Advancing the Print Head to Chosen Point of Origin

I don’t know if this topic has ever been discussed, so forgive me if this is a repeat.
One of the biggest issues with the GF is power failure or accidental cancellation of a design (due to the lid being lifted) and the loss of time trying to finish a design that’s been started. If it hasn’t been suggested already, would it be possible for the programmers to give us users a way, within the UI, to advance the head to the point where the design left off? Some designs can take more than an hour to engrave and if we lose power, the user has to know how to fix the design so that it only contains the parts left to engrave or, worse yet, start the design all over. That wastes time as well as materials. It’s beyond frustrating!
I own embroidery machines and I can push a button and advance my hoop (and back it up as well) to move the needle to where it left off, in the event of a power failure or something of the like, where the machine can pick up where it left off. It would be nice if the Glowforge, which costs thousands more than my simple embroidery machines, could offer the same feature.


Looks like you were quicker at posting this here than I was at recommending you do so. Good Luck.


Good idea!

A good suggestion.

Probably harder than it seems to implement. Hope you don’t mind me sharing some thoughts.

The motion plan for the job is generated from your design on a server in the Google Cloud somewhere, sent to your machine, and then no longer exists anywhere except in the volatile memory of your machine. If you lose power, it no longer exists anywhere.

The motion plan is also non-deterministic: you’re not guaranteed to get same plan back every time you send the same design up to the servers. So your first problem is that now you need to store these motion plans somewhere semi-permanent where they can be retrieved again after a power outage.

Your second problem is creating a UI to advance through that plan. It now needs to be downloaded to the browser (but without revealing the raw file, as GF doesn’t really want us to have access to the gcode or whatever actually makes the machine work), and they need to program an entirely web-based interface for parsing that file and rendering it to an interactive interface you can scroll through in time. And keep that proprietary web UI tested and working in constantly-changing web browsers for all eternity.

It’s not impossible but it’d be a huge number of engineering hours to develop, and to support forever, for what’d be a rarely-used feature that probably won’t move their sales metrics at all. A hard sell for management at most companies.

Let’s assume you just implement a “resume” button instead, which avoids the need for a UI to view/advance the plan. The third problem you have is that the print head is centered and homed with respect to lid camera photos, not to any physical point of origin or limit switches. Once you’ve lost power, it has to re-center and re-home, and it may not end up in the exact same home position as it did last time you powered on the machine. Hopefully pretty close, but no guarantees. If it’s not starting from the same home position, the two parts of your engrave/cut may not line up exactly even if you resume from exactly where you left off in the movement plan.

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Thanks for the suggestions, @sinistermoon and @dan84! I’ll make sure the team gets them.

I’m going to close this thread, but please feel free to post a new topic if you have any other issues needing support or suggestions!