Fitting the Sleeves
You should now construct a sleeve out of muslin, to test the fit. Only one side is necessary to test, and if you can do the left side, it is a little easier to set into the armscye (if you are right handed, that is). Begin by sewing the front seam together. Press open.
Sew the rear seam together, pressing that open as well. Line up the rear seam to the middle of the back body at the armscye, as shown for the wool sleeve. Baste the sleeve into the coat, right sides together, using a running stitch. It’s okay to pleat sections in to make things easier. After the muslin sleeve is attached, you should check for the following fitting problems.

Fitting issues
There are several fitting issues you may encounter when fitting the muslin sleeve. Try to correct these now, as they are much more difficult, with the exception of the Sleeve Pitch, to fix later on.
Too long or short
If you find the sleeve is too long or too short, this can be fixed on the draft by altering the measurement from C to H, and adjusting all of the points from the elbow to cuff accordingly. The sleeve should fall to just past the hollow of the wrist. This is a lot longer than modern sleeves, so be careful not to fall into the too-short sleeve trap.
Armscye too Full
You may find when basting on the sleeve that there is just too much extra ease on the sleeve head. If you have more than an inch of ease, I suggest adjusting point F, and bringing that closer to C in both the under and upper sleeve in equal amounts. So if you have an extra inch of fullness that you don’t want, subtract 1⁄2 an inch from point F on both halves of the sleeves.
Elbow too Wide
If you are a very large size, starting at about size 46 and above, you’ll find that the elbow is very wide compared to the length of the sleeve. In this case, disregard point L, and make the curve from F to G follow a more proportionate line if you can.
Pitched Forward or Back
If you distribute the fullness on the sleeve head incorrectly, you’ll find that the sleeve will want to hang too far forward or back, and that there are wrinkles on the front or back of the sleeve head.
If the wrinkles form at the front of the coat, you’ll need to rotate the sleeve back, and distribute more fullness towards the back. Likewise, if the wrinkles are near the back of the scye, you’ll want more fullness near the front. This can be easy to fix later on, but you want to be aware of it.

After you are happy with the fit of your sleeves, you can cut them out of the wool. Make sure the grain lines are aligned properly, as well as the direction of the nap.
This concludes the Drafting and Fitting a Frock Coat Workshop. As always, if you have any questions, feel free to email me or post on the support forum.
You may now proceed with confidence to the other workshops, knowing that you have a properly-fitted pattern upon which to base your work.