Figure 5-11.--Combination square.
scale by itself or with any one of the following compo-
-- The center head (2), when attached to the slot-
ted rule, bisects a 90-degree angle. It is used to deter-
mine the center of a cylindrical object.
-- The protractor head (3) has a level (4) and a
revolving turret (5) that is graduated in degrees from 0
to 180 or 0 to 90 in either direction. It is used to lay out
and measure angles to within one degree.
-- The square head (6) has a level (7), scribe (8),
and 45- (9) and 90-degree sides (10). When it is attached
to the slotted steel rule, it can be used to lay out 45- and
90-degree angles and to check level. The square head
may also be used as a height or depth gauge.
Trammels (fig. 5-12) measure distances beyond
the range of calipers. They also can be used as calipers,
if you have the auxiliary attachments.
The basic trammel consists of two heads (trams).
One head has a device for fine adjustments. The
wooden beam must be made by the HT as it is not
provided by the manufacturer. You can attach divider
points, caliper legs, and ball points to the tram. The
ball points with holder are used for scribing or
measuring from the center of a hole.