Working with a STEP file to make parametric copy

[cram]

Back again after a bit of time away from FreeCAD.

I've found a STEP file of a shipping container, as I understand it STEP files are not parametric and cannot be edited directly. I would like to go about making a parametric model of the STEP file however, I'm not sure where to start or how to go about it. The step file is downloadable from link below.

https://drive.google.com/open?id=1O6gfj ... 83HBwnP1IQ


OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13519 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 1a8b868018f45ea486c0023fdbfeb06febc1fb89
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/Australia (en_AU)

[openBrain]

Hi,

AFAIK your best chance is with the Defeaturing Workbench.

[NormandC]

Hi cram,

I'm unable to download your file. First Google Drive gave a warning that it wasn't able to make a virus scan on the file and offered me to download it anyway. Then there's a connection error and it tells me the file cannot be found.

STEP is a text format, please zip it, it will greatly reduce its size, and may solve the corruption issue.

[pl7i92LCNC]

a Step file is a parametric File and can easy be converted to a Solid
there is mutch more problem with a STL

[NormandC]

I think you may have misconceptions about the meaning of parametric. A STEP file is definitely *not* parametric.

Parametric means you can edit a model through parameters. A STEP file has no parameters, and no history tree when imported. A STEP file may contain a B-rep solid, or a surface model or an assembly of parts, which is probably what cram's shipping container consists of.

[cram]

Hi cram,

I'm unable to download your file. First Google Drive gave a warning that it wasn't able to make a virus scan on the file and offered me to download it anyway. Then there's a connection error and it tells me the file cannot be found.

STEP is a text format, please zip it, it will greatly reduce its size, and may solve the corruption issue.

Hi NormandC , sorry you were not able to download the file. I've zipped it, here is the link to it.
https://drive.google.com/open?id=1vg5w6 ... jwCqemd-Hh

[cram]

Hi,

AFAIK your best chance is with the Defeaturing Workbench.

Thanks for that I'll have a look at that WB, I didn't know that existed.

[NormandC]

Back again after a bit of time away from FreeCAD.

And it shows:

Version: 0.17.13519 (Git)

There were multiple bug fixes releases after 0.17.13519, the latest was 0.17.13541 back in August. But, the release of 0.18 is imminent, binaries (installers) have to be prepared, I'm guessing it may happen in the following days. 0.18 is really, really worth the upgrade.

Thanks for that I'll have a look at that WB, I didn't know that existed.

The Defeaturing workbench is useful to make simple edits on imported solids like remove faces, holes.

But since you state you want to rebuild the container in a parametric manner, I don't think it would be suited here. Is there a specific reason for doing so? It will be a quite intensive job if you want it fully parametric. What's your end goal?

Hi NormandC , sorry you were not able to download the file. I've zipped it, here is the link to it.

Thanks, it works fine now. BTW, FreeCAD now supports compressed STEP files (*.stpZ), thanks to the same author who did the Defeaturing workbench add-on.

I have a tip for when you import the STEP into FreeCAD: load the Part workbench, then go to Edit --> Preferences / Import-Export, STEP tab, and make sure "Enable STEP Compound merge" is unchecked. Then all parts will be imported separately instead of joined into compounds.

[cram]

Haha, yes I haven't grabbed the latest version, but will do. It seems not that long ago that 0.17 became the stable release and now 0.18 is on the verge of being so. Awesome stuff devs.

Ok, understand you on the Defeaturing workbench.


As far as wanting to make the shipping container parametric it was in order to make a change in order to replicate the different size shipping containers there are, ie 10ft, 20ft, 40ft and high cubes. However you have me very concerned, for you to say 'intensive' it must be very involved.
The end goal was to attempt designing a house using various shipping containers.

[NormandC]

Cool project, for curiosity I did look at this kind of house a couple of years back.

Well it's not complicated work, but it won't take half an hour. You'll have to take a lot of measurements on the STEP model to replicate the parts parametrically. Also, if you want it to be configurable for different lengths (and heights?) it will require some planning. I would use a spreadsheet to control main values.

You could maybe do it in a hybrid manner: use as many existing parts that you can, if you can be sure that their length won't need to change. For example, looking at the floor sub-assembly, if you know all containers have the same width, you could use one of the C-beams "as is" and not model it from scratch. Delete all the others, create Draft Arrays to replicate it. Use existing sub-assemblies that will not need to be edited (doors and end wall).

BTW this container was most certainly modelled in SolidWorks. The "up" direction in this document is the Y axis instead of the Z axis.