his is an excellent question since needles are the cheapest, yet most important part of a sewing project. Frankly, most people don’t replace them enough, hence the preponderance of injuries and damage to the machine. A good rule of thumb is to replace needles every four hours of sewing time. This may sound like paranoia, but needles on sewing machine go through fabric hundreds to thousands of times per minute, so it doesn’t take long before they get dull or bent. Once that happens, you get looped threads, skipped stitches, runs in your fabric, or worst of all, damage to the machine.
With beginners, you can probably go longer in between needle changes since they’ll be working on simple projects for short durations of time. As they become advanced sewers, they’ll start working for longer periods of time on more complicated projects. They may also start using thicker fabrics for projects like quilting, in which case needles may have to be replaced even more often. Finally, remember to read the manufacturer’s instructions regarding care and maintenance. This is particularly important for ensuring that you don’t do anything to void your warranty.