STEP and VRML file - different scale in 3D viewer

Hello,

I am using one of the latest build of Kicad 5.99 and tried to import one 3D model which doesn’t exist in Kicad. I found STEP model of the connector, imported it in Kicad on Windows with 1.0 scale and everything was OK. Then, I found that STEP model is not visible in Kicad on Linux and I converted STEP to VRML using FreeCAD and imported VRML model to Kicad. But it turned out that in order to have correct size in 3D viewer I had to apply scale of 1/2.54 = 0.3937 to VRML file.

I wonder if it’s Kicad bug or I need to set some additional options in FreeCAD during export

The model which I tried to use is this one:

https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Customer+View+ModelCVM_5499786-4B3d_stp.zipEnglishENG_CVM_CVM_5499786-4_B.3d_stp.zip5499786-4

and the footprint in Kicad is IDC-Header_2x10-1MP_P2.54mm_Latch_Horizontal

Thank you in advance

Cheers, Sanya

It’s not a bug, VRL dimensions default to inches iirc

Hello

I understand that in my VRML dimensions are different from what is expected by KiCad (actually, not inches, but 1/10 of inch).
Well, I naively thought that units can be mentioned inside VRML file, so that any program doesn’t need any assumption about units and can always visualize objects with correct scale. But if it’s not the case, do you know what is the correct way to convert STEP to VRML, so that VRML has correct units for KiCad “out of the box” ?

In FreeCAD I have mm as units everywhere, but due to some reason VRML file is not in mm.

Cheers, Sanya

Hi s2x3,
The VRML does not specify (or if it does, there is some debate about it) the unit.

For historical reasons, KiCad use that formula conversion you mentioned.

Since you are using FreeCad, I suggest you try the addon StepUp that is used to do the convertions to KiCad VRML files (so you dont have to worry about this things).

You will find a lot of help and information here on this forum about SetupUp plugin for FreeCad!

3 Likes

Thanks for suggestions!
I’ll definitely try StepUp

And one minor correction (just clarification for other people who’ll read this thread):
In my post above I made a mistake when described units: FreeCAD uses mm, nothing wrong with FreeCAD itself, while KiCad expect to see 1/10 inch as unit.

Cheers, Sanya

Just to confirm:
I was able to generate scaled VRML for KiCad using StepUp plugin in FreeCAD
Thanks!

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.