21 dec. 2017 kl. 00:24 skrev stefan_trethan <stefan_trethan@...>:I’d have to try that. The grinding medium would need to be small enough to deal with the grooves/knurls in the knob.
Alternatively, for visual consistency’s sake, a knob design “manual” more amenable to printing could be made and then an instrument would be completely retrofitted. The thing to understand is that 3D printed knobs are essentially free if you have a 3D printer. Once a process is set, getting more of them amounts to a few clicks.
Solvent polishing is a simple process that works wonders in ABS and PS. And that’s that, since IIRC no other plastics can be smoothed with solvents you can buy in a hardware store. Or am I mistaken?
Another thing worth considering for the material is plain old PLA. After annealing it becomes a very good performer in terms of softening temperature - better than ABS! And it’s ubiquitous and every printer will print it!
The rotary mechanism would not be too difficult to make, but I wouldNormal Marlin firmware will deal with the gcode of course; it doesn’t care much as long as you’re outputting gcode in coordinates of the printer’s axes. The issue is getting the non-Cartesian gcode. Since the knobs have simple shapes, a straightforward parametric gcode generator script can do the whole thing for output in cylindrical coordinates. I like vagrearg’s gcmc for that.
Another simple idea is to generate the 3D model unrolled onto the hub, i.e. using pseudo-cylindrical coordinates directly: X->axial position, Y->circumferential position, Z->radius. Then the gcode output from a slicer can control such a printer directly with no modifications!
If one were to generate the 3D model in true cylindrical coordinates (Y->angle), the slicer output will have to have the flow factor set at the beginning of each layer to a value proportional to the layer number, and the speed set to a value that’s an inverse of the layer number. That’s to accommodate the growing angle->circumferential position scale the radius increases.
On Thu, Dec 21, 2017 at 4:04 AM, Kuba Ober <kuba@...> wrote:19 dec. 2017 kl. 23:52 skrev Dave Seiter <d.seiter@...>: