After last week Bias: Definitive Essential Foolproof Guide post, today I want to go practical: how can I bias cut a rectangle, having only its measurements?

Math is closely related to sewing and I feel like a lot of self-taught sewists try to skip this part, but I think it’s a huge mistake: math is FUN – and I’m going to teach you a quick and practical trick!

Let’s talk about Pythagoras Theorem!

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

One of the features of The Sheer Plaid Top (my first pattern to be sold – actually under testing – release date February, 1st) is a softly draping collar, bias cut without a pattern piece, only having its measures…

I received so many questions about how to do that, that I realized it wasn’t as obvious as I though!!

Let’s clarify, and I hope that, when you’re finished reading this post, you’ll catch how easy is to bias cut a rectangle!

Bias Cut – Practical Trick

As we know that bias is at 45 degrees to a fabric’s warp and weft threads, then we can use Pythagorean’s  rules about triangles!

Look at my example photo: as you can see, my meter stick is placed exactly along the bias (hypotenuse of our right-angle triangle isosceles), because the width (A) and the height (B) of the same triangle (where I put my measure tapes) are the same length.

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

Believe me or not, if you know your hypotenuse length (=our bias length), you can calculate width (A) and height (B) with this easy formula:

formula

where square root of 2 is ALWAYS 1.4142135

…wait… what?

Ok, let’s simplify for those who don’t eat bread and math for breakfast!

Our example bias piece will be 25 cm long, 3 cm height, so:

  1. Measure from your fabrics angle between crosswise direction (A) and selvedge (B) the same measurement, that is:

25/1,4142135= 17,7 cm

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras) 

  1. Fold your fabric along the bias line (you can help yourself with some pin, of a chalk line…)

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

 and cut!

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

  1. Measure desired height at right angles to the bias (3 in our example)

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

and cut again!

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

  1. Finally, cut out your strip heads, just to have a rectangular (and not trapezoidal) shape:

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

 That’s it!

Is that hard to do? Not really…

Hard to remember? You don’t have to, simply …pin this post 🙂

That’s all for today, stay tuned to discover what comes next…

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