Designing a Simple 3D Printed Rubber Band Car Using FreeCAD

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Introduction: Designing a Simple 3D Printed Rubber Band Car Using FreeCAD

About: Our grandkids keep me busy!

As a retiree, I have designed and published 3D printable mechanisms for entertainment, educational and hobbyist purposes here and on other websites using Fusion 360, as well as have provided free consulting to local companies with their use of Fusion 360. Changes to the Fusion 360 "Personal" version I use have made it difficult to support local companies with the Fusion 360 "Commercial" version they use, so we decided to try FreeCAD.

My first foray into FreeCAD is a redesign of my Fusion project "Designing a Simple 3D Printed Rubber Band Car Using Autodesk Fusion 360". So if you're interested in designing with FreeCAD, stay tuned as I upgrade some of my previous designs from Fusion to FreeCAD, and create new designs as well! I just need to find a way to upload the FreeCAD files here, as they were rejected, even in zipped form.

As with any 3D printed mechanism, prior to assembly, I test fit and trim, file, drill, sand, etc. all parts as needed for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on you printer, your printer settings and the colors you chose, more or less trimming, filing, drilling and/or sanding may be required. Carefully file all edges that contacted the build plate to make absolutely certain that all build plate "ooze" is removed and that all edges are smooth. I used small jewelers files and plenty of patience to perform this step.

As usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make plenty of mistakes.

Designed using FreeCAD, sliced using Ultimaker Cura 4.7.0, and 3D printed in PLA on Ultimaker S5s.

Supplies

  • "R20" sized O-Rings (25mm ID, 3.5mm Section).
  • Thick cyanoacrylate glue.

Step 1: Wheels.

This video illustrates how to use FreeCAD to design and extrude the wheels.

Step 2: Axles.

This video illustrates how to use FreeCAD to design and extrude the axles.

Step 3: Chassis Sides.

This video illustrates how to use FreeCAD to design and extrude the chassis side.

Step 4: Assembly.

3D printing and assembly of this model is quite easy.

I printed two "Chassis Side.stl", two "Axle.stl" and four "Wheel.stl" at .15mm layer height with 20% infill.

Next, I pressed the two "Chassis Side.stl" together and if loose applied small drops of thick cyanoacrylate glue.

Then I stretched the O-Rings around the wheels, two O-Rings for each wheel.

Finally, I positioned an axle in the chassis assembly then pressed two wheel assemblies onto the ends of the axle. If the wheels are loose on the axles, again apply small drops of thick cyanoacrylate glue, then repeated this process with the remaining axle and wheels.

Apply the rubber bands as presented in the original video, then off you go!

And that is how I designed a simple 3D printed rubber band powered car using FreeCAD.

I hope you enjoyed it!

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    8 Comments

    0
    JON-A-TRON
    JON-A-TRON

    12 months ago

    Hey gzumwalt, I assume the "Changes to the Fusion 360 'Personal' version I use have made it difficult to support local companies with the Fusion 360 "Commercial" version they use..." comment above is referring to the removal of STEP export we announced. I just wanted to chime in to make sure you heard that we won't be removing it after all. We got a lot of community feedback that it was critical for hobbyists, so we decided to keep it.

    0
    gzumwalt
    gzumwalt

    Reply 11 months ago

    Hi JON-A-TRON,

    Can you possibly help me with this:

    https://youtu.be/nvXnr3NN51A ?

    I understand Autodesk's decision to place restrictions on the personal version of Fusion, but I cannot complete projects with their latest restrictions.

    Thanks,

    Greg

    0
    gzumwalt
    gzumwalt

    Reply 11 months ago

    An old friend sent me a link to this:



    I wrote this game in a combination of assembly (graphics engine) and C (game logic) programming languages for Electronic Arts on a Compaq 386 Color LCD "portable suitcase" model (sample picture is here: Compaq_Portable_486) designed for Intel 386 IBM PC format computers. No "GPUs" back then, just a video memory plane and a lot of math. It was an honor to work with Electronic Arts and Mr. Jordan in producing this game.

    I've long since sold my company, ZCT Systems Group, Inc., and as I've mentioned numerous times, I am retired and no longer "work for profit".

    This game, and the many others I had the honor to author, were fun.

    Greg

    0
    gzumwalt
    gzumwalt

    Reply 12 months ago

    Hi JON-A-TRON!

    Let me begin by stating that of all the CAD / CAM programs I've used in my 45 years of engineering and design of flight control systems for private, commercial and military aircraft, Fusion had become one of my favorites for its advance features, its support for the hobbyist, and its support for those, such as myself, who wish to share their experience and designs, for free, so that others may learn.

    As I shared in my description for this model, I am retired and no longer receive "income" for designing or consulting, other than receiving the wonderful gifts from Instructables for the contests I have entered, the few "tips" and/or rolls of filament from thankful friends and followers, and the most important "income" of all to me, the thousands of thankful emails I have received for my published designs.

    And at the same time, as a former (long, long ago) engineer, designer and commercial producer of entertainment software (e.g. "video games", 37 total including Tetris, Michael Jordan In Flight, Robocop, Predator, Microscopic Mission, etc.) for Tandy Corporation, Atari, Activision, Broderbund, Electronic Arts and many others, I recognize the business decision Autodesk has taken to protect its intellectual properties.

    However, the businesses to whom I provide free consultation in their use of the "Commercial" version of Fusion simply realized I am no longer able to provide the consultation they require due to the yet again downgraded features placed on my "Personal" version of Fusion which include, but are not limited to, milling, file formats, web based architecture, etc. As such they requested that I pursue a CAD / CAM alternative that would facilitate long term, stable, secure and unburdened consultation, hence my foray into FreeCAD.

    I more than likely will not cease to publish designs, for free of course, using Fusion. However, for those companies, mostly small, to whom I provide free consulting services, their livelihood depends on a stable platform and assistance, and with the ongoing downgrading history of Fusion "Personal" limitations, they were simply searching for a more stable platform that allows me to continue to provide consultation in order to assist in assuring their future. My only requirement was that it was for free.

    And for the hobbyist, I will always share my learning experiences, both good and, well, not so good: https://hackaday.com/2020/09/16/autodesk-announces-major-changes-to-fusion-360-personal-use-license-terms/.

    I sincerely express my best wishes for Autodesk's success in its latest changes to its business model.

    Greg



    0
    JON-A-TRON
    JON-A-TRON

    Reply 12 months ago

    Thanks for the thorough reply, Greg. That makes sense. Some resume you have there! Tetris was the first video game my family played together when I was a kid, and the only one my mom ever played. Well done!

    0
    gzumwalt
    gzumwalt

    Reply 12 months ago

    You are very welcome JON-A-TRON!

    Thank you very much for your kind words!

    I ported Tetris from the arcade environment to the Tandy environment (Color Computer and TRS 1000) for Tandy Corporation in, according to the attached image, 1987, 33 years ago. Boy does time sure fly...

    Again, many, many thanks for your kind words, they mean a lot.

    Greg

    Tetris.gif
    0
    JacenF
    JacenF

    12 months ago

    That's great! I was surprised and disappointed when the terms for F3D changed, but now my faith is restored that CAD is still possible!

    0
    gzumwalt
    gzumwalt

    Reply 12 months ago

    Thanks JacenF!

    As you, I too was disappointed in yet another terms change for Fusion, hence my foray into alternatives!

    Greg