RogerBW's Blog

Dear 3D print customers, please just use OpenSCAD 24 March 2017

My customers on 3dhubs use a variety of software packages to build the models they send me; in theory, anything that produces files in obj or stl format will work. Some are definitely better than others.

For example, if you want to have a cylinder with a smaller cylinder sticking out of it, you can I suppose go into your fancy GUI modeller and drag the points to where you want them. Or you can measure the original, fire up OpenSCAD and type the numbers:

cylinder(d=5,h=10); translate([0,0,10]) cylinder(d=3,h=4);

Yeah, sure, you may need to change those numbers when you look at the preview, but if you're trying to match an existing object surely that's easier than finding the right place to type a number on a crowded screen, or even worse trying to drag something to the right length with a mouse?

For more complex objects, fair enough, a full-on 3D modeller is a better bet. But that can cause trouble too. Here's a part I was sent recently:

which looks fine (a bit crude, but it's not intended for close-up inspection). But throw it into "X-ray view" in the slicer, and the problems become apparent:

there are voids throughout the inside of the part. Fused-filament deposition 3D printing has one big limitation: you can't (to a first approximation) print on top of open air. Each line of filament needs to lie on something underneath it. So a great big open space simply won't work on the printer. You can add support material, which is broken away afterwards, but support inside a sealed space like this can't be removed; it would just break off and rattle about inside.

Now, you might want to save filament to reduce your printing cost. That's fair enough. But the slicer already hollows out objects so that the insides are 80% air and 20% plastic gridwork, and it does a better job than you can. Even if these voids were printable, they'd make the object terribly fragile.

In this case I simply remodelled the object in OpenSCAD, which took me about ten minutes. (I'm sure the original designer took longer to produce the model, but he was designing as well as modelling, which is fair enough.)

Increasing the resolution of the circular parts is a matter of tweaking one variable – after the designing is done. But more to the point, on X-ray view:

all those nasty voids are gone, and this can be printed with no problems. (With support material for the socket at the bottom.)

Dear customers, please don't use complex modelling packages if they're going to produce voids and other confusion. Just use OpenSCAD. It's quick and easy and unambiguous, and if there are problems with the model they're trivial to fix.

  1. Posted by John Dallman at 04:57pm on 24 March 2017

    User psychology issue: lots of people want to feel like designers, and hence use the most designer-ish software they can (nearly) manage. Also, using numbers is uncool, while 3D-printing is currently fashionable.

  2. Posted by RogerBW at 05:08pm on 24 March 2017

    Also they tend to think that a GUI must be easier to use than editing a text file.

Comments on this post are now closed. If you have particular grounds for adding a late comment, comment on a more recent post quoting the URL of this one.

Tags 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s 2010s 3d printing action advent of code aeronautics aikakirja anecdote animation anime army astronomy audio audio tech aviation base commerce battletech beer boardgaming book of the week bookmonth chain of command children chris chronicle church of no redeeming virtues cold war comedy computing contemporary cornish smuggler cosmic encounter coup covid-19 crime crystal cthulhu eternal cycling dead of winter doctor who documentary drama driving drone ecchi economics en garde espionage essen 2015 essen 2016 essen 2017 essen 2018 essen 2019 essen 2022 essen 2023 existential risk falklands war fandom fanfic fantasy feminism film firefly first world war flash point flight simulation food garmin drive gazebo genesys geocaching geodata gin gkp gurps gurps 101 gus harpoon historical history horror hugo 2014 hugo 2015 hugo 2016 hugo 2017 hugo 2018 hugo 2019 hugo 2020 hugo 2021 hugo 2022 hugo 2023 hugo 2024 hugo-nebula reread in brief avoid instrumented life javascript julian simpson julie enfield kickstarter kotlin learn to play leaving earth linux liquor lovecraftiana lua mecha men with beards mpd museum music mystery naval noir non-fiction one for the brow opera parody paul temple perl perl weekly challenge photography podcast politics postscript powers prediction privacy project woolsack pyracantha python quantum rail raku ranting raspberry pi reading reading boardgames social real life restaurant reviews romance rpg a day rpgs ruby rust scala science fiction scythe second world war security shipwreck simutrans smartphone south atlantic war squaddies stationery steampunk stuarts suburbia superheroes suspense television the resistance the weekly challenge thirsty meeples thriller tin soldier torg toys trailers travel type 26 type 31 type 45 vietnam war war wargaming weather wives and sweethearts writing about writing x-wing young adult
Special All book reviews, All film reviews
Produced by aikakirja v0.1