Friday, June 8, 2012

The Chibikart

One fateful day while roaming the vast Internets I came across this: youtube link

Of course I wanted to build one after the first 10 secs of the video... and then a few weeks later: Instructables 

So after some pondering, and misguided thinking [always fun] it turns out this is something I could do, provided I get the funds. Makerplace has all the machining I would need for all the parts, the CAD model I can re-create and tweak a bit to fit something more to my tastes and tooling. And anything I didn't know/couldn't figure out can be redeemed by a few hours online, seeing there is quite a few people into this.

Personally a Solidworks user, a few hours in CAD and:

For anyone that has never used 80/20 it is cool stuff, being able to bolt anything to it without drilling holes is a bit of a god send. Of course the downside it is heavier then box and is a bit more expensive but for a project this small well worth the convenience. The frame is held together with 1/4 plates on the corners that double as wheel mounts. The main machining work that needs to be done is just 2d work on 1/4 and 3/16 inch plates. However unlike the DPRCibikart I have redesign the wheel and motor mounts with blocks and L brackets because I have access to a full sized mill. The steering "wheel" is something I might play with around more. And I am considering making the entire frame a bit longer but need to figure out the ergonomics of that first.

Electrical wise a pair of TURNIGY SK motors and controllers makes the round thingys in the back spin really fast. The exactly motor and controller combo is still up for debate, personally I want something with more power then the DPRC, but we will see how far I can stretch a budget and how feasible it would be for me to wire/program a Hall effect sensor. Using FRC CIM motors, gearboxes and controllers was considered for a bit but figures seem to show that buying all of that vs buying what I need for a brushless setup would require the same budget and the brushless is more effiecent and lighter. That leaves the problems of batteries which could be a whole post on it's own so lets not go there. Just suffice to say there will be 15-20AH at 24vs providing the power.

I also need to do some math to figure out what kinda reduction and wheels to put on, as this is not a blatant copy of the DPRC [okay maybe it is...], going to 6inch wheels with more reduction sounds like a good idea, or maybe not need to figure that out. Since 6 inch wheels allows for more reduction without loosing top end speed which should result in more torque. Personally my first goal with this is to make something that will give me a heart attack every time I or anyone comes near the pedal; quite a immature goal I know but I can't help it. I like speedy things.

The only problem in all of this is money, it an't cheap. About $800+ it is quite the under taking in the world of things I have done. With FRC being funded mostly by sponsors this is going to require some piggy bank cracking.

But damn would this be cool. :3

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