Embroidery Tension Test – I-Test Guide

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Short answer: Sew a tall satin column (the I-test, or an H shape) and look at the back. Good tension shows about 1/3 bobbin thread in the center and 1/3 top thread on each side. Mostly top thread on the back = top too loose; little or no bobbin showing = top too tight (or bobbin too loose).

What you see on the back	Meaning	Adjust
1/3 bobbin in center	Balanced	Nothing
No bobbin showing	Top too loose or bobbin too tight	Tighten top a little
Bobbin over half the width	Top too tight	Loosen top
Bobbin showing on front	Top much too tight / bobbin too loose	Loosen top, check bobbin

Set bobbin tension first (bobbin case drop test), then balance each needle’s top tension. Fresh, consistent bobbins (bobbin guide) make tension stable.

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Madeira Paper-Sided L Bobbins (144) White

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Madeira Polyneon #40 Cone (5,500 yd) Black

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FAQ

How often should I check tension?

At the start of the day and whenever you change thread type or see loops or breaks.

Do I adjust top or bobbin first?

Bobbin first, then top.

Does thread type change tension?

Yes — metallic and 60 wt usually need lighter top tension.

What is the drop test?

Hold the bobbin case by the thread; it should drop slowly with a gentle bounce.

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