GGG,

Tonight at our monthly Hand Tool gathering, a splinter group of the Houston
Woodworkers Club. we hit a stone wall.  Someone wanted to know how to sharpen
Yankee drill bits.  Even Mr. Leonard Lee's fine book did not cover this.
Previous searches on the internet had found no instructions.

I volunteered to post here as certainly one of the galoots must know how to do
this.  We tried sharping tips, we tried sharpening the bit by registering on the
flute, we tried holding our tongues on both sides of our mouth, but nothing
worked (although I still think we got a bit of improvement when the tongue was
on the right side).

Any tips, references, etc greatly appreciated.

Thanks,

Roy Parker

I've looked for period instructions on how to sharpen these and came
up empty in the past. I'd be curious to know if anyone can dig
anything up.

Lacking any concrete evidence, I looked at the NOS bits I have and
found that they appear to be simply ground across the flute at an
obtuse angle, maybe 135 degrees. I've done the same with my bits and
it works well. They are simple tools and pretty hard to screw up.

Josh

On Sunday, September 18, 2016, Roy  wrote:

>
> GGG,
>
> Tonight at our monthly Hand Tool gathering, a splinter group of the Houston
> Woodworkers Club. we hit a stone wall.  Someone wanted to know how to
> sharpen
> Yankee drill bits.  Even Mr. Leonard Lee's fine book did not cover this.
> Previous searches on the internet had found no instructions.
>
> I think I found directions somewhere on this list, years ago.  Will take
some poking to refind them, if they weren't a figment of my imagination.

But the simple answer was to use a stone with two tilts, downhill from
center, and slightly tilted for a relief angle.  I used a DMT diamond
sharpener, blue.  Worked much better after. I have even salvaged a broken
bit that way.

I can figure out the angles on an existing one in a day or two if it's
really important, or you can just guess.

Kirk Eppler in Half Moon Bay, CA, giving up for the day.


-- 
Sent from my iPad, apologies for the Auto Correct errors.
Kirk

Kirk,

As I'm having difficulty visualizing the stone needed and then angle of approach
(which may be due to being  in wake up mode).  Being so kind s to post a quick
photo or two would be helpful.  Those of us with an affliction for these drills
could all benefit.

Charlie Driggs

Sent from my iPhone

Simply, they get sharpened pretty much like a twist drill. They cutting is
primarily on the push stroke, so similar clearance angle is appropriate. You
don't want too much clearance, or there isn't support, and the bit will push
through the material, giving a poor hole and jamming up. You need some or the
bit will rub rather than cut. It isn't critical.

I have factory grinds from the 1980's and (roughly) the 1930's, and they are
different, but not much. The 1980's had the grind done as a flat at an angle to
give the appropriate cutting edge (roughly 120 to 130 degrees-- it isn't
consistent) and a bit of clearance -- maybe 10 degrees at the cutting edge, but
less farther back, making the cutting edge on the push a bit ahead of the
trailing edge. The older bits have roughly the same edges, but the bits were
rotated do the clearance is cut like it should be on a twist drill.

I generally sharpen like the 1980's edition, as it is easy and works just as
well. I don't worry about the details, only that there is a bit of a net
clearance angle so the cutting occurs on the push, not the return. No jigs, just
me and my fine wheel on the grinder, or a stone, or whatever. And, for the
smaller ones, magnification. If the cutting edges are at substantially the same
angle and same width, they are fine.


*** This message was sent from a convenience email service, and the reply
address(es) may not match the originating address

Fascinating question for those of us with bits needing fettling.  

how about drilling a bit size hole in a scrap offcut at the correct grinding
angle - then just insert bit - register it using the notch, and rub back and
forth on the stone?  It’s hard to maintain an angle for something that small.
Same idea - different set up to provide registration on a hand crank, if you
want to salvage a broken bit.


Richard Wilson
Yorkshireman Galoot
retired in Northumberland

On Sun, 18 Sep 2016 20:36:56 -0700, Kirk Eppler wrote:


> I think I found directions somewhere on this list, years ago.  Will take
>some poking to refind them, if they weren't a figment of my imagination.
>
Should have thought of the archive right off the bat.  Did a quick search last
night and found 289 references.  Will take a while to wade through all that, but
the answer is likely in there somewhere.  Thanks for the pointer.

Roy Parker

On Sun, Sep 18, 2016 at 8:36 PM, Kirk Eppler  wrote:

> I think I found directions somewhere on this list, years ago.  Will take
> some poking to refind them, if they weren't a figment of my imagination.


http://swingleydev.com/ot/get/113570/single/

Not a figment, and from someone I trusted, then and now.

Will work on some pix or sketches later.

Kirk


-- 
Kirk Eppler in HMB, trying to catch up on a ton of emails and software
updates, which are sort of mutually exclusive categories.