# Dual Range Miter Scale; Vernier Scale - Black & Decker 3680 12" Instruction Manual

12" compound miter saw

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N N O O T T E E : : If the cutting angle varies from cut to cut, check that the bevel clamp knob and the miter lock
knob are securely tightened. These knobs must be tightened after making any changes in bevel or
miter.
The chart shown on page 10 will assist you in selecting the proper bevel and miter settings for com-
mon compound miter cuts. To use the chart, select the desired angle "A" (Figure 17) of your project
and locate that angle on the appropriate arc in the chart. From that point follow the chart straight down
to find the correct bevel angle and straight across to find the correct miter angle.
Set your saw to the prescribed angles and make a few trial cuts. Practice fitting the cut pieces together
until you develop a feel for this procedure and feel comfortable with it.
Example: To make a 4 sided box with 25° exterior angles (Angle A, Table 1), use the upper right arc.
Find 25° on the arc scale. Follow the horizontal intersecting line to either side to get miter angle setting
on saw (23°). Likewise, follow the vertical intersecting line to the top or bottom to get the bevel angle
setting on the saw (40°). Always try cuts on a few scrap pieces of wood to verify settings on saw.

## Dual Range Miter Scale

The miter scale has two ranges of numbers for conve-
nience, as shown in Figure 18. One scale indicates 0˚
when the blade is square to the fence. At this position the
The 0˚ scale (larger numbers closer to the front edge) is
used when calculating angles. To calculate the proper
miter angle, divide 180˚ by the number of sides of the box
or frame. Refer to the chart on page 7 for some exam-
ples.
The 90˚ scale (smaller numbers behind the 0˚ scale) is
used when a corner of your box or frame is measured
with a protractor. F F o o r r e e x x a a m m p p l l e e : if you measure the cor-
ner of an 8 sided box, the protractor will read 135˚. To
determine the proper miter setting, divide the measured
angle by two. The proper miter setting in this example is
67-1/2˚. Set this angle on the 90˚ scale. This is most use-
ful when a corner is at an odd angle.
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ANGLE "A"
MITER
SCALE
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8
F F i i g g u u r r e e V V 1 1
KERF PLATE
MITER ARM
CENTER MARK ON VERNIER SCALE ALIGNS
WITH DESIRED WHOLE ANGLE ON MITER
SCALE (24˚ RIGHT MITER)

### Vernier Scale

Your saw is equipped with a vernier scale for added precision. The vernier scale allows you to accu-
rately set miter angles to the nearest 1/4˚ (15 minutes). To use the vernier scale follow the steps listed
below.
(As an example, let's assume that the angle you want to miter is 24 1/4˚ right).
1. Turn off miter saw.
2. Set the miter angle to the nearest whole degree desired by aligning the center mark in the vernier
scale, shown in Figure V1, with the whole degree number etched in the miter scale. Examine Figure
V1 closely; the setting shown is 24˚ right miter.
3. To set the additional 1/4˚, squeeze the miter arm lock and carefully move the arm to the RIGHT
until the 1/4˚ vernier mark aligns with the CLOSEST degree mark on the miter scale. In our exam-
ple, the closest degree mark on the miter scale happens to be 25˚. Figure V2 shows a setting of 24-
1/4˚ right miter.
For settings that require partial degrees (1/4˚, 1/2˚, 3/4˚) align the desired vernier mark with the CLOS-
EST degree mark on the miter scale, as described below (The plastic vernier plate is inscribed with
marks for 1/4˚, 1/2˚, 3/4˚ and 1˚. Only the 1/2˚ and the 1˚ are numerically labeled.)
When Mitering to the Right
To increase the miter angle when mitering to the right, move the arm to align the appropriate vernier
mark with the closest mark on the miter scale to the right. To decrease the miter angle when mitering
to the right, move the arm to align the appropriate vernier mark with the closest mark on the miter
scale to the left.
When Mitering to the Left
To increase the miter angle when mitering to the left, move the arm to align the appropriate vernier
mark with the closest mark on the miter scale to the left. To decrease the miter angle when mitering to
the left, move the arm to align the appropriate vernier mark with the closest mark on the miter scale to
the right.
F F i i g g u u r r e e V V 2 2
1/4˚ VERNIER MARK ALIGNS WITH CLOSEST
WHOLE DEGREE MARK ON MITER SCALE
(24˚ 1/4˚ RIGHT MITER).