Sunday, August 22, 2010

Drafting a Basic Sleeve Block - Part I

The fifth installment in the drafting series is all about drafting the basic sleeve block. And it is written by me(!) as a guest blogger for the series. I've reproduced the post below (with kind permission) for you my very own readers :)

There are many seemingly different methods to draft a basic sleeve block. Although the practical aspects (steps, procedures) may differ, the objectives of each step is constant, no matter the how. But admittedly, some methods are easier to follow than others. Old school tailors and dressmakers would take only 2 or 3 measurement points and rely on instinct to draw out the sleeve cap and armscye, free-handing the curves about as often as they use French curves.
The cutters on Savile Row all do it that way still, and I read somewhere that straight/square rulers are off limits to the apprentice cutter because nowhere on the human body is to be found a right angle! But of course, it takes years to go from apprentice to pro on The Row. We, (un)fortunately, only have a post or 2.

So here goes...
This method is adapted from (wonderful free resource) but re-processed in more straightforward language and I've modified one or 2 things which I've found make very little difference one way or the other. I chose it because it has proved a good method with very satisfactory results. It will draft a straight, long sleeve. From this, you can shorten it to 3-quarter, half, or any length you want. The procedure will seem lengthy at first, but don't be put off by this. And there is a neat summary at the end for easy reference.

Required measurements:

  1. Bicep circumference (typically around the arm adjacent to the armpit, but if the widest circ. is elsewhere on the upper arm, take that measurement instead)
  2. Overarm length (from shoulder point to wrist, arm slightly bent)
  3. Underarm length (from arm pit to wrist)
  4. Wrist circ.


Step1 - take a piece of paper, sufficiently large, and fold it in half, lengthwise.

Step 1

Step 2 - measure and mark out the overarm length on the fold of the paper. Label the top mark A and the bottom mark B.

Step 2

Step 3 - from point B, measure towards point A, the underarm length and mark this C on the fold.

Step 3

Step 4 - add 1" ease to the bicep circ. measurement and divide the answer by 2. [ (Bicep+1) / 2 ]

Step 5 - from point C, draw, towards the left, a horizontal line equal to the no. derived in Step 4. Mark the end point D.
Step 5

Step 6 - add 0.5" ease to the wrist circ. measurement and divide the answer by 2. [ (Wrist+0.5) / 2 ]

Step 7 - from point B, draw, towards the left, a horizontal line equal to the no. derived in Step 6. Mark the end point J.

Step 7

Step 8 - open up the paper (unfold it). From point C, draw, towards the right, another horizontal line equal to the no. derived in Step 4. Mark the end point E. The bicep line is now complete.

Step 9 - from point B, draw, towards the right, another horizontal line equal to the no. derived in Step 6. Mark the end point K. The wrist line is now complete.

Steps 8 & 9

Step 10 - draw a line from point A to point B to mark out the overarm length marked out earlier. This line will also function as the grainline.

Step 10
Summary so far

Step 11 - connect points D and J, E and K.

Step 11

Step 12 - divide line DC into 4 equal segments. Mark the first point F. [ DF = 1/4 DC ]

Step 12

Step 13 - divide line CE into 8 equal segments. Mark the last point G. [ GE = 1/8 CE ]

Step 13

Step 14 - add the lengths of DF and GE. From point A, draw, towards the right, a horizontal line equal to DF+GE. Mark the end point H. [ AH = DF + GE ]

Step 14

Step 15 - multiply the length of DF by 2. From point A, draw, towards the left, a horizontal line equal to 2DF. Mark the end point L. [ AL = 2DF ]

Step 15

Step 16 - connect the points F and L.

Step 16

Step 17 - mark a point, 1, on line FL, equal to the length DF. [ F1 = DF ]

Step 17

Step 18 - connect the points G and H.

Step 18

Step 19 - from G, mark a point, 2, on line GH, equal to the length of GE. [ G2 = GE ]

Step 19

Step 20 - from H, mark a point, 3, on line GH, equal to the length of AH. [ H3 = AH ]

Step 20

Step 21 - using a French Curve, draw a smooth curve from point A to 1, then 1 to D. On the other side, A to 3, then 2 to E.

Step 21

Summary of Steps 2 - 21:

  • AB = overarm length
  • BC = underarm length
  • DE = bicep + ease
  • Point C = mid point of DE
  • JK = wrist + ease
  • DF = 1/4 DC
  • GE = 1/8 CE
  • AH = DF + GE
  • AL = 2DF
  • F1 = DF
  • G2 = GE
  • H3 = AH

Step 22 - mark the left half of the pattern 'Front', the right half 'Back'. The front has a curvier sleeve cap, the back sleeve cap is less curved.

Step 22

Step 23 - measure the front cap from point D to point A, and then the back cap from point A to E. Compare to the front and back armscye on the bodice. The front sleeve cap must ideally be up to 0.5" (max.) bigger than the front armscye. Same for the back cap and armscye.
You can increase or decrease the sleeve cap measurement as shown below. The total length of the sleeve cap should be anywhere between 0.5" to 1" (max.) bigger than the total armscye measurement of the main bodice block (sloper). Edit- Sleeve caps ideally should NOT HAVE ANY EASE. Yes, that's right. What's essential is the SHAPE of the cap, the way I've drafted it below. The curve of front cap should be a lot more pronounced than in the back cap. Keep adjusting until the length of the front cap equals the length of the front armscye on the bodice, and the back cap equals the back scye of the bodice. 


Red lines = increase
Blue lines = decrease

An important point to note:

The drafting of the armscye curves on the sleeve is rather arbitrary. There really are no hard and fast rules/formulae to developing the one with the best fit. The previous steps simply aid you towards drawing a front scye that will accommodate the forward-jutting ball joint the shoulder, and a slopier one for the back. You must constantly measure and remeasure both the scyes on the bodice and the sleeve to ensure the ease differences as explained in Step 23.

Finally, you'll want to adapt the long sleeve block for a short sleeve. This is very easy to do. First, measure down from the centre of the bicep line the length of the short sleeve desired. In the example below, this length is 1.5".

Shortened to 1.5" below bicep line

You can also choose to measure from the top of the sleeve cap down along the centre line to a point where you'd like the sleeve to end.

Then draw a line, perpendicular to the centre line (or parallel to the bicep line), across the width of the sleeve.

Cut away the pattern below this line and you have your shortened sleeve.
Cut along the new hemline

A short sleeve!

Simple, right?

And that's basically how you draft a basic sleeve block. Just like a body sloper, you can adapt this block to create different types of sleeves, a few of which I will show you how to in another post. Coming up next - solving fitting issues with sleeves.
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