To figure out how much extra you’ll need, bend your arm and then measure around the centre of your bicep. Compare this measurement to the finished garment measurements to get an idea of how much you need to add. Deciding on the amount of room to add is down to personal preference, but bear in mind that you'll want around 2.5-5cm of ease in a sleeve. If you're not sure, hold the tape measure around your arm and loosen it by 2.5cm to begin with. If this feels comfortable, you'll need to add 2.5cm to the width of your sleeve. If you'd like more, keep loosening the tape measure until it feels right for you, and then use this measurement to make your adjustment.
Bear in mind that this adjustment will only work if you're adding up to 5cm extra to the arm width - outside this you'll distort the shape of the sleeve.
We recommend tracing off the sleeve pattern piece so that you can keep the original for the future. On your new piece, mark in the seamlines at 1.5cm from the edge where they intersect at the underarms, and also draw in the 1.5cm seamline at the top of the sleevehead.
1. Draw a line horizontally from underarm point to underarm point.
2. Draw a line in the centre of the sleeve vertically, parallel to the grainline.
3. Cut along these slash lines to the seam allowance marking, but do not cut through. You will need to snip from the other side also, but leave a small amount unsnipped to act as a ‘hinge’.
4. Place some extra paper behind your pattern piece so you can tape down the paper once you’ve pivoted.
If you need extra width throughout the whole sleeve, pivot the sleeve open so that each side of the arm is the same distance apart all the way down to the hem. (In the above example we're adding 2cm down the whole length.)
However, if just the bicep is tight, you only need to add extra room into this specific area. Pin the sleeve back together right on the hem line, as this will ensure the width at the bottom of the sleeve stays the same.
5. At the cross-section of the opening, open up the main sleeve by the amount you require, as indicated above. Tape this gap into place on the paper so it doesn’t move, and also tape the sleeve hem down at this point.
6. You’ll find that your sleevehead will have pivoted itself into the right place. We found it helpful to tape our paper down (particularly the side seams) so everything was laying flat, before weighting down the sleevehead with a pin dish so it didn’t move, then taping it in place.
7. You will need to round off the sleevehead back to a smooth curve.
You'll also have to re-draw the hem line to form a straight line.
You may need to straighten off your underarm seams at the underarm corner too.
8. Re-draw your grainline so it is perpendicular to the hem once more.
And that's your new sleeve piece created! Easy peasy right?
Next time on the sewalong it'll be time to start sewing! Yay! We'll see you to make a start on the bodice.