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Hi everyone! I finally took the big tank for a spin.

The conclusions from the test:

MOTORS

The motors are more than capable of moving the tank, I may add an extra reduction stage just to be able to go really slow and have finer control but as it is, these have more than enough power to rip the tank in half.

ODRIVE CONTROLLER

The ODrive is an amazing board, difficult to master but amazing. In this setup I'm just feeding the RC receiver straight to the ODrive and using velocity control. The encoder gives 8192 counts per revolution and the max RPMs of the encoder are 7000 which if I remember correctly gives me a top speed of 1000000 counts per minute. At the time of the test the speed was limited in the configuration to 300000 CPMs to be on the safe side and the RC transmitter was limited to 30% all the time apart from that brief moment where I give it the beans on the video. 

The ODrive kept shutting down one of the motors due to what I guessed was an excessive stall current. The day before the test I removed one link from each tread so it didn't have so much slack, that brought tension to the tread and I think the side that was stalling was getting the tread caught in the traction sprockets. When I designed the sprockets I used an ideal rotation pattern from the tread but when in tension the treads follow larger radii which can cause this problem. I may either add again the missing links or maybe redesign the sprockets to be more tolerant to different tread tensions. 

TANK

The tank itself held up beautifully, nothing broke, no links fell apart, nothing, and as you can see in the video I ended up getting the tank in some rough places. I'm really surprised by the lack of issues with the tank itself. Promising, really promising. 

DRIVABILITY

From the inside the noise is insane and that makes you think you're going really, really fast, which as you can see I wasn't. 

That little camera/screen was almost useless, poor detail and weird point of view + extreme fisheye. I need to work on that. 

It is pretty comfy, I'll never do a 2 hour trip on it but for small adventures it is a nice stance and I'll make it permanent. 

TRANSPORTATION

It did fit in the van, I had less than 1 cm free on each side so, tight, but in. 

AAAAnd thats's it for this test, right now I'm working on the rev 2 of the CNC which will be, if nothing else happens, the next video on the channel, including free files for everyone and detailed build plans for all my existing Patreons, wish me luck!

Tanks!!!



P.S.: For those of you waiting for the tank files, this thing is not near finished, the parts printed with the original files have been heavily modified so you may spend 6500+ printing hours and lots of money for something that still needs a whole lot of work. Let's wait a bit to see how this ends up.  

Files

3D PRINTED TANK FIELD TEST FOR PATREON

Tank!

Comments

Lluís Garcia

Maybe some magnets for the cover to keep it close... :)

Ivan Miranda

The cover is not matching the base, the gas cylinders are so powerful that they're deforming the rear pieces and that moves the entire cover forward, hence the two parts not mating correctly. I need to fix that and do some more testing to see how bad the issue really is. Magnets definitely a good idea 👍

Roy Ball

Wow! I'm surprised how awesome it works given the weight and minimal articulation. I thought with the weight (or lack thereof) a 4-track, each with independent articulation would be required. I was definitely wrong.