The Sleeve Block

For something apparently very simple, the sleeve seems to prove more difficult than any other area of pattern making. I've seen people cope better with bras than with sleeves. And the closer the fit, the harder they seem to be to make.

Let's begin by better understanding the shoulder area. Take a good at someone nearby who has their arms down. Try to find what you think is the outer most point of their shoulder line. Now draw a line along the center of their shoulder without bending. It must be a straight line. What you'll inevitably find is that the true shoulder line on a person does not line up with the center of the neck at all, but in fact points to the back of the neck. The neck actually sits forward on the body. Seems obvious, but not realising the implications of this causes people to use the wrong center line on the shoulder and hence the wrong center line on a sleeve. From there on in they never recover! Take a look at the image below.

Notice that the back arm hole is longer than the front arm hole. This is because we've moved the shoulder line forward on the block. The true shoulder line (dotted red line) is about 2-3cm behind, but parallel to, the shoulder line on the block. The black dot represents the center point of the sleeve head scye.

So why did we move the shoulder line forward. Two reasons. Firstly because it looks better. If you didn't move it forward the person's neck and back would look very hunched over. Secondly it's difficult to sew a shoulder seam with such an angle at the neck line. When you add an extremely angled seam allowance you tend to increase the number of misaligned panels coming out your machine room.

Hunching is greater for women than men. It also increases with age. This is not because the neck moves forward, but because as you get older your back arches more, actually increasing the nape to waist measurement with respect to the rest of the body. Standard retail shirts and blouses, then, appear to have shoulder seams that are set back even further. Not to mention collars which gape at the back.

Some designers create shoulder seams as a line from the sleeve head center to the neck center and do not stay parrallel to the true shoulder line at all. Whilst the shoulder may look better, this makes the neck appear to protrude up and forward at the same time. This garment does not sit flat on the shelf, and worse, the shoulder line is twisted on the hanger. This may not sound important, but subconsciously the retail customer views this as an inferior garment. Before you dispute this by claiming that people will buy what they think looks good on them, let me say that first they have to decide to try it on!

Before we get to sleeve head design let's consider where we want the sleeve to sit. Look at the image below. The red panel represents the sleeve. It is no more complex than a tube which is as long as the arm, having a hole at one end the size of the wrist and a hole at the other end the size of the top arm measurement. Cut that tube lengthwise and give it a center line and you have a sleeve. Notice I've lined the center line up with the true shoulder line and not the shoulder seam. Also notice the sleeve now sits central to the arm hole. Only it won't fit the armhole just yet.

Now let's look from a different angle. The image below shows how the sleeve will move up and down. Notice how each different colour sleeve either misses the bodice (purple), touches the bodice almost exactly (red) or overlaps the bodice in ever increasing amounts (orange, green and blue). If we were to design a T-shirt type sleeve in the red position, it would cause an excess of fabric to bulk up under our arms when we put them down. Conversely, when we lifted our arms above the horizontal, the rest of the garment would lift up and/or the sleeves would be pulled down. This same arguement applies to any starting position.

So what is the right starting position? Well that depends on the function of the garment. If we were designing for dance we could assume the arms would regularly be lifted above the head. If we were designing a stinger suit for snorkling we would expect lots of arm movement, but most of which is below the horizontal. If we were designing a promotional catsuit (think of cigarette girls or car racing grid girls) then we could assume the wearer would just be standing there looking pretty and rarely moving their arms any significant amount.

Now I should point out at this stage that you cannot create sleeves whose lower edge is lower than the armhole, at least not without first cutting the arm hole lower. You also cannot create sleeves higher than the shoulder (well it's possible but not practical). On our one piece block this means we cannot create the blue or puruple sleeves.

You must understand everything you've read on the page above to understand not just swimwear but really any type of pattern making, stretch or non-stretch. I say that because now I'm going to apparently argue against myself. In stretchwear, the sleeve is a close fitting or tensioned tube. Because it fits so close to the arm pit, the amount of fabric bulking under the arm (even if you create a raised sleeve), while it does exist, is actually minimal, and certainly doesn't significantly affect the performance of the garment. Instead the only real problem you have when you lower your arm is an increase of tension parallel to the shoulder line which can pull open the neck. This is why our one piece block has not had the shoulder measurement reduced by 12%, if you were wondering! In fact I'm about to show you how to lengthen the sleeve head and as such insert the only amount of positive ease in the whole garment. By doing this, we can create a well performing sleeve for all occasions, that also looks good at the time that most people will see it (in the arms down position).

A horizontal sleeve with positive ease in the head is the most common method by far. It does not mean you will not get movement ripples in your garment nor some tension ripples, but it is a fair compromise. You could remove the ease for a closer fit, but during movement you might reach the modulus limit of some fabrics. You could design the sleeve to fit better at 45° if you were certain the wearer would not raise their arms above, say, the horizontal (including putting on the garment). However, in a retail situation, your client expects a full range of motion. They have no understanding of patternmaking. Made to fit might be a different matter.

I'm now going to show you how to create the horizontal sleeve with positive ease in the head. Before you start each step, click on the link marked "Illustration for this Step". A pop up window with an illustration for that step will help guide you through the instructions. At the end of each step your draft should match the illustration. If it doesn't go back to the start of that step and work your way through again

Step One

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Trace your one piece blocks, puting them together at the shoulder seam. Rotate the blocks such that the shoulder seam is exactly horizontal. Draw a horizontal rectangle, as shown, that is the arm length wide and touches the back and front side seams and end of the shoulder line.

Step Two

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Find the exact center line of this rectangle. Create a new rectangle, centered on this line that is the top arm measurement high (without any reduction).

Step Three

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Draw a straight line from back side seam to front side seam. Notice the front armhole region is wider than the back. If you have a separate arm hole dart for a larger bust you need to close the dart before starting this step.

Step Four

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Rotate the whole sleeve section around the center point of the sleeve head scye (black dot) until it's parallel with the red line. If you look at anyone stood upright with their arms down you'll notice it's natural for the arm to tilt back a few degrees. This also helps to create a symmetrical sleeve.

Step Five

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Draw in the true shoulder line, parallel to the existing shoulder seam, starting from the center point of the sleeve head scye. We are not going to change the one piece block, just move part of it temporarily.

Step Six

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Rotate the whole sleeve section back to the horizontal. Mark in points 1 and 2.

Step Seven

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I tend to separate the front from the back at this stage. It's not necessary, simply more of a habit. I like to have separate front and back sleeve blocks as it makes for easier pattern tweaking later. I'm doing it here just to show where you'd do it if you wanted to.

Step Eight

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Draw a rectangle 1/4 arm length wide and 1/2 top arm high reduced by 6% (half normal reduction like we did with the leggings). Place these at the center of the front and back sleeve heads as shown. At the other end of the sleeve, measure out 1/2 wrist reduced by 6% from the center line.

Step Nine

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Measure 2cm along the shoulder seam from the armhole and square up and down. Draw a line from the outer cuffs to the top arm point of the rectangles to points 1 and 2.

Step Ten

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Measure the length of the front scye (blue line on front block). Mark this distance on your flexicurve and draw in the front sleeve head from point 2 to the 2cm squared line. Make sure your curve is square at the true shoulder line and curves away gradually. The sleeve head should also be square to the under sleeve seam at point 2. The red line and blue lines must be the same length. Some people add a little extra to the red line and ease the sleeve into the bodice. This is not necessary in stretch fit. Repeat for the back sleeve head.

Step Eleven

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Smooth off the under sleeve seam only enough to create a gradual curve.

Step Twelve

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If you're going to create a single piece arm block, join the two arm panels togther and draw in a gradual curve at the wrist that's right angled to the under sleeve seam.

Step Thirteen

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Remove unnecessary guidelines, points and numbers. Cut out or retrace the arm block(s). Make sure you clearly label your block with a title, panel name, size (and any ratio notation), date, author’s name and version number. Do not add seam allowance to the block!