A2plus circular edge constraint

Discussion about the development of the Assembly workbench.
adcnc
Posts: 2
Joined: Mon Mar 29, 2021 12:23 pm

A2plus circular edge constraint

Postby adcnc » Mon Mar 29, 2021 3:04 pm

using:
OS: Linux Mint 20.1 (X-Cinnamon/cinnamon)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24267 (Git) AppImage
Build type: Release
Branch: master
Hash: b2ca86d8d72b636011a73394bf9bcdedb3b109b7
Python version: 3.8.6
Qt version: 5.12.5
Coin version: 4.0.0
OCC version: 7.4.0
Locale: Dutch/Netherlands (nl_NL)

A2plus V0.4.53

the carriage jumps from the rail if I try moving it. Using <circular edge constraint>
If I make a new drawing with only the rail (fixed) then it works O.K.
Tried it several times.

this works, I can shift the carriage
Image

with the fixed U-beam the carriage jumped from the rial
Image
Attachments
test asm rail+carriage.FCStd
(20.24 KiB) Downloaded 1 time
test asm v1.FCStd
(26.11 KiB) Downloaded 4 times
Last edited by adcnc on Tue Mar 30, 2021 9:56 am, edited 2 times in total.
User avatar
Kunda1
Posts: 10245
Joined: Thu Jan 05, 2017 9:03 pm

Re: A2plus circular edge constraint

Postby Kunda1 » Mon Mar 29, 2021 3:23 pm

Moved to Assembly subforum
Alone you go faster. Together we go farther
Please mark thread [Solved]
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kbwbe
Posts: 1023
Joined: Tue Apr 10, 2018 3:12 pm
Location: Germany, near Köln (Cologne)

Re: A2plus circular edge constraint

Postby kbwbe » Sun Apr 04, 2021 9:25 am

adcnc wrote:
Mon Mar 29, 2021 3:04 pm
with the fixed U-beam the carriage jumped from the rial
Hi,
i can confirm this behaviour. The reason is, that trying to move the slider with the a2p simulation tool, the a2p solver switches to a special simulation mode, where all parts are moved at once. This mode does not work very well with chained constraints. In this case here the calculation is completely instable and fails to work. Where as static solving is working fine. (This mode solves the assembly step for step beginning with a fixed part)

There are two workarounds:

a)
- Place the fixed frame part
- constraint the rail completely to the frame
- after that, set the property "fixedPosition" of the rail to true.
- constraint the slider to the rail
- now you should be able to move the slider by simulation button

b)
- Place the fixed frame
- constraint the rail completely to the frame
- constraint the slider to the rail
- move the slider by using the transform tool of FC
- solve manually when needed.
KBWBE

https://github.com/kbwbe/A2plus
latest release: v0.4.53, installable via FreeCAD's addon manager
Tutorial: gripper assembly https://www.youtube.com/watch?v=QMxcQ5tssWk
Documentation: https://www.freecadweb.org/wiki/A2plus_Workbench
adcnc
Posts: 2
Joined: Mon Mar 29, 2021 12:23 pm

Re: A2plus circular edge constraint

Postby adcnc » Thu Apr 08, 2021 9:11 pm

thanks for the time taken, a late response I reinstalled linux + FreeCAD and got some problems with GRUB. but the problem is in A2plus, luckily there is a solution. I have copied your solution
Everything works now. :-)