The One Piece Block
Note: This technique suits bust sizes between 80cm and 94cm only.
The process for drafting the one piece block is fairly straight forward if handled in bite size steps. Before you
start each step, click on the link marked "Illustration for this Step". A pop up window with an illustration for that
step will help guide you through the instructions. At the end of each step your draft should match the illustration.
If it doesn't go back to the start of that step and work your way through again.
This example block has been drafted for a size 10B/C using 12% horizontal negative ease and 0% vertical ease.
The way to write this on the block is '88/100' meaning the block is 88% of the natural hozizontal and 100%
of the natural vertical. This is usually referred to as the reduction ratio. I still prefer to call it negative
ease as opposed to reduction, because sometimes you may have both positive and negative ease in the same garment.
Step One
Illustration for this Step
1-2 |
Square down nape to waist measurement. Square
across the page from points 1 and 2. |
2-3 |
Square down waist to crotch. Square across the
page from 3. |
1-4 |
Square down 2cm to point 4. Square across the
page from 4. |
3-5 |
Square down half gusset measurement to point 5.
Square across 7cm to point 6. |
3-7 |
1/4 natural hip. Square up to point 8. The hip
measurement is not reduced by 12% as the swimsuit does not wrap around the leg. |
3-9 |
1/8th natural hip plus 1cm. |
2-10 |
1/4 waist measurement x 0.88 (reduction of 12%).
Join point 7 to point 10. Mark point 11 halfway along this line. Create a curve
to connect points 6 to 9 and 11. |
Step Two
Illustration for this Step
7-12 |
1/4 natural hip (same as 3-7). Square up to points 13 and 14. |
12-15 |
Square across 3.5cm from point 12 to 15. |
12-16 |
Square down 9.5cm from point 12 to 16. +/- 0.5cm per
size from size 10 |
16-17 |
Square across 7cm from point 16 to 17. |
14-18 |
1/4 waist measurement x 0.88 (reduction of 12%). Join point
7 to point 18. Mark point 19 halfway along this line. |
19-20 |
Square across from point 19. Mark point 20 at 1/3rd along this
line. Create a curve to connect Points 17, 15, 20 and 19. Once the block is cut out, the
leg curves can be trued up. Leg curves are purely a style choice and can be moved once you
know what you’re doing. |
Step Three
Illustration for this Step
13-21 |
1/4 bust x 0.88 + 1.5cm. Square down to waist line.
The 1.5cm is added to the front block and removed from the back block to move the
side seam more toward its natural position. If you are designing for a larger cup
size on the block you may want to move the side seam back a little more. 1.5cm is
about right for a 10B/C.
|
1-22 |
1/4 bust x 0.88 - 1.5cm. Square down to waist line. |
14-23 |
Waist to bust. Square across from point 23 to point 24.
Join point 18 to point 24. |
23-BP |
½ Bust separation x 0.88. Draw a line from Bust Point
to point 25 which is square to line 18-24. This is the bust dart position. |
24-26 |
Mark point 26 3cm up from point 24. Square across block
and mark in point 27. Join point 10 to point 27. |
Step Four
Illustration for this Step
13-28 |
1/6th neck measurement. |
13-29 |
1/6th neck measurement. Draw in front neck curve. Joint
point 29 to BP. |
29-30 |
Draw a line shoulder width x 0.88 to meet a line squared across
from point 33. Mark the intersection as Point 30. Trace the line shown in red onto
a new sheet of paper. |
29-31 |
Draw in point 31 the
dart width from point 29. |
1-32 |
1/6th neck measurement. Draw in back neck curve. Draw a line
shoulder width x 0.88 to meet the line squared across from point 4. Mark the intersection as point
33. Draw down a line square to line 32-33 from point 33. |
Step Five
Illustration for this Step
Rotate the traced section as shown. Draw down a line square to line 31-30 from point 30.
Draw in armhole curves as shown. The armholes curves can be trued up after the block is cut out.
Draw in side seams as smooth curves.
Step Six
Illustration for this Step
Rotate the front shoulder section shown in red back to the neckline so as to re-open the bust
dart at the side seam. The rotation should be centered on the bust point. Mark in the bust line
position on the back block by measuring up from the waist line, along the side seam to the
bottom of the bust dart. If you're wondering why the front and back armholes have ended up a
different length take a look at the section on making the sleeve block.
Step Seven
Illustration for this Step
Remove unnecessary guidelines, points and numbers. Cut out or retrace the front and back
blocks and true up all curves. Make sure you clearly label your block with a title, panel
name, size, date, author’s name and version number. Do not add seam allowance to the block!
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