Follow this advice from All-in-One Rotary Cutting Magic with Omnigrid and you'll never cut a V strip again!
After cutting 6˝ worth of strips, you must re-square the fabric with the fold.
This process is extremely important to maintain cutting accuracy. After
re-squaring, you can continue cutting straight strips until you have cut
another 6˝ worth of strips; then you must re-square again. Repeat this
procedure every 6˝.
fold the fabric only once (two layers) before rotary cutting, but some people
like to fold the fabric twice (four layers). Folding twice is not necessarily a
problem, but if you are working with two folds, you must alignthe top of the ruler with one fold and
the markings on the ruler with the opposite fold. Aligning the ruler with both
folds will ensure that they are parallel to each other.
also that the more layers of fabric you rotary cut through, the more inaccurate
your cutting becomes. To prove this, stack six to eight layers of fabric
together. Now place the ruler as if you were going to cut a 2˝ strip. You will
notice that the ruler acts like a teeter-totter. The bottom layers of fabric
shift slightly, and this shifting will cause you to cut inaccurately.
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