Pattern Drafting: Drafting the Basic (Bodice) Sloper

Whew! This is going to be difficult you guys, because frankly I want to give you the exact directions from the pattern drafting book I use which feels quite...icky? I mean, I highly recommend you all invest in the book, Patternmaking for Fashion Design by Helen Joseph-Armstrong, as I continue to use my copy all the time, despite buying it ages ago originally as a textbook my first year of college. This is Joseph-Armstrong's method, and walking you through it feels very close to plagiarism. The question is if you can plagiarize text, which is obviously a thing, can you also plagiarizer methods and techniques? I dunno, but all I'm going to say before continuing is--- please go buy the book so I feel less bad.

Then again, perhaps my directions will be so confusing you will literally have to buy the book ;)

You all have your measurements from last time right? Great, though I have some bad news, if you start drafting your pattern and you notice things are just not working, it may be because your measurements are off (like- you think the end of the shoulder is one spot, and really it is off by an inch or something). This quickly happened to me, and so I turned to plan B, which in this case was to look at a measurement chart and find a "size" with measurements where most of the numbers matched mine as much as possible. The book I use to draft patterns has such a chart in the front, and the listed size 16 measurements matched over 50% of my own. The listed "size 16" (whatever that means?) had a 40 1/2" bust, a 32" waist, and a 42" hip, and my own measurements are 40 1/2" bust, 30" waist, and 44" hips. So they were a bit off there, but at we won't be using the hip measurement to draft the bodice sloper I knew that number wouldn't matter, and taking in the waist in the end would be easy since there are going to have to be adjustments to the final sloper anyway.

What's that? Adjustments? Why yes, my dear intrepid patternmaking folk, the odds of this first sloper pattern fitting you perfectly are slim to none (yes, even though you may be using your "exact" measurements). So sorry again, but them's the facts. I mentioned before that my own method of pattern drafting has all the real work upfront, once you have created your perfect bodice pattern, you will then be able to draft almost any style of dress from it, but you have to make that base bodice pattern first, and to do that there is going to be a lot of adjusting, mock-ups/muslins, and fitting involved. My guiding principal is this: it is always going to be much easier to fix something imperfect than to create a perfect thing from scratch. 

To that point I must mention again that you can buy sloper patterns, they are a thing you can purchase and skip this whole step. You will still have to adjust them to fit you, but hey you can skip the following mess if you'd like. I personally have the double quality of being impatient and cheap when it comes to patterns, I don't want to wait to acquire them (via ordering online or whatever) and I don't want to pay for them when I know it is possible to draft them myself for free. So if any of you are still with me, lets make a simple sloper so we have something to work with eh?

Three further disclaimers: firstly, I wish to formally apologize to metric users...so sorry bout that, and second the name of the measurement used for each line below will be in bold text. Finally, the letters in the instructions below correspond to Joseph-Armstrong's order of her directions, and while my directions may be in a different order, I have kept the letters the same (so we wont necessarily be using the letters in alphabetical order, but that doesn't actually matter). Mmkay ;)

Grab some paper, a long ruler (I needed my regular clear 18" ruler as well as a longer 24" ruler), a french curve will come in major handy and they are pretty cheap so get one of those, a pencil and a big eraser and we'll get going...

(don't say I didn't warn you)

Point A to B, draw a line equaling your full length measurement + 1/8". 

Draw a line from A to C equaling your across shoulder measurement - 1/8".

Draw a line 3" down from C at a 90 degree angle.

Mark a point D by measuring from B up to your center front measurement.

Draw a line 4" long to the left and squared out from point D.

Draw a line 90 degrees from B (parallel to A to C line) equal to your bust arc measurement + 1/4", mark the new point E. (So E to B is equal to the bust arc + 1/4"). Draw an 11" long line 90 degrees up from E.

To draw the line from B to point G, use the shoulder slope measurement + 1/8" starting from point B to where this measurement intersects the line you squared from C down. Wherever the measurement intersects the C line, that is now point G.

Mark a point along the G to B line by measuring down along the line from G equal to your bust depth, mark this point H.

Draw a line connecting point H to the center front line (that's the A to B line) and label the point where they meet J. From J measure back out along the line equaling the bust span measurement + 1/4" and mark this point K. K should be to the left of H. (mine wasn't the first time, that's when I started over using measurements from the size chart instead, and then it worked fine...).

Mark a point halfway between J and D and mark it L. Draw a line squared out from the left of point L equal to the across chest measurement + 1/4". Mark the end of this new line point M. Square a line up and down from line M (just a few inches up & down).

Starting from point G, draw a line equal to the shoulder length measurement so that it hits the C to A line. Label the point where they meet I. Square down (90 degree from G to I line) from I to intersect with the line emanating from point D.

Draw a line from I to intersect with the guideline above E at a distance equal to the new strap measurement + 1/8". Mark the point where the new strap measurement meets the E line as point N.

Measure up from point N using the side length measurement, label this point O. Square in a 1 1/2" line from O. (see above illustration)

Mark out from N 1 1/4", label point P. 

Draw a line connecting point P to point O.

Measure over 3 1/2" (use 3" for smaller measurements, reference the size chart I have linked above for proper dart placement measurement for your size) from point B along B to E line and mark a point F. Measure down 3/16" from F and relabel this new lower point as F. 

Draw a line from P to F.

To find and place point Q, subtract B to F measurement from waist arc + 1/4". (If your waist arc was 10" for example, 10" + 1/4" = 10 1/4" , minus the 3 1/2" dart placement measurement = 6 3/4"). Use the new measurement (in my example 6 3/4") to measure out to the right from P (along the line from P to F) and mark end of measurement as Q. 

Draw a line from K to F. Measure this line, use this measurement to draw a line from K through point Q. Label the end of this line R.

Tired yet?

Draw a slight curve to connect a line from R to the line from P to Q.

Draw a slight curve to connect a line from F to point B.

Mark 5/8" down from K in the center of the dart legs, redraw R to this point and F to this point (see above).

Use French Curve ruler (for best results, or try your best to draw a curve) to create the armhole from G to M to the squared line before point O. The curve doesn't need to hit point M, but it should meet the guideline emanating from M at some point. See above curve in the illustration for guidance.

Measure in 1/8" from the center of the line connecting point I to the guideline emanating from point D. Draw a curve from I to D using this 1/8" mark as a guideline for how much to curve into that I line. See above again.

I think that's it for the front? Goodness I hope I didn't miss anything, as me questions if I did in the comments!

Now for the back. Ahem, this is easier in my opinion so I promise it will be okay.

Draw a line equal to your back full length measurement and label the top of the line point A and the bottom point B. 

Draw a line 90 degrees out from A equal to your across shoulder measurement. Label the end point C. Draw 3" guideline 90 degrees down from C. 

Parallel to line A to C, draw a line right from B equal to the back arc + 3/4" and label the end point E. Square up guideline from E several inches. See above.

Measure up from B along A to B line equaling center back length, label as point D. Square out 4" from D as guideline.

To find point F, measure out from A the back neck measurement + 1/8" and mark as point F.

Draw line from point B equal to the shoulder slope + 1/8" where this measurement intersects the guideline from point C and label this point G. See above.

Draw a line from point F through point G equal to the shoulder length + 1/2". The end of this line is point H.

Measure using the dart placement measurement out from B and mark I. See above. Measure over 1 1/2" from I and mark K, center between the two is L. 

To find and mark point M, take back waist arc measurement plus the 1 1/2" dart intake and plus another 1/4" for ease. Mark point M out from B using this measurement, square down 3/16" from point M and relabel that as point M. See above.

Draw line from M to intersect with guideline above E equal to the side length measurement. Point where this measurement meets guideline is labeled point N. See below.

To find point S, measure down from D equal to one fourth of the measurement of D to B. So from D to S equals one fourth of the D to B measurement. 

Square out right from S a line equal to the across back measurement + 1/4". Mark as point T, square up and down from T as shown above.

To find point O, square up from L a line equal to the distance from M to N - 1".

Draw dart legs from O through I and K 1/8" beyond the points. See above.

Draw slightly curved lines from I to B and from K to M.

To find point P, mark half way between point F and point H.

To find point Q, draw a line 3" long down from point P towards point O (you can draw a line from point P to O as a guide if you wish). 

To complete shoulder dart, measure 1/4" either side of  point P, mark, then measure 1/8" up from these marks and label as R. Connect R 1 and 2 to Q to create dart legs.

Draw curve connecting point F to point D, see above.

Draw armhole curve from point H, touching the guideline from point T and connecting to point N. See above.

et fini.

See, I warned you this was not the fun part. Don't think about all the fitting and adjusting we still need to do too....or okay do start thinking about it as that's what is next! I have my freshly drafted patterns seen in the photo above. Next week we will add some seam allowances, cut these out of muslin and see how close they come to fitting. Once we adjust the sloper pattern we can really get going with the more fun stuff!

In this photo here we see the freshly drafted sloper pattern sitting on top of my basic bodice pattern that I usually use as a sloper for all intents and purposes. They certainly don't match yet do they? Part of that I think is due to there being that magical FBA on my bodice pattern, and also my shoulder line is different than the one the sloper has ended up with using those standardized chart measurements. We will fix the sloper to fit as nicely as my favorite basic bodice pattern next time...

Thaks for sticking with me, I promise I'll show you how I get my sloper to fit right, and gather lots of fitting resources so yours will fit you too. I'll also be showing you how you can skip this custom sloper if you already have a bodice pattern (perhaps from a commercial pattern) you like that fits well by making a basic bodice pattern out of that old favorite.

Enough math for now right? ;)