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 purple 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 with a square sleeve is when you lower your arm there is an increase of tension parallel to the shoulder line which can pull open the neck. This is because our one piece block has had the shoulder measurement reduced by 12% to maintain the tension across the bodice. If you were to remove the negative ease at the shoulder you”d get vertical ripples at rest. Instead you need to lengthen the sleeve head to compensate 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). Not having positive ease in the sleeve head is what creates the diagonal ripples from the sleeve head to bust point at rest.
A horizontal sleeve with positive ease in the head is the most common method by far. It does not mean you will not get any movement ripples in your garment nor some tension ripples, but it is a fair compromise. You could remove the ease for a closer fit t rest, but during movement you might also 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, look carefully at the illustration for that step as it 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.
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.
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).
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.
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.
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.
Rotate the whole sleeve section back to the horizontal. Mark in points 1 and 2.
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.
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.
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.
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.
Smooth off the under sleeve seam only enough to create a gradual curve.
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.
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!