Sewing Machines & Needles
Bobbin
The bobbin carries the lower thread and sits inside the hook, where the upper thread wraps around it to form the lockstitch. It is the least glamorous part of the machine and the one most often responsible for a fault that looks like a tension problem. If it does not turn freely, or it unwinds the wrong way, no dial setting will produce a clean stitch.
| Specification | Value |
|---|---|
| Class | 15 (front-load) or top-drop |
| Material | Plastic or metal, matched to the case |
| Winding | Even, from the bobbin winder |
| Capacity | 25 - 40 m of 40-weight thread |
| Fill level | 80 - 90 per cent, never overflowing |
| Extras | Keep one bobbin per thread colour |
Technical parameters
| Parameter | Detail |
|---|---|
| Rotation | Clockwise in the case on most machines |
| Thread path | Through the case slot and under the spring |
| Tension screw | On the case for front-load machines |
| Wind speed | Independent of the needle |
| Wear | Chips on the rim snag thread |
| Storage | Away from dust and lint |
Safety
The bobbin case and hook area have sharp edges and a needle that can still be loaded. Unplug the machine before removing the bobbin case, and never poke at the hook with the machine running.
What it is for
The lower thread supply. The wrong bobbin class, or one wound unevenly, breaks the stitch before any setting will fix it.
Compatible fabrics
Compatible stitches
Working notes
- Wind the bobbin at an even speed; a lumpy bobbin makes a lumpy stitch.
- Check the bobbin turns the right way in the case before you re-thread.
- Never mix plastic and metal bobbins in the same machine.
- Keep a wound bobbin in every thread colour you use often.
Related tools
Sewing Machine
A lockstitch machine, mechanical or computerised, that forms the stitch every other technique on this site is built on.
Serger / Overlock
A three- or four-thread overlock machine that trims, stitches and neatens a seam edge in one pass.
Needle Set
Universal, microtex, jeans and ballpoint needles, and the size-to-fabric table that decides which one belongs in the machine.