RogueTwo Robots

[harry hills]

Lol, shows if you sort through the shit hard enough you might find a diamond.

[Mouldy]

What wheel OD, voltage, gear ratio and motor are you going for on the banebots? And it don't look like a total rip off of 720... Mines got a gap between the motors so I can take them out without splitting the chassis :P

In all fairness 720 was a combination of drumroll/touro it's kinda the optimum shape for an invertible drum.

[Max]

it's kinda the optimum shape for an invertible drum.

Ahh roboteers modesty! Lol!

[Mouldy]

If you try designing it in any other way there's draw backs...although the latest touro feather being an exception.

[RogueTwoRobots]

I hone the overall shape (although I was heavily influenced by US/Aussie drumbots), Dave comes along and makes it better, then I come along and copy his improvements
But yeah, not a huge scope for major differences, Touro aside.

Wheel OD is 125mm, running on a 5S lipo, 16:1 gearboxes and still tossing up between 775 and 550 motors. The CAD is with 775 motors but there's literally just 5mm of space between the ends of the cans. I don't know how easy it is to pick up spare 775s over here compared to 550s so that could factor into things.

I also envisaged just being able to slide the motor/gearbox out through the cutout in the side, hence why the lack of space in the middle wouldn't be a problem, but now that you've drawn my attention to it, I've realised that the motors are larger than the surface area of the gearbox and wouldn't fit through the cutout. 550s would though. Hmm, deliberations!

[Mouldy]

I went through the same thought process with the hole for the gearbox, then decided to go for the 775's just because there rated voltage is 18v and i wanted to run 5s anyhow... and with the 98mm wheels on 16:1 they stay relatively cool, and spin the wheels easily... not sure what differance running 125mm wheels will make... might be a bit fast? I've turned my turn rates down to around 60% to make it controllable, and ive got way more pushing power then i need really.

[RogueTwoRobots]

Yeah I reckon it'll be stupidly fast on 125mm wheels so dual rates will be on. The added pushing power would be handy as the current version lacks that compared to the first Drumroll, and running them at their rated voltage is never a bad thing.

Was worried that 125mm wheels might be putting too much load on the gearbox as I reckon that's been the cause of having numerous drive failures over the past couple of events, but then those were drill gearboxes and 125mm is the biggest wheel Banebots make so they must be (reasonably) confident it's suitable to use on their gearboxes.

Will probably just go for the 775s then. If I need to get one of them out, worst case scenario I can rip the side bulkhead off in less than five minutes with a battery gun and a hex bit.

[daveimi]

Is there a big difference in power and stuff between the 550's and 775's? I like the look f the 775's

I also wondered, you know on the Banebot's gearboxes how the shaft is one long shaft? Once you've bought your hubs and wheels, what stops the hubs etc. sliding of the end of the shaft?

[Eventorizon]

Info on the two motors can be found here...

775 @ 12V: http://banebots.com/pc/MOTOR-BRUSH/M7-RS775-12

555 @ 12V: http://banebots.com/pc/MOTOR-BRUSH/M5-RS555-12

The 775 has just over double the stall torque of the 555. At peak efficiency the 555 has 4.67 oz-inch where as the 775 has 250% of that at 11.69 oz-inch. I would call that quite a big power difference.

[Maths was: (100/4.67)*11.69 = 250.32]

If you go up to 18V versions then the 775's have a massive 23.99 oz-inch, thats 513% of the 12V 555's.

[Maths was: (100/4.67)*23.99 = 513.7]

EDIT: The shafts on the BB gearbox's are keyed and have a thread tapped into the end, but some loctite and a nice tight grub screw usually do the trick. I did that with mine and I couldn't knock it off or pull it off.

EDIT 2: This will be interesting to see. All of us will be running 18V 775's on 16:1 gearbox's but we will all be using different wheel sizes. C3 uses 73mm, 720 is 98mm and drumroll 3 looks to be 125mm. In a pushing match who will come out on top? C3 will have the advantage of 4WD but will the shear speed of 720 and Drumroll give them an advantage?

[Ellis]

775s, cute!

#885represent.

(looking really good, it will indeed be interesting to see how the thing drives on the 124mm wheels, 18mph top speed give or take!)

edit: actually, pretty sure the 885s, mathematically, aren't as punchy as the 775s. So we'll see.