Drafting the flat body block - calculators at the ready? Then let's go

If you fast forward to the end of this tutorial, you will see that the resulting pinafore has been called Swampy because it is WAY Too Big. In Part IV of the tutorial, I explain how that came about and promise to put this section right.

First I'm doing the back body block. The front body block is based on this, with a few alterations for the shoulder slope, armscye and, of course, the front neckline. Just a reminder of what you will need for this exercise:

1. squared dressmaking paper (or ordinary paper and a set square. You're going to need the set square anyway so you might as well get the cheaper paper...)
2. a sharp pencil
3. a longish ruler - I only used a standard length one for this and boy, wouldn't it just have been easier with a metre-long rule!
4. a calculator
5. a rubber/eraser
6. a set square and
7. tracing paper

Mark point 0 on your paper. This is going to be the top of centre back. Then draw a line across the top of the page from 0 ("square across") and another line straight down from 0 ("square down"). You are going to mark points 1 and 2 on the squared down line, which will be placed as follows:

1 Back neck to waist plus 1.25cm (mark the waistline at the "back neck to waist" point)

2 waist to hip.

then square across from both 1 and 2. You will shortly be marking points 4 and 5 on these lines, but first you have to mark point 3, which is squared across from 0 and is 1/4 the chest measurement plus 1cm for sizes 80 to 116cm, 1.25 for sizes 122-140cm, and 1.5 for sizes 146-170cm. Square down from 3 and the intersections on the lines from 1 and 2 will be points 4 and 5 respectively. And here we need the picture to do the job of 1,000 words...

Line 4-5 is the hipline. Now you mark point 6, which is 1.25cm down from 0. This is the top of the back neckline. Next you put in the armscye at 7. So 6-7 is the scye depth plus (1.5 to 2cm). Essentially, the 1.5 is for the baby sizes and 2cm for bigger children. This is a 'suck it and see' measurement. I used 1.5cm for Laura's. Square across to 8.

Point 9 is the point to which the armscye will slope inwards and it is halfway between points 6 and 7. Square across (you will be drawing in the armscye later on). Point 10 will provide the marker for the top of the back shoulder and it's at (1/4 the scye depth) less 2cm. Square out. Time for another picture I think...

Point 11 marks where the back neckline starts. It is on the 0-3 line, at 1/5 of the neck size measurement. You will shortly be drawing the back neckline in from 6 to 11, but don't do it just yet. I'll explain why shortly.... this is all going to make sense soon, I promise!

Point 12 comes next. This is set on the line you squared out from 7 to 8, at a point equal to (1/2 across back measurement) plus 1 (or 1.25 from size 122 up, or 1.5 from size 146 up). Square up and mark points 13 and 14 on the intersections with the lines squared out from 9 and 10 respectively. The picture will really help here.

You are now going to put in point 15, which marks the tip of the shoulder and is on the line that squares out from point 14. It lies between 0.9cm and 1.3cm along that line.

Now you can start joining the dots. What Winifred Aldrich doesn't explicitly say (although it's implicit in the drafting of her blocks) is that each garment corner must be a 90 degree angle. This is so that you get clean lines across seam intersections. Does that make sense? Probably not. I'll draw in the garment lines in red and this will help me to explain what I mean.

Now this drawing is not to scale so if yours doesn't look like this, then you're probably doing OK. But what is correct in mine, is the right-angled corners. I have marked each one. The good news is that having each corner as a right-angle makes drafting the curves of the neckline and armscye much easier. The bad news is that you're going to need your set square to ensure that the right-angles are true right-angles. Draw in the line from 11 to 15 first and then you can do the line from 6 to 11. Keep the curves as smooth as you can but you must ensure that each line ends up straight so you can keep the 90 degree angle. Have I harped on enough about this 90 degree angle business? OK. Then draw in the right angle at 15 and 8 and join them with a curve, dipping in to meet 13 along the way. And that's it - that's the back body block complete.

Now for the front. I'm doing this on the same sheet of paper, which is how I did the real-life version too. I'm going to do these additional points in red.

The front neckline dips down to point 16, which is 1/5 neck size. When you trace off your patterns, you can put it wherever the heck you like, but it's good to have an 'official' start point.

The front armscye is deeper than the back so point 17 is between 0.6 and 1cm in from point 13. And the front shoulder slopes dips lower than the back (remember that right-angle rule? well this is it kicking in again - you've altered the neckline, so now you need to alter the shoulder line too. I may be mixing up cause and effect here, but the principle is the same.)

So draw a line below the 14-15 line. It's between 0.6 and 0.8cm below the line - again, use the smaller figure for the smaller sizes. I've drawn it as a dotted line.

The front shoulder seam is obviously going to be the same length as the back one so the line 11-18 will be equal in length to 11-17. Mark point 18 and draw the line from 11 to 18. You can now use the new shoulder line to draw in the armscye (which will have to dip into 17 in order to achieve the required 90 degree angle at 18) and the front neck curve from 11 to 16.

And that's the front and back body blocks done. Get yourself a cup of tea because if you've got this far, then you've earned it. I'm sure as I can be that there is an easier way of doing this but I can't quite see it yet. If I ever do, I will definitely be posting it and that's a promise.

Since the pinafore will be sleeveless, I shall leave the drafting of the body sleeve for another day and the next drafting post will deal with turning the block into the pattern.