ESSENTIAL GUIDE l equilateral triangles
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2
113232(^11)
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2
Fig (^8) Cutting60-degree angles with a quilting ruler
Equilateral triangles normally use a
in seam allowance all round (see also
Maths Facts for Equilateral Triangles
on page 71). There are several ways to
add this allowance, two of which are
described here.
Q Once you have drawn a triangle
accurately, use a school ruler to
accurately mark in out from the
edge in various places (Fig 6A). Now
take the ruler and join up the marks in
straight lines, extending the lines so
the points of the triangle are complete
these outer lines can overlap at this
stage (Fig 6B).
Q Alternatively, use a quilting ruler
to draw the in allowance all round,
positioning the ruler against each side
of the triangle in turn (Fig 7).
ADDING A SEAM ALLOWANCE
Fig 6
Fig 7
Marking a seam allowance
Using a quilting ruler to add a seamallowance
A
A
A
B
B
B
in
in
in
in
USING A RULER TO CUT AN
EQUILATERAL TRIANGLE
If you know the unfinished size that an
equilateral triangle should be, then you can use
a quilting ruler to cut the shape, including the
seam allowance. Fig 8 shows the process using
an example of a finished triangle with 2 in sides
(3 in unfinished) and a strip height of 3in.
1
Cut a fabric strip the height required (or
slightly larger if you prefer). Align the
60-degree line on the ruler with the top of the
strip and make the first cut to remove excess
fabric (Fig 8A).
2
Rotate the ruler so the other 60-degree line
is along the top of the strip and so the right-
hand edge of the ruler intersects the top corner
made by the first cut. Make the cut to create the
first triangle (Fig 8B).
3
Repeat this process along the strip, rotating
the ruler between the 60-degree lines each
time. 3in
60 ̊ line
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(^77)
8
(^95)
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10
9
6
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5
1
2
(^113)
12
10
60°
Discard