Saturday, 25 November 2017

Support Support Survey

With winter approaching on icicly feet, it's time to get back to the project of increasing radiator air flow tube. I have a design for the corner piece, but it's tricky to print - it's even somewhat slow to work with for having a large number of facets on the rounded pieces. Trick: add a variable indicating the "coarseness" of circles, multiply that according to the size of the circle, then increase it only when making the final piece.

I printed the top part to see how the overhang would work. It was surprisingly good, but at the flattest part there was enough hang that there were cracks and that there was dangling filament. I tried having Slic3r create support, but that added a huge amount of extra filament usage, and in previous trials with Slic3r support I've found it quite difficult to remove. This means either I need to handcraft some support, which is annoying for such an irregular piece, or find other software that can do better support.

Upside-down view of top part.
Last time I looked at the options for slicers, most options were blocked by security software. This time around, I'll also look at using my home computer, so should be able to try out more. Consider this my

Better Support Support Survey 2017
The contenders:

CraftWare 1.14Installed, blocked by security on laptop. Requires a serial connection to even install a printer. It has an X/Y offset feature, which would overcome my Y offset problem. It also has manual support generation, which could be highly useful. Its supports appear to go into the shape itself, which doesn't seem like a good thing. What I don't see is a Z offset setting, which makes it useless for me.

Cura (Ultimaker) 3.0.4Installed, blocked by security on laptop. The UI is somewhat rough - I can't believe their "settings" menu includes settings for which settings to show. They sure have all the settings there, except I can't find the Z offset that I need.

Cura Lulzbot Edition 21.08: Installed, blocked by security on laptop.  Works nicely on my iMac. Has nicely tunable support as well as the main features I need. It can do more reasonable support inside screw holes and printed well.

Print with support still on (upside down). Screw hole supports are just little pieces inside the holes, and the rest is fairly light.
The support came off nicely, also in the screw holes. The interior is a bit messy, but not horribly so

KISSlicer 1.6.2: Supposedly going to be available for Raspberry, which is nice. Installed, blocked by security on laptop. The UI is really old-style but has all the options I need. Doesn't show support until you click "Slice", but then the support is there. As is a strange purple object to the right that I can't seem to get rid of - looks like that's the equivalent of a skirt. What I first thought of as gaps in the slicing is apparently half-height layers, an interesting idea. The file is also a factor 5 larger than either Cura or Slic3r's. 

MatterControl 1.7.1: Installed, blocked by security on laptop. Works on desktop. Interestingly, the overhang setting is in percent of extrusion width rather than angle, and for this piece it ends up with extremely dense support even at 150%.

Meshmixer 3.3: Free from Autodesk, a giant in CAD. Installed, blocked by security on laptop. On desktop, doesn't seem to be able to export GCODE nor have appropriate settings. It apparently just calls out to something else for slicing.

Repetier: The Mac version is quite a bit behind the Windows/Linux versions. I don't want software that's been abandoned.

Simplify3D 4.0: It's not free, but at €149 isn't not outrageous. They give a two-week money-back warranty, so I'd want to have some good tests lined up.

Slic3r 1.2.9/1.3.0-dev: At least I know this, and it integrates with OctoPrint, which I am looking at switching to for running print control on a Raspberry Pi.

Printed piece with support still on it (upside down). Notice the little bit of extra support on the interior edge, and the heavy-duty support for the screw holes. 

It was really difficult to get the interior support off, would have been nigh impossible if this had been in its intended interior position.

Lulzbot Cura wins this hands down, I will use that if I need better support for a complex piece. Right now, I redesigned the piece to not require support. It might not draw air quite as well, but it's a lot easier to print.

I still want to try Simplify3D at some point where I have time for proper testing.

Another print: For the dark season, I want to finally totally organize the cables on the big light therapy lamp. So I printed another 10 of the clamps I designed long time ago. Interestingly, the two closest to the Y minimum position didn't stick, while the rest was fine. 

Wednesday, 1 November 2017

Scary prints

For Halloween, I'm printing various things downloaded from Thingiverse. Mainly spiders:

These print flat, but you can always heat the legs (or other parts) to pose them. They print really easily with my black flexible PLA, though getting them off the bed has been a smidgen tricky. So now, since I need more spiders, I'm doing prints at increasing Z offset, and once I see what offset is the highest they can still hold on to, I'll go back and do my calibration routine. At 1.1mm Z offset, they printed somewhat tightly on the bed. At 1.2mm there was some filament visible on the bottom, which is fine. At 1.3mm the legs started coming apart from lack of bed adhesion. Calibration (the day after) had only a bit of resistance at 1.1mm, not the full stoppage I usually go for.

Attempting next to print a large box, I ran into dimensional trouble - my print surface wasn't quite big enough for the full size I wanted. Testing the size, I ran the fan into the clips holding on the glass on the bed. I was able to improve this a bit by having the clips clip onto the cardboard insulation under the bed, making them flatter. But even so, I cannot currently print larger than 17x20 cm. I could possibly squeeze out about 1/2 - 1 cm by adjusting the Y direction a bit, it prints a bit towards the back. However, the point is moot, since when starting a reduced-size print, it turned out it would have taken multiple days to print, and I don't want that running in my bed room. Also, the bed isn't quite flat out at the edges - I had it calibrated a bit low, and the middle parts got too low, leading to stripping. On the upside, it made for a pretty feather-like structure:

Fixing the strippedness showed two interesting things: 

Firstly, the pulled filament was rather dark. This could be carbon build-up over being heated to full temperature for several minutes, but more likely it's a bit of the flexible PLA left over. A couple of minutes of heating shouldn't do this much carbon buildup.

Second, the stripped material on the hobbed bolt is fairly loose, which is different from the grey material on my first bolt. I'm not sure if it's the bolt design or the PLA, but in either case it's possible to just brush away the filament rather than having to take out the bolt and pry it out with a needle. I should possibly invest in a small stiff brush for the purpose.

The hobbed bolt after simply brushing it with a standard small pain brush
After cleaning, and with measuring Z height only to where the paper starts having a bit of traction (1.7mm), I ended up with a nigh-perfect test cube (#69). It's curious that it moved up so far - maybe each time I pull the filament out I pull the Z axis bolts a little further into their sockets. If the sockets aren't perfect near the top, it may take some pulling to get them all the way in.