Monday, April 14, 2014

SSDA 7: Measuring darts

We discussed many possible fit issues that are direct result of incorrect measurements of circumference (waist and hips), front-back balance, as well as started talking about darts.

We also have covered how to take five measurements, waist circumference, hip circumference, and front, side and back length. It is time to finish the measurement posts with darts.

In my last post I briefly showed you the purpose of darts and how standard dart calculation can cause problems with the fit. In most patternmaking methods we are instructed to use standard values instead of measuring darts. Why? I believe there are two reasons:


  • Most common patternmaking methods are developed for ready-to-wear. They are based on adopted standard measurements, and therefore there is no need for additional measurements.
  • Dart are tricky to measure if you don't know how to do it.


Note: One modern patternmaking method that uses dart measurements was developed by Galya Zlachevskaya, a Russian pattern-maker and designer. However, her method requires taking more measurements for very accurate results. 

It is not such a crazy idea to  measure darts. Some methods ask you to measure the distance from your waist to hip on your side. How is it different from a dart length? In fact, what you measure in this case is the side dart length, from the waist to the most protruding part of your hip. That is not tricky, wouldn't you agree?

Let me warn you before starting, I am explaining every step in a great detail. This should help you take measurements yourself understanding what you are doing. The actual process of measurement taking is rather fast, and the calculations minimal. To make it even easier for 'draft-alongers', I will later include a measurement taking and calculation chart. 


BEFORE MEASURING

I hope you are rubbing hands, readers! Let's start! This measurement should be taken as a part of the measurement taking session, but for practice you can measure only darts. You should wear some moderately tight clothing, leggings and a body-hugging T-shirt would do. You should be wearing an elastic, and for your measurements use consistently either its lower or upper edge as a reference line.  To make it easier, let's mark the most protruding parts on the back, front and side with a pin, pinned horizontally. We will be measuring only one side. If you have an asymmetric figure (indicated by the difference between the left and the right side length), logically, you will need to measure on both sides. I won't be covering asymmetric figures in this post, however, because I would like to explain the concept first.

We now have two reference points for each dart, the waist and the most protruding points in the front and the back.  What we need now is two rulers. I like 1" transparent acrylic rulers for quilters, or even better this Westcott 10ths/Metric Beveled Ruler, 12-Inch/30cm (B-65). If you don't have those you can make rulers yourself with two layers of manila folder and mark ruler units using metric system. We will be making some calculations, so using metric values makes it a lot easier.


MEASURING

We will be taking two measurements - Dart Depth (DD) and Dart Length (DL) - and repeat them in the front (F), left side (L)  and the back (B). For asymmetric figures, measurements are taken on both, left and right side.

Let's start with taking measurements in the back as an example. Position one ruler vertically from the most protruding part of the buttocks, toward the waist. Position the other ruler horizontally, so both rulers cross at 90 degree angle as in the illustration below. Measurement units should start from the waist and the most protruding point accordingly.
Rulers (grey rectangles) must cross at right angle, with one ruler being parallel, and the other - perpendicular to the floor. 

Write down Back Depth (BD) and Back Length (BL), and proceed with the remaining dart measurements in the same manner.


FD =                         FL =
LD =                         LL =
BD =                         BL =


TIP: Practice on a dress form, a friend or family member to gain some confidence. Make sure that the rulers cross at right angle, and that the horizontal ruler is strictly parallel to the floor.


CHECKING FOR ERROR

Now, unless you are a measurement wiz, there will be an error in your measurements. In addition, when measuring darts we cannot consider the 2cm ease that we added to our waist circumference (1cm for half pattern). With darts, because the are key to the fit, only a little error is tolerable. So, at this stage we need to check how big the error is. To do so,

1. calculate total dart intake (DI). This is a more accurate value, so we will use it to calculate the error.

DI = (hip circumference - waist circumference)
                                                                                    2

Note: Your waist circumference value must include ease. Also, we divide the total dart intake by 2 because all the calculations are done for half body. 

2. add up all the dart depth values you measured, to calculate the total dart depth (DD).

DD = FD + LD + BD

I wanted to note that terms dart depth and dart intake are only nominal, to help differentiate between the different ways we measured or calculated them for this particular post series. Normally, both terms are interchangeable, with dart intake being more common. 

3. subtract dart depth from dart intake to get the error value (e)

e = DI - DD

If you measured more or less accurately the difference between the two values should be about 0.5 to 1.5cm. If not, try to re-measure yourself.

We finished the measurements, readers. In the next post, we will calculate darts, and then, determine the location of the side seam. I hope you are not discouraged by the amount of information. Please do ask questions and post comments!



Previous Straight Skirt Draft Along (SSDA) posts:


Coming up:

SSDA 8: Calculating Darts
SSDA 9: Side Seam Placement
SSDA 10: The Measuring Session
SSDA 11: Drafting the Skirt
SSDA 12: Making a Toile and Analyzing the Fit


12 comments:

  1. I just wanted to say THANK YOU for posting this. As a new sewist, this is very helpful!!

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  2. THANK YOU so much ... like the previous review i am a new sewist myself and i have NEVER read such logical material ...hope you keep this series going on..

    ReplyDelete
  3. Thanks, Marina! This picture will help to get my husband, an engineer, on board to help take these measurements. Rulers at straight angles, now we're talking technical stuff ;)

    ReplyDelete
  4. This is such a wonderful series of posts, Marina. Thanks so much.

    ReplyDelete
  5. Thank you for taking the time to do all this. This is so very helpful and interesting.

    ReplyDelete
  6. I must have been thorough with my measurements, the difference between DI and DD is 0,4 cm \o/ *on to read part 8*

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  7. Hello, Maybe its me that didn't understand completely the article, specially I normally do all my patterns using draping, but you said: "To make it easier, let's mark the most protruding parts on the back, front and side with a pin, pinned horizontally."

    When I see the pictures the front part shows DL from Waist to hip, or shall we measure from waist to the most protruded part of the area between Waist and hip, because for me according to the pictures will be mostly in the middle and there I will have the pin marking.

    Thanks so much

    ReplyDelete
  8. Hi there, great set of posts, going to try it!
    A question -
    You say above that the waist measure should include ease when calculating the total dart intake - does the hip measurement not need ease too?
    Many thanks, Kat

    ReplyDelete

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