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GoKart Tank

Build a real tracked vehicle out of off the shelf parts

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Once it was a GoKart. Then it became a half track. Now it's a full on tracked vehicle. A tank! Runs on a pair of 1000W electric scooter motors at 48V each. It's a beast, but it works. It was on display at the NoVA Mini Maker Faire on March 19, 2017 and will continue to be modd-ed and improved for months to come. The design philosophy is to use as many commonly found materials as possible and custom engineer as little as possible. The tank is able to be remote controlled since it operates off 2 twist throttles (servos anyone?) and can handle a payload of some 100lbs -- a large child. You can see some details here: https://hackaday.io/project/10164-go-kart-tank-formerly-half-track. Check out the video on Youtube as well: https://www.youtube.com/watch?v=ELpyAEJJMVo

This started as an ATV build using big tires with the hope of using rubber tracks made from a treadmill. But over time it evolved into converting my very fast (30mph+) go kart. Originally, a differential was planned so that I could use differential braking and the same gasoline motor. But an invitation to a Maker Faire and the prospect of rolling it around indoors as well as outdoors said "no exhaust", so I went all electric.

In the end I had to devise a track tension/sprung bogie system to keep track tension. Used a BMX bike shock, some pieces of angle and a small piece of square tubing. Works like a charm. The tank is underpowered though. I might convert it to gasoline engine power just because I can put a 6.5hp motor that weighs 30lbs in place of the 80lbs of motor and batteries and get triple the power. Very happy with the outcome. I had a 100lb kid ride it just fine, but a 200lb adult is too much for the 2.5hp I can get out of the electric motors.

Suspension Arm.jpg

This is the suspension arm with bearings and shock installed. Next, make 7 more of these, mount the wheels and onto the chassis it goes.

JPEG Image - 2.12 MB - 04/07/2017 at 00:34

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Suspension Drawing.png

This is what the suspension will look like (mostly)

Portable Network Graphics (PNG) - 542.41 kB - 04/01/2017 at 03:32

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Suspension Test Fit.jpg

3D printed the suspension arm to test fit the shock and road wheels to it

JPEG Image - 2.44 MB - 04/01/2017 at 03:31

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20170312_172657.mp4

Test run using no seated operator. The tank is in tethered remote control!

MPEG-4 Video - 15.77 MB - 03/20/2017 at 17:21

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  • Updated Drive System

    samern06/17/2017 at 17:59 0 comments

    After much introspection, it looks like I am going to make some changes:

    • 3D Printed drive and idler sprockets at 17 teeth instead of 11
    • 3D Printed road wheels (yes, printed), but also at 17 teeth, that will raise the chassis of the tank higher off the ground.
    • Move forward with making the tank based on a metal frame instead of a wooden one. 2 of the 2x4s will be recycled as longitudinal support members
    • Fiberglass surfaces so that the batteries can be mounted inside the frame cavity

    Plastic wheels and sprockets will save the track a lot more, and based on initial estimates will suffice for prototyping. They may not handle heavy duty operations, but it's pretty easy to cast aluminum replacements afterwards. I do intend to print in PLA at 100% in-fill.

    Here's an image of the sprocket/idler:


  • Keep the Motors...says everybody!

    samern05/02/2017 at 02:18 0 comments

    Everyone who commented on the Hackaday article is saying I should stick with my 1KW motors. So I went back to the drawing board amd redid a few things. I think I can, I think I can. Meanwhile, as I wait for the tank to return from April's STEM Faire, I started mocking up an idea for eliminating the need to tension the tracks beyond a certain point. That does involve letting the track 'sit' on the road wheels. I will be testing this idea in miniature....here's a picture:

  • GoKart Tank Story featured on Make Magazine

    samern04/07/2017 at 00:56 0 comments

    I wrote an article for Make on the tank and you can read about it here:

    http://makezine.com/2017/04/05/gokart-tank/

    Enjoy!

  • Metal Frame Idea

    samern04/07/2017 at 00:51 0 comments

    I am debating V2.0 of the tank to abandon the wooden frame and go with all metal. Here's what I am considering:

    When I moved all my servers from my CoLo, I also brought back all these rails from the server rack made of 1/8" powder coated steel. These are L shaped rails that have one piece that slides into the other so that you can adjust it for different length/depth racks. I have maybe 10 of these things (for 5 servers). These aren't the ball-bearings sliding rails. They are fixed. They are strong, heavy duty, very solid. I measured them up and I have enough to make a pretty big and solid metal frame to replace the wooden one. I also have a lot of sheet metal from my airplane builds, tons of rivets and of course my drill. I think I can make a solid frame out of these left over materials that I would otherwise have to give away or sell off for peanuts. Yeah, I think it's viable. In addition, I have 2 dead 4U servers I had custom built years ago. The cases themselves are also steel. Bolt those onto the frame and you have a full enclosed box frame that is rigid and hollow AND fireproof. My thinking is that I can make a box frame with panels and a hollow space to install batteries, electronics and whatever else I need using recycled computer junk and still make it look good. Here is a grainy picture of the tank with one rail laying on it.

    And here is one of those cases. Pretty hefty.

    What do you think?

  • Suspension Arm Prototype is done

    samern04/07/2017 at 00:37 0 comments

    I have refined the suspension arm after 3 prototypes. 2 arms side by side with the shock in between. Bearings press fit and epoxied in place and we are ready. The arms themselves are 3D printed. And when I tell you they are rigid, they are super super rigid. Before I mount them, I will treat them all with XTC3D to weatherproof and of course make them even stronger.

  • Suspension!

    samern04/01/2017 at 03:35 0 comments

    Yes, it may be finished, it may be working, but it's time to get improving. Before I install the gasoline motor and differential (and triple the power), I am adding suspension. I've 3D printed the prototype to test fit stuff before I send the drawing off for the arms to be cut out of 6mm alumimum.

  • It Lives!

    samern03/20/2017 at 17:23 0 comments

    Phew. All done and ready for the Maker Faire. And it runs and runs great! In the end, I learned:

    1) My choice for track works well in one direction only. Going in reverse throws a track

    2) 2.5HP is not enough

    3) I over engineered it in the effort to make it 'Heavy Duty'. I should have stuck to a metal body

    4) I would use straight through axles for the road wheels. I have 16 pillow block bearings there. Each weights close to 3lbs. I could do fine with axles and 8 bearings instead.

    5) The lexan sprung bogie is not strong enough for heavy duty work. I have to switch to metal

    6) Electric is not the way to go for something this heavy. The motors are way too heavy and the 8 batteries are killer in terms of weight.

    But...I love it!

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Discussions

anfractuosity wrote 05/01/2017 at 20:10 point

Heh, this is awesome, only a shame adults can't ride it!

  Are you sure? yes | no

samern wrote 05/10/2017 at 17:56 point

If I have my way, adults absolutely will ride it.  I am in the middle of re-doing the frame so it's a lot lighter, which should allow the 2 1KW motors to drive my oversized carcass around on it.

  Are you sure? yes | no

Craig Eden wrote 04/01/2017 at 15:31 point

Where did you get the tracks?

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samern wrote 04/07/2017 at 00:53 point

Sorry I missed your message.  The tracks came from IntraLox.  They are conveyor belts.

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Dr. Cockroach wrote 03/26/2017 at 00:13 point

Man, all I can say is that I love it :-)

  Are you sure? yes | no

samern wrote 03/26/2017 at 00:54 point

Thanks!  A new version is in the works, using the same frame:

1) Larger motors, or gasoline engine with a differential

2) Suspension

3) Dozer blade

A larger version is also in process: 

1) Steel frame

2) Operates as both a 2x6 and a tracked vehicle

3) 2 seats

4) 6.5HP motor

  Are you sure? yes | no

Luis Diaz wrote 03/22/2017 at 16:34 point

Hi!

Very cool project! Do you have any videos on youtube or so?

Thanks

  Are you sure? yes | no

samern wrote 03/26/2017 at 00:53 point

Yes.  Look me up there and you will also find an MP4 here.

  Are you sure? yes | no

Luis Diaz wrote 03/26/2017 at 11:58 point

Thanks!

  Are you sure? yes | no

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