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In a message dated 8/4/03 9:49:37 AM, pinewoodel@hotmail.com writes:


> Here is a rough draft of an article I had started for Nafex Pomona last
> March on grafting knife sharpening and use.   Have a read anyone, write back
> what needs clarifying, what you disagree with, whatever, help me make this a
> functional useful article. thanks, Del Stubbs
>
> " Having just finished a couple hundred whip and tongue grafts, as well as
> teaching a woodcarving course - I have been thinking about  parallels
> between knife woodcarving and knife grafting.
> 1. Don't do the normal action one uses in the kitchen with a paring knife -
> of squeezing the thumb and hand together to get the knife to move. This
> endangers the thumb, and is not a particularly flat movement.
> 2. Rather, lock the thumb and hand in a very solid  position, with the knife
> at a long angle to the scion, and pull with the arm. Do not move the thumb
> toward the hand at all, keep this in a frozen locked position.  If the arm
> is not steady enough  - place it firmly against the body and let it slide.
> 3. Why the 'long angle to the scion'? When wood is cut at an angle  (rather
> than at 90 degrees to the edge) one gets a slicing cut which is a far more
> efficient and clean a cut. If one takes a protractor to a knife at 90
> degrees to the edge it will read - say 16 degrees - the  angle the knife was
> ground at.  However if you angle the protractor at a slant to the same edge
> it might read 10 degrees.
> 4. The second reason to draw the knife at an angle to the scion is that it
> presents twice the length of flat steel to the wood, and the idea of whip
> and tongue grafting is to get two very flat surfaces to join.
> 5. The edge. It cannot be stressed how important it is to have the bottom
> side of the blade absolutely flat.  However, even this is easily
> misunderstood. The back may seem very flat upon a cursory inspection, but
> the most critical part - right at the edge - is likely to be microscopically
> rounded or dubbed from normal wear - or improper sharpening. This defeats
> the point of having the back flat. If the flatness does not go absolutely to
> the edge - then the tool must be lifted off the plane of the cut - and thus
> the flat back can no longer guide the blade.
> 6. One way to tell if the blade is properly shaped and sharpened if to
> lightly touch it to a finger nail at a low angle - if the nail catches it,
> then the geometry is good.  (This is done so lightly there is no danger of
> cutting  the quick if the the blade slides on the nail, and so lightly no
> scar need be left on the nail). If the blade slides - rather that catches -
> keep raising the back of the blade until it catches. If it never does, you
> have a very dull blade. If it catches only when the back is angled up 25
> degrees or more, then the back is not flat clear to the edge.
> 7.Safety:  Always have a safety stop built into a cut before proceding with
> power. For instance, the knife hand in a w&t cut should be aimed so the back
> of the thumb hits the body instead of the knife. Test this by moving slowly
> and gradually increase speed and power as you develope confidence that it
> truly is safe, it most certaily can and must be.
> 8. When doing the tongue cut it is easy for the wood to give way and the
> knife to continue into the other hand - if a stop is not employed. To do
> this pinch the thumb of the knife hand between the thumb, scion and index
> finger of the other hand. Instead of cutting forward with knife hand rotate
> the knife and hand all locked together, pivoting on the trapped thumb. Set
> it up so that, if the knife keeps going,  the fingers will stop the travel
> before it goes too far. Also, by pivoting you achieve an efficient slicing
> cut.
> 9. All this can get laborious in words, the key is to have the attitude of
> working with as many grips as one can invent until there is a safety stop
> employed.
> 10.Sharpening:  A hardware store variety of carborundum stone can be used,
> however it is really only useful for coarse reshaping, even the 'fine' side
> is quite coarse. If you have a knife that is in good order, thy this to
> maintain it.
> Acquire a flat surface, at least 2" by 6". I used a 6" x 12" square of high
> grade plywood. One could use thick glass, plexiglass, masonite, steel,
> whatever. Buy a can of all purpose spray adhesive , spray the back side of
> wet/dry sandpaper that is cut to fit the flat surface (don't spray the board
> or it may be difficult to remove and replace the sandpaper). On my 6x12
> plywood piece I glued down 4 grits 220 400 600 1200
> With this homeade 'whetstone' you can now lap your knive's flat side truly
> flat. Be sure to have a good incandescent light nearby so you can examine
> very carefully the bottom side of the knife, there will be a microscopically
> thin reflection of light right at the edge, keep honing till it is gone. To
> hone the bottom side perfectly flat, push straight down on it with a finger
> while moving it around on the sandpaper. I see no reason to use water or oil
> on this sandpaper strop. 600 is the grit I use the most, 1200 is to give a
> slight microbevel to the top side, and as a final polish to the bottom side.
> I rarely use the 220, as I have diamond lapping stones which cut more
> efficiently.


Thanks Del.   Waite