Step 3.

Select approximately "pencil" sized scion wood. Make a smooth, flat cut slanting across the lower end of the wood, leaving an exposed area about 1 1/2 inches (40 mm) long.

Warning: this is the most difficult step to do correctly, and the most important. Practice makes near-perfect. If your knife is sharp enough to do this job right, be careful that you do not slice a hunk off of your hand during this process.

See the comment below the picture for a tip on how to make an easy flat cut.

To Step 4.

"To guarantee a good flat surface on the scion stock, hold a small sharp block plane, Stanley Tools has one that fits nicely into the palm of your hand, with the cutting surface up and facing away from you. Holding the scion stock in the other hand in an exaggerated pencil grip with the butt end facing away from you, draw across the knife of the plane two or three times.
Start the cut in back of the lowest bud on the stock you want to save. Apply a little pressure on the butt end of the stock to get the desired angle. We typically then rotate the wood and make one stroke on the opposite side to achieve a chisel point. Very seldom do I have to waste a bud because the knife of the plane whittled away too much wood. For someone who is handy with a knife carrying two tools is maybe redundant. But for someone like me who is not handy this is very fast. Using bark grafting we get very good take. In a very short time you learn the different pressures you need to apply for differences in the scion wood."

Contributor of the above:
Bill Bier
Moose Hill Orchards
Londonderry, NH