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Filament Supply Status - Printable Version

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Filament Supply Status - mike - 07-28-2014 03:41 PM

Integrate a load sensor into the filament spindle arm such that the arm acts like a lever, and apples pressure to the load sensor. Using a simple calculation based on the moment of the arm, calculate the mass of the remaining filament. Subtract an approximate (or configurable) amount for any adaptors and the arm, and the remaining mass is filament. PLA and ABS have predictable mass, sufficient for our purposes, anyways, even if they might vary based on the quantity of moisture.

Provide some metrics about the remaining mass, length (for 1.75mm), and percent (of a 1KG roll, or configurable starting mass) of the roll that remains. Provide that output on boot, and at other key times, such as after a print, and possibly after long printing intervals.

I haven't looked at the firmware, or at the communication spec, or gcode in enough detail, but I suspect it would not be a great challenge to hack in some pre-print validation/verification/warning notifications if the gcode (assuming this info is given to the printer at all) is predicting using more filament than is believed to be loading on the printer.

There will, naturally, be some variability in the readings during printing, from vibrations, movement, and due to feed tension, and some debounce and some form of read filter may be required.

Here is a sensor which, depending on the moment of the supporting arm, might be suitable. It can be had for a reasonable price, integrates with Arduino-type microprocessors, and might handle a reasonable range of weight (up to perhaps 10Kg at a 5/1 distance from the axis)


RE: Filament Supply Status - edkman - 07-28-2014 04:08 PM

Hi, Mike.

Thanks for the suggestion. That sensor looks like a handy package.

I think it is worth considering. It could be made an optional upgrade, I suppose.