I'm thinking about adding a switch or sensor to detect the end of a

I’m thinking about adding a switch or sensor to detect the end of a piece of filament entering the extruder so the printer can be paused just before it runs out of plastic (I’ve had this happen a few times when printing unattended).

The idea being that if we stop just before running out, we can resume where we left off, instead of the printer continuing to “print air” all night leaving no idea where things went wrong.

Has anyone tried this, or can you think of a reason it wouldn’t work (other than the typical reasons pausing and resuming can go wrong)?

Makes sense to me!

Yes please - also would be nice to measure if actually filament is entering (in my case) the bowden tube - if the wheel (Ultimaker) grind into the filament there is no fwd motion anymore, happend a few times to me

Not a bad idea, you could use an optical sensor just above the extruder when the filament runs out the sensor would trigger and some minor firmware mods could pause the print and turn off the hotend to make it less likely to mess up the print(assuming unattented) until new filament is added

That is pretty smart. Never saw it before. I don’t see why a micro switch wouldn’t be sufficient. (lever operated and as close to the extruder bolt as possible to minimize false alarms.)

For feed sensing, an encoder wheel that rides the filament…

Yes I have had this problem and also another similar problem where there is a joint in the filament you get a short section which is fat and won’t go through the mechanism so I was thinking of having something like 2 sets of rollers riding the filament set at 90 degrees to each other. The filament running through would have two conditions tested: the rollers too close together; (indicating no filament)
and also test when the rollers move apart; (indicating oversized filament).

Either condition would switch the printer off and sound a warning so that you can attend to the problem.

Plans on Thingiverse, code on Github, we <3 you! :slight_smile:

Cool, I have some ideas that might make it easier that it seems; I’ll experiment and report back, thanks for the feedback (and encouragement!).

People have been talking about this forever, nobody has done anything about it. Keep us updated!

Sweet, maybe I can finally give something back! :slight_smile:

Idler with rotary encoder also detects stalls.