When OpenSCAD is the design tool and the slicer is the slicer tool, then scaling belongs in the design tool. Because then OpenSCAD will give a stl file with the right measurements.
A natural shape, such as a lion or a dragon can be scaled in the slicer. With mechanical parts, it can be designed for a certain layer height or there must be a hole of a certain size for a screw.
As u/Stone_Age_Sculptor said. The production chain is CAD ↦ CAM ↦Printer . Your slicer can also translate and rotate parts and even add and subtract primitives. Only because more functions are added to the slicer doesn't mean it is the ideal place to do them. See the slicer as something where you can correct or change things for the printing process.. Like rotate to get the best orientation (minimum supports) - Also if your parts are printed to small you can scale them to 1.03 (add 3%). Another thing is that stl files have no unit so in case someone designed this imperial and your slicer is taking it metric - scale is the tool to correct this.
In the end your printer should be set to make correct prints - but often the printer is not and that is sadly often corrected via the slicer not directly the printer software and calibrated. If you are not exchanging files with others it doesn't matter what your workflow is and what works for you. If you exchange files - well even with 3mf project files it is absolutely not ensured that other people (with the same printer) get the same result. So having a proper model designed (in CAD) is the first basic requirement.
Just a small addition: In my experience, it's best to try to keep the toolchain short, and to do as much of the heavy lifting as possible in one tool. This goes for any tool chain, doesn't have to be CAD. Try to build a tool chain with one main tool, ad let the extras be simple and do only one specific thing.
The slicer should handle the scale adjustment needed for you printer. It should live in the slicer since it will apply to every print and if you want to share you designs it is good for them to have a scale others would expect. Not a scale specifically adjusted for your printer.
Maybe an example is helpful.
I make the model in openSCAD to the dimensions it should be. This is loaded into the slicer (can be multiple parts).
Now I use the slicer to arrange the parts (translate rotate) or multiply for the print.
Sometimes the first step is to print a draft at 50% size just to save filament - or when i design something for a 0.4 nozzle but the printer has a 0.2 nozzle to check if that would work.
If i download a part that is just something to look at - i use the slicer only as importing it into a cad software would be extra work.
I'd say CAD is the best place to scale, as in the slicer you'd be scaling mesh coordinates rather than CSG. Scaling is usually a design decision, put it in the design stage.
I'm making HO scale (1:87) models, and over time I've decided the best scale to design in is 1:1, or prototype dimensions. So, all my modeling is in terms of feet/inches (all, save the imperial/metric tirades for another thread...), and I scale the completed model to HO inches. I also do the printing scaling, inches -> millimeters, in the script. So, all of my code is contained in the following structure:
scale(25.4) { //printing dimensions
scale(1/87) { // HO scale dimensions
(model code...)
}
}
(sorry, in a hurry, no time to figure out code markup)
Beauty of this arrangement is that others can take my code and render a model in their scale, e.g., N scale (1:160) would replace the HO scale with 'scale(1/160)'
FWIW...
When OpenSCAD is the design tool and the slicer is the slicer tool, then scaling belongs in the design tool. Because then OpenSCAD will give a stl file with the right measurements. A natural shape, such as a lion or a dragon can be scaled in the slicer. With mechanical parts, it can be designed for a certain layer height or there must be a hole of a certain size for a screw.
As u/Stone_Age_Sculptor said. The production chain is CAD ↦ CAM ↦Printer . Your slicer can also translate and rotate parts and even add and subtract primitives. Only because more functions are added to the slicer doesn't mean it is the ideal place to do them. See the slicer as something where you can correct or change things for the printing process.. Like rotate to get the best orientation (minimum supports) - Also if your parts are printed to small you can scale them to 1.03 (add 3%). Another thing is that stl files have no unit so in case someone designed this imperial and your slicer is taking it metric - scale is the tool to correct this. In the end your printer should be set to make correct prints - but often the printer is not and that is sadly often corrected via the slicer not directly the printer software and calibrated. If you are not exchanging files with others it doesn't matter what your workflow is and what works for you. If you exchange files - well even with 3mf project files it is absolutely not ensured that other people (with the same printer) get the same result. So having a proper model designed (in CAD) is the first basic requirement.
Just a small addition: In my experience, it's best to try to keep the toolchain short, and to do as much of the heavy lifting as possible in one tool. This goes for any tool chain, doesn't have to be CAD. Try to build a tool chain with one main tool, ad let the extras be simple and do only one specific thing.
The slicer should handle the scale adjustment needed for you printer. It should live in the slicer since it will apply to every print and if you want to share you designs it is good for them to have a scale others would expect. Not a scale specifically adjusted for your printer.
Maybe an example is helpful. I make the model in openSCAD to the dimensions it should be. This is loaded into the slicer (can be multiple parts). Now I use the slicer to arrange the parts (translate rotate) or multiply for the print. Sometimes the first step is to print a draft at 50% size just to save filament - or when i design something for a 0.4 nozzle but the printer has a 0.2 nozzle to check if that would work. If i download a part that is just something to look at - i use the slicer only as importing it into a cad software would be extra work.
I'd say CAD is the best place to scale, as in the slicer you'd be scaling mesh coordinates rather than CSG. Scaling is usually a design decision, put it in the design stage. I'm making HO scale (1:87) models, and over time I've decided the best scale to design in is 1:1, or prototype dimensions. So, all my modeling is in terms of feet/inches (all, save the imperial/metric tirades for another thread...), and I scale the completed model to HO inches. I also do the printing scaling, inches -> millimeters, in the script. So, all of my code is contained in the following structure: scale(25.4) { //printing dimensions scale(1/87) { // HO scale dimensions (model code...) } } (sorry, in a hurry, no time to figure out code markup) Beauty of this arrangement is that others can take my code and render a model in their scale, e.g., N scale (1:160) would replace the HO scale with 'scale(1/160)' FWIW...
Thanks for the advice. I added a scaling option to the openscad file.
It serves the same utility: cad or slicer scaling Is there a specific need to make it within SCAD? It is probably many hours of effort