The best mechanics observe the following order in planing a board to dimensions:

1. Plane a "working face" and mark with a "face" or "witness" mark.

A working face should be a true plane surface, i. e. smooth, out of wind, and not warped. See winding strips, scraping,, and sanding.

It is a fundamental principle among mechanics that, since mistakes are always likely to occur, all measurements, all gaged lines, and all squared lines in any particular direction, or upon any particular surface, are to be made from one starting place. This, then, is the reason for establishing the working faces and for following the order of steps as are here stated. The witness marks are placed on these faces so that they can always be distinguished.

2. Plane a "joint edge" and put on a witness mark.

A joint edge should be straight from end to end and square with the face side. Test for squareness with the try-square. Sight down the edge or use a straight-edge to test for straightness.

3. Gage and plane to width.

4. Gage and plane to thickness. This step may often be omitted. (See notes on judgment, following.)

5. Square one end. (See sawing and end planing, Chapters IV and V.)

6. Measure for length, measuring from the end just squared.

7. Square lines about the board at the required length, using knife and try-square.

8. Saw to the center of the knife line, keeping the saw kerf in the waste stock.

Test for squareness both from the working face and the joint edge. If the knife line was properly made and the saw handled skillfully the end of the piece will show a burnished streak all about the cut. (See (b) Fig. 16.)

9. Give the end a planed finish.

Judgment in using the rules. The boy, as the mechanic, should always follow the above order of procedure. If he omits any step, it should be because the project he is making does not require him to perform that step, e. g., if the end of a piece does not show, it need not be given a planed finish. Again, if the thickness is unimportant, it is not necessary that it be planed to exact dimensions. In a word, then, one should understand the complete method of planing to dimensions, but he would not be expected to perform unnecessary operations simply for the sake of following a rule. Judgment when and when not to follow a rule, as well as skill, distinguishes the true mechanic.

Pointers:

1. Do not forget to put witness marks on your working face or your joint edge. Why?

2. The joint edge must be not only square with the working face; it must also be straight, otherwise lines squared from it will not be parallel.

3. The ends must be square with both the face side and the joint edge.

4. Do not be afraid to use your try-square and your rule.

Reference Work: The matter of squaring stock to dimensions is of such fundamental importance that we would urge you to:

1. Ask, say, ten good mechanics whether or not they follow the rules for planing as stated above. If not, find out their reasons for changing the order.

2. Look up this matter in ten text books (or as many as you can find). If the order is changed, find out the reason.