Keeps breaking needles - Sewing Machines

Needle breaks
1.the needle is damaged
2.the needle is not correctly inserted
3.wrong size needle for the fabric
4.the wrong foot is attached
5.the needle clamp screw is loose
6. Top tension is too tight
7. Machine could be out of time

Slow down and watch what you sew over.
No needle is going to sew through the metal part of a zipper.
With many layers of fabric you have to slow down. If you have multiple layers of a thick fabric you may have to resort to using the hand wheel to get through the layers.
Another tip would be to not pull on the fabric. The machine is capable of "feeding" the fabric at the rate it requires. When sewing with many yards of fabric the weight of the fabric may create a pull on the needle. If the needle is pulled so that it no longer goes through the need plate properly it will hit the metal of the needle plate and break. Instead rest your hands on either side of the fabric and gently steer the fabric. Do not pull it out of the back of the machine or shove it into the needle. With large yardages wad up the fabric around the machine so that the weight of the fabric isn't causing strain around the needle.
One other tip. If you have a needle plate in your machine that only supports straight stiching, that is one with a needle hole that is just big enough for the needle to move up and down, and you switch to a zig-zag stitch, you will break the needle. Most factory installed needle plates have a needle hole large enough to support the largest zig-zag that the machine can support. But some machines have custom needle plates (for quilting) that only support a straight stitch.