Of the various types of woodturning tools, the skew chisel is probably considered the most dangerous, and for most beginning woodturners, the most intimidating. Even the slightest mis-step with a skew chisel can cause a dig-in, gouging the wood, and likely, the woodturner's nerves at the same time. The worst dig-ins could even cause the tool to be pulled from the woodturner's hands. Every woodturner has experienced a dig-in at one time or another, but with careful actions and the proper techniques, they can easily be avoided.
What is a Skew Chisel?
A skew chisel is a long, flat, bevel-edged chisel with an angled tip. The long point of the chisel's cutting edge is called the toe, whereas the the shortest point of the cutting edge is called the heel. In most cases, it's the toe of the skew chisel that gets the novice woodturner into trouble with the skew chisel. If presented improperly, the toe can easily dig-in to the turning in a most unnerving fashion.
Learn Before You Turn
Before beginning to work with a skew chisel, spend a little time learning about how to present the tool to the wood safely. Since most dig-ins occur when the toe contacts the wood too aggressively, in most cases, you'll want to position the skew chisel so that the toe is not in contact with the wood.
To learn the techniques properly, I'd strongly suggest you become comfortable with the positions described below with the lathe turned off. Presenting the skew chisel with the wood in a stationary position will give you a chance to make a few "dry runs" before you start using the skew chisel for real.
The skew chisel is unmatched in its ability to smooth a spindle. Let's assume you've rounded out a 2-inch square piece of stock into a relatively smooth round spindle with a gouge. You can use the skew chisel to fine-tune the spindle with a very smooth finish.
To do so, you'll be using the center portion of the skew chisel down to the heel.
Assuming you're a right-handed turner, with your right hand on the handle and left hand against the rest, position your rear hand farther to the right than your fore hand. This will actually shorten the length of edge that can be presented to the rounded spindle.
Then, tilt the skew chisel blade about 25-degrees counter-clockwise, so that the toe is pointing toward about 2-o'clock, all the while keeping the heel side edge of the skew chisel on the tool rest. At this angle, only the center of the chisel's edge should come into contact with the spindle. It is vitally important that the toe remain off the spindle to avoid dig-ins, and also that the heel side of the skew chisel remain in contact with the tool rest at all times. One should never attempt any kind of "free-handing" on a lathe, and that advice goes double for the skew chisel.
To smooth the spindle, the action would be to start on the right side of the tool rest, and work to your left, maintaining the two angles as you cut (one with the rear hand remaining to the right of the fore hand, and the other being the tool tilted counter-clockwise with only the heel-side of the chisel in contact with the tool rest). Keep your eye on the toe as you work to ensure that it doesn't contact the spindle.
With practice (and a sharp skew chisel), your smoothing action will actually produce long ribbons of wood. These ribbons are a good indication that you have the smoothing action down pat.
Once you have mastered smoothing, the next step toward mastering the skew chisel is to learn how to make long tapers. The action is the same as smoothing, but you will likely employ the heel of the edge a bit more by altering the angle of the chisel's presentation to the spindle. Most tapers should be created by first using a parting tool to cut a groove in the spindle, and then working the taper down progressively to the groove. The skew chisel should simply feather the stock in thin strips until the desired shape is obtained.
V-Cuts and Beads
Making V-Cuts and Beads are quite a different technique. These profile elements are typically cut using only the toe of the skew chisel.
The chisel is positioned so that only the toe-side of the chisel comes in contact with the tool rest with the tool handle nearly parallel with the floor, and the toe tip is eased into the stock. The idea is to ease the tip into the wood, then roll the tool to one side or another to create the bead or V-cut. Only the toe tip of the tool should contact the spindle, and the handle should remain perpendicular to the floor. Being too aggressive only invites dig-ins.
The heel of the skew chisel can also be used to cut rolling beads using a similar technique. Just remember that your rear hand controls the action and aggressiveness of the tool. Work slowly, always keep the tool in contact with the tool rest, and, most of all, practice, practice, practice. Woodturning is a learned skill, one that can only come with timely instruction followed by lots of repetition.