We're going to ease into our blazer-making adventure with some tracing. We need to make some extra pattern pieces for the inner structure which will be cut from hair canvas and muslin. I took a ton of pictures to show you these pieces, so I'm going to break it down into the canvas pieces today and the muslin pieces tomorrow, to avoid a mega-post.
Once you've chosen your pattern, of course the first thing you will probably need to do is to either make a fitting muslin or do a tissue-fitting. This sew-along is going to focus on construction only - it's beyond my skill right now to do a series on fitting. One of the reasons I recommend the McCall's 6172 pattern so often is that it's from the Palmer/Pletsch series, so the first couple pages are all about getting a good fit. It's the pattern I'll be using here. I've made it 4 times already because for me, there are usually a lot of fitting adjustments to make - on this blazer I had to make 10. So having a TNT just makes sense.
I'm a big fan of tracing patterns, for the very reason that I tend to do tissue fittings these days, and all those adjustments make for a lot of wear and tear on the tissue. Once I've got a pattern fitted the way I like, I transfer my final copy (if I think I'll be making more than 2 of that pattern) to Swedish Tracing Paper. I've also seen people fuse a lightweight fusible interfacing to their tissue patterns to strengthen them. Do whatever works for you.
Ok, let's get down to business. You'll need to make the following pieces to be cut from hair canvas:
2. Front shoulder reinforcement
3. Under collar
That's it! I've taken photos of these using my traced M6172 pattern. This blazer has princess seams front and back, so there is a front, side front, back and side back. If your fronts and backs don't have princess seams, I'll mention as I go how to approach that.
Here's how my front interfacing piece looks, on top of the front piece:
My pattern has a front dart, so the vertical edge of the interfacing follows along the edge of the dart, up to above about an inch above the top of the dart, then over to the side front seam. Here's a closer look - you can see the red curved line I drew on my original front pattern. Curve it over until it ends at 3" below the armhole seam. Now, mine is not an armhole seam but a side front seam, so my curve is quite curvy. But I kept it at 3" anyway because anything less seamed too flimsy to me - the canvas has a tendency to fray. You can use your judgment.
If your front piece doesn't have any darts, lay your facing piece on top of your front piece. Draw a vertical line on your front piece 1" wider than the facing extending up to 1" above the bust apex*, and then curving over to the side seam to 3" below the armhole seam line as above.
*My tailoring book says above the apex for larger busts, and 1" below the apex for smaller busts. Honestly, I haven't done a non-darted blazer before, but I will say that the canvas is very flexible so I wouldn't worry about it too much. You'll find this seat-of-the-pants approach throughout the sew-along :-)
Finally, mark the grain line on your interfacing piece to match the grain line of the front.
Take your front piece again, and if you don't have the seam lines marked on it, do that at the shoulder, neck and armhole edges. Also make sure the roll line is marked.
Now make a piece that looks like this:
The top (shoulder) and sides (armhole and neck) will be 1/8" inside the seam lines. The bottom edge will be about 2/3 of the way down the armhole, extending out parallel to the armhole. That curved edge needs to be about 1/2" away from the roll line. With this piece, I don't think it's super important to be exact. You just need a little extra support at the front shoulder to keep the blazer from collapsing into that hollow below your collar bone. But it is important that this piece not get into the seams or interfere with the roll of the lapel.
Mark a bias grain line on this piece.
Take your under collar piece and trace it again. Then cut away the full seam allowance from the outside edges and cut away 1/2" from the neck edge. Keep the center back seam allowance. Here's what it looks like:
I'm hoping you can see that only that neck edge (the one next to the collar stand marking) has a 1/8" seam allowance, and the center back seam allowance is intact. The remaining seam allowances have been trimmed. Please note that this pattern piece is exclusively for the machine tailoring method - the other methods use different seam allowances.
Mark the same bias grain line on this as the under collar piece.
That's it for today. Seems I couldn't avoid a mega-post after all :-) None of this is very difficult, but I wanted you to have plenty of pictures. I'll be back tomorrow to show you the pieces you'll need to cut from muslin.