Drill bits - what to buy and how to sharpen?

[58Apache]

I have broken and dulled more drill bits during my restore than I care to count. I have come to the point where I have to admit I don't know beans about what is the best kind of drill bits to buy for drilling mild steel. I have drilled everything from mild 18 ga sheet metal to real thin stainless. I have also ran into problems where I had to drill into the thicker steel on the frame and similar parts.

I bought a drill doctor a while back, and it seemed to work for a while. I guess I need to recheck the settings and pay closer attendtion to what angles the bits are ground at, but things didn't work so well these last few times when I had to use a 1/8 bit to drill thin stainless. I gave up sharpening and went and bought several two packs because I knew I was going to break several and dull several.

You guys had some great tips on removing screws/bolts, I figured I could use a good education on drill bits. What to buy, and what you do to sharpen and any other tips you might have.

                                                 Steve

[WZ JUNK]

I use my drill doctor a lot.  I can still sharpen the large bits by hand but the drill doctor fills in on the smaller ones.    I started having trouble with it recently and I was told you could turn the stone end for end and get some additional use out of it but it did not help mine.   It would still sharpen the cutting edge but it was not grinding the relief correct. Saturday I bought a new stone and now it seems to work just fine again.

[Crosley.In.AZ]

My Drill Doctor works great.


I need to get a new abrasive  drum thingy for it .


Any body here sharpen left handed drills?  I use left handed stuff for broken bolt removal in tranny work

[enjenjo]

What he said. I have a drill doctor too, but fatcat is the one who uses it. I grind them by hand, learned to do it many years ago. I like AceHanson bits, but lately I have been buying Vermont American. the quality seems to be ok. If you have a machine shop supply around, they usually have good bits at reasonable prices.

[rooster]

About all my bits are dull to. I got this tool at a swap meet but have never used it, its made by Craftsman , I need the right stone to attch to my bench grinder before I can try it out.

[jaybee]

Is this where the tech on sharpening drill bits goes?

[DRD57]

When I was a little jr. gearhead and used my pop's tools, I was always frustrated by the drill bits. They were all just tossed in a box, lots of sizes missing and none of them were sharp.

I'm sure there is a psychological explanation for this. Now I have 4 or 5 drill indexes full of drills which I keep sharp with my best friend, the Drill Doctor.  

I was helping one of my buds in his shop a few weeks ago and I had a flashback. Drill bits everywhere and all of them as dull as a 14 year old in the second grade.

It's hard to do good work without good tools.

[Pep]

I learnt years ago how to sharpen bits on a bench grinder. The important aspect is getting a grinder with a tool rest with a "V". This "V" is the right angle the cutting edge needs to be. What you do then is hold the bit in the "V" with one cutting edge parrallel with the tool rest. Then push the bit into the stone slightly. At the same time, lift the bit straight up ( not rotate as some seem think ) This should create  a champher so the cutting edge is not foulded by the shoulder of the bit. Do the other side the same and try and grind the same amount off. The end result should look like two even cutting edges with a small straight line seperating the cutting edges...It's fairly hard to do small bits and as I get older the minimum size gets larger....I think in a couple of years I'll be sharpening 1/4" and above only

[EMSjunkie]

Pretty good tips guys, thanks. my neighbor has a drill doctor, the hardest thing he drills is maple wood. may have to go borrow it next time he leaves his garage door open. I like the Hanson bits too, they seem to last pretty well. I know you don't want to buy drill bits from Harbor Freight. don't have much of an edge to begin with, then after 1 or 2 uses they are useless.

thats my story and I'm sticking to it.

Vance

[BarryM]

Freehand is the only way I have done it.  Can always compare to a fresh one if it go's funky, a commonmistake is a tendancy to make a point on it. I would try a 3/8 or bigger at first so you can easily see what is happening. It  mostly consists of a motion that grinds  back from a leading edge along with breaking away from the center so as not to hit the next leading edge.
Once you get it figured out  variables are possible, I once flattened a  bit to do a countersink. Took at least a dozen trys but it cut a flat bottom hole like an end mill. Too much angle  from the leading edge and it can be fed too fast, chip's the edge easier. Have a cup of oil to cool them in if whittling a lot off. Trial and error just like learning to sharpen a chain saw.
I have lately taken to using oil every time I drill and going slower so they can actually cut, amazing how they last when used right.  The old saying "Too soon old, too late smart"

[Bruce Dorsi]

As usual, you get what you pay for!
....My attempts to save money often result in frustration and then subsequently buying what I should have purchased the first time!

I have learned that bits made in the USA are far superior to most of the bits from India or China.

I avoid buying any bits that are not marked HSS or cobalt.

Bits for sheetmetal usually have a 135(?) degree angle compared to the usual 118 degree point.  ....The flatter point has less tendency to wander, and drills a more-circular hole.  Common 118 degree bits tend to make 3-sided holes in thin materials.  .....Uni-bits (stepped drills) work well in thin materials.

When drilling stainless, I am most sucessful when using a slow speed, but a high feed-pressure.

I always sharpened my bits free-hand, with good results.  ....I bought a Drill Doctor a few years ago, and it works great.  ....I still sharpen a few bits free-hand if that is more convenient, but the Drill Doctor provides consistent results with minimal concentration.

[DocsMachine]

Drill bits can be a books' worth of information all by themselves.

The first thing is, 90% of the time you're turning it too fast. I see guys with 1/8" bits in air-drills turning 2,000 RPM, or guys with a 1/2" in a HoleHawg doing 500 RPM.

Slow down some- most of the time you'll find the thing cuts better at a slower speed, and you'll be less likely to make a triangular hole. Of course, that means you need a variable-speed drill...

Second, use a pilot hole. The center of the drill moves the slowest and has the shallowest edge, so cuts the poorest. For anything over 1/4" or 3/8", it's useful to pilot drill with something about the diameter of the center web of the final-size drill.

Also, use lube. WD-40 in aluminum, any ol' motor oil in steel. If you're going any real depth in stainless, it can't hurt to get some of the black high-sulfur cutting oil. And remember that stainless can work-harden at the drop of a hat. Never let the drill "idle"- if it's turning, it should be cutting. If it's not cutting, it shouldn't be in contact with the surface.

If it work hardens, either by trying to go too fast or letting it idle, you can sometimes get through with a new, sharp drill, but I've seen it bad enough you'll have to bump up to a carbide or cobalt drill. You can also try coming through from the other side.

On that note, coatings are worthless. "Titanium", "Titanium Nitride", "cobalt coated" and all that... TiNitride- the gold-colored stuff- does add a small bit of surface hardness, but it's only a few microns thick, so it doesn't add much. It's mainly a lubricity thing- it keeps chips from "welding" to the cutting faces. Useful in a CNC production enviroment, but pretty much worthless in a home-shop. It's just bling-bling to get you to pay more for the bit.

Same with cobalt- if the bit is a real cobalt alloy (usually referred to as M2 HSS, or 10% Cobalt) then that's a good improvement over 'plain' high speed steel. Cobalt adds heat toughness- the metal doesn't soften as much as it gets hotter, as plain carbon steel does.

But cobalt coatings are as worthless as the Ti coatings. Might be useful in a production enviroment where you're making 5,000 pieces, but just an extra cost for the home-shop user.

Buy good quality American-made drills, NOT ones that come in bubble-packs at Wal-Mart or Home Despot. Those ones might be okay for woodworking, but I wouldn't use 'em for anything critical. Try and find a real live industrial supplier, or barring that, mail-order some from a machinery supplier.

Good drills are worth every penny.

Doc.

[enjenjo]

Not to say we shouldn't buy American, but I find a lot of drill bits made in Britain in what I buy from the local jobber, and they are excellent.

[WZ JUNK]

Not to say we shouldn't buy American, but I find a lot of drill bits made in Britain in what I buy from the local jobber, and they are excellent.

I am going to try a set of Grizzly HSS bits.  I was going to pick up a set Saturday when I was there but they were out of stock.

[Mikej]

Leading point needs to be higher than the trailing end. Both sides about the same. Angle close but not that important. Lots of practice. Don't over heat. Small bits seem to be getting harder to sharpen for some reason.