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  1. #1

    Help please. Trying to design a drive cog.

    Hello I am new to design and 3d printing.

    I am trying to find a program to create a ring with teeth on it to drive a snowmobile track. I have been using Freecad to try and design it with no success.

    I essentially want to make a gear with a large inner circle and largely spaced teeth. I am trying to make a ring 1.5" wide x .25 thick with a circumference of 30.5" and 11 equally spaced teeth. teeth size is .75"x.75"x.75". The teeth should work out to 2.86" approx. apart from each other on center.

    I have tried using freecad FCgear Module but it won't let me make something with the teeth so far apart or I just can't figure it out.

    If someone could please help figure out how to lay this out that would be greatly appreciated or at least point me to a software that could make this easier for me.

    Thanks in advance.

  2. #2
    FreeCAD should be able to make what you're looking for, but is a bit clunky. If you're new to 3d design I would recommend Onshape as a near professional level CAD tool that runs in your browser. You can use it for free, but a free account does not let you keep your documents private. I just use it for odds and ends so I have no problem with my documents being public. Onshape also has a lot of tutorials that cover a lot of the basics of 3d modeling. Another option would be Fusion 360, since it also has a free subscription tier, as well as a lot of tutorials. I'd say that Onshape is easier for a person who's new to 3d CAD to learn on, but your mileage may vary. Another option that some of the people around here use is OpenSCAD, but I have no experience with it and would have to defer to other community members to answer any questions you have about it.

    As to your gear question, I'm not sure there is a simple answer. I'm unfamiliar with the FCgear module, but I imagine a good spur gear script/module/plugin/whatever will probably get you the most details for a real gear the quickest. If you're fine with something close enough but not perfect, you can try modeling it yourself. Below is a starting point for you that I got going in Onshape. I'm not 100% certain that I interpreted your description correctly, but it should give you something to work from. Let me know if I can answer any other questions.

  3. #3
    Super Moderator curious aardvark's Avatar
    Join Date
    Jul 2014
    tell me in millimetres - I have no idea if you mean feet or inches.
    What's wrong with using: ft or in Instead of apostrophes and speech marks ?
    Which is all moot as you really need to switch to mm for 3d printing.

    What you want is a very simple script in openscad.

  4. #4
    All measurements are in inches. I will try and convert it for you.

    I also have the piece welded together out of steel but I wanted to 3D print one to see if it would work for me.

    I will upload a photo of steel one tomorrow it will make it easier to understand what I am visualizing.

    I will check out the link as well to that site.

    Thanks again

  5. #5
    +1 for onshape, it will take time to learn it and figure it out but well worth the effort. I have not made any gears yet but if you can get a photo and provide the sizes I can give it a try as I learn something new with every effort.

  6. #6
    Have you tried Blender? It should work fine for this type of project. I think it is also worth considering the type of tracks under which you will print this part. I would recommend using composite tracks, btw. I used them on my snowmobile, good choice.

  7. #7
    Super Moderator curious aardvark's Avatar
    Join Date
    Jul 2014
    for the record - tpu with steel pins at the hinges - would work really well and be pretty much indestructible.

    And it really is a three line openscad script :-)

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