Laser Filament Monitor - test results
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Yes, that's why I suggested to use something transparent, but reacting to IR...
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@fma Well.... That should work but then there is the issue of finding a paint or marker that does not add color, mess with filament properties or is chemically innert to most of them, is opaque to IR and worldwide available
One alternative to that would be use the old hob wheel against a bearing and then read the bearing surface as this sensor is very good at reading stainless steel. Nut we would be back to the limitations, higher cost and issues of a hardware dependent filament monitor.
Another thing would be use some optics focus the sample filament length to the full sensor area available... But: expensive... complicated... can scratch and get dirty..etc....
I believe that with enough real world data and a good sample area they can tune it and suggest good margins.
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So, I've tested printing a sensor housing, and then painting it in black 2.0 paint. An IR cam & IR light shows the black 2.0 is very IR absorbant. However, I've seen zero difference between the painted housing and the Carbon Fiber PETG housing I started with. (Which also seems to absorb IR very well on camera at least).
I keep forgetting to record the results after prints.
https://docs.google.com/spreadsheets/d/1a5suKtijUsatl3DhUFiox_rfW39qo9kHSlihYHaAcxo/edit?usp=sharing
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@brunofporto said in Laser Filament Monitor - test results:
@fma Well.... That should work but then there is the issue of finding a paint or marker that does not add color, mess with filament properties or is chemically innert to most of them, is opaque to IR and worldwide available
I would like to make some tests, with different stuff. My idea is to use some sort of gear to put something at regular steps. What length of filament does sensor see? Just to design the gear pitch...
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@fma said in Laser Filament Monitor - test results:
I would like to make some tests, with different stuff. My idea is to use some sort of gear to put something at regular steps. What length of filament does sensor see? Just to design the gear pitch...
My guess is not very much, because the laser spot should be small. Unfortunately the data sheet doesn't specify the beam divergence. It does say that the distance between the sensor and the target should be at least 3mm to get maximum resolution.
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Ok, thanks. I'll try to make a small pitch...
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Has anyone considered uncoupling the filament from the laser and having the laser read a constant metallic surface for example (much like an idler bearing maybe?)?
That's pretty much the solution used by jtx on his skelestruder and it would at least allow all filaments to be calibrated against a constant....
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I may have a new "least accurate filament" - Atomic Marble PLA
Duet3D laser filament monitor on endstop input 3, disabled, allowed movement 40% to 120%, check every 3.0mm, current position -1.1, brightness 96, shutter 17, measured minimum 12%, average 71%, maximum 167% over 92403.1mm
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I do also compare the slicer predicted filament usage with the measures filament usage and have a very unusual inverse relation where the ones with the worst reading % also have the most accurate measurement of total filament usage!
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@kraegar wow. so opaque to visible light but possibly not to IR...? strangely bad!
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@snypes well the magnetic monitor does that and if we add that complexity then it's easier to use the hall sensor than the laser
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How can I register the readings of the entire print instead of max, min and avg?
I would like to see the full information, alongside retract and extrusion commands.
then I will be able to really visualize skipping/clogging effects and separate them from the "normal flow" average and deviation to better tune the thresholds.
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@brunofporto thats not a function in the firmware right now. the documentation:
https://duet3d.dozuki.com/Wiki/Duet3dFilamentMonitor_LaserVersion
explains the protocol used however it would need to be a firmware feature request to have some way of logging/outputting this information. When the filament is detected as moving there is a movement data packet sent ever 40ms, fair bit of information to handle.
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Would hurt the duet's processor asks a lot of M591 and log with M929? I mean, it is possible to use these commands to register the readings over time?
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@kraegar Sorry to be off topic, but curious if you have you set non linear extrusion or pressure advance for the Atomic Marble? The PETG version is way different than other PETG's extrusion wise.
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That was the PLA marble, and I left the pressure advance at the same setting as my other filaments. No other changes.
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@wilriker I have finally updated the design here:
https://www.youmagine.com/designs/duet3d-laser-filament-monitor-housing-v2 -
@t3p3tony I had merged your changes manually into the original SCAD file by David. It did not improve the results in my tests. They were actually a little bit worse.
But currently my printing is completely on hold and will be for another couple of weeks. After that I will compare your updated version with the one I had created.
