We may consider this question from another stand-point, however, inasmuch as that the tool action is a cutting one whenever the pressure of the cut is in a direction to force the tool deeper into the work, and a scraping one whenever this pressure tends to force the tool away from the work, assuming of course that the tool has no front rake, and that the cut is light or a “mere scrape,” as workmen say. This is illustrated in [Fig. 1301], the tool at a acting to cut, and at b to scrape, and the pressure of the cut upon a acting to force the tool into the work as denoted by the arrow d, while that upon b acts to force it in the direction of arrow c, or away from the work.
In addition to these distinctions between a cutting and a scraping action we have another, inasmuch as that if a tool is pulled or dragged to its cut its action partakes of a scraping one, no matter at what angle its front face may stand with relation to the work.
Fig. 1302.
The end face of a flat scraper should be at a right angle to the body of the tool, so that both edges may be equally keen, for if otherwise, as in [Fig. 1302], one edge as a will be keener than the other and will be liable to jar or chatter.
The flat scraper can be applied to all surfaces having a straight outline, whether the work is parallel or taper, providing that there is no obstruction to prevent its application to the work.
Fig. 1303.