In this second part of this bra pattern drafting and making series we will be drafting (drawing) the blocks/patterns for the cups, cradle and wings of a simple under wired “Darted Cup” Bra. Think of this bra as your first test into the world of bra pattern drafting and making. It may not offer the best support for the fuller bust, but it will allow you to check your measurements and fit, particularly cup volume / shape and wing tension.
In this part, I will be screaming, “ACCURACY” ... NO cheating by “pin copying” or pulling your favourite bra apart!
This bra is the simplest bra to make as the cups only have one short dart seam to sew. The bra has underwires and it will be the shape of the underwire that you will use as the start of the cradle/wing pattern. This bra can also be made without any underwires, but the cup shaping and support may suffer in larger sizes. If you wish to make the bra without any wires, you will need to use a “Breast root trace” to give you the right curves to the bra cradle to fit you.
I know that the debate on underwires in bras is always a hot topic, but the correct sized, properly “sprung” underwires can do a good job of supporting the cup / cradle shape to support the breast weight, and until an alternative to the bra under wire comes along (I am still working on that one) we will try to work with them. (For people who have missed some attempts at alternatives to underwired bras, Charnos had a financial disaster with their “Bio Bra”, and Playtex have a non-underwire bra on sale at the moment that uses some sort of plastic “fingers” for the cup/breast support. Does anyone remember the “Magic Fingers” pattern Playtex sewed on the front panels of their girdles? They were supposed to help hold your tummy in, like the fingers on a pair of hands, or so the advert went).
We will come to “Breast root tracing” and “springing” a bra wire in a moment, but first we must get some drafting/drawing tools together.
If you have read Cathy Hay’s excellent articles on corset pattern drafting you may already have the right drawing equipment for the job, but I will give you the list of tools anyway.
One of the most important tools you will need is a “Flexible Ruler” to measure curved seams. Using a tape measure will not be accurate for bra making.
If you cannot get hold of a flexible ruler you can make one by photocopying a normal ruler (a ruler with black markings on white plastic works best) onto an clear acetate plastic sheet (make sure the acetate plastic sheet is the right type for a photocopier) and then cut out the ruler image.
“Flexi Curve” for drawing smooth free curves and for taking a “breast root trace”, and a set of “French Curves”
Taking a breast root trace using a Flexi curve (right)
If you have one or have access to one, a Technical Drawing Board, consisting of around an A2 (42 x 59cm or 16.5 x 23.4 in) size board, “T” Square, 45o Set Square and 30o/60o Set Square.
Drawing parallel lines or lines at right angles to each other is so much quicker with a drawing board. But you can do all the drafting/drawing without one.
Pencils and sharpener. I was always told at university to use a mechanical “Clicky” Pencil but you can draw much finer lines with a properly sharpened ordinary pencil.
Spring Bow Compasses, one large and one small. (These are usually sold in a handy box set)
Tracing wheel and Carbon Paper.
A3 size paper (lots of it - that's approx size 30x42cm or 12x17 in)
Drafting a Bra Cup Block
We will start with the bra cup block (remember in industry, a pattern without seam allowances is called a Block). We will draft a Size 4 cup (about a UK size 34”B) and then grade (resize) it to your breast size. Remember, gentlemen who are following the articles, or those not making for a specific person: please use the Size 4 cup / 50cm back measurements, but please do try the cup grading.
TRY TO BE AS ACCURATE AS POSSIBLE. I have quoted the measurements to two decimal places. I know that one millimetre is a very small division on a ruler scale but try to judge the second decimal place number and keep your pencil / compass lead sharp. Use an emery board or nail file to sharpen the “lead” in your compasses.
On a sheet of A3 paper in landscape, draw a horizontal straight line 12.85cm long near to the bottom edge of the paper.
With your compasses set at 8.72cm, draw an arc from one end of the line and another intersecting arc from the other end of the line.
Join up the points with straight lines, as in the diagram.
This will form the “Dart” of the cup. You can write “Point of Bust” or “PB” next to the intersection of the arcs.
From the left end of the 12.85cm base line, set your compass to 9.4cm and draw an arc.
From the “Point of Bust”, set your compass to 10.26cm and draw an intersecting arc to the first arc.
From the right end of the 12.85cm base line, set your compass to 9.4cm and draw an arc.
From the “Point of Bust”, set your compass to 9.24cm and draw an intersecting arc to the first arc. Join up the points with straight lines, as in the diagram.
Still using your compasses, draw arcs from the 12.85cm base line at 11.5cm and 10.45cm from Point of Bust on left (Underarm) side and 10.8cm and 9.25cm on right (Centre front) side.
Join up with lines from base line and point of bust.
Next, to mark the “Cup Apex” (the point were the bra strap joins to the cup).
From point of bust, arc out a line 11.57cm, an arc 13.6cm (this line will become the “Neck Line Hem” of the bra cup) and an arc 7.13cm (this line will be curved to become the “underarm” hem of the cup) See diagram for start points of the arcs / lines.
Later this cup apex point can be moved to suit individual fit / styles.
In woodwork we measure twice and cut once, so check the cup measurements.
You should now be ready to draw the curved lines (red lines in diagram) of the cup outline using a Flexi Curve or French Curve.
Try to make the curves smooth and flowing through the points.
Next, extend the lines that “radiate” from the Point of Bust point to the edge of the cup and beyond, number the lines 1 to 7 clockwise starting at the “cup apex” as in the diagram.
We will use these lines to “Shift Grade” the cup to your size.
Lines 3 and 6 are very important. When you tape together a test paper bra cup, lines 3 and 6 should form a straight, horizontal line over the fullest part of your breast (we will not put the lines on the fabric! The lines will only be on the paper block/pattern). When we come to adapting the cup block for other styles we will use lines 3 and 6 to split the cup into panels.
Step Seven: Shift Grading
Copy the cup plus radial lines onto another sheet of stiff paper (photocopy or use a tracing wheel and carbon paper) and then cut the copy of the cup out. You will use this second cup to mark around on your original drawing as in the diagrams.
You now need to measure along each radial line (1 to 7) from the centre “Point of Bust” of the Size 4 cup you have drawn the right number of grading “steps” for your cup size, To save you time and your calculator batteries, I have given you the line lengths (1 to 7) you need to mark on your Size 4 cup lines in the table to grade the cup to your size. All measurements are taken from the centre Point of Bust point of the cup.
OVER BREAST MEASUREMENT
(All Measurements in cm) grading step = 1.7cm
||LINE 1 LENGTH (STEP 1.07cm)
||LINE 2 LENGTH (STEP 0.85cm)
||LINE 3 LENGTH (STEP 0.81)
||LINE 4/5 LENGTH (STEP 0.76cm)
||LINE 6 LENGTH (STEP 0.86cm)
||LINE 7 LENGTH (STEP 0.98cm)
||14.1cm to 14.7cm
||15.8cm to 16.4cm
||17.5cm to 18.1cm
||19.2cm to 19.8cm
||20.9cm to 21.5cm
||22.6cm to 23.2cm
||24.3cm to 24.9cm
||26.0cm to 26.6cm
||27.7cm to 28.3cm
||29.4cm to 30.0cm
||31.1cm to 32.8cm
||32.8cm to 35.6cm
||34.5cm to 38.4cm
||36.2cm to 41.2cm
||37.9cm to 44.0cm
||39.6cm to 46.8cm
||41.3cm to 41.9cm
||43cm to 43.6cm
||44.7cm to 45.3cm
||46.4cm to 47cm
||48.1cm to 48.7cm
||49.8cm to 50.4cm
||51.5cm to 52.1cm
||53.2cm to 53.8cm
||54.9cm to 55.5cm
||56.6cm to 57.2cm
||58.3cm to 58.9cm
||60cm to 60.6cm
||61.7cm to 62.3cm
Grading Example: - Size 4 to Size 8 cup
Now use the cut out copy of the size 4 cup as a template to draw each “corner” of the new “your” size cup.
Align the size 4 cup to the lines and grade marks on your original draft and draw in the corner. Do not completely draw around the cup at each step, just draw the corner.
You can see this process in the diagrams below.
Now using your Flexi Curve / French Curve, smoothly join up the “corners” to give you the new cup outline.
Copy the new “your size” cup onto another sheet of paper (photocopy or use a tracing wheel and carbon paper) and then cut the copy of the cup out. Using sticky tape, stick the cup “Dart” together and check the “look” of the cup. Do not worry that the cup comes to a point, paper will not “flow into shape” like fabric and when you sew the fabric cups you should sew outwards from the point of the dart to remove the “point”. When we come to adapt this cup to two and three panel bra cups we will have smoother over bust seams.
Drafting the Band
If all looks OK with the cup, we are now almost at the stage to start drafting the Cradle and Wings of the bra, but you need to find the correct curve for the Cradle to Cup seam.
As this Cradle to Cup seam is where the underwires will be sewn and it is the seam that sits up against your Breast Root, these are the two things that we will use to draft the length and curvature of the seam: a Breast Root Trace and an Underwire.
Breast Root Trace
To take a breast root trace, use a Flexi Curve and a sheet of paper.
Put the Flexi Curve around your breast (right breast as we are drafting the right half of the bra or you can trace your left breast and flip the trace over on the paper) and make sure it is up against the point around where your breast tissue joins the chest wall. This is the same point around the breast where the underwire of a correctly fitting bra should sit, not on breast tissue (pain) and not away from the breast (poor fit).
Now mark on the Flexi curve, with chalk or thin tape, the point directly (vertically) below the nipple or fullest part of the breast.
Next, imagine a horizontal line across the fullest part of the breast and put two marks on the Flexi Curve ether side of the breast and about 2cm above the imaginary horizontal line.
You may need the help of a close friend to do this while you hold the Flexi curve against yourself.
Now CAREFULLY take the Flexi Curve away from your breast without moving its curve and place it on the sheet of paper. Again carefully draw around the edge of the flexi curve that was up against your breast and transfer the three marks to the curve on the paper.
You now have a curve to help you find the correct underwires for your size and to draft the correct cup to cradle seam. Hurrah!! You just may be on the way to a bra that actually fits you.
Now you need to get hold of two underwires for your bra that match your breast root trace. If you are obtaining your wires in person from a shop you can take your breast root trace with you and try their wires against it. If you are planning to get your wires from the internet see if the company has “to size” drawings or pictures of the wires they sell, so you can again match up your trace to the correct wires.
An Internet company I use for corset and bra bits is www.sewingchest.co.uk; they have a downloadable PDF document that shows all the underwire sizes that they sell. You could try to find “MS20” underwires in your size, the MS20 underwire is a good “day bra” shape and it is the wire shape that the largest UK underwear retailer (clue: give us an "M"; give us an "S") have as their standard.
One major point: the wire that is closest to the size and shape of your breast root trace will veer away from the trace curve at the underarm side (right).
This is because when the wires are in the bra and worn, the wires are “pulled open” or “Sprung” to the curve of your breasts by the elastic pull of the wings of the bra.
So do not worry if you cannot find underwires that exactly match the curve of your trace.
Another tip: choose a “Day wear” underwire. Steer clear of “Plunge” underwires and “Strapless” styles at this stage.
Here is the shape of a typical Daywear wire for a UK 34”B bra which will work with the Size 4 cup, for readers who do not have “client” to make a bra for. Print the picture off and use it to obtain two underwires.
When you have got your wires, you can continue with the pattern drafting, or you can use your Breast root trace if you want to have a go at making the bra without any underwires.
The Cradle and Wings
We will draft one half of the bra and when we come to mark and cut out the fabric we will turn the pattern parts over to give us both halves.
Finding the “balance point” of your underwire.
On a sheet of A3 paper in landscape mode, draw a horizontal line across the centre of the paper. Near to the right hand side of the paper draw a line at 90 degrees (vertically) to the first line.
Place one of your underwires on the two lines so that the inner edge of the centre front end of the wire touches the vertical line and the bottom of the wires curve (again inner edge) touches the horizontal line as in the diagram.
Now where the wire touches the horizontal line, put a mark on the paper. This is called the “Balance Point” of the wire. Next, lightly draw around the inner edge of the wire onto the paper and mark the end points of the wire.
On the paper, measure down 5mm from the centre front end of the wire's curved line and mark the point.
Place the wire back on the paper on its curve and then shift the wire around the curve so that the wire's CF end now aligns with the 5mm point on the paper.
Again, draw around the inner edge of the wire onto the paper and mark the end points of the wire.
This slight “tilting” of the wire helps for a better fit against the curvature of the chest wall.
Now you need to “spring” the wire and redraw its curve. You may need the help of a friend to draw the sprung wire curve whilst you hold the wire open.
On the paper, at the underarm end of the wire curve, place a mark 1.5cm horizontally to the left of the wire curve. Now whilst holding the underwire on the paper so that the CF (centre front) end of the wire stays in position against the first vertical line / curve, pull open the underarm end of the wire to the 1.5cm mark and redraw the wire's curve.
Without an Underwire
For those of you who do not want to use underwires, copy your breast root trace onto a sheet of thin card and cut the card along the line of the trace. You can now use your trace as an underwire template. DO NOT try to “spring” your trace, as it is already the correct curve for your bra!
As with the wire drawing, place your trace template against the horizontal and vertical lines and do the 5mm “tilt” using the centre front mark you placed on the trace as the “CF end of the wire” and draw around the curve. Remember to copy the three marks (centre front, under bust and underarm side) on the trace on to the paper. Please remember that with the larger size cups, using the correct size underwires helps the shaping and support of the breasts.
After you have drawn the curve of the wire in the “sprung” position, you need to add to each end of the curve 5mm for “Wire play” and 3mm for “Bar tack sinkage”. So that will be 8mm added to each end of the underwire curve. Extend the curve.
Marking in the centre front line of the bra:
From the CF top point of the wire curve, draw a horizontal line 1.2cm long then draw down a vertical line at the end of this line. This is the CF (centre front) line of the bra.
As the underwires will be in “wire casing” you need to add 3mm allowance to the inner edge of the wire curve.
This is not “seam allowance” - we will add that at the end.
Now that we have drafted the curve and length of the “cup to cradle seam” for the cradle, we need to transfer the length of the curve to the cup.
As the “Balance Point” marked on the paper is also the alignment mark for the “cup dart”, we must measure from this point up either edge of the cup and adjust the cup.
Use your “Flexible Ruler” to accurately measure Length “A” and Length “B” and transfer the lengths to the cup.
You may need to shorten or lengthen the cup curves to match the cradle curves and then redraw the Neckline hem and the underarm hem.
We will now draft the rest of the cradle and wing. Remember, we are drafting just one half of the bra (right side).
Measure down from the first horizontal line you put on the paper and mark four lines, at 6mm, 18mm, 28mm and 76mm respectively, horizontally across the paper.
From the top of the cradle / wire seam at CF, draw a horizontal line across the cradle to the underarm side.
Where this line intersects the underwire curve line, draw a line vertically down to the “28mm” line and mark the crossing point “A”.
Now for some Maths. If you have been following Cathy Hay’s Corset drafting article you may already understand how to calculate a measurement using a Percentage.
You will use your “Back Measurement”, taken from side breast root, around your back, horizontally to your other side breast root.
If I asked you to draw a line 32% of your back measurement the calculation would be:
Back measurement = 50cm,
Divide 50cm by 100 = 0.5,
Then multiply 0.5 by 32 = 16cm
So the length of your line would be 16cm.
Again if I asked you to draw a line 17.1% of your back measurement the calculation would be:
Back measurement = 50cm
Divide 50cm by 100 = 0.5
Then multiply 0.5 by 17.1 = 8.55cm
So the length of your line would be 8.55cm.
We will now draw in the Cradle to Wing side seam.
From point A on the 28mm line, measure alone the line 4.56% of your back measurement (BM) and place a mark.
Example, BM = 50cm, 50 / 100 = 0.5, 0.5 x 4.56 = 2.28cm
Follow the diagram to put in the other lines. From the new point on 28mm line, draw a line 17.1% BM (back measurement). From top of wire curve at underarm, 9.3% BM to intersect 17.1% line. This 17.1% line will be the Cradle Side Seam.
From the bottom of the 17.1% cradle seam line draw a line 32% BM long so that it intersects the 76mm horizontal line.
At this intersection point draw a line 2.5cm long at right angles to 32%BM line. This 2.5cm line will be the CB (Centre Back) of the bra and the point to sew on the hook & eye tape. 2.5cm should be wide enough for a two hook & eye wide fastening, although for the larger cup sizes you may need to go for a three hook & eye wide fastening. You can change this measurement when you have obtained your hook & eye tapes.
On the 32% line, put a mark 4.8cm from the 2.5cm hook & eye line then at right angles to the 32% line draw a line 6.6cm up from the line.
Now that we have the main points of the cradle and wing marked out, we can join up the points with smooth curves.
Using your Flexi Curve or French Curves, draw the “underband hem”. Start on the 6mm line at right angles to the CF line, then take the curve through the 18mm line below the “Balance Point”, continue on through the 28mm line /side seam line intersection, curve up slightly above the 32% line and end at the bottom of the 2.5cm line.
For the “strap platform”, a simple curve from the top of the 2.5cm line to the top of the 6.6cm line. For the “Underarm hem” start at the top of the 6.6cm line, go through the top of the side seam line and finish at the top of the cradle to cup seam line/curve.
Copy the Cradle (from CF to side seam) onto a new sheet of paper and copy the Wing (from side seam to hook & eye CB) on to a new sheet of paper.
Now add 5mm seam allowance to all three patterns (Cup, Cradle and Wing) plus cutting and sewing marks i.e. pattern name, number of parts to cut out, direction of fabric weave and seam alignment marks. There is NO seam allowance added to the Wing at CB (centre back) as the hook & eye tape wraps around the end of the wing.
The pattern instruction “Cut one pair” means we will cut out a left and a right side. So when we mark out the fabric we will mark out the right side of the bra parts then “flip” the patterns over and mark out the left side bra parts. We will not fold the fabric and try to mark / cut out a pair at one time! That way is “Home sewing": for accuracy in industry nothing is “cut on the fold” and we will not pin the patterns to the fabric.
But more of that next time...