27-10-2003 23:33

Kevin A

Could you take another tire and have them run perpendicular to eachother, and the friction would transmit the power?

28-10-2003 00:02

sanddrag

Hmm. Not a bad idea. I found these:
http://www2.towerhobbies.com/cgi-bin...?&I=LXDE95&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXDE95&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXFU85&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXFU85&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXKK04&P=7

All of them do come in larger sizes too but I thought you would want something small.

28-10-2003 12:55

Rich Wong

SWEET!

Any chance of a copy of the plans?

28-10-2003 17:09

OneAngryDaisy

Niiiice....

I made an similar crab-drive edubot, only problem is the wheels won't turn, it appears like there is way too much friction- do yours successfuly rotate?

28-10-2003 18:04

Tytus Gerrish

it spins like crazy dude, don't even start

I still need a beval

29-10-2003 21:47

Sachiel7

You crab system looks much like my large scale design, Tytus, cool! I just screwed the wheel assemblies into 2 servos for my crab drive
The only prob. is that the servos only range 100deg, I need 180. I'm lookin into some new ones. But for now, that's what I'm doing.
I actually built a edu prototype of my full crab drive, and just stuck 2 of the gears together at 90 deg. They worked OK. But, I would look into getting some nice beveled gears. I think there's an easy way to mod up lego beveled gears to fit the edubot's shafts... I did it last year. I'll try and dig up that project...

30-10-2003 10:12

Tytus Gerrish

edu is realy anoying me, there are only so many parts in the kit and there are only chains and sprockets. I used a Victor an FP motor on my hoverbot

as far as crab goes my turntables just came in from Pitsco and i built a coax lego crab with arakeen correction, i hope my Legoleague kids wont tear it apart for the motors untill i take a picture tho

30-10-2003 14:03

Joe Johnson

bevel gears...

Berg sells miter gears that can be made to work with the EDU kit.

It will not be pretty but it can be done.

I recommend a 1 to 1 ratio with a relatively small diameter to keep "tilt" from disengaging your teeth ( like the pair M72N-1A for example).

This gear set is aluminum and has a 1/8 inch bore. You will have to make the hole square. To do that, I recommend the following broach from McMaster.com 3156A11 -- the problem is that it costs a bit more than I like -- but I have used it and they are beautiful for making EDU compatible square holes in aluminum parts).

Also, the pitch of these gears is a bit danty (72DP -- that means . You will likely have issues trying to get these gears to stay engaged reliably -- the teeth are only a little more than a half mm tall!)

To be honest, I suppose that for the most part, you could modify something from another toy set (Lego maybe) and have better success.

Good luck just the same.

Joe J.