this post was submitted on 27 Jun 2024
18 points (100.0% liked)
FreeCAD
808 readers
1 users here now
Your own 3D parametric modeler.
FreeCAD is an open-source parametric 3D modeler made primarily to design real-life objects of any size. Parametric modeling allows you to easily modify your design by going back into your model history and changing its parameters.
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
When I'm using FreeCAD, I'll use a spreadsheet for all of my variables, so everything is linked together by formulas. Next, I'll use datum planes rather than drawing directly on object faces (which completely solves topological naming), although I wouldn't attach the plane to the surface--just geometrically define the distance and angle in the spreadsheet and reference it directly (e.g. if I want a datum plane halfway up my object, I'll make its height h/2)
I haven't had a chance to try FreeCAD, but this is generally good advice in other parametric CAD tools, too. Create "skeleton" features early on (planes, datums, simple sketches) and define later features by referencing the skeleton as much as possible. It avoids creating a long chain of feature dependencies where Feature A changes and breaks Feature B, which breaks Feature C, etc.
It is good to note that the datum plane technique completely breaks sometimes when changes on earlier shapes when dealing with angles and rotation, and non-planar geometry unless you reference it to a face (in which case topo naming again) because rotation of a datum plane is rotated and shifted with respect to the origin and not the desired face. Not to mention getting an exact face takes a long time of tweaking with complex parts.
Also be careful with spreadsheets. Is one variable is referenced more than 15 times or so, every mouse click in the spread sheet starts taking minutes to calculate. I had an outer shell dimension in a PC case in a design that I referenced a lot and clicking a spreadsheet cell would trigger an 8 minute recompute before I was even able to enter the cell to edit the variable (so then another 8 minutes after editing)
Whoaa that's really good to know, thanks!
Ohhh, that's brilliant! I've been using named sketch constraints and then formulas referencing those so far, but AFAICT you can't seem to name the parameters in pads/pockets/etc? Using a spreadsheet sounds much better, thanks!