I am not sure how to word this so Im going to try to describe it. My GF makes a hesitating sound when it’s working. Think of a car that almost dies but then revs back up. I can’t think of any other way to describe it. It’s only a slight hesitation that at first I thought was my ears, then my daughter also heard it. Its like it’s going to quit but then regroups and keeps going. I don’t think it has any effect on the engraving in the form of missed spots or lighter spots. I am just trying to figure out if this is normal. It makes me nervous because it just feels like it’s just going to quit. It just did it again and my daughter says it reminds her of when you stick the vacuum against the wall or floor and it makes it ref up.
It might help if you shoot a video with your phone and post it to YouTube. There are times during the operation when you will notice a change in sound…it sounds different for instance when the head is moving horizontally than when it moves vertically. That’s because different stepper motors are engaged to move the head in different directions. There is also a pause when the operation changes or the focal point shifts.
Anyway, posting a vid will make it easier to see if it’s acting normally.
3 Likes
I bet you are hearing the stepper motors.
The GF laser head is moved around by stepper motors. These are electric motors but when a voltage is applied to them they rotate a small fixed amount and stop instead of running continually like a typical electric motor. They emit a sound each time they step.
The machine is mostly moving continuously during a print, so the stepping is continuous the sound the motors make takes on a somewhat “tonal” quality. But as the carriage moves, the speed it’s going in any direction (X or Y) is constantly changing, so the sound made the the motors is constantly changing. When the GF goes from a motion with a high step rate to one with a lower rate, it would sound like the machine is slowing down. The step rate has to be decreased to zero for the carriage to change directions or to start or stop moving along an axis. It can’t be an instantaneous change, the controller has to ramp down the step rate to zero, or ramp it up from zero, so at some points it might even sound like the machine has stopped for a very brief moment.
The sound changes because the GF’s controller wants to keep the laser moving at a constant speed, so the depth of cut will be constant. Depending on how the combination of X and Y are moving, the step rate of the motors has to change to keep the laser moving at the same speed. For example, if you are moving at a given step rate in just the X or Y direction, (so 90º motion) and the motion changes to a diagonal (X and Y are stepped equally), if the step rate is maintained the speed of the laser is going to be sqrt(2)=1.41x faster. So moving along in just the X or Y and transitioning to motion on both the X and Y will result in the step rate decreasing and it’ll sound like the GF is slowing down.
Of course, it might be presumptive of me to assume you don’t know this stuff. So if you do, sorry for the pedantic response. Please ignore. 
2 Likes
This actually makes perfect sense. You also presumed right that I had no clue about any of this but now I am a little bit smarter, so yay for that. People should learn something new everyday. I would also like to thank you for taking the time to explain it.I also appreciate that you explained it without making me feel stupid.
Thanks for that great explanation, @randy.cohen! This does seem to be the sound you’re describing, @melindaoliver79, and it’s perfectly normal. However, if you’d like to provide a video of your Glowforge during operation, we’d be happy to make sure that everything sounds right. You can either reply to this thread with a video, or email us at support@glowforge.com if you’d rather not post it on the forum.
It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email support@glowforge.com.