Practice parts

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Agnillev
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Practice parts

Post by Agnillev »

I just started using FreeCAD coming form SolidWorks i made a couple of parts to practice on.

Handwheel
https://grabcad.com/library/handwheel-f ... ice-part-2

Bicycle rim with special spoke boring,
https://grabcad.com/library/rim-20-etrto-406-40mm-1
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M4x
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Re: Practice parts

Post by M4x »

Interesting. How did it go? What worked as expected (or even better)? What was hard.to achieve? Why did you used several bodies and fused them together afterwards?
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Agnillev
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Re: Practice parts

Post by Agnillev »

M4x wrote: Sat Aug 14, 2021 9:13 pm Interesting. How did it go? What worked as expected (or even better)? What was hard.to achieve? Why did you used several bodies and fused them together afterwards?
At first it was a bit of a struggle, but I guess learning any new CAD tool is a chore.
It was less difficult than starting out with CAD the first time, and many things I learned using SolidWorks were valid in FreeCAD.
For a free opensource system FreeCAD has functionality you would have to pay substantial amount of money for.
Some cheaper systems lock you out of your own designs when you stop using their subscription service.
Knowing my designs are mine in the long run and the idea of supporting a CAD system that is withing reach of anyone wanting to get things done is what pulled me towards FreeCAD.

The learning curve using FreeCAD is quite steep, and I don't know if I would see this trough without any prior CAD experience.

What made things more difficult were the following things;

In other sketch tools I was able to make a diameter dimension around a construction line prior to revolving the part.
When using the revolve function I was asked to automatically close the sketched construction line.

I was not able to make a horizontal / vertical dimension towards the tangent of an arc. I solved this by drawing an extra line tangent to the arc and making a horizontal dimension from line point to line point.

I takes getting used to to have to select line endpoint instead of just the line itself to dimension a sketch. It feels less intuitive.
M4x wrote: Sat Aug 14, 2021 9:13 pm Why did you used several bodies and fused them together afterwards?
When making the wheel I wanted to first draw the hub and right thereafter the rim part so I could easily connect the first spoke from the hub to the rim part. In solid works this would automatically create a second solid body that would also be automatically be merged back in to one after sweeping the spoke part. This is the reason I fused multiple bodies, I was working with what I knew at that time. Perhaps changing the build order would have allowed me to make this as a single body the first time.

Due to the soon to be solved (?) topological naming struggle I thought it would be unwise to dimension height from an external face as I would normally have done. Instead I defined the Z height of the plane I sketched upon.

When mirroring a fully defined sketch Sketcher it gains new degrees of freedom and thus loses its full definition. I also miss the handy function that when mirroring a parallel or coradial line it creates one single line in its place instead of two lines. In fact I miss the coradial constraint.

Thing that were easier
Creating a spreadsheet with my dimensions and using those in my sketches, on my sketch planes, and in the various functions was a breeze.
This made my design a lot more adaptable and more easy to understand if you don't know how the part was build up.
In example; if you open the file an you decide 3 or 5 spokes is a better idea and you want to redefine the height of the spokes you only have to adjust those values in the spreadsheet, and re-select the correct fillet lines*.
(*This is normal in Solidworks aswell and the reason I use fillets and chamfer features as last features in any part)

Working with formulas felt like more of a chore in Solidworks.

Spreadsheets would be even nicer if there was Libre Office Calc intergration. I think I read someone is working on that.

There is a high chance with my just hours of experience that I'm simply not aware of certain functions and could have got things done in less steps. Please comment if this is the case I'm here to learn.

There are of cause many ways to create one and the same CAD model.
I know of other CAD systems where they challenge users to make a certain model in the least amount of time and with the least amount of functions used. Perhaps this is a fun way to challenge other Freecad users an learn a thing or two from them.
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chrisb
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Re: Practice parts

Post by chrisb »

In this case: instead of the construction line you could have used a Point element placed on the arc with horizontal constraint to the center.
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Agnillev
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Re: Practice parts

Post by Agnillev »

chrisb wrote: Mon Aug 16, 2021 2:55 pm In this case: instead of the construction line you could have used a Point element placed on the arc with horizontal constraint to the center.
Good tip, Thanks!
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Shalmeneser
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Re: Practice parts

Post by Shalmeneser »

:arrow:
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Agnillev
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Re: Practice parts

Post by Agnillev »

Shalmeneser wrote: Mon Aug 16, 2021 4:28 pm:arrow:
Thanks for the tip.
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Agnillev
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Re: Practice parts

Post by Agnillev »

I needed a chain wheel that fits on the mounting face of a standard bicycle disc brake.
Using formulas in the spreadsheet workbench allowed me to make a chain wheel model that adapts to the number of teeth I enter. :D

Edit; This part allowed me to create any 0,5" chain chain-wheel or chain-ring within seconds.
https://grabcad.com/library/104-bcd-4-h ... enerator-1

OS: Ubuntu Core 20 (ubuntu:GNOME/ubuntu)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24276 (Git)
Build type: Unknown
Branch: releases/FreeCAD-0-19
Hash: a88db11e0a908f6e38f92bfc5187b13ebe470438
Python version: 3.8.5
Qt version: 5.12.8
Coin version: 4.0.0
OCC version: 7.5.0
Locale: English/United States (en_US)
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Last edited by Agnillev on Sat Aug 21, 2021 1:51 pm, edited 1 time in total.
chrisb
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Re: Practice parts

Post by chrisb »

Is it an optical illusion or on purpose that the mounting bolts don't look evenly distributed around 360°? You probably use a polar pattern for them, don't you?
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Agnillev
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Re: Practice parts

Post by Agnillev »

chrisb wrote: Sat Aug 21, 2021 4:03 am Is it an optical illusion or on purpose that the mounting bolts don't look evenly distributed around 360°? You probably use a polar pattern for them, don't you?
Hi Chis I did use a polar pattern, it's just the isometric view messing with the brain.
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