offhand i'd say we're againts it.

SURFACE HEIGHT GAUGE
A surface gauge is a measuring tool used to transfer measurements to work by scribing a line, and to indicate the accuracy or parallelism of surfaces.

a. Description. As shown in figure 3-45, the surface gauge consists of a base with an adjustable spindle to which may be clamped a scriber or an indicator. Surface gauges are made in several sizes and are classified by the length of the spindle. The smallest spindle is 4 inches long, the average 9 to 12 inches, and the largest 18 inches. The scriber is fastened to the spindle with a clamp. The bottom and the front end of the base of the surface gauge have deep V-grooves. The grooves allow the gauge to measure from a cylindrical surface. The base has two gauge pins. They are used against the edge of a surface plate or slot to prevent movement or slippage.

b. Adjustment.
The spindle of a surface gauge may be adjusted to any position with respect to the base and tightened in place with the spindle nut. The rocker adjusting screw provides for the finer adjustment of the spindle by pivoting the spindle rocker bracket. The scriber can be positioned at any height and in any desired direction on the spindle by tightening the scriber nut. The scriber may also be mounted directly in the spindle nut mounting, in place of the spindle, and used where the working space is limited and the height of the work is within range of the scriber.

c. Setting Height on a Surface Gauge.
To set a surface gauge for height, proceed as follows:

(1) Wipe off the top of a layout table or surface plate and the bottom of the surface gauge.
(2) Place the squaring head of a combination square on a flat surface as shown in figure 3-46.

NOTE : If a combination square is not available, use a rule with a rule holder. A rule alone cannot be held securely without wobbling, and consequently an error in setting generally results.

(3) Secure the rule in the squaring head so that the end of the rule is in contact with the surface.
(4) Move the surface gauge into position, and set the scriber to the approximate height required, using the adjusting clamp that holds the scriber onto the spindle.
(5) Make the final adjustment for the exact height required with the adjusting screw on the base of the gauge.

d. Care of Surface Gauge.
Observe the following practices for the care and upkeep of surface gauges:

(1) Coat all metal parts of the gauge with a light coat of oil to prevent rust.
(2) Carefully store the gauge in the separate container provided by the manufacturer.
(3) Do not drop any surface gauge. Small nicks and scratches can result in inaccurate measurements.
(4) Protect all pointed parts from damage.

Bend Allowance

When a piece of material is formed around the nose bar of a bending brake, the inside of the material (next to the nose bar) becomes compressed, and the outer surface is placed in tension. The actual amount of material used in the bend, or the rounded portions of the material only, is the Bend Allowance. Each end of the bend allowance is bordered by the Bend Tangent Lines.

When we are calculating the amount of material required to form a bend, we should consider each of three parts of a bend. There are two “Flat Leg” sections on either side of the bend, and in between is the “Bend Allowance” portion. The points at which the Bend Allowance meets the Flat Leg section becomes the Bend Tangent Line, or the point at which the bend straightens out to become flat.

A common formula for calculating the amount of material consumed in the bend is:

Bend Allowance = 2 x 3.14 (R + T/2) / 360

This allows us to calculate the amount per degree of bend.

In another form, if our bend is required to be 90°, the formula can be simplified to:

Bend Allowance = 2 x 3.14 (R + T/2) / 4

In both these formulae, R = Radius, and T = Thickness of material.