This is a model of a tube bender designed by C. Horace Clarke (1956). Drawings can be found in the Model Engineer magazine dated 22 March 1956, pp.470-473.
The model was created with the Assembly4/PartDesign workbench using a top-down, in-context approach referencing a master sketch of all the articulating components. All parts including ISO fasteners were created in one file and then assembled and animated with the Assembly4 workbench.
The Assembly4 workbench provides a convenient means to assemble Parts using Links and local coordinate systems (LCS) from separate Part files or from Parts in the same file, the latter which nicely facilitates a top-down design work process. A simple master sketch is used as the assembly solver for any combination of variables.
Several screenshots are as follows with a few comments on the design process:
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The Assembly4 workbench has become my go to workbench when working on articulating assemblies or those in which key dimensions must change parametrically for given design variables. IMHO it is a serious no-frills essential tool for top-down design and in-context modelling.
EDIT: The Assembly4 > Add Variables tool is especially valuable and quite useful for any model, an example as shown in:
https://forum.freecadweb.org/viewtopic. ... 40#p363215
OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.19311 (Git)
Build type: Release
Branch: master
Hash: 120b69c74f7dac8c4fa6dbc0a7e10674bde9216c
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)
V0.19: Tube Bender Tool Design using Assembly4
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V0.19: Tube Bender Tool Design using Assembly4
Last edited by ppemawm on Fri Jan 24, 2020 9:52 pm, edited 1 time in total.
"It is a poor workman who blames his tools..."
Re: V0.19: Tube Bender Tool Design using Assembly4
Awesome.
I know it's boring, but with every model that you create can you provide a description of your computer, file size, modelling time (days, hours, minutes?!), and problems that you encountered, if any? I think it's nice to give new users an idea of what is already possible with FreeCAD without using a very expensive system. I presume you don't use a supercomputer to make these models.
And in the topic of articulating assemblies, I just thought about this: can you model a mechanism with a chain or a rope (pulleys)? The specific thing I'm thinking about right now is a garage door. I just fixed mine so I thought, it'd be nice to model this in FreeCAD so next time I disassemble my door, I know how to put it all back together without taking days and days of testing. I have a door that folds horizontally, so not up and down, but sideways, like an accordion.
Last edited by vocx on Fri Jan 24, 2020 3:09 am, edited 1 time in total.
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Re: V0.19: Tube Bender Tool Design using Assembly4
Awesome project! Thanks for sharing it!
Check out my designs on https://www.youmagine.com/funkysod/designs, my videos at https://www.youtube.com/user/funkysod
Re: V0.19: Tube Bender Tool Design using Assembly4
Thank you for your comments.
I am using a mid-range Toshiba Satellite laptop with Intel I7 2.50 GHz chip and 16 Gb RAM in touchpad mode, no external mouse.
File size is 792 Kb.
I work on these kinds of small projects, several at a time, for 2-3 hours/day to stay current with the software development. This particular project probably took me about 10 hours including research.
The biggest problem I have encountered is making sure that sketch constraints are not ambiguous as the sketch is animated over its full range of variables. My recommendation is to check each body over its range of its variability as its built. It gets easier and more sure as you gain experience.
A problem for me with Assembly4 when using it for top-down design is the difficulty keeping track of all the seemingly redundant Part and Body origins, and LCS's especially when created in context and then used in the Model assembly. I am still experimenting with this.
Hmmm...I'll have to think about that one, but probably not with a simple master sketch. But, I am sure @zolko could figure it out!
"It is a poor workman who blames his tools..."
Re: V0.19: Tube Bender Tool Design using Assembly4
I think it's actually easy: the Variables object can store variables, and their value can either be set manually, but can also be calculated by its ExpressionEngine. For a chain, you'd define the angle of the driving pulley Angle_drive, you'd define the gear ratio Ratio, and the angle of the driven pulley would be Angle_driven = Angle_drive * Ratio. And you attach the LCS for the 2 pulleys with their respective angles.