust. I was never able to make it work (or felt that it worked) well enough to justify buying it.
I would suggest getting the common drill bit sizes that are used in a RV project
#40 and a #30 for 3/32" and 1/8" rivets
#28 (or #27) for size 6 screw
#19 for size 8 screws
#12 for size 10 screws and AN3 bolts
1/4" for AN4 bolts
A package of 10 of each sizes listed above are probably all you will need to do an entire build for any of the RV types. As you get further into it, you may find you need something else.
For larger holes invest in a reamer or the cheaper alternative a "step" drill. Large drill bits don't work well in thin aluminum or (4130 steel or SS), they tend to rip holes rather than cut.
Personally, I like the piloted double margin drill bits that Pan American tool sells. The hole quality they produce is on par with what you get with a reamer. The drill bits and reamers that Pan American sells are high quality. My only complaint with Pan American is their shipping charges tend to be higher than other tool providers like Brown, Avery and Cleveland.
aparchment
Well Known Member
Drill Doctor - Don't Waste Your Money
Ditto what James said. I couldn't make the Drill Doctor work for small drill bits (#30 and #40), so I resorted to just buying the HSS in lots of 10 as I needed them.
Ditto what James said. I couldn't make the Drill Doctor work for small drill bits (#30 and #40), so I resorted to just buying the HSS in lots of 10 as I needed them.
BillL
Well Known Member
Good list. I have found the long reach #30 and #40 to be very helpful in getting the drill away from the action. One each is enough. Especially in working in the upper forward fuse for avionics/wiring. My HF step drills actually work pretty well. I turned down the drive shank on one to fit my angle drill.
BTW - I have a Drill Dr too, and it sharpens maybe 3/16 and up pretty well, below that new ones are best. The only thing that would be better than the Dr is a professional sharpening machine. It is the best sharpener I have used and I have tried many in the last 5 decades including by eye against a bench grinder.
Sam Buchanan
been here awhile
The best way to sharpen #30 and #40 drill bits is to hold them firmly between thumb and forefinger as you make an underhanded swinging motion in the direction of the nearest garbage can. Release the bit at the apex of the swinging motion, with practice you can launch the bit with a graceful trajectory into the can with one attempt. 
ColoRv
Well Known Member
The best way to sharpen #30 and #40 drill bits is to hold them firmly between thumb and forefinger as you make an underhanded swinging motion in the direction of the nearest garbage can. Release the bit at the apex of the swinging motion, with practice you can launch the bit with a graceful trajectory into the can with one attempt.
Underhanded? Seriously? Like girls softball?
Personally, I throw anything under 3/16 at my hanger mates Piper Cub. Five step drop, Manning goes deep to Thomas.... Broncos beat the SeaTurtles 51-3 in New York!
It's remarkably difficult to penetrate that fabric with a #40 bit!
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380mxc
Member
Don
Well Known Member
Drill Doctor
I have a Drill Doctor and I've been satisfied with its performance?but not until after I figured it out. There was a learning curve and as simple as it is to operate, I don't know why. There seem to be two "tricks" if you will. The first is simply following the directions to line the bit up in the holder so you sharpen the correct angles on the bit. If you don't get this step right, your bit won't come out sharp. The next "trick" is to take an even number of light passes. It doesn't take much unless you've abused the bit, in which case, Sam B's sharpening method is what I'd use.
I wasn't happy with my initial results and after some frustrating results I took an hour or so and carefully read and followed the directions and practiced until I got decent results on 1/4" bits and larger, then proceeded to apply what I'd learned to the #30 and #40 bits. They're harder to 'feel' when they're in the bit holder correctly and harder to keep in alignment while you tighten the holder.
And of course the disclaimer - I am not affiliated with Drill Doctor other than owning one.
The other thing I'd recommend is buying at least decent quality bits. Avoid the cheap ones as you'll regret the purchase. I have a full numbered and fractional set from Harbor Freight and they're not decent quality bits (the box and the price are the two best things going for them). I happen to like the bits Bob Avery sells but I'm sure others see bits just as good.
I have a Drill Doctor and I've been satisfied with its performance?but not until after I figured it out. There was a learning curve and as simple as it is to operate, I don't know why. There seem to be two "tricks" if you will. The first is simply following the directions to line the bit up in the holder so you sharpen the correct angles on the bit. If you don't get this step right, your bit won't come out sharp. The next "trick" is to take an even number of light passes. It doesn't take much unless you've abused the bit, in which case, Sam B's sharpening method is what I'd use.
I wasn't happy with my initial results and after some frustrating results I took an hour or so and carefully read and followed the directions and practiced until I got decent results on 1/4" bits and larger, then proceeded to apply what I'd learned to the #30 and #40 bits. They're harder to 'feel' when they're in the bit holder correctly and harder to keep in alignment while you tighten the holder.
And of course the disclaimer - I am not affiliated with Drill Doctor other than owning one.
The other thing I'd recommend is buying at least decent quality bits. Avoid the cheap ones as you'll regret the purchase. I have a full numbered and fractional set from Harbor Freight and they're not decent quality bits (the box and the price are the two best things going for them). I happen to like the bits Bob Avery sells but I'm sure others see bits just as good.
The big box of drills from Harbor Freight or Northern tools is good. Then go buy 5 each of the cobalt drills in common sizes from Spruce - 40, 30, 19, 10 etc.
You wear those out quickly, the others only get used occasionally.
You wear those out quickly, the others only get used occasionally.
Mike S
Senior Curmudgeon
Yep, a good bench grinder, with a good wheel-------and a bit of operator training, and a lot of practice.
If you know any old time machinists, talk to them. Drill and tool bit sharpening is one of the first things you learn in a machine shop.
This guy has it correct----at least as I learned to sharpen drills way back in high school, and in the machine shop. http://www.youtube.com/watch?v=-wXBbbDVksk
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acroflyrgirl
Well Known Member
The best way to sharpen #30 and #40 drill bits is to hold them firmly between thumb and forefinger as you make an underhanded swinging motion in the direction of the nearest garbage can. Release the bit at the apex of the swinging motion, with practice you can launch the bit with a graceful trajectory into the can with one attempt.
Who would have thought I could be so entertained while learning about sharpening theory here on VAF.
Too funny y'all. Too bad about the little Denver ponies, going to get sent to the proverbial glue factory in NY by the Seahawks.
Shame on me
I bought a Drill Doctor twice. You know the old saying, "Fool me once, shame on you, etc."
The first one was the old vertical Green model 750. Top of the line. Worked for about 50 to 100 bits before becoming unserviceable. Called the company, and ordered "overhaul" parts. Never could get it to work.
Was told the new gray model was much better. Spent more money. It worked only for bits in the 1/4" to 7/16" range. Others no good. Wasted more Franklins.
If you look at the machine, the working parts are plastic. Once wear starts, the alignment and tolerances go out the window. IMHO, the newer model has even less support in the rotating mechanism. Plus the adjustment range of drill relief angles wasn't even in the ball park.
Darix makes drill sharpening machines that are orders of magnitude more expensive for production work, but I'm not buying any more of their stuff.
If you Google "drill sharpening" and "4-facet bits", etc., you can come up with some interesting stuff. Like making your own sharpener for small bits. Down to #80. But it takes a lathe and a mill to do it. If you have a lot of time and energy on your hands you can probably make it work.
The problem with sharpening small bits for aircraft aluminum use, is, that the bits wear in diameter as well as at the tip, and can affect rivet fit, etc. In machining work, drill bits are like horseshoes, getting it close counts. Then you ream for exact fit. So sharpening bits may be the way to go. For aircraft sheet metal, you can't afford to ream #40 holes.
My 2 cents.
DA
6A build
I bought a Drill Doctor twice. You know the old saying, "Fool me once, shame on you, etc."
The first one was the old vertical Green model 750. Top of the line. Worked for about 50 to 100 bits before becoming unserviceable. Called the company, and ordered "overhaul" parts. Never could get it to work.
Was told the new gray model was much better. Spent more money. It worked only for bits in the 1/4" to 7/16" range. Others no good. Wasted more Franklins.
If you look at the machine, the working parts are plastic. Once wear starts, the alignment and tolerances go out the window. IMHO, the newer model has even less support in the rotating mechanism. Plus the adjustment range of drill relief angles wasn't even in the ball park.
Darix makes drill sharpening machines that are orders of magnitude more expensive for production work, but I'm not buying any more of their stuff.
If you Google "drill sharpening" and "4-facet bits", etc., you can come up with some interesting stuff. Like making your own sharpener for small bits. Down to #80. But it takes a lathe and a mill to do it. If you have a lot of time and energy on your hands you can probably make it work.
The problem with sharpening small bits for aircraft aluminum use, is, that the bits wear in diameter as well as at the tip, and can affect rivet fit, etc. In machining work, drill bits are like horseshoes, getting it close counts. Then you ream for exact fit. So sharpening bits may be the way to go. For aircraft sheet metal, you can't afford to ream #40 holes.
My 2 cents.
DA
6A build
