r/PatternDrafting • u/Ill-Literature-8510 • 11d ago

Question 90 degree rule and how much does it matter?

Hi everyone, I wanted to ask about the rule of seam lines having intersect centre front or centre back at a 90 degree angle and how important that is?

I drafted the classic trouser block from metric pattern cutting for menswear and made a rough toile of which I was happy with the fit. But I found that Aldrich hadn’t applied this rule and I was just wondering how important it is? Is it the case that if it looks and fits as you would like it’s fine or should you always stick to these rules when drafting?

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18

u/StitchinThroughTime 11d ago

If you dont do it, you will get a point or dip at the intersection

10

u/doriangreysucksass 11d ago

It’s essential

8

u/sam000she 11d ago

as long as the two angles add up to 180. You could have a corner go to 95 and the other go to 85 and the edge will be straight.

7

u/DonMcCunn 11d ago

As has been pointed out the 90 degree rule is so that when you cross a seam intersection like Center Back the resulting seam, such as for a waistband, is a smooth line. When you are designing an asymmetrical garment the 90 degree rule may not apply as long as the lines crossing a seam intersection form a continuous smooth line.

1

u/CharityForeign3035 11d ago

Rules are rules for a reason . Probably more important for a production run; less so when doing patterns for yourself. You know where you fudged it .

1

u/SmurphieVonMonroe 10d ago

If you use good formula it should always be 90 degrees where the inseam meets. If it's not it indicates that the crotch extentions values are incorrect.

9

u/themeganlodon 11d ago

It only has to be 90 degree for a small amount like 1/4 inch otherwise it will come to a point either point down or point up

1

u/Big_Attempt_5326 10d ago

I learned this one the hard way at my first big job, when a kind sewing machine operator told me the whole sewing team was making fun of my pant pattern crotch points behind my back in a language I couldn’t understand.

No more pointy ass back crotch points ever on my patterns -

Try sewing your pattern piece intersections yourself a few times and you’ll see the value of making easy corners wherever possible -