View Full Version : How do you sharpen small drill bits?

07-09-2007, 12:18 AM
By small I mean under 1/8 down to about .040

07-09-2007, 12:27 AM
This works well but takes some effort to build:


Edit: updated address above but it still doesn't seem to go directly to the section, so use this one:


07-09-2007, 12:28 AM
not worth the time when they are so cheap buy.

07-09-2007, 12:40 AM
Why, you just use a Black Diamond Model A drill grinder for #70 to 7/32 drill bits. Doesn't everyone have one?

Actually, I buy new ones from McMaster-Carr to refill the letter-number-fractional set the chief of science at a former employer left on my desk one day after I'd been unable to complete a small job for him due to having had my last #29 drill bit stolen...

BTW, it's for sale...the grinder, not the drill set.


Forrest Addy
07-09-2007, 01:54 AM
I use a pocket stone and a 10X loupe. Makes a great TV watching job.

07-09-2007, 02:45 AM
First I find my most powerful reading glasses- then I bring the tip of the bit close to the sanding wheel. With my hands in a comfortable position, I rotate the bit in my fingers until the angles look right. Touch the bit to the wheel, rotate 180 without losing the angles, touch the bit again. With luck, my second touch hasn't taken off quite as much material as the first touch. Without rotating the bit in my fingers, I bring my hand up to inspect the bit, then bring it down again to do a touch-up. If I find that I need to rotate 180 again to touch up the other lip, so be it. I have basically three things in mind- relief behind the cutting edges, equal angles on the point, and equal length lips. If it looks good to my eye, I'm done. Sometimes I have to rotate, touch, inspect, rotate, touch, inspect- until the result looks good. For very small bits it's so easy to over sand, so it becomes a matter of for what small fraction of a second do I lightly touch the bit to the wheel.

I made a crude tool to hold any size bit up to 1/2 inch. This tool has a bottom and a top which are parallel. I can secure the bit into the tool, paying attention to the angle at which the lip comes in contact with the sanding wheel. As I turn the tool over, I'm rotating the bit by exactly 180. The bit is held at a height which allows the sanding to make a relief angle behind the cutting edges. I have, or had, a line drawn on the table of the sanding wheel which I align the holder to for the point angle. I'll try to post a pic of this holder.
First pic shows the holder with a bit ready to touch up. Next pic is set for the other lip. Third pic shows the details of the holder. The piece with the threaded hole in it is drawn towards the vee in the body by turning the knob. The drill bit is centered automatically in the vee, and I make sure the lips are parallel to the top and bottom of the holder. If more than a touch is needed, I may have to re-orient the bit slightly in order to make the lips parallel again.

Mike W
07-09-2007, 03:57 AM
You can sharpen smaller than 3/32 drills in the Drill Doctor by using a pin vise to hold them. You have to align them by eyeball but it does work. I have plans for a jig to do small ones on a stone if I can find the plans.

07-09-2007, 04:20 AM
I've got a Drill Dr 750, that in spite of some comments to the contrary, does a rather decent job on bits from something like 1/8 (pushing it due to difficult setup) up to it's upper limit of 3/4" (also pushing it due to LONG time to do more than touch-up should you chip or something). On the big stuff when it needs more than a touch-up, I generally hand grind than finish with the DR if I want it to cut close to on size. It provides a nice consistent angle and edge that works well, particularly when split.

The real problem for me was the small ones. Yeah, cheap to replace, not so cheap when you mess up 2 at 10 pm on Saturday night and don’t want to wait to over-pay for a piece of crap bit after driving to HD on Sunday. So I bought a Christen small bit drill sharpener. If I remember right, it will sharpen from a #80 up to a max of ” with standard config (and I’m told is capable of splitting a point on most of that range!!!). There is an add-on package (which I seem to have most or all of) that takes it to 3/8”. This is supposed to be one of THE best for small drills. Problem is, it’s a complicated little bugger with tiny alignment anvils and a built in microscope. I finally had one of the fine gentleman here send me a manual some time back. I fooled with it a bit, but never spent the quality time with it that I really want and need to in order to really figure it out. But then I stumbled on some “can’t pass up deals” on several pieces of machinery and they have consumed all my “free time” since then. So the gist is that I can’t really comment on it from experience, but if you can find such a little gem for a good price, they are apparently the ultimate for small bits short of a high end tool grinder or pro-CNC setup.

Anyway, I got lucky and picked mine up, complete with accessories (I think it has everything but the web thinner), for $100. The wider range units cost a fortune in collets and fixtures as well as taking more room. For my purposes, I was happy with hand grinding + Drill Dr for the bigger stuff, and this handles the small stuff VERY well (so they say) without taking a lot of room.

Good luck!

07-09-2007, 05:54 AM

07-09-2007, 11:32 AM
John, my Adaware component "Adwatch" refused to load the URL as it had/has a tracking cookie "com.com" attached which it "wiped".

I could have turned Adwatch off but decided not to.

Tracking cookies are usually not a big deal and are on a lot of sites.

Just thought I'd let you know.

Thanks for the heads up. I use this free statistics widget:
and they use tracking cookies to identify return visitors. I like the feature because return visitors indicate an interest (and/or a difficulty with my text) in an item so I check pages for clarity if they have a lot of return visitors. The site should still work OK if the cookie is rejected.

I hadn't considered that this might put people off the site... not sure what to do about it.


07-09-2007, 11:58 AM
I use a pocket stone and a 10X loupe. Makes a great TV watching job.

You must be a fun date Forrest :D

The wire-sized drills are so cheap, it's not worth the time to sharpen them, IMHO.

07-09-2007, 12:02 PM
I use this free statistics widget:
and they use tracking cookies to identify return visitors.

I hadn't considered that this might put people off the site... not sure what to do about it.

It doesn't bother me John. Heck, 90% of the Internet doesn't work if you don't allow cookies, including MSC, Enco, J&L Industrial, Ebay, Yahoo Groups, ...
(the important ones! :D ).

If you're paranoid about cookie tracking, just set your browser to use temporary session cookies.

Rusty Marlin
07-09-2007, 02:05 PM
By small I mean under 1/8 down to about .040