New robot with chain drive

[Laser]

Ok I want to build a new robot using speed 900 and a chain drive reduction system.
I'm basing it on a toon(cant remember which one).
For the gear ratio I'm thinking of using 1:100 or 1:60. Is this suitible? If not what is a better ratio?
what kind of gear ratio does this toon have? And what wheels does this toon use?
[attachment=0:1o4aodtk]a.png[/attachment:1o4aodtk]

[joey_picus]

Re: New robot with chain drive

100:1 and 60:1 are far too much - you'll be looking at something in the region of 5:1 to, at most, 20:1 I'd think.

[Ellis]

Re: New robot with chain drive

If you can give an RPM rating at so and so voltage for the motor you're halfway there. You'll want to take into account if you're going to over volt and how that affects RPM, a bit into account obviously how the RPM is affected by load, wheel diameter, what top speed you want, etc.

(Or at least that's how the guys making go karts do it, it's the same principle for working out any gear ratio surely. Once you know wheel diameter and RPM, and the top speed you want, you can work out what you want. Probably best though to go by what the pros say, experience is often better than doing the math).

Just from the top of my head though, 100/60:1 is slightly insane. Unless of course you want to climb walls.

[Laser]

Re: New robot with chain drive

sorry i miss tyyped it. It was 10:1 or 6:1.
I'll be running at 22.2v (will that be a bit of a overkill?)

[PJ-27]

Re: New robot with chain drive

I do believe a Speed 900 is 6K RPM at 12v. (although you may want to check that.....)

I was also thinking about using a chain drive in a FW, but dismissed the idea thinking it would be far too heavy, I guess it is possible.

[Ellis]

Re: New robot with chain drive

Well say if you're running at 12v and the RPM at that voltage is 6000 (ignoring the fact it will have weight behind it and will most likely not come close to that speed), with a ratio 10:1 and say 15cm wheels, you'd have a top speed of around 11mph or 18km/h and plenty of push.

Really you need to get more design info before deciding ratios. And I think you'll struggle to get sprockets in a suitable size to get the reduction you need, you'd have to use a tiny chain size and even then for a FW I think it'll be a struggle. If however you're simply using chain to transfer drive, that's a different matter.

[Laser]

Re: New robot with chain drive

Will where did you get the sprockets for 4 Baa 4?

[team_orr]

Re: New robot with chain drive

Didn't he buy that one?

[RogueTwoRobots]

Re: New robot with chain drive

4 baa 4 was originally built by Ian Lockhart of Team Lambsy. It then changed hands and became a Team Shock robot before changing hands again and becoming 4 4 Toon (in other words, that robot gets around :wink: )

By the looks of things, the sprockets are just ones that are readily available from Technobots.

[teamshock]

Re: New robot with chain drive

Jamie just beat me to it but he's right that robot has been around a bit

When we bought it we had to replace a couple of sprockets and I'm fairly sure they came from technobots (but this was back in 2007 so I can't be completely sure)

As it's been so long since we had the robot I can't even remember the ratio for it but Clive may be able to help out with that one. something in the region of 8:1 seems to come to mind but that is probably wrong

[Laser]

Re: New robot with chain drive

I looked at the sprockets from Technobots and the description said they were quite(very) heavy!I am going to use a 8:1 gear ratio and run the speed 900 at 30v.
how many toothed sprocket did you attatch to the shaft of the motor?
Are the bigger sprockets heavy?

[RogueTwoRobots]

Re: New robot with chain drive

What sprockets are you looking at? Technobots list the weight of their products underneath the part number so you should be able to look there, see the weight and roughly work out how heavy your drive system would be.

For featherweights, you'll want to be looking at the 6mm or 8mm sprocket sizes. I'm not sure what size 4 4 Toon uses, but as an example, I think DB5 uses the 6mm size and they have been very reliable. And for an average guide, a 40-tooth sprocket from the 6mm range weighs 144g, which isn't too heavy.

[Laser]

Re: New robot with chain drive

http://www.technobotsonline.com/tbot-st ... tooth.html
this is what im looking at.
ive gone off the idea of chain, I'm going to buy 4 speed 900 and have spur gears and make a gearbox

[typhoon_driver]

Re: New robot with chain drive

that's the half inch pitch sprockets. Only ever used it in heavyweights as it's industrial type chain. You want to look here at the 6mm pitch stuff

http://www.technobotsonline.com/sprocke ... ckets.html

btw the pitch describes the distance from one tooth to another on the sprocket.

[Laser]

Re: New robot with chain drive

i've gone off the chain drive and i'm going to have 4 speed 900 with gearboxes (using spur gears) directly onto the wheels