Motors for a featherwight battlebot

hello,

im desining my own featherweigt battlebot and i dont kown witch motots i have to put juse...

so i got a few questions about it...

1 -i want to make a spinning disk on my robot arrount 2 or 3 kilos. can i juse a astroflight 940 for it or an other motor...?

2 - witch Pulley ratio do i have to juse between my motor and spinning disk.

3 - witch voltage for the motor that im jusing for my spinning disk

4 - and witch motors for my weels (i have 4 weels),i want to juse 2 motors on for 4 weels (should i juse also astroflight 940 motors for my weels?)and again witch Pulley, and witch voltage (24?).

and my last question: witch speedcontroller should i juse if i have 4 weels?

let me know please...

yoeri

First question is budget

1)If you can pay for Astroflights and the batteries needed, then thats a no-brainer.

2) depends on size and weight of the disk/spinner. But I would aim for 6000 rpm on an 8 2 kg disk.

3)Voltage, always as high as possible , according to the motor.

4)use the same as for the disk, then you can use 1 batterypack. if this is too high for the motors for drive, you can adjust this with the speedo- just dont crank it to 100% duty.

Speedo. The Sidewinder or IBC. If you really are richt, the smaller vantec.

ok,

about the budget...

are there other motors like the astroflight 940 that are so powerfull and small?

because 3 astroflight motors is expanzive.

mabye i can juse only for my disk a astroflight motor and to power my weels a 2 cheaper motors...

witch motor would you suggest for my weels then?

let me know...

yoeri

For ten pounds you can get an electric drill complete with battery pack and recharger. Two of these can form the basis for a robot, especially a first one.

I wouldnt advise powering the astroflight of the drill batteries though, Ewan sells drill motors and gearbox already stripped down pretty cheap, combine those with the astro for the disc and some batteries from http://www.overlander.co.ukwww.overlander.co.uk and your on the right track.

Can i be rude and ask what your budget is? An astroflight is a nice motor, but there are cheaper alternatives, not as light but pretty powerfull, fan motors on 24v pack a punch.

Give Geoff an e-mail, he seems to know his stuff on the subject.

ok,

im now thinking of jusing a astroflight 940 for my wapon, and jusing drill motors for my weels...

i want to make my robot pritty fast.
but my robots weels are only 6 cm high...would it go fast enough whit drill motors?

an can i juse this accu?:
http://www.teamtornado.co.uk/photos/yuasa-1.jpghttp://www.teamtornado.co.uk/photos/yuasa-1.jpg
in stad of overlander accus

whats the differends?

yoeri

The battery you have pictured is a lead acid, the least efficient in power to weight but very forgiving. The one at overlander is a lithium ion, most efficient but VERY unforgiving. Why not start with the batteries and chargers that come with the drills and get your robot going and then think about your weapon?

John, overlander do pretty much all types of SLA alternative, and have more on an enthesis on lithium polymer than lithium ion at the moment, which is a more forgiving battery certainly.

stay away from lithium, my advice.

someone needsto try it soon enough! if i had the money to buy them just to test i deffinatly would. Aslong as they can discharge enough all should be fine if they are looked after well!

Little spinner has run them no problems at all apparently (Lithium Polymer - I dont think anyone should dare to use the ions)

Tanto ran lithium ions at folkestone winter tour final, actually ran better than ive seen her for ages, theres so much crap being said about lithiums there are cells avalible that can power cars let alone heavyweight robots, and all this was said about nicads

About motors, for a power to weight ratio the astroflights are incredible, but so is the price. If you can afford them, go for it, but also make sure you can afford to lose one in a battle. No sense in making a robot with expensive materials, and not being able to afford replacement parts.

About the batteries:

SLA can blow, nicads can blow, Nimh can blow, Lipo and Li-ion are no different. The material gets lighter, the fires more spectaculair, thats all.

yep :) i hgave just been doing alot of research on these, and you can get some cell balancers for lithium polymers that check each cell and re-balance them evertime before you charge. This can make your batteries just as safe as others. If i ever ran on lithiums, i would deffinatly keep them well packed in foam, and charge out of the robot- but if looked after carefully, they woould be good - and expensive lol.

What is a cheap alternative for good accus in stad of lithium polymers? But also good.

And the same question again: i want to make my robot pritty fast.
but my robots weels are only 6 cm high...would it go fast enough whit drill motors?

Nickel Metalhydride is the best buy for weight/power/pricetag.

Now, about speed. Cheap batterydrills do about 500-600 rpm on the chuck. This gives you about 5.5 -6 km/hour.

Its maybe an option to remove the second stage gear then.

ewans drill motors can do 1000 rpm on 18v.
so thats: pi x 9 = 28 - x1000= 28000

28000 x 60 = 1680000 cm p/h so thats 16.8 km/h (if im not wrong) but thats still not verry fast...

is there no other alternative in stad of drill motors (not to expanzive), that make more rpm?

Not easy to fix no.

And what do you call not expensive?

about 40 euro

each? or all together? Gold motors are good and very reliable.

each

16.8km/h is really above average for a featherweight - certainly if youve got a spinning disc as you should be focusing weight into this.

Whats your budget for the weapon?

But can i really let my robot run 16.8 km whit your motors?
And should i juse 1 motor for 2 weels or for each wheel 1 motor?

If i buy NiMH accus whats the leest MaH i need (like 2400 or 3600...)
And does somebody know a cheap place to buy NiMH accus?

Motors for Disc you could try the HTI motors from http://www.robotmarketplace.comwww.robotmarketplace.com motors section misillanious motors they are cheap but powerful 1.44hp at 24v. On our feather Kishar we use 2 to power the Disc. Go to http://www.teamdragon.org.ukwww.teamdragon.org.uk kishar page there are some pics and videos of the set up. For drive we use 18v drill motors at 24v plenty fast enough.

http://www.hopf-modelltechnik.de/http://www.hopf-modelltechnik.de/ if you can read german. Very good pricing for their batteries.

We use the graupner speed 900 with good effect. Bit large and heavy with 660 gram each, but very powerfull and efficient for a low RPM (6000 rpm @12V) and good pricetag £20-25 if bought over here.
But the Graupner speed 720 BB torque could also be a good option.

For batteries, if you go pusher, I would take the Hopf Sanyo 3700 sub C NiMH in the 12V 2*5 stick pack cells. £20+P&P per pack.

Hello,
http://www.batt-mann.dewww.batt-mann.de (German homepage)
I think, you can order in English.

im netherlands so it will be ok

If youre dutch, Yoeri, why dont you join us on the Dutch forum? http://www.dutchrobotgames.nlwww.dutchrobotgames.nl

he already has.

now im gonna juse 2 gold motors to power my 4 weels. 1 or 2 HTI motors to power my spinning disk. and SANYO 3600 nimh accus. and make one blok of accu (14.4 volt to power my motors.

is this ok?

I would use 2 HTI motors for the Disc

ok... but do i have enough on one accu, if i power al my motors whit one accupack... (i wanne use an accupack whit SANYO 3600 nimh on 14.4 volts)

I think it will do, if you get the gearing right. The lower the rpms your motor due to a too a poor chosen gear ratio, the more amps you will draw. And with four wheel drive which tends to draw more current to make corners anyway it is very important to keep a good gear ratio.

I dont know the specs for the HTIs exactly but they seemed like high power drillmotors to me. As long as they get the disk quickly up to speed, the current draw should drop quite quickly.

All in all it will be close, but I think 12 cells should do it. Specially since those Sanyos are great cells, they do pack a punch.

While on the subject of motors. I just bought a second hand Astro cobalt 940. I saw on the Astroflight website they are discontinued, anyone know a place where i might find a replacement in case of an emergency?

try team whyachi

we use a 5 to 1 ratio on the HTI for the Disc 6 to 1 would probaly be better they get up to speed very fast about 2 seconds.

According to the Astroflight site the 940 is still listed. http://www.astroflight.com/e/env/store/store-Industrial.html?sid=0001a0PRDdPofIgqdM7S401&link=/store/store-type-tem.html&item=products:af-940http://www.astroflight.com/e/env/sto...001a0PRDdPofIg qdM7S401&link=/store/store-type-tem.html&item=products:af-940

They have changed the design slightly but it is still the same specs.

but my voltage to the HTI motors is 14.4 volts, and kishar juses 24 volts...will 14.4 volts be enough? (my disk is gonna weight +/- 2 kilos)

and sould i juse beld or chain from my motors to my disk. (i planned to juse 2)