How To Use Your RIDGID Wood Lathe (continued)
If the rest is placed too low, so that the chisel is held with the bevel out from the work (sketch 2), the cutting edge will con- tinue to dig deeper into the work. It will dig in until the "bite" becomes so deep that your hands have difficulty holding the chisel - then the improperly supported chisel will begin to bounce, or chatter, against the workpiece.
If the rest is placed too low, the chisel must be held extremely high to position the bevel against the work (sketch 3). Then the rest loses most of its value as a fulcrum, and the down ward force of the revolving workpiece tends to kick the chisel back out of your hands.
If the rest is placed too high (sketch 4) and the chisel is correctly positioned for
cutting, it strikes the workpiece near the top where the direction of force exerted by the workpiece is nearly horizontal - and kickback will again result.
If the rest is placed too far out from the work surface (sketch 5) - then, when cor- rectly held, the chisel is again too high on the work. Also, you have less leverage on your side of the tool rest - and it is even more difficult to hold the chisel.
With large diameter work (sketch 6), the tool rest can be above the workpiece cen- terline, and somewhat out from the work surface. With small diameter work (sketch 7), the rest should be lowered almost to the centerline, and should not be far from the work surface. As work grows smaller, the rest should be repositioned.
How to Position Tool Rest for Circumference Scraping
In scraping operations, the tool rest posi- tion is not as critical as it is for cutting operations. The chisel generally is held horizontally, though it can be held at an angle to reach into tight places. Consider- ing that the wire edge of the chisel does the scraping, sketches 9 and 10 show the results of too low or too high a position for the rest; and sketch 8 shows the chisel action with the rest correctly positioned.
9 Edge | 10 | |
Digging |
| |
In |
| |
| No | |
Correct | Stock | |
Removed | ||
|
How to Position Chisel and Rest for Diameter Scraping
When scraping on the diameter, that por- tion of surface to the right of center is moving upward (sketch 11). If chisel is placed in this area, it will simply be carried up off the rest and out of your hands. All diameter approach operations must be done at the left of center.
Three different chisel contact points are shown in sketch 12. It will be noted that, when chisel is above the workpiece cen- ter, or below it, the work surface sweeps past the chisel edge at an angle and tends to carry the chisel in one direction or the other along the rest. Only when the chisel contacts the work on the centerline does the work surface pass squarely
under the chisel edge. This, then, is the position in which it is easiest to hold the chisel steady. To obtain this position, place the rest approximately
11 | 12 |
1/8"
Rest
Face Edge
32