Filament tracker opinion

[hugues touzot]

Hi,

I want to track and monitor my filament on my next big printer and i want your opinion about this little sketch.
The global idea is to compare the extruder drive gear with an other point of the filament.
Before asking some friend to help me with arduino, i wanted to know you opinion about reliability and precision with this.

Thanks !

[dan...@puptv.com]

Why do you want to compare the extruder drive gear with an other point of the filament?

When is this an issue?  What would knowing that you intended to extruded 100 m of plastic on a part, but the other encoder indicates that you only extruded 99.4 m?

If instead you wanted to detect when the filament ran out, it would be very easy to put a limit switch against the filament as it went through a guide hole...  When the filament runs out, the limit switch will detect it.

Daniel - http://www.TriDPrinting.com/

[dan...@puptv.com]

Inspiration for an improvement to the bowden system...

What if we could drive a bowden system using the feedback provided by the encoder on the head?

A system like this could learn to adjust for changes in the bowden system as the part was made...  compression or snaking of the filament changes, the temperature changes, the location of the head changes...

The trick is that now you have a feedback loop predicatively controlling or adjusting the bowden drive...  That is going to be some interesting software that is likely to be very very challenging to perfect. Over time and with experience, it should be possible to accurately model the bowden tube dynamics for a significant improvement in print quality.

It seems like this may be an even better idea than the flexi-drive system, where you have a stepper motor on the frame driving an encoder gear.

Daniel - http://www.TriDPrinting.com/

[hugues touzot]

You're right, this system need some alarm value to prevent slippage of filament so if encoder from extruder motor (bowden or direct) send 100mm and encoder from 2nd point 95 (or any value from user) arduino send a pause... And of course if the 2nd point doesn't turn you could have not more filament into your roll.
Systems who send a pause from out of filament just know if filament are over or not...and i just try to figure out how to prevent an other source of error for long print.

I like your idea about live bowden compensation, i would love that DC42 implant something like this in the firmware, i will test this on my duet wifi ! You can make a request in the duet forum for this implementation ! I will support you !

[Ryan Carlyle]

As far as filament monitoring goes, Repetier has that capability built-in. You just need an encoder and to wire it up and turn on the feature in firmware.

There's also a bolt-on solution available for most other firmwares called the Tunell Filament Monitor. It keeps track of whether the filament is moving or not and sends a pause command if there's no motion of the encoder. I have a bunch of those on my printers.

The Bowden feedback idea is good. It might even work well as a simple servo loop with no feed-forward or predictive component at all.

[hugues touzot]

Thanks for your input Ryan, i didn't know this feature on repetier, it looks great on paper but i don't find any feedback,do you test it ?

[Ryan Carlyle]

I haven't tried it, no.