Intro: Selection Guide of Conductive Thread for Machine Sewing
- In this article, we describe conductive threads suitable for machine sewing (e-Textile)
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Step 1: What's Conductive Thread
Conductive thread was originally developed for industrial use such as heat resistance material. These day, it is used for e-Textile or wearable computing due to it's electrical conductivity. It can make "sewn circuit" by connecting micro-computer, LED, touch sensor, etc.
Some Makers/Crafters use conductive thread for e-Textile, but by hand sewing. Today, no home sewing machine vendors recommend using conductive thread with their machines, but some of the conductive threads can be practically used for machine sewing. This article can help you finding such threads.
Note : Officially, our company (Brother Industries, LTD. ) does NOT recommend conductive thread use in our sewing machine & embroidery machine. Please use them at your own risk.
Step 2: Material of Conductive Thread
There are roughly two kinds of conductive thread.
- Very thin metal wire
- Plated chemical fiber
Most of conductive thread available in consumer market (web shop etc.) are this kind. Many of them are stainless steel wire, some others are copper wire. Although called as thread, basic characteristic is steel wire itself. They have good conductivity, but their mechanical inflexibility makes sewing difficult.
Something like silver plated on nylon fiber. These kind of thread is soft, very similar to normal sewing thread except for color. Sewability is much better than metal wire, but electrical conductivity is relatively worse.
How to distinguish
When you purchase, check the material.
- Steel (Fe) or copper (Cu) : It may be thin metal wire.
- Silver (Ag), nylon, polyester : It may be plated fiber.
If you already have conductive thread, contact a soldering iron on the thread. If it is plated fiber, it will easily melt.
Step 3: Basic of Thread (Thread Structure, Twist)
Sewing threads are consist of some yarns twisted together. Following twist parameters effect sewability.
Ply means number of yarns twisted together. 2 yarns twisted is called as "2 ply thread", and so on. For machine sewing, 2 ply or 3 ply threads are used in general.
Twist directions are identified as "Z twist" or "S twist". (see image attached) For machine sewing, Z twist is used.
Most of machine sewing threads have 18 to 21 twist per inch.
Step 4: For Machine Sewing
First, we strongly recommend NOT to use metal wire with home sewing machine & embroidery machine.
- It's difficult to adjust thread tension.
- Long use of metal wire may wear and damage your sewing machine parts.
For machine sewing, you should use the plated fiber similar as usual machine sewing threads ( 2 or 3 ply, Z twist, around 20 twists per inch ). This kind of conductive thread may be used as upper thread.
Step 5: Machine Sewing Examples
Attached picture shows conductive threads sewn by machine. All conductive threads are used as upper thread.
- A : Silver plated fiber. This thread has good sewability.
- B : Stainless wire. Very bad stitches.
- C : Stainless wire. This thread make stuck in thread take-up, can not complete sewing.
- D : Stainless wire. Best in stainless wire, but we can not correct thread tension (upper thread is too tight).