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Some Tutorial for CAD beginners for FreeCAD available ?

Discussion in 'CAD' started by Pumlux, Sep 1, 2015.

  1. Pumlux

    Pumlux New
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    Hi all,

    I'm new here and also new to CAD software and I struggle to find my 'best' CAD software.
    FreeCAD looks fine for me at this point and there are lots of 'tutorial' videos in the net, but I still not
    get the workflow to work with the parts libary here from Openbuilds.

    Do you have some documentation showing how to place and connect the parts to a working build ?

    On a buzzword level, I think it uses contrains, but I failed to get even a V-Wheel with bearings, shim, screw, spacer etc. in the right order to use it for a further build.

    Is there anybody, who can point me to such a documentation or video showing for FreeCAD (or a different free Software for CAD beginners) to use the part libary for a 3D printer build ?

    For FreeCAD, my struggles starts already to know to run which operation in which workbench.
    The contrains button are almost greyed out.
     
  2. Pumlux

    Pumlux New
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    I see noone answered here to my question.

    And I think I know the reason.
    You can not explain the way of working with CAD software in just some simple sentences. It is quite different to normal paint progamms and it has it owns philosophy.

    I put my current findings so far in this thread, it may be helpful for others coming here through a search engine hit.

    There are many CAD programms out there, which one you want to use may depend on required
    - purpose and functions
    - suported formats , input and output wise
    - user and graphical interface
    - how everyone himself feals comfortable in the handling
    - amount of budget, you want to spent for the prgramme
    - reliability, scaleability
    - and more things

    For me, the reasons for FreeCAD are, it is available for free, it seems to be manageable for me (at least at this point of time), I hope it supports all my demands to build a 3D printer with the Openbuilds system and I can use the drawings to get laser cut parts from the industrie.

    Note : At the time being, FreeCAD is version 0.15 and I expect it is not finished, still in development and somehow contains bugs. This is an issue , compared to comercial software.

    I wanted to use the Openbuilds part libary to assemble a project and struggled without the right commands in the standard FreeCAD version. I found the Assembly 2 Workbench delivers what I need to assemble parts to a project. But this Assembly 2 Workbench needs to be added separtely.
    This can be found with instruction for installation on the Githug site :

    https://github.com/hamish2014/FreeCAD_assembly2

    The Assembly 2 wb seems to deliver what is required to put parts together to a complete build.
    Depending on what function you need for your next step, you may need to change to a different wb like sketcher, part or part design. You will not find in each wb all kind of functions and sometimes the function is a bit different, depending on the wb you are in.
    When writing this text, I'm still far away from having my drawing completed or being confident with it, but I think I'm on a good way.
    Here some showstoppers I need to overcome and tips I used to solve challenges on my way .

    Save allways your work from time to time with a separate filename e.g. a version number, if you have a small success. e.g. when you managed to define a new object completely. I used to to do this with each new object when I was confident I can move over to the next one.

    Note : FreeCAD (yet 0.15) is in development and you may hit a bug and loose the drawing.

    In the Tree View on the left side, you can rename things to make it more human readable and I strongly recommend to do this. After having a small number of objects and constraints, I suffer on not finding the right object or constraint and I need to force myself again and again to put some explaining names on objects.

    This is already one of the buzzwords in the assembly wb, (or just in the CAD world) contraints provides dependencies of objects. In general each object has 6 degrees of freedom. x- y - and z - coordinates (when using an orthogonal system) and the rotation in x- y- and z- direction. An object is completly defined if you have destinct values for each of this 6 degrees of freedom. (Please use the web and search function for detailed explainations, buzzwords may be DOF Degrees of Freedom CAD)

    The Assembly 2 wb provides contraints for planes, edges, circulars, spheres and multi circular. You can use more than one way to eliminates the DOF to fix your object to the place you want, but you should not have too much contraints. FreeCAD is complaining if a object is overdefined with constraints and please be aware, there are some some constraints obvious by nature, but you may not see it on the first view. e.g. in a retangle some edges are parallel and have a 90 degree angle. This was challenging me quite often, to see here a constraint is obvious and I already overdefined an object.

    Note : Here I was glad to have lots of different build version of various building status stored, so I could reload an older status to try a different approach. And it was more than helpful to have understandable and human readble names in the Tree View for objects and contraints. Otherwise I had been lost on lost of similar names with just numbers as defferentiator. And you can create groups to keep objects and constraints in a container. This is helpful for logical grouping e.g. x-axis , y-axis, sockel, etc.

    For old and expierenced CAD fellows it may be normal, but for newbies, you find in the constraints data tab a couple of detail fields to set offset, if you want to place parts at a specific distance. Also the alligned field is more than required, because it defined a portion of the direction. Have a try and you see what I mean.

    Note: I noticed that the solver from FreeCAD sometimes do not updated the drawing correctly with all constraints. This is a bit anoying, as I do not know if my change was the correct one. It help from time to time to refresh the drawing and if I'm right, than this can be done with pressing the F5 key. But sometimes this did ont work.

    I strugled to rotate the same object (in my case a C-Beam object for Z-Axis) to be on the left and a copy on the right side. I spend a couple of days without finding a solution. What looks pretty promosing is mirroring one part , which provides me the second one in a 180 degrees rotation. I follow this path and hope it will not end at some point of tim in a dead end road.

    My current challenges I'm searching for solving is a way to attach the wheels with constraints to the V-Slot rails. I made a gantry plate with 4 wheels, but can not attached this group to the rail objects ...

    If you can give me a hint how to make this, it is appreciated.
     
  3. Ronald van Arkel

    Staff Member Resident Builder Builder

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    I'm working with CAD and 3D programs since 1996 (in a few months 20 years back!) and have found that freeCAD is only "free" if you have loads of "free" time. it's one of the most complex programs I've come across and I left it in a corner after a few hours of digging trough it... no thank you.

    Now I can't say what is best, but for 2D I use DraftSight (free); same commands as AutoCAD and works well for 2D, didn't border with 3D as I have SketchUp Pro for 650USD and use SketchUcam (free) for 2D cuts. SolidWorks is over 4.5k USD and some use it here while they complain about spending 550USD on hardware to build a machine with Openbuilds hardware (hell, they are even too lazy to post and try things out :troll:).

    Do you use Linux?

    -Ronald ;)
     
  4. Pumlux

    Pumlux New
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    Hi Ronald,

    thanks for your feedback. Starting with your question, I'm using Windows 7. My expierence with Linux is very limited and almost based on the GUIs like Xwindow.
    I never get used to the comand line tools.

    I have spend a couple of days with Freecad now and at this point of time I utilize the 3D function of the Assembly Workbench to put the Openbuilds libary parts into a
    modell that should be in the near future a 3D printer. I see what you mena with 'free' time. It tooks me quite long to position the parts and very often Freecad accepts not the
    constraints as expected and this gets more and more anoying, as complexity of the modell is increasing. I failled for hours to get a X-axis rail into the right position to 2 Z-axis rails and
    this problem is still not solved with Freecad. Not sure if the beta status is making the life hard, or if the problem sits infront of the PC :blackeye:


    I tried also Autodesk 123D Design so far, but did not found a function to assembly the part libary to a 3D modell.

    I spend only a few hours with sketchup from Trimble and somehow did not find my path to assemble parts.
    If you have a link to a good video explaining a bit 3D modelling here, it would help me much.

    I still have some test days left over on the Autocad Mechanical 2013, may be I retry this programme.

    I made a beginner mistake, I thought it would be easy ...

    :oops:

    Regards
    Andreas
     

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