Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: boyardee12 on February 10, 2008, 10:51:29 AM

Title: What part do i need
Post by: boyardee12 on February 10, 2008, 10:51:29 AM: Well im new at this and i am building a robot for this competition and i need to lift a box that weighs around 5lbs and i was think of making a forklif but i don't know what i need to make it go up

so like do i need a chain (to make the platform that the item will go on rise up and down) or do i need something like tracks and i need some kind of motor to right?
Title: Re: What part do i need
Post by: airman00 on February 10, 2008, 12:11:03 PM: any website or something?

All you need is a motorized lever , like a seesaw (except motorized)

Forklift requires a rack and pinion gears
(http://www.fi.edu/time/Journey/Time/Escapements/rackpinion.gif)
Title: Re: What part do i need
Post by: Trumpkin on February 10, 2008, 12:19:03 PM: yep you do need a motor don't use a servo unless you wanna spend big $. i would not do a forklift (very complicated). if I were you i would use windshield wiper motors because they have reasonable torque and are cheap. here is a CAD of my arm design
Title: Re: What part do i need
Post by: airman00 on February 10, 2008, 03:48:25 PM: windshield wiper motors are over kill ;)

just look for motors with the torque you need , there are PLENTY out there for cheap
Title: Re: What part do i need
Post by: Trumpkin on February 10, 2008, 07:11:39 PM: Quote
windshield wiper motors are over kill
5 lb box is pretty hefty. and you can get windshield wiper motors at surplus stores with no shipping costs. although it may be hard to get a big enough battery, you would have to use lead acid batteries.
Title: Re: What part do i need
Post by: boyardee12 on February 13, 2008, 06:36:21 PM: so are these lhttp://www.vexlabs.com/vex-robotics-advanced-gear-kit.shtml (http://www.vexlabs.com/vex-robotics-advanced-gear-kit.shtml) Rack and pinion pack seem right? I cant seem to find them anywhere else cheaper.
Title: Re: What part do i need
Post by: airman00 on February 13, 2008, 06:44:34 PM: Quote from: boyardee12 on February 13, 2008, 06:36:21 PM
so are these lhttp://www.vexlabs.com/vex-robotics-advanced-gear-kit.shtml (http://www.vexlabs.com/vex-robotics-advanced-gear-kit.shtml) Rack and pinion pack seem right? I cant seem to find them anywhere else cheaper.

lego also has

I built a forklift once with my friend's lego mindstorms a year ago

but ed1380 said soemwhere else that forklifts use a piston ( though rack and pinion works as well)
Title: Re: What part do i need
Post by: boyardee12 on February 13, 2008, 07:21:57 PM: o yea does anyone has a diagram or something of how a fork lift works? I already tried google but didn't find none.

Also im not sure if i can get underneath the box to lift it up so i was thinking instead of a platform/forks i could something like a gripper. However the thing is the box im picking up is 30x30x30 cm is also the box the robot has to fit in at the begining. there for i would have to make it contract then expand. Do you guys think that this is overdo?
Title: Re: What part do i need
Post by: airman00 on February 13, 2008, 07:55:17 PM: Quote from: boyardee12 on February 13, 2008, 07:21:57 PM
o yea does anyone has a diagram or something of how a fork lift works? I already tried google but didn't find none.

Also im not sure if i can get underneath the box to lift it up so i was thinking instead of a platform/forks i could something like a gripper. However the thing is the box im picking up is 30x30x30 cm is also the box the robot has to fit in at the begining. there for i would have to make it contract then expand. Do you guys think that this is overdo?

why not have a bar on a fulcrum , kinda like a catapult that goes up slowly. Pick up the box that way
Title: Re: What part do i need
Post by: boyardee12 on February 13, 2008, 10:19:04 PM: can you elaborate on that idea more?

And sorry i forgot to post some details the box doesn't have a top or bottom so it not really a box. Also i need to pick this "box" up and put it over items.
Title: Re: What part do i need
Post by: airman00 on February 13, 2008, 10:32:36 PM: (http://financialphilosopher.typepad.com/photos/uncategorized/2007/08/20/lever_image.gif)

Bottom part slides under box . Motor turns the lever at the fulcrum point( so you don't need a downwards force)
Title: Re: What part do i need
Post by: Admin on February 17, 2008, 10:51:46 AM: Quote
o yea does anyone has a diagram or something of how a fork lift works? I already tried google but didn't find none.
you didn't try very hard . . . very first result for 'forklift' says hydraulics . . . ;)
http://images.google.com/images?sourceid=navclient&ie=UTF-8&rls=DGUS,DGUS:2006-11,DGUS:en&q=forklift&um=1&sa=N&tab=wi

why not do a pulley system, and just wrap the string around the motor shaft?
Title: Re: What part do i need
Post by: boyardee12 on February 17, 2008, 04:09:38 PM: I can't use hydraulics system but i was asking for a more internal diagram since im a beginner anyways im actually not in need of of one anymore i got a different design
Title: Re: What part do i need
Post by: paulstreats on February 20, 2008, 06:35:09 PM: Why not attach a long bolt to a motor/servo output shaft and have a nut slide up and down it when it turns? if the linear parts are connected to the nut, this will also move up and down.