They should be changed for every 8 hours of continuous sewing, and for each new project or different fabric.They need to be the right choice of needle for that fabric. If sewing denim, and you try and use the same needle for chiffon, you will very likely snag the chiffon.
Sewing machine needles are generally all universal for domestic machines, but it is worth checking your manual to ensure you get the right needle for your machine. In general the larger the needle number, the thicker and bigger the needle is.
The needle I use the most for dressmaking is a Schmetz universal 705H needle number 80/12. This is a great needle for fairly fine woven fabrics.
If sewing heavier cottons I use Schmetz universal 705H needle number 90/14
When sewing jersey I use a ball point needle. This type of needle seperates the fibres, rather than splitting them like a regular sharp needle does. The tip of this needle is rounded, and it is only useful for knitted fabrics, and won't work on woven fabrics.
There are lots of job specific needles for trickier fabrics available. These are the ones I commonly use-
- A denim needle. Some people just use a thick needle, but the point on regular needles may not pierce the denim as well as a denim needle. Denim needles are strong, but have extra sharp points, allowing the needle to pierce the densely woven fabric.
- A leather needle. The point of a leather needle is actually shaped more like a blade, this creates a triangular hole in the leather. Using a regular needle creates a small split which will over time tear and ruin the garment
- An extra sharp microtex needle. I use these for delicates like silk and satin.
- Stretch needles. These are great when stitching really stretch stuff like elastic and lycra, or any stretch fabric where your machine has been skipping stitches.
The choice of brand for machine needles, is to me a very important one. Some of the very cheap needles, just aren't good, and you'll pay twice! I use schmetz, or groz beckert needles. Both of these brands are German and they have proved to be the best needles I've used.
Changing your needle is a really simple operation.
- Hold the needle with your left hand and unscrew the screw at the top of the needle. Holding the needle ensures it doesn't drop inside your machine. I keep a sharps box to dispose of my needles.
- The flat side of the needle is the back
- With the flat side at the back, push the new needle up inside the sewing foot as high as it will go, and then tighten the screw.
- Just to double check that the needle is in the right way, run your thumbnail up the front of the needle, you should feel a groove if it's in correctly.
All done, and you're now ready to continue sewing...