oh dearOriginally Posted by typhoon_driver
As someone who's concrete garage floor has been attacked by Jamie's axe I can say that the scooter motors are indeed well suited to this application. well I will get one later down the line after I make my first feather weight.
As Jamie said, my robot Hatchet uses a 350w scooter motor on a 5:1 ratio running from a 6s (22.2v) lipo.
This video shows best how effective a weapon and a selfrighter those motors can make, and they're damn cheap too.
Can I ask what voltage is your drive motors and the scooter motor?
cause the scooter motors I've seen on eBay use 24volts and I didn't know if they could handle a lower voltage input
Yeah 24V is their rated voltage for the application they're designed for (electric scooters) but they will handle less. Sam's runs on 22.2V and mine runs on 18.5V, and even at that it still has a good amount of power behind it and can self-right the robot without issue.
You can overvolt motors as well to get increased speed and power out of them, though this does shorten the lifespan of the motor. As a general rule, never go more than 50% over the rated voltage, so for example, a 12V drill motor can be run on 18V without it being too detrimental, but don't be surprised if it fails somepoint down the line.
Ok, good thing I didn't go with my dad's old drills, they might not even last 5 minutes.
so I take it both you and Sam use 12volt motors?
I think we both use 18V drill motors, slightly larger than the standard ones you get from the likes of Argos and a little tougher. You can still use 12V motors on a higher voltage if your radio transmitter has a feature called dual rates. This allows you to set a lower limit for the drive motors so that they don't get the full voltage and risk being burnt out.
I'm thinking of using my Spektrum DX5e, but I don't think it has that dual rates feature.
and as I can't afford to waste money I'll use 12v motors and a 18v battery for my ram bot and use 18v motors and 22.2v battery for my axe bot (most likely a upgrade on the ram bot)
IIRC me and Jamie both use 18v drills that have 600 sized motors (slightly larger than the standard 550 sized you'll get in your bog standard argos drill), i do run both my axe and drive on 22.2v but i reduce the rates on my drive to try and make my motors not dead.
A dx5e doesn't have dual rates unfortunately, there is a switch you can flick to reduce the rates to 50% but that's not really useful in a combat robot.
I see I'll have to make a note of that, do you know a transmitter that does this dual rates?
You would need one of the newer digital transmitters to get anything other than the 50% dual rate switch.
The cheapest I know of is the new Spektrum DX6 at £130. It seems a lot to buy that for just 1 feature but actually it provides a load of additional settings that can make driving much easier. I've only scratched the surface myself but at GSL this year Hatchet was put on the new DX6 and went from being crazy to drive to being downright amazing with about an 30 minutes of tweaking.
I believe it was set up to have 90% forwards on the axe, with just 40% return so it wouldn't waste power or jump around to much. Turning was similarly tuned to be slower but forwards was left at 100% so that it could slam its opponents into the wall.
Its a tad off subject but I would recommend the DX6 despite its price. It can store up to 250 models (Wow.. I was expecting 50 at most) so it can be used on every robot you ever build at the same time and each one can have custom settings to make it suit your driving style, optimise its weapons and control anything from Robots and RC cars to drones and Helicopters.
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