Assembly3 and circles/cylinders tangent to lines/faces

Discussion about the development of the Assembly workbench.
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quohdea4oh
Posts: 4
Joined: Tue Apr 27, 2021 1:20 pm

Assembly3 and circles/cylinders tangent to lines/faces

Post by quohdea4oh »

I'm not sure if this is the right place to ask for help with assembly3 (or assembly in general) but I didn't find another area where assembly was being discussed. Please let me know if there is a better place.

I have a project I'm working on which involves a roller rolling in the grove of a piece of extruded aluminum tube (think ender series 3d printers if you're familiar with them). For this I have chosen to use assembly3 since I currently use realthunder's assembly3 fork and though it would be fun to learn. I have been using FreeCAD for various personal projects on and off for a little over a year. I have no prior experience with assemblies in any CAD software.

I would like to make a roller "roll" along the channel of an aluminum extrusion tube. I have attached a model (with several dependent files) which demonstrates what I'm trying to do and what I currently have.

In SW I'm fairly sure the operation I want is called "tangent mate". I asked a friend who uses SW daily about this, but I do not have access to SW my self. Basically I'd like to attach the cylindrical or conical shape of the roller to the 45deg grove of the extrusion so that it is constrained in it and I can accurately represent the interference fit that is produced by rotating the adjustment on the lower part of the carriage (see model).

So, to the questions:

1. Is "rolling" possible in FreeCAD with assembly3 or any other assembly workbench? The only thing I found that sounds similar is ArcLineTangent however that does not work with circles, only arcs, and only on the ends of the arcs.
2. My attached model does not solve if I enable "Colinear002". I'm guessing that is because the constraint is too specific and there is some error even though the position of the circle element around the line element is exact. Is there a different way to do this with a "tolerance" or something?

Thanks in advance, and even though I am running into a few snags I'm really enjoying using assembly3!

P.S. For some reason only half the attachments are showing up. If some dependencies are not working let me know. In the mean time I'll try to post on thingiverse or something and link back to here. The full list of files should be:

adjustable_bearing_spacer.FCStd
bearing.FCStd
extrusion.FCStd
fixed_bearing_spacer.FCStd
full_assembly.FCStd
plate.FCStd
plate-spacer.FCStd
roller.FCStd
wheel.FCStd
Attachments
plate-spacer.FCStd
(17.8 KiB) Downloaded 34 times
bearing.FCStd
(31.9 KiB) Downloaded 27 times
wheel.FCStd
(28.5 KiB) Downloaded 31 times
roller.FCStd
(24.67 KiB) Downloaded 31 times
full_assembly.FCStd
(87.78 KiB) Downloaded 33 times
quohdea4oh
Posts: 4
Joined: Tue Apr 27, 2021 1:20 pm

Re: Assembly3 and circles/cylinders tangent to lines/faces

Post by quohdea4oh »

Here are the rest of the files. It seems there is a limit to the number of files you can upload at a time.
Attachments
extrusion.FCStd
(51.37 KiB) Downloaded 29 times
plate.FCStd
(59.66 KiB) Downloaded 35 times
fixed_bearing_spacer.FCStd
(21.26 KiB) Downloaded 28 times
adjustable_bearing_spacer.FCStd
(46.67 KiB) Downloaded 31 times
User avatar
jpg87
Posts: 809
Joined: Thu Mar 16, 2017 7:16 am
Location: Limoges - France
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Re: Assembly3 and circles/cylinders tangent to lines/faces

Post by jpg87 »

quohdea4oh wrote: Tue Apr 27, 2021 4:41 pm I'm really enjoying using assembly3!
Good !

According to my personal experience, I see several problems with the structure of your assembly:
- the "plate-assembly", "plate-spacer-assembly" and "fixed-bearing-spacer" sub-assemblies should only make one sub-assembly (these parts form a block).
- on the other hand, "roller-assembly" can only contain one roller (the 3 are independent of each other).
As for the constraints, here is how I would do to allow the rotation of the skates and the setting of "adjustable-bearing-spacer":
1- preassemble "trolley" which contains "plate-assembly", "plate-spacer-assembly" and "fixed-bearing-spacer".
trolley.png
trolley.png (14.01 KiB) Viewed 2042 times

2- temporarily fix "trolley" in "full_Assembly".
3- position "roller-i0" and "roller-i1" on their axes (/ trolley) then "roller-i0" with respect to the plane of symmetry of "plate-spacer" (added beforehand from the body of "plate- spacer ".
4- position "adjustable-bearing-spacer" on "trolley".
5- position "roller-i2" on the axis of "adjustable-bearing-spacer".
6- deactivate (or remove) the constraint "Locked_tempo_plate-i0" from "trolley" in "full_Assembly".
7- position "roller-i0" and "roller-i1" with respect to the vertical plane of symmetry (XZ) of "extrusion".
8- position "roller-i2" with respect to the vertical plane of symmetry (XZ) of "extrusion".
9- position "roller-i0" with respect to the horizontal plane of symmetry (XZ) of "extrusion" (PointPlaneDistance) and adjust the distance.
trolley_with_rollers.png
trolley_with_rollers.png (15.55 KiB) Viewed 2042 times

10- select the "PlaneCoincident_adjustable-bearing" constraint, go to Property / Constraint, pass the LockAngle property to True.
trolley_with_rollers_and_adjust.png
trolley_with_rollers_and_adjust.png (42.38 KiB) Viewed 2042 times

Changing the Angle value adjusts the angular position of the eccentric, and therefore the vertical position of the roller.
full_assembly.png
full_assembly.png (17.43 KiB) Viewed 2042 times



The files :
https://www.dropbox.com/s/igxjhb85ceb8l ... rs.7z?dl=0
My website : http://help-freecad-jpg87.fr updated 2023/11/06
quohdea4oh
Posts: 4
Joined: Tue Apr 27, 2021 1:20 pm

Re: Assembly3 and circles/cylinders tangent to lines/faces

Post by quohdea4oh »

@jpg87 . Thank you so much for your detailed explanation. I apologize for not responding, I was new to the forum and I expected to get an email notification of replies. It seems this is not the default configuration.

I will review all this and try your suggestions.
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