OT - anyone re-sharpen drill bits ?

[AJMD429]

Anyone use one of these to re-sharpen drill bits...? I've accumulated boxes and boxes of dull bits over the past several decades...


http://www.northerntool.com/shop/tools/ ... _200320247

[Lastmohecken]

I have not used it, but I have used others over the years. It will probably work, although I have never been a big fan of drill bit sharpeners. I learned to sharpen drill bits by hand and eye on a regular grinder. I have even used a right angle grinder in the field on many occasions. I work construction.

The main think is try to keep the same angle, and make sure that you get the shoulder lower then the cutting edge, or it won't hardly cut butter, but take too much off the shoulder and the bit will grab a lot worse when it breaks through the material you are drilling. The problem I have had with some factory sharpeners is they would leave the shoulder too high, and the bit just wouldn't cut worth a darn.

[Chuck 100 yd]

I free hand them. Learned how in the tool room at Schurman Machine Works when I worked there.

There is no trick if you understand how a machine tool cuts,Rake,primary and secondary clearances etc. There should be one on the internet one could Google.

[geobru]

I learned to use a grinder to sharpen drill bits from my dad and have never used a sharpener. It sounds difficult, but if you don't have it right, you know immediately when you try to use it. Keep trying until you get it to cut. You can look at it this way, a dull bit is worthless, so you are not out anything if you ruin a few bits in the learning procewss! A sharp bit will cut ribbons of metal as it goes through thick metal.

[fordwannabe]

Doc, I use one of those and it works pretty well...IF you remember how to index the drill bit in the holder each time. I only sharpen bits occasionally and often forget which way they go in the holder so I have to drag the instructions out, but I am glad "the kid" got me one for Christmas 2 years ago and yes they are much sharper when done. I used to use old bits as pins for various gun projects but now that I can reshape and sharpen broken bits I have fewer to use as pins. Tom

[Nate Kiowa Jones]

Yep, I got one of those. I like it because it will do split points. Hard to do by hand.

[rogn]

The split point thing is worth it too. I wouldnt mind reading the directions for that also.

[Buffboy]

I always freehand sharpened bits when I had the machine shop, from 1/8" to 2" and I am still pretty good at it. I've used friend's Drill Doctors, they are easy to use and work very, very well. If I was still doing the machine shop gig I'd definitely own one, but for the few I sharpen now, I use the DDs that my brother and friends own or just freehand them. Still have to do bigger than 1/2" freehand but IMO, worth the money. If you use quality bits($) and use them a lot, it will pay for itself pretty quick.

[TedH]

I've had one for years. Very happy with mine.

[Peter M. Eick]

I free hand them myself.

After a bit of practice it can be done quickly and accurately. Not as good as a machine, but I am good enough for wood and soft metal.

[dennie]

I learned to sharpen drill bits by hand while working in machine shops. It can be learned pretty quickly if you have a good teacher. However, as my eyesight continues to diminish, the smaller bits get harder and harder to see to do it by hand. I am seriously thinking of getting one of the machines. If you are near a Lowe's they carry 2 models on the shelf. Both models are cheaper than the one you referred too, and may work just as well for you.

[vancelw]

I don't have that exact model, but I do have a Drill Doctor.

Works great.

You can sharpen a lot of bits in a short time.
If your previous habit was to buy a new bit when the old one got dull, the Drill Doctor can pay for itself very quickly. It's also easy to sharpen broken bits into something useable again.
I haven't used mine in ages. Got all my bits sharpened and just haven't been in the situation where I needed to drag it back out again. I'm sure I'll have to read the instructions again when I do.

[AJMD429]

The split point thing is worth it too. I wouldnt mind reading the directions for that also.

Since I usually lose the actual paper instruction manual anyway, I just find them on the internet, and download them...

http://www.northerntool.com/downloads/m ... 560930.pdf

When I was a kid, my uncle would hand-sharpen drill bits then dip them in whatever motor-oil was handy, wipe them off, then flame them with a propane torch until the oil all burned off and the bit was hot, then stick them back in the oil "to harden the tips" - is there any point to that, and if so, I assume there would be a more 'scientific' way to do it similar to tempering springs, etc...?

[Nate Kiowa Jones]

The split point thing is worth it too. I wouldnt mind reading the directions for that also.

Since I usually lose the actual paper instruction manual anyway, I just find them on the internet, and download them...

http://www.northerntool.com/downloads/m ... 560930.pdf

When I was a kid, my uncle would hand-sharpen drill bits then dip them in whatever motor-oil was handy, wipe them off, then flame them with a propane torch until the oil all burned off and the bit was hot, then stick them back in the oil "to harden the tips" - is there any point to that, and if so, I assume there would be a more 'scientific' way to do it similar to tempering springs, etc...?

For most modern bits it's pointless and you can actually do more harm than good. If you grind slowly you won't loose the temper. For HSS if it seems soft then heat to a low red and water quench. Then if it seem brittle resharpen, reharden then drip it in the oil, then burn it off to draw it back some.

BTW, I never throw a bit away. I use the chuck end to make pins. The chuck ends are usually annealed so the chuck doesn't slip. They can be turned and then hardened.

[Birdman]

I have always used a grinder and a light touch. I hadn't done it for a few years and really messed one up this past week. Now I got to get some of my old ones out and practice.

[kimwcook]

I bought a Drill Doctor a couple of years ago and it works as advertised.

[stretch]

I've always done 'em freehand.

Kepp a little bit of water handy to keep the
bit cool. If it turns blue, you've drawn the
temper and it won't hold an edge for long
in steel.

If you've got boxes of 'em doc, you've got
plenty to practice on! The idea is to maintain
the same geometry of the tip - just take a little
bit off until the cutting edge is sharp. Make sure
that each cutting edge is the same length as the
other one.

-Stretch

-Stretch

[Ben_Rumson]

Always freehanded them too...Trick I figured out for using bits in a drill motor when you're standing on a ladder and drilling holes overhead in metal 1/8th inch or more.... Grind a steeper included angle on the bit... say about a 90 degree angle with steeper than normal back relief... The bits don’t last as long as a regular grind does.. But they cut much faster and are easier on the arms...They really rip when you can push down one them when not drilling out of position... Of course oil of any type will always make for easier drilling...

[Old Ironsights]

Sharpen bits?

Mine usually break before they are dull...

[Hillbilly]

Ironsides... you can salvage a broke bit if you grind by hand. I have a lot of "short" bits....

Any of those sharpening machines will eventually wear the wheels ... if the wheel isnt perfectly flat you won't get a good result.

Free hand grinding requires a flat wheel too... if you do much ... you need a grinding wheel dresser to true up the grinding wheels.

I learned how to sharpen twist bits in 11 grade- Machine Shop. They don't do "machine shop" in schools any more. Kids under 35 think I'm a super genuis when I sharpen bits or any thing else by hand. (Irrelevant at 51... sad aint it)

[AJMD429]

Well, I ordered the sharpener, so I'll try to post a 'range report' when I use it a bit (no pun intended).

While I think I could sharpen bits with a nice sharp and hard edge (I have a tool-box with nothing but stones, diamond sharpeners, and hard-Arkansas stones/polishers, and can make most knife blades useable for shaving), I'm afraid the various angles and 'split' type drill bits would be such that I'd NOT get good controlled drilling in hard steel, which is really what I want most.

Naturally, I'll use and reserve my best bits for the critical 'gun' projects, and the 10th-resharpening ones will go for woodworking or farm-projects where the drilling need not be as precise or the material as hard. Still, I'd like to get all the angles right, and especially with the smaller bits, I'm not confident that I'd be able to see them well enough to detail them, much less have the experience to know what angles to make them for good function.

I find myself wondering though if I won't feel obliged (like with a good knife) to do the 'fine grit diamond' sharpening, but FOLLOW that with a good polish with the hard-Arkansas stone. For knives (admittedly I don't cut much metal with my knives) that final 'polish' seems to make all the difference between a lasting edge and a temporary one.

[Ben_Rumson]

Don't forget to study up on the PROPPER way to dress a grinding wheel.... Hint...They have to be round when you're done with the dressing...

[AJMD429]

Got the Drill Doctor model 750 with an extra 'coarse' wheel (helps when you need to really re-shape a bit that is messed up, or to start a really dull 3/4" bit faster).

Here's the worst bit I've done so far...

Before:




After:




I couldn't resist the urge to 'polish' the bits up a bit after the above sharpening, using a hard-Arkansas stone. Maybe it's just my imagination, but it always seems that a final finish with that stone on any cutting edge maybe doesn't make it sharper, but makes it last longer.

FYI the shiny part on the bit that isn't on the cutting edge is due to my using the 'make split point' feature, where you can 'convert' a regular bit to a split-point one; I'm still getting the hang of it, and learning the terminology, but that shiny area appeared after that step.

[soon 2 retire]

After:

I couldn't resist the urge to 'polish' the bits up a bit after the above sharpening, using a hard-Arkansas stone. Maybe it's just my imagination, but it always seems that a final finish with that stone on any cutting edge maybe doesn't make it sharper, but makes it last longer.

The edge just may last longer with polishing because what you're doing is removing microscopic heat cracks caused by the grinding.


Bob in NE Indina

[Buffboy]

After:

I couldn't resist the urge to 'polish' the bits up a bit after the above sharpening, using a hard-Arkansas stone. Maybe it's just my imagination, but it always seems that a final finish with that stone on any cutting edge maybe doesn't make it sharper, but makes it last longer.

The edge just may last longer with polishing because what you're doing is removing microscopic heat cracks caused by the grinding.


Bob in NE Indina

Absolutely, it will make them last longer by a considerable margin. IMO the reason is more: that you aren't "making" heat cracks on the rougher surface cutting edge that break off, making the bit dull again. You have a smoother, wider, consistent, cutting edge and not a series of short, very small, edges.