Hey all - I thought it might be helpful to ask this. I have a print that I need to do in separate chunks in order for the Glowforge UI to handle it. So I can print one chunk, then another without leaving the Glowforge app or opening the lid. Just ignore the old chunk and fire up the next. It’s working great, but I still have a few hours to go.
Can I leave the Glowforge app open overnight if I need to maybe NOT stay up until 4am? Will everything stay ready to go the next day or will it kick me out and force me to have to perfectly line things up on top of what I’ve already done? What should I expect to happen?
Thanks for sharing that! I’m currently rocking print 6 (ish/at least?) within the same area and have a couple more to go, and everything is looking good. So I’m guessing when he said “many” he meant it.
The steppers do not have position encoders, so they use “dead reckoning”. Traditionally, the current position would be known by keeping track of how many steps they moved in each direction. If it misses a step, or there is a glitch in the code that keeps track of the current position, it doesn’t know and this causes alignment “drift”.
On the Glowforge, it works only slightly differently. The device itself does not keep count. It just plays back the steps it receives in the file it gets from the cloud (the cloud’s motion planner does all the math).
The GF stepper drivers have a home indicator (these are not limit switches, just internal step counters that can be set when the head is at the home position) that will give feedback to the processor to tell it they think the head has reached home. I don’t know if the current GF firmware verifies that the drivers indicate the head at the home position when the program finishes, though it is capable. Of course, neither would know if there were missed steps, so it wouldn’t make much difference.
All that being said, it should only experience alignment “drift” when it is actually moving. Sitting still shouldn’t cause any issues unless you bump the head.
EDIT: It appears my statement “The device itself does not keep count” was incorrect. The device does appear to keep count, as the return to home steps are not coming from the cloud.
I’ve done exactly this before over the course of at least a week. The alignment was the difference between visually placing the preview and the actual cut made. That will drift, but the computer precision stays the same.
I could not find when software updates get pushed to our forges, I’m guessing when we turn it on and it calibrates, since we don’t leave them on all night, usually. So I would hope it would not happen in the middle of the night while you are on pause, that could cause it to lose alignment? Dan, do the occasional software updates happen at forge boot up?
Isn’t any pause that I’m aware of. As far as alignment goes, my unit maintains the same alignment after re-calibration. Only time it would be off is if the head or gantry struck something during a previous operation.