Let's back up a bit. We seem to be talking about 3 mm filament here. Cross section is pi*r^2, so the error (if it's round) would be about 2%. If it's not round, then you have to know just what sort of shape it is to guess the errors. I suspect that things like clear filament will be a bit harder than flat black. First issue would be contrast. Second issue would be optical bending at the edges of the filament. If it's a single line sensor, any skew / bend in the filament is going to contribute to the error. Minimizing that probably will add a bit of mechanical complexity. It's an issue that also comes in when manually measuring really stiff / tightly coiled filament. Net result - you may / may not be at the 2% (or better) level with this gizmo.
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The bigger question is more simple - Bad filament can be bad for a number of reasons (it has trash in it ...). From what I have seen, these guys get the diameter right before they get the other stuff right. Put another way, I do have an inventory of bad filament. It's all got very consistent diameters (to below 0.02 mm) ....
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The bigger question is more simple - Bad filament can be bad for a number of reasons (it has trash in it ...). From what I have seen, these guys get the diameter right before they get the other stuff right. Put another way, I do have an inventory of bad filament. It's all got very consistent diameters (to below 0.02 mm) ....