One variable I was concerned about in making the test prints was the USB connection. Sometimes the flow of instructions can get interrupted, causing the printer to pause and wait, leaving a blob in the process. If a little too much CPU gets tied up for a moment, it can create one of these pauses. To prevent this, I ran the test prints from an SD card mounted on the printer itself.. I did a comparison between USB and SD with Slic3r 096, and there is a slight, but noticeable improvement in the SD print-
Overall it looks pretty horrible, at least in the columns. On to the overall results. At the end I will have a link to download all of these at high resolution since the viewer on the blog doesn’t let you really get into the detail. Warping at the corners was always a problem. These were printed on Kapton with hairspray in a closed case. On some I used a heater to get the ambient up to 60C which helped keep the corners down, but never completely eliminated the warping. Even though the corners lifted the prints were very hard to remove even at room temperature.
I’m surprised to see stringing across the holes in the Cura print, even though the retraction settings were the same for all. The sides of the cube with Cura and SF39 split in a few places because the narrow walls were left hollow and weak. Slic3r had a consistent problem with the end of the arch coming loose. The echo pattern to the left of the holes is supposedly due to the outer perimeter speed being too fast. Ideally you would set that to a low speed, and run inner loops and infill faster to save time, but not all of the slicers had that ability. The Slic3r 096 print doesn’t have the holes because I had already run that one before I thought to add them.
Kisslicer wins for best arch. Slic3r might have been better, but it is hard to tell since it knocked it over every time. Kisslicer and Slic3r also had more consistency in the flat walls. The columns were a challenge to all slicers, and I don’t know why they all came out so poorly. You might think it would be mechanical issues with the printer, however they sucked in different ways, and did it in a consistent manner. I did some more testing related to that, which I will get into later.
Kisslicer handled the columns best, with some slight gapping at the point where the outer perimeter turns inward to the fill. In Slic3r I left Randomize Starting Points unchecked. That setting is supposed to prevent a seam running up the side of cylinders from the perimeter starting at the same point in every layer. However it usually causes blobs to be spread all over the surface. I suspect Slic3r 096 was randomizing anyway, while 097 respected that setting.
Cura and SF39 had a lot of variations in the flat wall, and especially the column perimeters. Kisslicer and Slic3r 097 had the best walls and a little variance in the column perimeters, while 096 had a lot of random blobbing. 072b is OK, somewhere between 096 and 097 with a little more pronounced seams. In the 097 print you can see a little blobbing on the face of the cube toward the bottom. This is from moves between the column and wall, so retraction is a little less effective there than the Kisslicer print.
Kisslicer, Slic3r 097 and 072b are doing the best on the texture wall. 072b managed to avoid dropped loops and maintain layer alignment all the way through. Kisslicer and 097 also didn’t drop threads, but had some layers with a little setback.
Cura had the best solid top layers, watertight and consistent. 096 was decent, 072b borderline, and 097 and Kisslicer were far too loose. This could be fixed in 097 by reducing the nozzle diameter so the threads get placed closer together. I’m not sure how to fix that in Kisslicer. Increasing the flow rate will close up the gaps, but it will also make the perimeters wider, making the outer and inner dimensions incorrect.
Cura and SF39 left the narrow walls of the cube unfilled, which weakened them so much that some of the layers split apart at the corners. 096 filled the thin wall with a zig zag fill, executing it better than 096. Kisslicer and 072b seem so have used straight lines to fill the wall which I prefer since it looks a little neater.
096 didn’t handle filling the thin wall of the hollow column at the upper left very well. 072b did a little better but mangled the inner perimeter. Kisslicer’s is decent with some concentric fill, but Cura has the best one, as well as the smoothest surface of the arch. The corners of the arch show quite a bit of overshoot, demonstrating that 50mm/s is too fast for the Solidoodle to be running outer perimeters.
Slic3r 097 and 072b predictably had the best bridging performance. Slic3r has the ability to run the fan for bridges, though 096 seems to have ignored that setting. Cura and Skeinforge can only speed up and lower the flow to stretch the filament over open space (which Slic3r was also set to do) and was moderately successful. Kisslicer doesn’t have any bridging settings at all.
The chamfer under the large cylinder was a challenge that none of the slicers was able to handle, though 096 came close. If the placement of the thread is a little too far to the inside, it won’t stick and get pulled into a straight line instead. I’ve printed this kind of feature without trouble at 60-70mm, but at 20mm or so the curve is too tight. A slower speed might have helped, to provide as much time as possible for the extruded plastic to bond to the lower layer. Even though it didn’t do very well on the chamfer, Kisslicer handled the overhanging perimeters on the underside of the arch better than the others.
The overhanging corner is something that no printer will accomplish neatly without support, but Slic3r 097 managed with the fewest dropped loops, most likely due to the fan.
I was surprised at how badly the columns came out overall, which would seem to point to a problem with the printer. However the errors were different for each type of slicer, and consistent between versions. Also they happened the same when the same print was run twice as in the SD/USB comparison. These prints were scaled up 150% from the original model so it wouldn’t be too torturous, but I did also print them at the original, smaller size.
Skeinforge 39 still mangled the columns, Kisslicer had small gaps up the seams, 096 was blobby, and 097 had misaligned layers. All of the Slic3rs still knocked over their arches. I did a few tests to try and figure this out, which I will cover in the next post.
Later I will have tests with Cushwa’s Owl from Thingiverse for something a little more organic, as well as tiny Yodas at .1mm layers.