There are times you are going to want to shorten or lengthen a pattern, and I thought I'd show you how to do that today.
Sometimes, you can simply cut off some length from the hem of a garment, but there are times when you may want to remove (or add) the excess length to the interior of a pattern piece, so that the piece still fits properly with the rest of the pattern. For example, if you wanted to shorten a sleeve that had a cuff, you wouldn't want to just lop the excess off the bottom. The sleeve would no longer fit the cuff correctly, and you could also lose important details like the placket position. This is also the case if you have a pattern with an interesting shape - such as an A-line dress. You would not want to just cut the excess off the bottom of an A-line dress, as it is likely you would lose the shape of the A-line.
For the case of the example, I will use the simple summer top pattern I showed you how to draft a few weeks ago.
Take a copy of the pattern, with seam allowance. Normally when making alterations to a pattern I suggest to remove the seam allowance, but with something as straight-forward as this, there's really no point removing it. Take note of any important details, such as pattern markings (notches etc.) and the grainline.
Draw a horizontal line through the pattern, roughly half-way between the armhole and the hem, on the side seam. If you are using a ready-made pattern, it is likely that your pattern will have a "Lengthen and shorten line" already on it, so you can skip this step.
Cut through the horizontal line, splitting each piece in two.
Work out how much length you would like to remove from the pattern. This is when a toile can really come in handy!
For the sake of this example, I will be removing 5cm (2") from the length of the top. On one of the pieces, draw a horizontal line 5cm (or whatever length you are removing) from the cut line (parallel to the cut line).
Now, simply move the lower half of the pattern up to the line drawn on the upper half of the pattern and tape (or glue) in place.
Take a separate piece of pattern paper and trace the new pattern pieces, creating a new side seam that runs smoothly between the underarm and hem.
Be sure to add all pattern markings, as well as the grainline. And you're done!