Team MedBots

[daveimi]

Oh wow are they bosch motors? Which gearboxes do you have

[Max]

They are bosch 400 motors running off 12v, they are a lot cheaper than the bosch 750s but not as powerful.
They were custom gearboxes but where relatively simple to make but I did use a milling machine with a digital readout to drill the holes to ensure the hole spacing was correct. I think there is a video of just the gearboxes earlier in this thread.

[Max]

Tried again with the pair of SLAs in parallel but it still kept cutting out
Other than buying a set of lipos all I can think of is putting the batteries in series then setting the travel adjusts to 58% to give 14v so hopefully it won't drop so low the esc cuts out.
Anyone got any other ideas?

[Mega Masher]

Use some NiMHs if you want cheaper batteries
Or NiCads

[razerdave]

I've got some NIH bot packs for sale, 3 x 24v, 3000mAh packs if you're interested.

[Max]

Ok, rather than start a new thread for every question I'll just ask them here, after some more opinions for this potential featherweight:
- what are people's opinions on using 2 brushless motors to power a single drum? They would each have their own timing belt going to the drum with toothless pulleys on the drum so they are not completely forced to go the exact same speed like they would be if you used 2 connected by gears say. Would it work? Should I use one esc or 2? Am I better to spend the same money on a single more expensive motor?
- what are opinions about using aluminium wheel hubs? I know most people who make their own use HDPE or similar but due to my design i have relatively thin walls on the hubs (5-10mm) so think I need something stronger, is the aluminiuk just going to bend if I get thrown in the air and land on the wheels?

[Flag Captured]

2 brushless motors on one drum can be done but it's not advised... what motors were you going to use? You'd need two ESCs too, definitely. Would probably work out cheaper just to get -a- motor and esc combo really.

Aluminium hubs are decent, what sort of design are you looking at? it's all subjective, really... Plastic is better in some scenarios, not as good in others - ditto aluminium

[Eventorizon]

The only machine I know that uses 2 brushless motors on the same weapon is Toro Maximus, the Brazilian HW Drum Spinner. In a FW class machine there is no point. 1 is more than enough and 2 just adds complexity and cost.
Thanks now to Hobby King, powerful brushless motors are dirt cheap. A NTM 50-50 would be more than enough power. Combine it with a Red Brick 100A ESC and you are sorted. Total cost there, around £50. Power on 6S - 2000W!

Aluminium is good for hubs, the BaneBots ones are a great example of how it can be done. It does have its downsides but I would take Alu over plastic as it is less likely to get twisted or loose its thread/hold on a bolt which is uses to attach it to the wheel.

[Max]

Ok I'll stick to the one motor, it was only that it fit quite nicely having 2 motors but 1 will work. I also figured that whilst there was more to go wrong it also meant if there was a failure of one motor, belt or ESC it would still keep working for the rest of the fight or even for the rest of the competition.

The plan with the wheels is to have them come back over the motor/gearboxes allowing me to have reasonably wide wheels but still keep the robot narrow

[maddox10]

We use thin walled plastic RC hubs on the current generation of machines.
Didn't have to replace a single one after a year of fights.

And yes, the hubs have enough space to fit a GR02 in, with the frame to support them.

[Max]

Do you have a link Mario?
I've been looking at getting something like this: http://pages.ebay.com/link/?nav=item...obalID=EBAY-GB
But was planning on just removing the tyre and making a new aluminium hub but perhaps I wouldn't have to bother

[maddox10]

No link needed, as you're spot on. We have hex 17 wheels.
Larger wheels, like 1/5 or 1/4 scale are hex 24.

If those wheels can take an 2 kg RC car @80kph doing a Dukes of Hazard over 20 meters.....

[Eventorizon]

I also figured that whilst there was more to go wrong it also meant if there was a failure of one motor, belt or ESC it would still keep working for the rest of the fight or even for the rest of the competition.

If you do it right you should only ever need 1 motor and 1 ESC. Binky has been using the same Motor and ESC for 3 years, unmodified, and many machines have been running the same parts longer than that.

[RogueTwoRobots]

Just carry a spare motor, ESC and belts. If you lose your weapon during a match, just try to win through driving and then swap it out afterwards. Also buy a decent motor as well, will help towards having a reliable weapon system. My original brushless motor was on the go for three years (or three events, depending on how you look at it) and probably would still be going if it hadn't got vapourised in a massive impact. It's a 40-sized Scorpion motor, more expensive than some Hobbyking options but worth it in my opinion. If you scour eBay you can usually get a used one in great condition for about half the 'new' price.

[Mouldy]

360 had 2 brushless motors, can see why you'd want to do it… redunancy etc, but the power gains arent really noticeable… and if the one motor buggers up, the chances are it will lock up - causing the 2nd to fail anyhow. Buy once and buy good quality.