Sharpening twist drill bits freehand

[Derek Cohen]

For many years I have used a Drill Doctor to sharpen drill bits, always feeling a little guilty as I have prided myself in sharpening just about anything freehand. This is excusable for very small bits, but 1/8" and up should be doable by hand ... well, I have seen these demonstrated for some years. Anyway, recently I decided that it was time to learn, and especially with bits 3/8" and up since these were time-consuming on the Drill Doctor.


For woodworking, twist drill bits have a 30 degree slope to each side. One cannot, however, simply grind the side slopes square and expect them to work. The cutting edge requires a relief angle otherwise it will not cut. In other words, sharpening a drill bit is not like sharpening a chisel or plane blade - the drill bit cutting edge needs to be both square (at the face) and rounded (from the face back).


To train my hand, I came up with a guide (or jig). This presents the bit to a bench grinder wheel at 30 degrees, and then holds this constant as the bit is lifted against the wheel to create the relief. Here is the guide ...






The fence lies at 60 degrees to the front, and there is a 19mm (3/4") dowel to rest the bit on.






The jig is clamped to the platform on my bench grinder (which uses an 80 grit CBN wheel here).






The drill bit is pushed along the fence and against the wheel, with the cutting edge on the horizontal ...






Once the cutting face is ground, rotate the drill bit upwards so the the back is ground at an angle (actually, it should be rounded). That is the relief edge ...






The result is like so ...






Proof of the pudding ...






Regards from Perth


Derek

[Frank Pratt]

Great idea! I sharpen them by hand as well and this will help.

[Edward Weber]

Title is a bit misleading IMO
Using a grinder platform and a guide jig is not what I would consider "freehand"
Your results look good, glad it works for you

[Cameron Wood]

Aren't you showing that backwards? Lower the bit to create the relief angle.
Do you have a drill gauge?

[Tom M King]

I like the jig. The relief angle is nothing like as critical for drilling wood as it is for metal. As long as there is plenty of clearance cutting wood is easy for it, but having the least bit too much for drilling metal shortens the cutting life noticeably.

[andy bessette]

Aren't you showing that backwards? Lower the bit to create the relief angle...

This.

Though I have a Drill Doctor and other aids, I now usually just sharpen freehand. Easiest to learn using the side or the wheel, no support. But I'm usually drilling stainless.

[william walton]

Glad you're getting better results. I'm getting old now and eyesight isn't what it was, but still remember the way i learned in machinist apprenticeship. This was one of the first things we were taught, along with memorizing all decimal equivalents.

[Bill Dufour]

Looks like a little web thinning is in order.
Bill D

[andy bessette]

...memorizing all decimal equivalents.

That memorization has stood me in good stead. Though I have to think about the 64'ths in the larger sizes. Especially since my 80'th birthday.

[Derek Cohen]

Aren't you showing that backwards? Lower the bit to create the relief angle.
Do you have a drill gauge?

Cameron, you're correct! I took these photos a few weeks back, and lost the memory of what was happening at the sharp end.

Also .. Edward, note that the jig is to train the hand. I could have stated that in the title - more accurate, but not as direct.

Regards from Perth

Derek

[Tom M King]

In the pile of machinist tools that a dear friend left me when he passed is an old yellow Darex drill shapener. It has a bunch of collets that go with it, and probably has everything that came with them. I used it once but don't have anywhere to set it up. Drill bits come out just like they are new. I just freehand mostly.

This is a newer and I'm sure better model, but the old one does a fine job. This is the bottom of the line. I'm not sure which model the old one is comparable to, but I doubt the bottom of the line.

https://darex.com/shop/sharpeners/v-...ill-sharpener/

[andy bessette]

...
https://darex.com/shop/sharpeners/v-...ill-sharpener/

Looks like quite a nice piece of gear.

[Tom M King]

The old ones, like the one I have, is more like a regular bench grinder with an attachment on one side for drill bits. There is a collet for every size bit instead of a chuck, but there also is a chuck I guess for oddball things. I haven't spent much time messing around with it. My friend was a welder for NASA and when they stopped the Apollo program he spent another career teaching welding and machining. They closed the program when he retired, and he ended up with all the equipment. We became good friends while he was building a house for himself next to one of my spec houses while I was building it. He left me all his tools. That's the second shop I need to build.

Here's one like the one I have. It does a perfect job with a drill bit. https://www.ebay.com/itm/26634747203...Bk9SR7bLkJT4Yg

[Cameron Wood]

Brad points are easily made.

IMG_4196.jpeg

[Edward Weber]

Cameron, you're correct! I took these photos a few weeks back, and lost the memory of what was happening at the sharp end.

Also .. Edward, note that the jig is to train the hand. I could have stated that in the title - more accurate, but not as direct.

Regards from Perth

Derek

Derek, I believe you and I have a slight difference in the english language we use.

To me, "freehand" means without the aide of jigs, reference surfaces or measurements.
Seems like a bit of clickbait to me.