Wednesday, December 12, 2012

Jacket Blazer Pattern Drafting Tips

Important things I learned about drafting jacket patterns:

  • The basic block rectangle is drafted using the CBL, and the bust measurement (wearer’s measurement +2~3” ease) divided by 2, +1”. Much of the excess ease will be drafted out when style lines are added.
  • Back HPS is 1 ¼” above CB neck.
  • Front HPS ¾” above CB neck, unless you are drafting for a larger than “average” bust. When doing a classic FBA adjustment length is usually added to a CF pattern piece. This can be avoided by raising the front HPS. I raised my front HPS to 2" above the CB neck. 
  • Shoulder slope is usually ½” lower than CB neck. adjusted front shoulder slope will differ accordingly.
  • Curve the shoulder seam toward the back for a nice shape.
  • The back shoulder seam gets 3/16” extra length than the front. This is in place of a shoulder dart.
  • The front armhole is longer than the back armhole by about ½” ~ 3/4”. About 5/8” excess is usually removed from the front armhole to achieve this, but the exact amount varies (ie: fuller or flatter bust).
  • Under lapel darts are used to eliminate the excess in the armhole for simple styles. They are not necessary for all styles.
  • Square collar stands are harder to sew than curved collar stands.
  • Seam allowances: neck/stand: 3/8”, stand/collar: ¼”, collar/lapel/front edge: 3/8”, AH/seams: ½”.
  • Pressing is VERY important to construction. When pressing the seam closed (prior to pressing seams open), steam can be used to stretch the seam allowances. This eliminates the need for clipping subtle curves and narrow darts.
  • Add 1/8" to collar and lapel points on front facing and top collar for turn of cloth (more depending on the thickness of the fabric). Blend to 0 at the notch and to the lapel break point. The top collar should also have 1/8" turn off cloth along the fall edge.
  • The Lapel should have 3 notches: the break point notch, 2" above the break point, and 2" bellow the lapel point. The facing should have corresponding notches, but the notch above the break point should be shifted up 1/8". This builds extra ease in above the break point to help the lapel roll correctly.
  • Do not tape the roll line if it is not needed (if the jacket does not gap) as this may cause the front to be shorter than the facing which can cause excess fabric (wrinkles) in the lapel roll line.

10/1/13 ETA: Sleeve Ease:
  • Top sleeve back seam should be +3/16" (longer) than under sleeve seam.  Ease top sleeve onto under sleeve when sewing; top sleeve on bottom. 
  • Top sleeve elbow seam (front seam) should be -3/16" (shorter) than under sleeve seam. Stretch top sleeve onto under sleeve; top sleeve on top.

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