[HN Gopher] Determine mesh rotations to minimise overhangs for 3...
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Determine mesh rotations to minimise overhangs for 3D printing
Author : alonfnt
Score : 50 points
Date : 2024-06-24 05:39 UTC (3 days ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| amelius wrote:
| Very nice, but often minimum overhang is not the only constraint.
| Sometimes you want to take (directional) strength into account.
| And sometimes it simply looks better if an object is sliced in a
| certain way.
| VBprogrammer wrote:
| It's very familiar to anyone who's done some woodwork. Keeping
| the grain direction in the same direction as you require
| strength is 90% of joinery.
| progbits wrote:
| This might be good for slicing random decorative models that
| weren't designed with printing in mind.
|
| Because when I care about strength and printability I do so
| from beginning and base the whole design around it. There is no
| need for a tool to pick print orientation for me because I know
| before the first CAD extrude how it's going to be printed.
| Filligree wrote:
| How would you design a screw thread adapter that needs to
| resist shear?
| progbits wrote:
| I certainly wouldn't 3d print it, that is a job for off the
| shelf metal part.
| Filligree wrote:
| Nobody has any clue what the thing is. :D
|
| It claims to be BSP, but it's 1 inch (1.1?) with 19
| threads per inch (18?), which matches no standard I've
| ever found.
| linsomniac wrote:
| Print a mold, cast it in wax, put that in casting sand,
| then do a lost-wax casting in aluminum or something more
| exotic if necessary and you're able?
| Filligree wrote:
| I think at that point I'd have to ask someone to make it
| for me.
| r2_pilot wrote:
| Lathe would be the tool to use in that case.
| nmeofthestate wrote:
| A 3D printed plastic part could be fine depending on the
| application. Certainly worth considering/testing.
| Printing it flat on the bed (with a small flat side) so
| layers are lengthwise may work.
| 83 wrote:
| If it needs any amount of strength you'll want to find
| someone with a lathe. BSP tells me it may be tapered(?)
| so find someone with a taper attachment. Even as a
| hobbyist I could probably make one of those on my lathe
| faster than drawing it and printing it on my 3d printer.
| hinkley wrote:
| See also threaded inserts for the other half of that
| fastener.
| Aurornis wrote:
| At some point you have so many competing compromises that
| you're sacrificing one aspect to improve another. When this
| happens, I pick what's easiest to print and make up the
| strength with a lot of extra wall loops, slightly higher
| print temperature (for better layer adhesion, as print
| quality allows), and stronger material selection.
|
| If this is a critical or load bearing part, I'd skip 3D
| printing entirely and get it machined.
| JofArnold wrote:
| Although true, you can optimise this considerably by using
| materials with very strong layer adhesion like PET (which I've
| never had break along layer lines) or by annealing or even
| remelting. So for me at least who prints entirely in PET or
| PET-CF (note PETG to be clear) this is super helpful.
| lmpdev wrote:
| Tangental:
|
| Most consumer printers I've come across have differing XY and Z
| axis spatial resolutions
|
| I've been wanting a decent algorithm to determine the optimal
| angle to print models such that the result is _aesthetically_
| as high fidelity as possible
|
| Take for example a rigid model crane set to a non orthogonal
| angle. Is it pleasing to print with respect to one vertical
| column or the other? What if they are not equally sized? What
| about which is most likely to be viewed up close?
|
| Generalising that problem to more organic shapes is
| incomprehensible but I can't even answer the aforementioned toy
| example
|
| I'm sure there are dozens of excellent potential approaches but
| I can't easily find it for arbitrary XY and Z (or other
| combinations thereof) spatial resolutions
| dotnet00 wrote:
| If you need detail in more than one axis, you should use a
| smaller nozzle and lower speed. Along z-axis, the feature
| size limit is layer height, and along XY it's linewidth.
| Layer height can be very small with any nozzle (I've seen as
| small as 50 microns), but linewidth will typically need a
| smaller nozzle hole to work well, particularly to get below
| 100 microns.
| jyxent wrote:
| I think XY actually has better resolution depending on your
| perspective. I agree that the minimum extrusion is
| approximately a line width circle. But that circle can move
| less than the line width for features on larger surfaces.
| For example, if you emboss something on the side of an
| object with 0.3mm depth using a 0.4mm nozzle / line-width,
| it will work fine.
| dotnet00 wrote:
| Yeah, I suppose it depends heavily on the kind of detail.
| I was mostly thinking along the lines of printing
| lithophanes or hueforge prints.
|
| With lithophones it's typically recommended to print
| upright so the image is formed by stacking layers, as
| that allows for "pixels" to be thinner. Hueforge instead
| is typically printed flat because color stacking/blending
| needs more resolution than the shapes.
| krisoft wrote:
| My cheeky observation to that would be: if you need detail
| in any axis use a resin printer. ;)
| dotnet00 wrote:
| Yeah, if you're doing detailed prints often, especially
| decorative stuff, resin can't be beat by standard fdm.
| JofArnold wrote:
| Great stuff, but working with STLs isn't a good option for me.
| Doing this in STEP would be amazing. But I suppose I could use
| STL to guide me on orientations I can then set up manually with
| my STEP files?
| delecti wrote:
| This tool makes total sense to me as-is, but I don't quite
| understand why it would be _more_ useful to work with STEP
| files.
|
| As-is, this is a tool I could see myself using when I've
| already got an STL which I maybe don't have input in
| (downloaded from printables/thingiverse/etc, or extracted and
| converted from a source like game files). But if you've got the
| STEP file, you have far more ability to make modifications to
| it to make it more compatible with 3d printing, like reducing
| overhanging bits or adding structures to support the overhangs.
| JofArnold wrote:
| I directly print STEP files. Faster, quieter and better
| finish than STL for curved surfaces. I print at fairly high
| speeds (300-400mm/s, >20k accels, 25 SCV on quality) so this
| might not be a universal consideration but for me it's a deal
| breaker usually unless I'm doing something silly
| jepler wrote:
| you could convert the STEP file to STL just for the
| purposes of this tool, it looks like you have to apply the
| resulting rotation manually in your slicer anyway using the
| rotate tool.
| tonyarkles wrote:
| Well I'm quite curious what you're using for a printer now!
| JofArnold wrote:
| Nothing especially unusual I think. Mostly use it for
| fixtures (for woodwork, DIY), improving/fixing random
| things and bike mods. Currently designing a derailleur
| for a folding bike.
|
| Reason why I've optimised it to print fast is that
| there's only so many hours between getting back from work
| and then going to bed (I don't trust my wiring enough to
| leave it overnight)... So pretty much everything has to
| be printable in max 5 hours... which is especially hard
| to achieve if I'm printing at high infills and 0.1mm
| layer heights.
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