Assembly4 stupid question about assembling

[mox]

Hi everibody,
here my sys

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.29177 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: 68e337670e227889217652ddac593c93b5e8dc94
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.2
Locale: Italian/Italy (it_IT)
Installed mods: 
  * Assembly4 0.12.3
  * fasteners 0.3.50

I was doing some tutorials about simple assembling without master sketch (no movements or simulations in this phase) and when I made a lamp I placed an arm (as the images shows) joining two LCS from 2 distinct parts and giving an orientation to the arm to obtain a fake joint in the end where I can't find a method to join my other LCS. If I hide the screws it is possible to see that the position is not perfect in this particular situation, so the simple question is: without a master sketch (that can be a solution for this problem from what I understood) is impossible to simple assembly in a CAD perfect manner a single part using 2 LCS of the same part in a redundant assembly like my tutorial, correct? I can't add supplementary points of joining other than the first to accomodate more needs?

Cheers.

[Zolko]

impossible to simple assembly in a CAD perfect manner a single part using 2 LCS of the same part in a redundant assembly like my tutorial, correct? I can't add supplementary points of joining other than the first to accomodate more needs?

I'm not sure to understand your question, so I'm trying to answer:

1) in your example, a master sketch is typically the good way to go.

2) an attachment by LCS in the Asm4 sense is fully deterministic, therefore you can't add another attachment by LCS to the same part because that would conflict with the first one. This is a mathematical impossibility.

3) redundant constraints are never a good idea even with dedicated solvers, some solvers can't handle them anyway.

[mox]

impossible to simple assembly in a CAD perfect manner a single part using 2 LCS of the same part in a redundant assembly like my tutorial, correct? I can't add supplementary points of joining other than the first to accomodate more needs?

I'm not sure to understand your question, so I'm trying to answer:

1) in your example, a master sketch is typically the good way to go.

Here the answer. Perfect. Thanks!

2) an attachment by LCS in the Asm4 sense is fully deterministic, therefore you can't add another attachment by LCS to the same part because that would conflict with the first one. This is a mathematical impossibility.

Here the part 2 of the answer. My tutorial was intended only to attach parts with others, so ASM4 probably is not the best tool to do so because it was developed to do more. Tanks again.

3) redundant constraints are never a good idea even with dedicated solvers, some solvers can't handle them anyway.

I apologize for my little precision but my words where directed to the structure of the joints where there is the matematical impossibility to join all togheter using a single "pivot" for every part and following a path to make everithing really connected by this method - as point 1 and 2, what I really need was a different method to use ASM4 (M.S. I know) or a different tool to make an assembly that rely on a n-point of connection directly.

Not my priority to make again the same tutorial, but have you a simpler tool to suggest to do this work? Just like take some parts and make them correctly positionated in CAD perfection by their "holes" or "pins" without checking for interferences and others, a way more "build like a jointer"

[Zolko]

My tutorial was intended only to attach parts with others, so ASM4 probably is not the best tool to do so because it was developed to do more

hum ... Asm4 was designed exactly for this task