Large size wheels to fit on cordless drill motors

More details will follow - can't remember the exact drill motor. psycho_fling should be able to tell me.

The wheels have got to have a minimum diameter of 20cm.

they are just normal drill motors

what are you building? not sure if the motors will like 20cm wheels....

alex

20cm may be a bit of an over exaggeration.

I'm building a FW thwackbot, and have been for about 100 years :)

I'd say about 13 - 18cm...

if you can dont use 20cm wheels with nut inserts on drill motors, i've got 15cm wheels on drills on one of my robots and its shocking, VERY wobbley and just doesn't see to have such toughness- or rugidness to the whole thing, dnt get me wrong the wheel size makes it very fast but its alot of strain on the drill motors and shaft n all

What would you suggest then? Would welding them on be good?

hey, what robot are you making? something like the saint but a feather?

Sort of... Except that it is more of a box... and it's wooden :rofl:

If you're looking for lots of speed over decent torque, you could use smaller wheels and gear the motor up with belts, gears or chains. Or overvolt the motors a bit.
Drill motors are very speedy on 12cm wheels, or if you put a layer of bike tyre over the 10cm Robo Challenge wheels, you get something near to 12cm diameter and you gain some additional grip from the tyre.

EDIT: I wrote this thinking of a horizontal thwackbot, but having seen Calum's post, if you want a Saint-style overhead thwackbot, using the suggestion of smaller wheels may be less practical. If you're going with the overhead design and want wheels of 15cm or above, you may have to look at gearing down the drill motors or using different motors with a more substantial built-in gear ratio (windscreen wiper motors etc)

lol, wooden box aside i wouldn't use drills on a robot like that with that big of a wheel because you'd idealy like a larger dia axle than a drills shaft has n all.

just remembered craig who made the saint has made a feather version aswell, i think he used wheel chair motors or something, best off ask him

As I already have the drill motors, I think that gearing them down would be a good idea.

Problem is, I have never understood gears. I understand the ratio (semi), but the rest of it... No.

well gearing down is fairly simple to get in your mind but doing it is the harder part

ok say you want a ratio of 10:1 which means you want the wheel to turn a 10th of the speed of the motor you could use in a one stage gear box (ie just to gears) a 10 tooth gear on motor and a 100 tooth gear on wheel

this would give the desired result

it gets complex when you introduce more stages more stages come into it when you want like 512:1 for example have alook at the below ratio calculator

http://www.technobotsonline.com/gearbox ... lator.html

alex

Well what would you suggest? Do you want the measurements for the robot (minus the axe handle and axe), and where I intend to put the drill motors? I'm going to try and get as much help from the experts as I can, rather than jumping ahead, as I usually do :uhoh:

Make your own wheels from nylon or something! :proud:

yeh give us some more info then it's easier to suggest how to do things and what wheels to buy to suit all your robots needs

Hi when it comes to big wheel robots perhaps I may be able to help, The Saint has 600mm wheels but with the tyres they are 670mm diameter the Mighty Seraph (Feather weight robot) has a wheel diameter of 500mm.

Material used UHMWPE or the green stuff from Plastics Direct Bolt the tyre on I used bike tyres for both robots.

The transmission, the rule of thumb would be double the diameter of the wheel, half the speed of the wheel, to get the same speed for the robot.

So if you connected a sprocket to the drill motor say 12 tooth sprocket, and the wheel had a 24 tooth sprocket, the speed of the 200mm diameter wheel robot would be the same as an equivalent 100mm diameter wheel robot.

Hope this helps