Tutorial 2. The parameters for the petticoat calculation.
For better understanding I will make the calculation for the full-size skirt first and then explain and demonstrate the calculation of the half-size mock-up using the calculation of the full-size skirt.
As we have already discussed I will start from the calculation of the petticoat, which is the most inner layer of our skirt.
I open the sheet “Skirt” in the table “Calculation using the bottom length with the fixed parameters” and enter the measurements for the full-size skirt.
I am using the measurements of my dress-form. Now we don’t discuss the particular customer as in this course I am showing how to make the mock-up that is to do some preliminary work before making the full-size skirt. Trust me, when you have made the mock-up, the full-size garment will be a piece of cake!
You will not waste time to think over how to attach soft Rigilene to the ruffles or how to attach the ruffles.
Having made the mock-up, you will see the constructions of each part of the skirt and the sewing sequence! There will be no any complex tasks for you!
You are well aware: the most complicated task over the skirt, which actually stops and complicates your work, is the preliminary preparation, calculations and pattern construction! As soon as you see the mock-up, everything becomes clear as you see the miniature skirt and you just need to upscale it to its normal size.
There is reasoning behind the existence of the mocking-up in many industries! For instance, construction and architecture. An architect never submits his project to builders without a prior experimental model. It is logical and correct. I am still surprised with the people, who are skeptical and even negative about the skirt mocking-up and say: “Try to sew the full-size skirt, why do you play with the dolls?” However “playing with dolls” is the most important preliminary work, which will help you to avoid mistakes when you cut and sew the expensive fabric. It is also important, that you can calculate the real amount of the expensive fabric. This amount will not comprise 2 or 3 meters, it will be tens of meters. Please answer how you can calculate the fabric if you sew the structured skirt for the first time. I often receive the photos of the structured skirts from my students with questions about the footage of the fabric required. There can be the only answer – it is necessary to sew the mock-up of this skirt.
So, I entered the measurements of my dress-form (red arrows).
- the top circumference (waist) – 90 cm. This is the circumference of the upper edge of your future skirt, or the top circumference of the petticoat as we calculate the petticoat now.
- the length of the skirt (petticoat) - 88 cm.
- the bottom circumference – 280 cm. This is the length of the bottom hoop of the petticoat.
- the gathering coefficient for the top of the skirt (petticoat) – 1. If you don’t want to make gathering in the top part of the skirt or the petticoat, enter the coefficient 1.
Let’s check the table to see the automatic filling of the cells (blue arrows).
The waist circumference with the gathering coefficient is 90 cm. It does not change as the coefficient is 1.
We see the radius calculations for the top and the bottom of the skirt. Why do we need these parameters?
You know that each skirt can be cut as sections of the circle or gores.
Most often we cut in gores.
Although there are rare cases, when we need to keep the certain fabric pattern or the color transition and you don’t want to cut the fabric in such places. Such situation may occur when you have a very wide patterned fabric of 3-3.5 m. If you want to preserve the fabric pattern, you will need to cut the fabric as a section of the circle. So, that is why you have the calculated radiuses in the table.
The table also calculated the angle α of this section equal to 124 degrees.
This angle α of 124 degrees will be often repeated and used in our calculations. In our case we make our inner skirts namely the petticoat, cover, lining and the main skirt in such a way, that they are inserted into each other as cones. In other words, the volume or flare of those skirts has to be identical and the length should be different.
So, this angle α will be the main parameter, which characterizes this flare for all internal component of the skirts! Only with the identical angle α we will be able to create the identical cones of various lengths.
To underline the importance of this parameter (the angle α) it is written in the table: “when you have identified the angle of the skirt section, it is possible to calculate the parameters for the skirt cutting with this angle for various lengths (cover, petticoat and so on)”.
We will calculate the cutting of the petticoat with gores, so that we need to move to the next sheet. Although, we have not completed the work yet and we stay on the sheet “skirt”. But we move down.
By the way, if you move the cursor over the word “Illustration”, you will see a picture, which illustrates all my words. You will see the pictures of the circle section, the radius and the angle α.
A part of parameters has already been filled in the table “Main parameters of the skirt for the necessary angle”:
- the top circumference of skirt/petticoat – 90 cm;
- the gathering coefficient for the top – 1.
We enter the following data:
- the front length of the skirt/the petticoat – 88 cm. This is the final length of the petticoat, which I want to have.
- the back seam length with the train – 88 cm. We are making calculations for the petticoat, which should have the same length. When we calculate the main skirt, we set the value equal to the length of the back seam with the extension to the train.
- the width of the finished belt – 4 cm.
- the α angle of the section – 124. We enter the calculated value. Simultaneously the table calculates the maximal hip circumference for this skirt, which is equal to 129 cm.
Thus, we have entered all data for the calculations of the petticoat.