BobH wrote:
On 01/17/2018 06:58 PM, Bob La Londe wrote:
I started free hand grinding my own drill bits a few months ago.? Not
out of choice, but out of necessity.? Since I started doing it I have
reground a fair number of them.? Sometimes the same one two or three
times in the same set of jobs.? Now I have old eyes, but my glasses are
pretty good, and I have a magnifier lamp I swing over my bench grinder.
It allows me to free hand better than I ever thought I would be able to.

I've also resharpened some of my stub length Silver and Deming bits.
That's where it really pays off.? I bought a set of those some years
back, but I've never seen them available singly.? The 5/8 took quite a
beating over the years since its the standard injection port size for
hand injecting plastisol.? I actually make injectors .620 and sprues
.63, but sometimes you just have to brute force a solution.? It was nice
to finally be able to just sharpen it right up.

No more piles of drill bits to be sharpened someday.? I just sharpen it
right up and drop it back in its spot.? Which brings me to the other
size limit.

The smallest I've reground so far was a #21.? I picked that one to push
the smaller size limit because I have several of them on hand.? I
ordered a half dozen of them once from McMaster in stub screw machine
length to drill molds for 10-32 clamping screws.? It came out ok.? I'm
not sure how much smaller I could grind free hand.? Probably not much. I
was squinting a bit at it and gritting my teeth.? LOL.? So how small of
drill bits do you free hand regrind.? I don't have a drill doctor or a
Darex or a knockoff.? Just a bench grinder.? Well a couple of them and a
small belt grinder now.

I think one of the limits is grit size, but another would be heat.? It
would be really easy to overheat a tiny little drill bit.

I got a Drill Doctor at a metal club swap meet a few years ago. If you
follow the directions, they work pretty well.

The instructions are pretty weak at best, and you can end up with some
really weird an nonfunctional bits even if you "follow the instructions".
At least you can see if they're all jacked up and just keep trying with
different amounts of "touch" until they look about right.

I think the lower limit on them is 3/16" or maybe 1/8"

I got some 1/8" bits working again with the drill doctor. Never bothered
with smaller ones yet, although they will chuck up OK.

My attempts at free-handing a drill bit were disappointing at best.

Same here. The drill doctor hasn't paid for itself by any means yet but
the box of trashed bits is now a box of bits that just don't belong to an
index, so that's handy.