Thursday, April 05, 2007
Getting the drift under control
The drift pretty much went away. I put in the maths to keep track of the absolute position of the extruder head and I'm down to a 5 pulse overshoot correction now. I set the first layer to smear, which seems to provide enough of a footing for the perimeter I'm printing to keep it from peeling.
I'm getting blobbing at the corners, but that is because I'm not turning off the polymer pump when I reach the end of an extrusion path and I'm pausing for 100 milliseconds between line segments. Otherwise the layering is looking very good.
The extrusion thread as put down is right at 1 mm wide and 0.5 mm high which is just about right for a 0.8 mm extrusion thread. The HDPE is pigmented white and looks just like toothpaste being extruded from the Tommelise Mk 1. It's a pleasure to watch in operation.
I'm getting to feeling really good about HDPE as a polymer for 3D printing.
We pretty much know how to make the filament extruder, but nobody has worked on a plastics grinder yet.
how about tweaking the code to not pause / stop the extruder? seems like its worth a try =)
Multiple passes results in small chips but it hard to do because the throat of the shredder is too thin for safety reasons. When I get a chance I will open it out and see if it is practical to pour shredded bits back in. I suspect the shredder may not last long with this kind of abuse, but you never know. Paper is very abrasive so may actually be more wear on the blades than HDPE although I expect the plastic takes more mechanical effort to shred.
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