ceremcem wrote: ↑
Thu Aug 09, 2018 12:12 pm
OakLD wrote: ↑
Wed Aug 01, 2018 12:47 pm
ceremcem wrote: ↑
Sun Jul 29, 2018 12:16 am
Regarding to #2, I'm convinced that it can not be done unless some scripting is involved, so it should be left out of ASM3 context. Thanks for the answers, I'm moving forward.
You could/should use Spreadsheet
workbench to drive the dimensions in a logical way. No scripting required, if I understand your scenario correctly.
I didn't get to fully test it with FreeCAD, but I used it a lot in SolidEdge many years ago and it's really worth learning. In example, I had a common product, a small tank with conical bottom and typical inlets and outlets done this way. So when we received order for a custom (always) tank of this type, I simply typed in diameter and height, saw the volume (to check if it is matching the request), modified in/outlets diameters and about 90% of work on drawings and documentation was done... Very effective.
I'm experimenting with a custom Library-type Workbench in FreeCAD to allow to make such input-driven models (and drawings too!) of common parts (brackets, tanks, links, connection plates, etc.), but I am extremely slow in the progress due to lack of time and lack of experience in the development environment used in FC...
Does this have a name or can we call it "Assembly Referenced Dimensions"? Anyway, I propose to track this feature/howto here
for the sake of clarity, if there is no other refences exist at the moment.
Actually, both the example you gave and the practise I experienced in past, does not (usually) involve referencing the assembly
constraints. In your example, if you change the width
of the car, you want to change the width of all the parts
in between left and right side, i.e. the bumpers you mentioned, the hood, roof, base platform, cross members, rear and back window, etc. So typically, it does not affect the relation of the parts, i.e. bumper or the "right" and "left" parts stay attached to base platform, the cross members in turn to them, etc.
There are catches, though. For example, if you fix hood via welded hinges and their position is related to the sides, the distance between them will expand with the hood. So you should contrain the other halves of the hinges in the same fashion. Or vice versa, you can constrain both halves to the symetry plane and then they'll always keep the position. If you mix the methods, the assembly will appear broken.
The very best way IMHO to fix such parts is to sketch a helping geometry on the base part (hood in the exaple above), use spreadsheet reference for it's position and constrain the half of the hinge to that geometry. If you i.e. rivet the hinges, you have to do holes anyway. This should make a stable assembly.