# Distorted curve / Courbe qui se déforme

Hello,

I made my basic sloper in size 38 but why do my curves distort in size 34?

Bonjour,

J’ai fait mon buste de base en taille 38 mais pourquoi mes courbes se déforment pour une taille 34?

Merci pour votre aide.

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salut emmababi,

Your curves are distorted because while changing sizes will enlarge or decrease your pattern (including line and curve segment lengths) but it will NOT change the length of your reference points for the curves. So the curves’ start and end point parameters change, but not their length and angle parameters. Hence the distortion.

You need to determine the curves’ reference point values in proportion to the lengths and values in the pattern (i.e. 1/3 of length from Y to A13 or similar) in order for curves to shrink or grow proportionally.

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thank you for your help. How do I determine the reference point value? I don’t know which formula I should put.

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Hi @emmababi!

To achieve a scalable curve, use formulas.

First, draw the reference lines of your armscye. We will use these lines in the armscye’s formulas:

• First draw a line from Y to T’ (eg Line_Y_T’)
• Then draw a line from Y to V’ ( eg Line_Y_V’)
• Then draw a line from V’ to T’ (eg Line_V’_T’)

Remember that angles move anti-clockwise, starting with 0 degrees at 3 o’clock

Also, remember the guidelines for creating scalable curves.

• Control handle lengths are initially 1/3 of the line between endpoints (eg Line_Y_V’ / 3)
• Never use a number as the length of control handles, always use a formula.
• Angles at endpoints are relative to the connected side lines. For example, use AngleLine_W_Y then adjust with -90 or +90 for right angles or -180 to reverse direction.
• Angles at midpoints are relative to the line between endpoints.
• Never use a number as the angle of control handles, always use a formula.
• After creating the curve with these guidelines, adjust the length of the control handles as needed to achieve the fit you want.
After you’ve created a curve this way it won’t be confusing

So, for @emmababi’s design: We have a curve with endpoint Y, midpoint V’, and endpoint T’

Define the curve from Y to V’:

• 1st control handle length: (Line_Y_V’ / 3)
• 1st control handle angle: (AngleLine_W_Y - 90) --> Creates a right angle to Line_W_Y
• 2nd control handle length: (Line_Y_V’ / 3)
• 2nd control handle angle: (AngleLine_Y_T’ - 180) --> Creates a line in the opposite direction of Line_Y_T’. You can enter a formula here or enter it for the other side of midpoint V’.

Define the curve from V’ to T’:

• 3rd control handle length: (Line_V’_T’ / 3)
• 3rd control handle angle: (AngleLine_Y_T’) --> Creates a line in the same direction as Line_Y_T’. If you entered the 2nd control handle angle formula, you won’t need to enter this one!
• 4th control handle length: (Line_V’_T’ / 3)
• 4th control handle angle: (AngleLine_T’_U’ + 90) --> Creates a right angle to Line_T’_U’

Then when you know the lines and curves are working in general, finalize the curve to achieve your fit or design requirements. Armscyes tend to be deep at the bottom and flat-ish in the middle. The following adjustments tend to work well to achieve a good fit for my armscyes. Of course, if you have an unusual armscye or design you would make different adjustments :

• Under the armscye lengthen the control handle (eg Line_Y_V’ / 2)
• At the midpoint shorten the lower control handle (eg Line_Y_V’ / 4)
• At the shouldertip shorten the control handle alot (eg Line_V’_T’ / 6) . The 90-degree control handle at the shouldertip basically ensures that the front and back pieces line up without having to manually adjust them. This control handle can be very short. I know of patternmakers who just draw a 1cm line at the shouldertips for front and back, but I still like to make it a formula because I object to putting actual numbers in a curve because I like the curve to be EXACTLY THE SAME FIT (which is not “exactly the same curve”) for everyone.

One last thing you need to know about creating curves with multiple segments:
Enter one angle formula at any midpoint of a curve, and the midpoint’s other angle is automatically calculated and appears as a number. The number is a calculated value that will change with respect to the angle formula.

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Because the control point lengths are not changing with the sizes. Also I can see the angles of the control points are off.

Take read through this thread. Curves with Formulas - #17 by Grace

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Thanks for your help. But I don’t understand how the angle control points can activate if I start the curve at this point?

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Hello, Thank you very much for your very precious help. I never would have done it without your help.

I try to understand and translate (I am French). I have tried to do all the steps and some little things escape me. Like that of the 2nd angle of the control handle (angleline_Y_T’- 180).

I will repeat the exercise several times to fully understand and adapt it to the other curves I have to do. thanks again

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Move (AngleLine_Y_T’ - 180) to the 1st control handle of the point V’. This vocabulary is very confusing.

Here’s what’s up:
Each endpoint has one control handle. Each midpoint has two control handles. The dialog is prompting for formulas relative to the point, not the curve.

The words should be changed from ‘first control handle’ to ‘incoming control handle’ and ‘second control handle’ to ‘outgoing control handle’

Y has the 1st control handle
V’ has the 2nd and 3rd control handle
T’ has the 4th control handle

2 curves= 3 points = 4 control handles.
3 curves = 4 points = 6 control handles
4 curves = 5 points = 8 control handles

N curves = N + 1 points = 2^N control handles

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thank you. I understood everything but when I use 180 ° it makes a twisted curve so I didn’t add anything. It’s correct? I have another question if you will help me.

I have to draw the neckline it must be 7.2 cm in length and I don’t know how to draw this parametric curve.

warum muss der Ausschnitt genau 7,2 cm sein? Für mich ist ein Ausschnitt immer eine Ausgangssituation:)Darauf wird dann aufgebaut. Ein ungefähres Maß kannst due ja erkennen, wenn du eine Verbindung zwischen den Punkten Aj und Ai ziehst. Bei diesem kleinen Ausschnitt ist die Kurve dann natürlich länger. Hat man eine längere Kurve ( Armloch) kann man ein Gerüst um die Kurve bauen. Wenn interesse besteht kann ich es gerne mal zeigen wie ich die Kurven baue.

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Bonjour, Je suis également intéressée par le tracé des courbes avec lesquelles je rencontre quelques problème. Je pense avoir compris la méthode de Susan mais j’aurai encore besoin d’éclaircissements et j’ai lu tous les articles sur les courbes sur le forum mais ne me sens pas encore sereine sur le sujet. Merci d’avance

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Regardez plus haut dans ce post, @slspencer à mis des photos et je réussi toutes mes courbes maintenant.

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Ganz, einfach: da hat jemand seinen Halsumfang gemessen, und dann z.B. Halsumfang / 4 gerechnet.

Womit wir zur Frage kommen: Wie konstruiert man eine Kurve mit fester Länge?

Randbedingungen: Es gibt einen Startpunkt: Aj mit fester Position und der Endpunkt Ai soll auf einer Linie liegen, welche senkrecht zur Linie Aj-Ah ist.

Angaben für die Linie Ah-Ai wie ‘neck_circ / 5 + 1/4’ und dann zu hoffen, dass die Kurve eine Länge von mindestens ‘neck_circ / 4’ hat, sind doch nicht schön.

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Bonjour,

Personnellement, malgré les explications de Susan je ne maîtrise pas toutes les courbes. C’est OK pour les courbes à 3 points mais dès qu’il y en a plus je galère. C’est pour celà que je suis preneuse de tout complément sur le sujet.

Bonne journée

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Rebonjour,

Je suis vraiment maudite avec les courbes Je poursuis dans mes essais avec les formules Voici mon schéma initial Et dès le premier point blocage. Je voulais mettre mon 1er angle par rapport à ma ligne A6-A1 mais il ne la trouve pas ! Et pourtant ma ligne est bien créée Il y a une notion qui m’échappe. Merci pour votre aide

Erreur dans ma deuxième capture d’écran voici celle que je voulais mettre

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en fait il ne faut pas passer par tous les points. Seuls les points de pointe d’épaule, sous bras et carrure comptent.Les autres sont là comme guides. Et en jouant ensuite sur les valeurs vous arriverez à les placer au plus prés. Ex Ligne_A_A1/3 +0,5

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Hast du die Linien vor der Kurve gezeichnet?

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ok merci, je n’y avais pas pensé

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Non je les ai tracé après car je les avais oublié. Maintenant je comprends pourquoi je ne les trouvais pas. Je vais réessayer. Merci pour cette info.

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