-6-
4.
Measure from the right angled line
along the side of the string, the going
length and mark this point. From the
same corner point intersection, measure
across the end along the right angled
line, the rise, and mark this point. Now
draw a line between these two points.
This line creates your pitch angle.
(Measure pitch line and note for point
15 - page 8).
FIRST RISER
AT BASE OF
STAIRS
5
.
To find your start point along the
margin, you need to draw a line at
right angles to this pitch angle line.
This line must be no less than the
length of the rise and must be at
right angles with the pitch line
angles. The intersection of this line
(The first riser line) with the margin
will be your start point and the angle
at which this line is drawn will be the
angle to set the jig.
6.
Finally, mark a line (The first tread line) at right
angles to the first riser line from the
intersection point with the riser and the pitch
line.
Setting Up the Jig
7.
The final thing to calculate is the offset value
between the edge of the cutter and the
edge of the jig cut out.
8.
This offset value varies according to which
tread thickness you require.
9.
Select from the table (page 7) the tread
thickness and nose projection you require. As
a general rule the nose projection equals the
tread thickness. This will tell you which cutter
size to use and the resultant offset value
required to set the jig. Refer back to the table
to determine which guide bush and cutter
to use, before cutting.
10.
Mark the offset value against the first riser and the first tread line as shown in the
diagram above.
NOTE:
If a 30mm guide bush is going to be used instead of the supplied guide bushes,
then refer to table below.
38mm Fixed Nose
Ø16mm Cutter
25.4mm tread - 8mm offset
Ø22mm Cutter
32mm tread - 5mm offset
Pitch Angle Line
Offset Value
Rise
Going
