How To Make Sewing Patterns By Donald H Mccunn

Working Through Pattern Drafting Without Losing Your Mind

Most people trying to figure out sewing patterns end up spending three to four hours on a single block because they're overthinking the math. I used to do the same thing. Then I started approaching it differently. The Donald H Mccunn approach works best when you stop treating it like geometry and start treating it like following a recipe you already know by heart. Here is what that actually looks like on a Tuesday night when you have a deadline and the fabric is sitting on your cutting table waiting.

How To Make Sewing Patterns By Donald H Mccunn

The core idea is straightforward but the execution has some teeth in it. You begin with your master measurements. I measure my bust, waist, and hip, then add ease based on the garment type. For a fitted jacket, I add two inches of ease at the bust. For a flowing dress, I might add four or five. The Mccunn method does not prescribe a single ease value - it gives you a framework for calculating it based on fabric stretch and garment function. You draft your block on paper. Heavy paper, preferably tracing paper or kraft paper taped to a flat surface. I use a French curve ruler for the armhole and a hip curve for the lower section. Standard straight edges for everything else. You lay your tape measure flat, not hanging loose, and record each number twice. That step alone prevents about sixty percent of the errors I see beginners making. The armhole depth calculation is where most people stumble. You take your back waist length plus half your bust circumference divided by six, then subtract a small correction factor. Mccunn suggests a factor around 0.75 inches for average builds, more for broader shoulders, less for narrower frames. I found that my own build required a 1.25 inch adjustment because of how my shoulder blades sit. If you skip this adjustment, your finished sleeve will pull across the upper back every single time.

From there you transfer the block to your pattern pieces. Cut along your seam lines, not your pencil lines. Mark your grain lines with a clear plastic ruler and a fine Sharpie. I usually mark them with a cross at both ends so I can see them from either side. Not marking grain lines correctly is probably the number one reason garments twist after washing. I also add notches at key points - center front, center back, sleeve caps, armhole bottoms. Three notches for the sleeve helps you identify the correct orientation every time, which saves you from having to pin and repin while you're half-asleep. One edge case that nobody warns you about: when drafting patterns for knit fabrics using this method, the ease calculations flip. Instead of adding ease, you subtract. Mccunn acknowledges this in later editions but the original printing skips over it. If you are working with a stretchy jersey or interlock fabric, use his negative ease chart instead of the woven formula. I learned this the hard way when I made a knit dress that rode up my torso every time I sat down. Took me an hour to realize I had applied woven ease to a stretch fabric and the garment was simply too tight through the chest.

Another thing that catches people out is the difference between a sloper and a basic block. A sloper has no seam allowance. A basic block includes it. Mccunn's method assumes you are working from a sloper and adding seam allowance later during the toile stage. If you add seam allowance too early, your measurements drift and your muslin fits wrong. Keep your initial draft clean, then trace it and add your allowance on top. The toile or test garment step is non-negotiable. I know people who skip it to save time. They do not save time. A proper toile takes about forty-five minutes to an hour and reveals problems that are invisible on paper. Pin your toile together, wear it, move around in it. Sit down, raise your arms, cross your legs. If anything binds or gaps, mark it with chalk and adjust the pattern before you cut into your fashion fabric. If you want the actual text, search for Donald H Mccunn sewing patterns PDF. The material is widely available through independent pattern publishers and some university extensions that license technical drafting content. Some of the scanned editions from the mid-twentieth century have slightly different notation but the math remains identical.

What this method does not do well is accommodate dramatic size differences. If you are drafting for someone whose measurements fall more than four inches outside the standard range, you will need to grade the pattern manually rather than relying on the built-in sizing charts. The proportional math in the book assumes a fairly typical body shape. It works fine for that, and poorly for everything outside it. For extreme curvy figures or very broad shouldered builds, pairing Mccunn with a custom fitting session produces better results than trying to force the standard formulas to work. I use both methods together myself - Mccunn for the base structure, then personal adjustments layered on top. The process itself, once you have the rhythm, takes about twenty minutes for a simple bodice block and forty minutes for a full skirt with a zippered opening. Before I understood the method, I spent roughly two hours on those same pieces because I was constantly second-guessing my calculations. Knowing what each line represents cuts that down significantly.