Struggling with DAG ('nearly' newbie)

doxley · Post by **doxley** » Sat Nov 07, 2020 11:00 am

I am trying to develop an assembly (Assembly 4) with a top level frame (base for a furniture wall shelf) and inserts (additional shelves, etc.). I have gotten into an issue where I've obviously broken the DAG requirements so if I save the package and attempt to reload it, I generate the dreaded 'graph must be a DAG' message. The idea was for the master assembly to design the frame and specify a set of LCS origins to be used to connect later parts.

I've chased this for quite a while and am guessing that I've committed an error in one or more of three places:

I have an unconnected Origin (visible in DAG view)

I have some sort of loop in variable references though I think I have all variables defined at top level

I've done something in the sequencing of Pad operations caused by changing the design as I go

I think I've seen all the forum and doc entries in the area and am searching to understand

How do find/identify DAG problems as early as possible (I use both the DAG view and Dependency Graph)

Is there guidance for avoiding the problem in the first place

How to correct a problem once found (it seems that it is possible to create a problem in the development history such that it is difficult/impossible to unwind without redeveloping the entire structure)

I would imagine that many capable designers, but less mathematically inclined users could really get tangled up here. I certainly have.

I would much appreciate it if someone can show me were I have gone astray in my model, but I'd be even more appreciative of guidance on how to stay out of the soup in the first place.

I'm running a recent (but probably not quite latest) daily build:
OS: Ubuntu 20.04.1 LTS (ubuntu:GNOME/ubuntu)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.
Build type: Release
Branch: unknown
Hash: 0a42189173b9d50a2849d9b2aa79c110a7565c89
Python version: 3.8.5
Qt version: 5.12.8
Coin version: 4.0.0
OCC version: 7.3.0
Locale: English/United States (en_US)

Thanks,
--Don