Team BLEEP: Un-named Melonbot (BW)

[voorsk]

Hi all!

So, for ages my plan has been to build an antweight melon-slice-shaped bot. I first tried a front flipper, but it didn't work out, then I decided an axe would probably be pretty cool. I never got around to finishing it, as I tried to refine the bots I'd already built (which still need refining...)

However, recently it seems like it's been beetle/feather season, and I'm kinda jealous! I'm thinking that maybe I need a beetle in my life, and an axe-wielding watermelon seems like a good fit. It's really just a 2wd wedge with an axe mounted at the top. Not even a powerful axe - it's gonna be used more for grabbing than anything. In theory.

So, here's my complicated design, rendered in incredible detail:



For parts, I'm gonna start with the standard 1000rpm motors from ebay, then maybe a 250rpm motor for the axe/grabber. Will fingertech sumo wheels work? I dunno what ESCs work best, but I suspect I need 3 of them and some TX mixing. armour will be a mixture of things, depending on scale. it feels weird not having a size limitation!

oh, and my team name has changed from the unwieldy and ant-specific 'Antescher Assault Systems' to 'Team BLEEP'. Is it a swear? Is it the noise a robot makes? Is it almost a Deftones side project? Yes!

Time to start scouring the forum for other build threads to borrow ideas from..

[Ocracoke]

Looking forwards to seeing this one, I did catch sight of the AW attempt on the RW101 forum I think.

Will fingertech sumo wheels work?

I think OMG uses something similar and they work fine so they should work for you, though you'd have to make your robot fairly wide if they are to be hidden in the bodywork I think.

[voorsk]

I think the AW melon might be easier to finish than tweaking the other AWs, as it requires less printed parts. Just need to build an axe mechanism, and it'll be ready to go!

I'm quite looking forward to something bigger, tho. Hopefully it won't be so bloomin fiddly!

[voorsk]

The motors arrived on Saturday, so now I have a sense of scale.

I now have a question, tho.. is 3S enough to power 12V motors? I looked through a few build diaries, and most seem to use 3S, but wouldn't 4S be a better fit, or don't the motors like being overvolted in the same way as N20s?

edit: After doing more research, a 650mAh 4S and some Vex 29s seems to be the way to go. That means I need a BEC for the receiver. I might see if I can build that myself.

[Roboteernat]

Using a 4s battery may be overkill for this as you have the rated speed from the motors running at 3s - 3s is 11.1v. Plus you would save some weight from not using the 4th cell.

[voorsk]

Thanks for the advice! I'll give 3S a try, then. It has the advantages of being unlikely to explode the motors, and also means I won't need to buy a new charger.

With that in mind, I've done a bit more interweb shopping, and have bought:
A Zippy 850mAh 3S LiPo
Some Vex 29 controllers
A 500RPM weapon motor

Now I just need wheels (might use Lego), and a BEC for the RX.

oh, and the body of the robot..

[voorsk]

Cor - it's been a while since I started this!

I got all distracted by Christmas, and a few antweight compos, and some doubt about whether I wanted to still make my BW a melonbot after the AW version was such a PITA to construct. However, the AW version was lots of fun to drive, and didn't do too badly at its last event, so melonbot it is!

Since my last update, I've acquired some fingertech wheels, motor mounts, a receiver, BEC, and various HDPE sheets. I spent the last couple of nights cutting and crimping the wires so that the components are all easily swappable. Once I've soldered the power distribution board (fancypants name for some veroboard covered in JST connectors), which I'll be doing tonight, it'll be ready for a test run on a sheet of plywood.

I'm pondering applying to Bugglebots with this (they must have sooooo many entries to sift through!), but that means I'm gonna have to spend time making a bloomin CAD. I wonder if I can get away with scaling up an antweight CAD.. :P