Drafting the Bunka Sloper
The Proportional Bunka Block only requires a few body measurements
After Block is drafted waist circumference will be needed for shaping with darts.Poster board is ideal for drafting sloper blocks. You may use any type of paper such as Kraft paper and trace your finished sloper block carefully onto a thicker board. Keep in mind you will want to work with papers that you can cut with ease. The symbols on the diagrams, like triangles and circles represent the measurement that will be used for other areas with the same symbol. Broken curved lines mean divide and use one portion for calculating.
SNP = Shoulder Neck Point
BP = Bust Point The sloper block is a template and will have NO seam allowances.
In the top left corner write your 4 key measurements
Start about 5cm from the top of the paper (use the edge of the paper if using poster board) make a rectangle (called pattern frame) using the back neck to waist measurement for the vertical line, and the formula BUST divided by 2 add 5cm (this is the sloper’s ease) for the horizontal line.
Make sure your angles are true right angles – take your right angle or square and verify.
The left side of the rectangle is the Center Back Bodice Line and the right side of the rectangle is the Center Front Bodice Line.
Divide the rectangle horizontally using the formula BUST divided by 6 plus 7cm. This will be the Bust Line, square across.
Divide the bottom horizontal line in half and mark this point. Equals Bust divided 2 plus 5, divided by 2.
Draw a vertical line from the horizontal line on bottom to the horizontal line midway in the rectangle up to the Bust Line.
Then from the left side, which is the Center Back Bodice Line measure the formula.
BUST divided by 6 plus 4.5 cm. Mark this point and draw a vertical line that is perpendicular to the horizontal line.
Then from the Center Front Bodice Line on the right side of your rectangle, measure out the formula BUST divided by 6 add 3cm.
Mark this point and draw a vertical line that is perpendicular to the horizontal line.
Divide by 2 the amount between the far left vertical line and the lower vertical line (that bi-sects the bottom rectangle).
This MEASUREMENT is designated by the SOLID TRIANGLE symbol.
Mark a distance that is the SOLID TRIANGLE symbol measurement PLUS 0.5cm from the corner at a 45degree angle outward. Mark this point.
Looking at the diagram again, mark a distance that is the SOLID TRIANGLE symbol measurement from the corner at a 45degree angle outward. Mark this point.
On the top left corner of the Back Bodice measure out the formula BUST divided by 20 add 2.9cm.
Mark this point from the top left corner across on the horizontal line.
This MEASUREMENT is designated by the DOUBLE CIRCLE symbol.
Looking at the diagram at the top left corner, divide the DOUBLE CIRCLE symbol measurement by 3.
This new measurement is designated by a SOLID CIRCLE symbol.
Draw a vertical line the SOLID CIRCLE symbol measurement upward (perpendicular to the top horizontal line) as shown in the diagram.
Looking at the diagram you need to find the center of the second 1/3rd measurement previously made.
From this point a line is draw (shown as a dash line) from the point to the top of the vertical line just drawn. This “shape” will be used to draw the back neckline curve.
On the first vertical line located within the large rectangle (not the Center Back Bodice Line) Locate a point the SOLID CIRCLE symbol distance down from the top horizontal line.
The measure out perpendicularly out 2cm. Mark this point.
On the second vertical line located within the large rectangle mark a point two SOLID CIRCLE symbol distances down and mark this point.
Then draw a perpendicular line towards the left about 3-4cm; there is no precise measurement needed here.
On the Center Front Bodice Line (the right vertical line of the rectangle) mark a horizontal distance from the right corner the distance of the DOUBLE CIRCLE symbol MINUS 0.2cm. Mark this point.
On the Center Front Bodice Line again mark a vertical distance downward from the right corner the distance of the DOUBLE CIRCLE symbol PLUS 1cm. Mark this point.
Draw a box with right angles.
Look at this box. Using the bottom horizontal line of this box, divide it in half. This measurement is designated by the SOLID CIRCLE WITH AN “X” symbol.
Look at the box again. Using the lower left corner of the box, draw a 45degree angle line towards the center of the box; the length of this line being the measurement of the SOLID CIRCLE WITH AN ‘X” symbol MINUS 0.3cm.
Now we move to the bottom half of the sloper rectangle.
On the midway horizontal line, the Bust Point will be marked.
Divide the horizontal distance between the Center Front Bodice Line (the right side of the sloper) and the second vertical line on the upper half of the sloper rectangle. This will be the second vertical line contained within the sloper rectangle, not including the Center Back Bodice Line.
Find the center point and mark. Now mark a point to the left of this center point a distance of 0.7cm.
Draw a vertical line perpendicular downward to the bottom of the sloper rectangle.
Measure down 4cm and this marks your Bust Point (BP). It may be necessary to check the Bust Point against the person’s body once the sloper is complete.
Working on the CENTER FRONT BODICE LINE of the sloper, from the bottom horizontal sloper rectangle line, mark down the SOLID CIRCLE WITH AN “X” symbol measurement.
Extend the vertical line used in creating the Bust Point downward the measurement of the SOLID CIRCLE WITH AN ‘X’ symbol.
On the vertical line located in the lower half of the sloper, the line that bisects the bottom half of the sloper vertically, mark 2cm towards the left of this line on the bottom horizontal line of the sloper rectangle.
Now we are ready to create the shoulder lines.
On the BACK BODICE draw a line diagonally from the shoulder neck point (SNP) —
see diagram— to the shoulder point (SP). This measurement will be designated by the OPEN TRIANGLE WITH A SLASH symbol.
On the bodice front at the neck point (the left top corner of the box we created) mark a point 0.5cm down.
From this 0.5cm point draw a diagonal line towards the shoulder point (SP) — see diagram — the distance of the OPEN TRIANGLE WITH A SLASH symbol MINUS 1.8cm.
The mark will land somewhere on the previously drawn short horizontal line.
Using the French Curve, start drawing the back neck curve, the front neck curve, the back armhole curve,
and the front armhole curve.
Three points should land on the French Curve. Make sure your curves match those shown on the diagram.
Draw the bottom lines as seen on the diagram. This is your waistline (WL).
Draw the diagonal line that separates the front and back bodices as seen on the diagram.
Label your sloper pieces include name and date.
Cut out your front and back slopers, make a hole where the BP is so you can easily mark the BP with a pen/pencil onto your pattern drafting paper later.
Make a hole for the BP (bustpoint) so you can make a mark on the pattern piece for the BP.
