Sleeve Alterations

Widening a sleeve pattern for a fuller upper arm:

This is a more extreme example than many of you will need. The principles and steps remain the same.

The sleeve, its placket and its cuff. The difference in width between the cuff and the sleeve at its hem is how much gets pleated out (under the narrower rectangle of the placket)
Pattern paper (physician’s exam table paper)
Wash-out marker
Permanent market
Straightedge (ruler)
Flexible, non-stretching cord – I use drapery weight, little pellets in a thin cotton tube
Pins, straight for pinning down into the mat, and safety for marking the cross lines on the armscye line

All changes are made using the dashed sewing (not cutting) line
Traditional pattern making has one mark at the front of the armscye and two at the back. Trace off the armscye, keeping its registration marks. Here, front, front of yoke, back of yoke, back. If your pattern doesn’t have a yoke there will be a mark slightly forward of the top that matches where the shoulder seam will hit.

Lay a flexible but not elastic cord along the armscye seam. Place pins at each end and at the cross marks. Trace off the front and back armscye areas with several fingers’ worth of side seam.
Determine optimal biceps width, including ease. (see photo at top of page). Extend the cross line at the bottom of the armscye to this new length.

Place your small paper with the front armscye under your master. Pin through its corner and the mark for the extended biceps line. Repeat for the back.

Rotate the small pieces, pivoting on the pins, until the armscye lines more-or-less align with the old armscye.
Pin your cord’s ends to the new biceps width. Do NOT try to incorporate this with previous steps!
Align the ends of the cord with the underarm areas. Pin through so those bits won’t shift.
With your spread fingers, ease the center part of the cord into a curve.
With a wash-out marker, draw along the cord.
Mark the cross lines.
Redraw armscye “under cord” using washable marker as reference.

This completes your sleeve cap master. Label it.

Using the Cap Master for a sleeve:

On a piece of paper long enough (plus a little), draw a grain line. Copy the armscye length.

Transfer the registration marks.

Label.

The length of your underarm seam of your new sleeve must be the same as your old one. Likewise, the widths at the elbow, forearm and wrist.

If you’re determining these from scratch, be sure you’ve added wearing ease. A common problem when going from a sleeve with a cuff to a straight sleeve is not having enough width at the hem. Be sure you can get your knuckles through.

Old and new sleeves when finished.
The underarm lengths from armpit to cuff must remain the same.
Many pattern instructions have you taper the sleeve from the armscye to the cuff. This leaves no room to go around the biceps.
Instead, draw the upper sleeve the measured width of the biceps almost to the elbow (halfway along the seam) and then taper it down to the cuff. Do not lose the slight curve right under the armscye.

As long as your bodice/sleeve blocks use this armscye length, any variation of this sleeve will fit it.

Method if you don’t have a suitable cord:

Trace off the armscye length with cross marks as above for a temporary armscye. Trim and slash. Expand it to the new biceps width. Place a fresh piece of paper (your sleeve cap master) over it and trace your final version. Your underarm seam at the armscye will gentle into the old seam.

Determining sleeve length and biceps circumference (with ease). Your sleeve will pull up as you bend your elbow, so fudge extra length in there. This is why the elbows of cheap shirts blow out.

Shapes of Sleeve Caps

As long as the length of the armscye seam remains the same, there’s flexibility in its shaping.

At left (a) is a sleeve that’s symmetrical front and back, a bad design as our bodies are not. Next (b) is a better design for most genders. European design (c) scoops the front armscye and flattens the back, which builds in a better range of motion (my default choice). A more extreme version is below. The one at right (d) shows the modification for a wider bicep.

Asymmetrical Sleeve Caps

European Sleeve

Drafting a sleeve from an existing bodice/shirt/top

https://carolkimball.net/creating-sleeves-from-a-bodice-pattern/

Find and add this PDF for knitting sleeves with various amounts of ease

The Beta Test Sleeve pattern PDF