Over the weekend I modelled a simple shovel, to 3D-print as a game token. It's somewhat squat and fat. Approx. intended length is about 45–55mm.
Blade was coming out ugly: Too thin in some places meant Cura was producing an unpredictable quantised edge. Maybe there's a way to make Cura fill out to any volume, rather than quantise within it?
I worked out I got the nicest print if I angled it upwards at 45° with the handle (the largest end) acting as the base, and extra supports in the first few layers, and then where the handle meets the blade, for added strength. It turned out pretty nice at 0.12mm resolution.
I did one with closely-coupled supports all the way up the shaft, and another with default supports (except for the extra reinforcement up the handle). Both seemed to turn out fine.
It's possible this would have worked if the model was printed vertically, but then: (1) there would be less attachment to the base, which I did as a raft; and (2) there would be potentially worse overhangs, such as the back lip of the blade. It's possible also that the back lip would be too thin, and hence turn out distorted.
I started modeling enclosures in Blender that I wanted to use to house electronic components. One part a pretty simple square PCB with 4 screw holes. I think I got the model/dimensions right, but it wasn't a perfect fit when printed: fractionally too short on the X axis, and screw holes didn't line up all that well.
Observations:
- Screw holes measured visually from centre, rather than edge. I know the holes are ⌀3mm. Should instead measure PCB edge to whole edge, then add 1.5mm (i.e. the radius) to get centre.
- Don't assume all holes fit square aligned offsets. Measure each individually.
- Inner PLA corners are slightly rounded. This creates a tighter fit for the sharp PCB corners.
- X axis seems to be off more than Y axis. Is this a scaling error on one axis, on both, or an overflow of PLA? Can probably adjust in Cura to apply horizontal contraction (instead of expansion).
- 1mm walls of the enclosure seem OK, though might be a little too narrow/weak in PLA.
Overall it seems like this would be easier to parametrically model using (say) OpenSCAD.
I want to work out the best way to model something to fit a non-uniform shape. I have a Digispark plugged into a USB extender plug, which has a certain rounded shape and other features. What's the best way to match this shape, initially just the X/Y, and later Z profile?
I could possibly use my scanner, for which maybe I could 3D print a "measure box" of some kind that both holds the object and allows verification/correction of dimensions or optical scaling issues.
I figure I could do this:
- Hold the object/shape carefully in a measurement box that sits on top of the scanner and (if necessary/possible) blocks out external light and remains straight and stable even if the lid is open.
- Make sure the measurement box rulers are properly X/Y aligned, i.e. straight.
- Make sure the measurement box is dimensionally accurate.
- Scan the target object.
- Check the X/Y scaling accuracy of DPI to mm in the resulting scan image.
- Adjust accordingly.
- Trace the shape using a vector path, and scale to some known measurement to get precise mm real-world match.
- Use "outside" path stroke of (say) 2mm, and expand the stroke to a solid "outline" path.
- Export to SVG, import to Blender, check dimensions/units.
- Extrude (or whatever -- OpenSCAD?) and print that shell, optionally even a very thin version of it, and see how well it fits around the object.
- Adjust accordingly, being aware of flex of the PLA when fitting around the object.