![\"\"](\"\/pics\/mb\/mb67.jpg\")
<\/a><\/p>\nAbove is the product of one night’s printing. Tons and tons of calibration cubes, then a few reruns of shapes I tried already to see if the quality improved on anything but a cube.<\/p>\n
Let’s start with the first one, which I have nicknamed the Abortion Cube:<\/p>\n
I tried the advice on the Makerbot Blog<\/a> about one way to calculate a workable feed rate for the machine. From pulling a test extrusion, I found that the extruder actually worked at around 26mm\/s. Unless I really missed something, that did not<\/em> work out at all. It was clear from watching the epic blobular formation that the machine was in fact moving far too slowly. So I went for the logical next step: turn it up.<\/p>\n So here’s a test print of a 20mm cube at 40mm\/s.<\/p>\n Muuuuch better. Now it’s on par with the stuff I see coming out of other peoples’ Makerbots. This was still on 0.4mm layers, though. I began playing with the “aspect ratio” of the filaments by adjusting the Width Over Thickness values and making more cubes. A wider thread adheres better to the one below it and can fill areas quicker, but appears to make the machine more prone to globbing.<\/p>\n After Cube #2, I decided that a stiffer platform was in order. Further lowering of the layer height was probably a futile effort if the platform itself has more “rock height” than the layers. With Advanced Circuits<\/a> still working on my trippy heater PCB<\/a>, I elected to make a stopover solution in the form of a 7 inch square chunk of 6mm acrylic. This represents the final outline of the PCB (yes, it’s massive), but the heated area is a 6×6 inch\u00a0 patch in the middle.<\/p>\n Here’s another cube that turned out great. This represents the numbers I ended up settling on for the time being. The layer thickness is now 0.3mm, and the feed rate is 55mm per second.<\/p>\n I began logging all the settings used for each cube as I made them. From left to right, the lineup represents a gradual reduction in the layer height and increase in the feed rate while trying to maintain a constant thread aspect ratio.<\/p>\n While making the solid test cubes, I noticed the internal fill cooling unevenly with respect to the outside edge, causing “cube obesity”. To mitigate this, I adjusted the aspect ratio of the infill threads such that Skeinforge takes them to be wider (the 1.75 in “1.5 \/ 1.75”), and thus puts less infill paths down. This solved the bulging issue exhibited by the two middle short cubes.<\/p>\n The cubes were some times stopped after 20 layers or so because I figure by that time I got the point already and could move onto the next.<\/p>\n I sent MaB off on a mission to make another funky quarter sphere thing<\/a>. The effects of the increased feed rate were primarily seen in the outside shells, where there was less “globbing” from the machine pausing briefly. I also went back to using the ‘straight criss-crossed lines’ method of infill, over squares or circles.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n