Scaling issue

[Ken Hubbard 0]

I have created a 1" cube in Autodesk Inventor Pro. I have saved the file as a .stl file. When I load the file to Cura 15.04.6 size is much, much smaller than 1" cube in the Cura print window. I am unable to find a way to scale it back to the 1" measurement desired. How do I fix this, oh, 3d printing gods?

[gr5 2,172]

Well you have a bunch of choices.  Cura expects the units of the STL to be in mm.  Not inches.  But STL files are unitless.  So one solution is to design a 25.4 inch cube (which will come out as 25.4 mm which is one inch).  A second option is that when you save to STL, most cad programs ask what unit you are exporting in.  Tell Inventer Pro that you want the STL to be in mm.  This is probably the best solution.  Finally, in cura you can simply click on the tiny 1mm cube and scale it up by exactly 25.4X (2540%) or you can tell it to set the height (or any of the 3 dimensions X,Y,Z) to 25.4mm.

[geert_2 557]

Another solution is to make the design in metric dimensions from the start. In the future, engineering in the USA and UK will switch to the international metric system anyway. They are about the only countries that are still behind. So if you do the switch now, you will have a very gradual and smooth transition, and you will be used to it by the time it becomes compulsary. Once you are familiar with the metric system, you won't regret it, because it is so much easier to do conversions. No more horrible multipliers to go from inch to feet to yard to miles to nautical miles... Just move the decimal point a couple of places, that's all. Idem for volumes and most other units.

 

[ahoeben 1,948]

If you want to do the scaling in Cura, there's a neat plugin for that (aptly called the "Barbarian plugin"). It is available through the "Plugins -> Browse plugins..." menu in Cura 3.x.

Edited January 12, 2018 by ahoeben

[ronstew 1]

Useful part of the post:

 

It took me a while to figure out that to use the Barbarian plugin, I need to zoom in on my part (which at 2 mm x 1 mm x 1 mm is too small to see at first) then click on it, THEN click Extensions/Barbarian plugin/Convert to metric.

 

Opinion:

 

@geert_2 - I have used SI units at work and school for 45 years. But for personal work, I prefer inches and mils (thousandths of inches). Please do not suppose that I will grow to prefer millimetres.I prefer software that has a preference setting that allows the choice. But hey, Cura is free, and there is a functional plugin to convert after loading if I work in inches. What should I expect for free?

[gr5 2,172]

Or even better, most (all?) cad programs that let you export to STL also let you choose the units.  Just tell your cad program that the STL file should be in mm and it should do the conversion for you.  And in my experience you never have to set this up again (the cad program should remember what units you want the STL in).

[SteveCox3D 85]

@gr5. - There's a slight contradiction in what you say in your last post.  

 

You correctly stated earlier that .stl files are unitless, so you can't actually tell your CAD programme to save the stl file in mm or inches.  You should model in whatever units suits your design needs, the fault then lies with this unitless format that stl files get saved in.  It's only when you import into the slicing software that the unit length of say '2.5' in your .stl becomes either 2.5mm in a slicer that uses metric, or 2.5" if it's a slicer that uses imperial.

 

It does work the other way round - if I import an .stl file into Autodesk Fusion 360 it asks me before displaying it what units I want to use so that it knows what units to apply to file to determine the size.

 

All of this should get fixed when .3mf becomes the de facto file format standard for 3DP/AM, as this will take away this potential error point by carrying the units that it was originally designed and saved in (it might take a long time before we get to that point though!)

[ronstew 1]

Solidworks export to stl info that I could have found before I posted yesterday:

 

https://forum.solidworks.com/thread/207557

 

Thanks @gr5.