Hello all,

I have a Sorby bowl gouge, .375 I believe, purchased the same day I bought
my lathe. It has what is called a fingernail profile. Learned that
freehand sharpening is not yet in the cards for me, so I purchased a jig.
(see:http://www.leevalley.com/wood/page.a...62&cat=1,43072)
Now I am certainly not wanting to call up all the sharpening posts we get
here on a perhaps monthly basis. They are interesting but my interest lies
mainly in the different types of gouge grinds aka profiles. What are they?
What are their strong points? Weak points?
I do find that the profile I am now using is quite fine for the outside of a
bowl. (It's the only gouge and profile I have so the previous statement is a
bit weak. Kinda like doing a stat analysis from an N of 1) Working on the
inside is a bit more problemmatic. From the rim to the bottom presents no
real problem. Making the turn from the side wall to the bottom is where I
find a scraper to be most useful.

Pointers to pics on websites displaying different profiles would be a
tremendous help.

Kevin said:

Hello all,

I have a Sorby bowl gouge, .375 I believe, purchased the same day I bought
my lathe. It has what is called a fingernail profile. Learned that
....
Pointers to pics on websites displaying different profiles would be a
tremendous help.

Try these...

http://www.woodcentral.com/newforum/grinds.shtml

http://www.laymar-crafts.co.uk/linkn.htm

http://www.woodturninglearn.net/grinding_part_2.html

A black science all on it's own...



Greg G.

In article ,
Greg wrote:

A black science all on it's own...

Isn't it just. I'll have to see if I can borrow a digicam again for long
enough to grab some pictures of the weirdest one in my stable, which was
a throw-in with the 20x60. If I was a know-it-all I'd have been faced
with a massive regrinding project, because it is _way_ off from a normal
gouge grind, but I figured there might be a point to it (someone went to
a lot of trouble to grind it this way in the first place), so I've tried
using it to see what makes sense, and it does appear to work. Don't know
that it works better than anything else one could do, but it works. Text
description is a bit difficult - basically two smaller gouge faces
ground at angles into a wide shallow gouge.

--
Cats, coffee, chocolate...vices to live by

"Kevin" wrote in message
...
They are interesting but my interest lies
mainly in the different types of gouge grinds aka profiles. What are
they?
What are their strong points? Weak points?
I do find that the profile I am now using is quite fine for the outside of
a
bowl. (It's the only gouge and profile I have so the previous statement is
a
bit weak. Kinda like doing a stat analysis from an N of 1) Working on the
inside is a bit more problemmatic. From the rim to the bottom presents no
real problem. Making the turn from the side wall to the bottom is where I
find a scraper to be most useful.

Pointers to pics on websites displaying different profiles would be a
tremendous help.



Take some time to reconsider the principles of cutting. That's the key to
your profile.

I start with Frank Pain's "cut the wood as it wishes to be cut." How can I
tell I've succeeded? The wood complains the least. Wood complains by
resisting the tool, which means there are a lot of people out there
shooting themselves in the foot trying to make the cut with their bulk
rather than their brain engaged. You find them writing of flying shavings,
impacts on full face shields and catches, wearing tendonitis supports and
working with heavier and heavier tools which exacerbate the tendonitis.

Wood which is cut as it wishes to be falls away easily rather than ripping
and flying. It has a clean edge where it parted with the parent piece,
which leaves a cleaner surface on that piece as well. Best way to get that
clean edge is to skew the tool to direction of rotation, and control the
thickness of the shaving by rotating the trailing portion of the edge so
that the shaving has a wedge or barrel cross-section, tapering toward the
final cut. Best way to get this consistency is to let the tool do it, not
the operator. The tool should be on the rest well enough (no more than
20-30 degrees up/down angle) , with the bevel guiding on the freshly cut
surface on a broad enough area so that you have only to provide directional
control. Means that bevels ground at varying angles are not normally your
best control choice, as they can roll from flatter to more steeply ground
portions and dig the tool, while a constant angle meets its image in the
freshly-cut surface and tends to climb out of the cut if it begins to roll.
The fingernail grind, if used from the nose down a quarter of its side, will
give quick ejection - sometimes too quick - if lightly referenced on the
surface, which is why I like larger radius grinds with little fall-off from
a nose shaped as a chord of a circle. If you have a death grip and are try
to force it, however, the fingernail grind can catch and rotate over the
top. Same with a fingernailed deep gouge.

So why do people use deep gouges with variable-angle fingernail profiles?
Because they hog wood so well. If you are willing to fight the piece, you
can get the inside out pretty rapidly by cutting almost straight in. You
can also get the handle of the tool in your chin if you let it roll. To me
this means my handsome face is best protected by grinding edges back at a
constant angle, not rolling, and only as far as to give me a 20 degree down
angle on the handle as I cut. That way my fulcrum - toolrest - is working
near its best, and the mechanical advantage I have by not extending the tool
any farther than I have to beyond it makes me stronger. I can hold the tool
as the wood protests, and get it out of my face by referencing the nose of
the tool as I cut primarily with the edge.

Take a look at the difference in grind-back and how I use 'em.

http://i35.photobucket.com/albums/d1...e/422896ce.jpg With the
big Sorby cutting center out. Look how long the ears.
http://i35.photobucket.com/albums/d1...e/c7f143b2.jpg With the
smaller diving edge in. If the ears were as long, I'd have to stoop over
center.

Of course, when I want a good surface, I peel.

http://i35.photobucket.com/albums/d1...e/639fb765.jpg 1/2"
forged gouge. Note the twisted endgrain shaving. Not dust like the hogger.
http://i35.photobucket.com/albums/d1...e/7c6d6541.jpg The
surface from the gouge, you'll note the wood is damp and punky, because
this demo piece is year-old firewood. Within easy sanding tolerance,
however.


Start with some profile -perhaps those above- and listen to the wood. The
less a shaving protests on its way to the floor, the better it will be for
you, your lathe, and your surface. Go with the grinds that let you do it.

On Thu, 03 Nov 2005 16:15:11 -0500, Greg wrote:

Kevin said:

Hello all,

I have a Sorby bowl gouge, .375 I believe, purchased the same day I bought
my lathe. It has what is called a fingernail profile. Learned that
...
Pointers to pics on websites displaying different profiles would be a
tremendous help.

Try these...

http://www.woodcentral.com/newforum/grinds.shtml

http://www.laymar-crafts.co.uk/linkn.htm

http://www.woodturninglearn.net/grinding_part_2.html

A black science all on it's own...



Greg G.


Excellent. Thanks for the URLs.

George Max said:

On Thu, 03 Nov 2005 16:15:11 -0500, Greg wrote:

A black science all on it's own...


Excellent. Thanks for the URLs.

You are Most Welcome.

I remember when I approached a lathe for the first time. Never had
much of an interest. I only thought of chair legs, stair spindles and
such - BORING!

But then I saw some of the fantastic bowls and goblets - and segmented
vessels - it really changed my perception of what a lathe (and
experience) could do.


Greg G.