Several years ago one of the magazines, I think it was Quilter's Newsletter, ran an article about needles. A quilter who had access to an electron microscope at her day job got electron micro photos of needles, new and at various stages of wear. What an eye opener!!
Remember needles are coated with a thin layer of "chrome" and it can chip or wear off in places. Think of what chrome bumpers look like after wear. Those little chips and worn parts can affect the way the needle operates. And can work with or against the thread and fabric.
It is important to change needles often because they wear, worn needles do not make good stitches. Worn needles can cause the yarns in the fabric to fray and pop, which causes holes. and all sorts of things.

Buy needles when they are on sale, or in bulk and change frequently. If you wait until you hear it "pop" through the fabric you are way past when you should change it. <G>

Have fun,
Pati, in Phx

Sewing machine needles dull after hours of use, and can also develop little burrs. Sewing with a damaged needle creates larger holes in your fabric, and if it is really damaged (burrs) it can bend as it goes through your fabric and possible break in your bobbin area. They can damage your machine or cause a problem with the timing.

When you hear a popping noise as you sew, you are overdue for a new needle. They should be replaced after each project or approx. 8 hours of sewing...sooner if you hear the popping.

I should change my needle more often that what I do. I have always been taught to change a needle for each new project. But I usually watch my sewing line and if it looks rough or the upper thread keeps breaking, it is time to change.

I purchase my needles in bulk and change often. Much cheaper to buy in bulk than to use % off coupons at JoAnn and such places

When I first started quilting little over a year ago, the quilting guild I belong to had a program on sewing machines and said it was a good ideal to change the needle after every project, since you could have stitched more than a million stitches for one project.

Where do you buy in bulk?

I buy in bulk from J Hittles.
http://www.jhittlesewing.com/visitor/index_jhs.html
You will need to register with them first. I get an email every week telling me what their specials of the week are.

A sharp needle is like a sharp knife - when dull they hurt like sin.

Ditto. I asked my Pfaff dealer if I could buy 100 Schmetz needles at a time, and I could - at a discount that was better than 50% off at JoAnn's. I imagine you could do the same at a LQS. Probably not at JoAnn's LOL. I agree with everyone regarding changing needles often - cheaper than machine repairs or ruining a quilt.

I normally break them way before they need changing. A new needle often makes better stitches.

Blessings,

Sharon