MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
... sub class is just an ordinary assembly which becomes a subclass by the fact its contained in a higher assembly...
yes
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
...You use the constaint assembly to attach the legs to the rail...
I use
"Attachment" constraint
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
...which is as I would expect, when I do this the attachment is at the centre of the rail...
correct
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
... how do you align the leg at exactly the end of the rail...
as per my post
elements were "flipped" to get correct orientation of the legs and were "offset" to align edges as you wanted.
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
....I can drag it to the end but this is inexact as I have to zoom out to see the drag controls, when I zoom in to see the junction the controls are off the ecreen...
wrong idea
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
...when I resolve constaints the leg snaps bck to the middle of the rail ...
correct
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
....how do I weld it in place...
it is "welded" in place (that's what "Attachment" constraint does) - just the place is wrong.
use element offset
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
.... I tried plane alignment on the front of the leg and end of the rail, but just got an error...
using "Attachment" constraint will leave you with 0 degrees of freedom
trying additional constraint is an error
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
...there must be way to hold it in place by removing the remaining degrees of freedom...
there are no "remaining" degrees of freedom left after you "attach" two parts
MikeM wrote: ↑Tue Jun 14, 2022 9:25 pm
...For even the relative few items want to put together the tree wil get very large, is there any way to keep it managable
I don't use assembly workbench for "everything"
I use it selectively, where appropriate.
For example in your case I would use part placement to get it right rather than assembly workbench.
Who needs assembly workbench for simple stuff
- Screenshot from 2022-06-15 08.21.17.png (71.69 KiB) Viewed 792 times
create the frame using placement as a subassembly (but without assembly workbench)
and use it later in a larger assembly (with assembly workbench if needed)
I am using Link branch and Assembly3
you can also download ... and try it
here
excellent Assembly3 tutorials
here