Rango - Build diary

[RogueTwoRobots]

I've still got a genuine S900 kicking about that I'll bring with me in case it's needed. But all this talk of different motors and machining is crazy as it's obvious what the most logical and practical remedy is; Ellis, you just need to win all your fights in about 20-30 seconds. Job done

[Ellis]

Just called production off, going on 3:30am. Up again to catch a flight in a few hours. Despite several 14-15 hour workshop days neither machine is properly ready. We've had to haphazardly cut out some top protection and make a stab at the wiring for Rango. Comes in at 13.2kg, it works on the bench, had no time to clean anything up or paint anything, let alone do much testing. Seems to failsafe correctly and should otherwise be in the rules, so it can at least enter. It's a bummer, it'll be there, but expect it to go out in the first round in a puff of smoke, lol. I'll get it ready and looking smart for next year. Already got 1-2bajillion ideas.

T2 is still largely in bits and has a partially rebuilt lifter mech, the plan is to occupy ourselves with that once Rango has eaten itself. :P

Thanks again for all the help and support folks, see you all in a couple of days.

[Revsmin]

Aww, that's a real shame mate! I had you down in the top 18 as well. Whether it works or not, it'll look good in the arena and out of it, can't wait to see it. I'd offer Skyfalls S900s, but they have big pinion gears welded/glued on the shaft.

[Mega Masher]

Aww no, I was hopin that would be a top contender
At least you can try
Still looks great though

[harry hills]

3rd place you jammy git

[overkill]

Let me know if you are still interested in those single stage planetary gearboxes - I had a couple of ideas about them overnight that overcome the problems we talked about. Also looking forward to any plans for brushless drive you are investigating.

[Flag Captured]

It's a bummer, it'll be there, but expect it to go out in the first round in a puff of smoke, lol.

Lol indeed! It's quite ironic, looking back - and you said you called off the build at 3:30, almost as if it were a sign or something!

Very solid design, and it's definitely deserving of it's podium finish, because you didn't half work for it throughout... If you can get those flaws sorted for next year, that's going to be a very powerful machine and a tough one to stop! It's a real shame you got caught out a little with the Beauty fight too, it looked like you had him on the ropes at the start...

Still, you got yourself on the podium - congrats on 3rd place, that's a fantastic achievement!

[Ellis]

Been a while!

As that super rich Bulgarian guy has yet to transfer his billions into my account (as promised by email), Rango hasn't had any love since the champs. I have various upgrades/changes in mind for next year, but the one thing that remains up in the air is the drive. There's no promise that sensored brushless will work as necessary yet (fingers crossed, Nick!), building a custom planetary extra stage in somewhere is heavy $$$, and there is no drop-in suitable brushed motor that I have found. We're going to be over
to play in September, hopefully taking in MMM, so it needs to be driving. Harry was over earlier in the month and we sort of stumbled across a motor which *might* work in the existing setup.

It's an oldschool RC boat thing, called a Robbe 755/40 (basically a short 775 can). It is rated at 8400rpm @ 18v which is perfect. The downside is that in the kind of boat it would go into they actually want super low power. Robbe say to keep it below 8a. That's 160w on a 5s LiPo, which is less than a pair of 18v 550s (what T2 runs). However the experiment is ten times cheaper than going brushless and fitting in a planetary.

To that end I bought a pair from a German hobby site and they arrived this morning:



As you can see they're smaller (and 150g lighter) than the 885s.

The bolt pattern and front boss are different to the 885's, so I'm modding the existing mount setup to work for these, with making a purpose-built plate in mind should they do well in testing.

The bolt holes had to change from 32mm to 29mm; a really awkward amount. I had to turn and press aluminium plugs for the original holes and re-drill partially across them. The pins and plate aren't the same grade and the holes wandered a little but it's good enough for testing:





Several other bits need making/modding to make these fit but it shouldn't take long. Here's hoping the motors can put out enough power to actually move the robot without melting.

[harry hills]

Swiggity motors man. Hope they have enough balls to move the robot.

[Max]

Why couldn't you have just drilled the mounting holes at 90 degrees to the old mounting holes?
Really cool solution though and good luck with the new motors!

[Revsmin]

Lemme just get something straight... This is your third featherweight, entering your third UK champs that you called off at 3:30 three days before the first day of the champs... and you came third. That's a bit weird if you ask me!
Looking nice anyway, sure it'll be just as relentless as it was this year.

[overkill]

It could be that the motors are rated very conservatively over a long running time. Most hobby motors are very optimistic with their power ratings, so for the low cost its definitely worth a try!

PS: don't bother with Bulgarians, the Nigerian oil minister will fix you right up with some cash

[Ellis]

Cheers guys.

@Max: there's too much other stuff in the way!

@Nick: yeah that's the hope. They claim 8-10a for 60sec @12v. Hoping that means it could handle double the draw for half the time. I can sap the heat out really well as they're surrounded by aluminium, so certainly worth experimenting.

Also yeah this Bulgarian guy is being slow, what little was in my account has been taken... I assume to make space or something. I'm sure he'll put the billions in soon.

[knightrous]

What's the size restriction for motors to fit into the robot and what RPM range do they need to be in?
I might be able to help you out

[Andy]

Looking good Ellis mate, I hope those motors work well for you