Tank Track
 

For the current VEX game 'elevation' my team are currently using a horizontal tank track to storee and deposit cubes.
Everything works perfectly except for one thing,
at the start of the track there is a large lump caused by the sprocket, which means we cannot get cubes over it and on to the track
we didnt think to account for this problem at the beginning (probably should have) and due to a shortage of equipment are unable to find a way to solve it.
can anyone think of any possible solutions - no matter how half-baked they are? we would appreciate it so much as our competition is This Saturday (Monday Now)
thank you all so much

-Steph
(Team GCEC - Auckland, New Zealand)

Please note: We have a severe lack of motors. we have one motor and a ton of servos

Re: Tank Track
 

I don't exactly understand what you mean by "lump." Pictures may help.

Re: Tank Track
 

I think it looks something like this: (rotate 90*)
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You could try using a counter-rotating wheel or similar item above the "lump" to guide the cubes in. It can be done without any additional motors-- use gears.

Or--flip the cubes over it using a lever of some form, maybe.

Re: Tank Track
 

To minimize the lump instead f the drive wheel you could use one of the single bogey wheels. That would make it smaller but not make it disappear.

Re: Tank Track
 

These pictures - Compliments of Team 42 (Mostly Harmless) - might help out.

Tread Mounting Pic 1
Tread Mounting Pic 2
Tread Mounting Pic 3

The scenes in the photos are rather messy, but if you zoom in on the ends of the three devices and look at the flat sections/sides of them, you might find something you can use.

There aren't many ways to avoid using at least one sprocket, and there are precious few that are very useful; but there are a few tricks.

Good luck - See you in Dallas -Go Kiwis!

Blake
PS: Whether you win or lose on Saturday - Send us a picture!

Re: Tank Track
 

put a Tank Tread sprocket on its side. that is the height of the end of our track. we are unable to get the cubes over it to get them on the track.

a few good ideas in there - tempted by the lever and definitely going to use the smaller wheel.

or would it work to put a metal plate on the other side of the cube firmly against it and just roll it against that? anyone know?

also, if you put a large gear on a servo with a small gear meshed to it, will the smallgear be able to turn something 360?

Re: Tank Track
 

It might turn in 360 degrees once but it would then have to turn back which might cause you to be able to get the cube partway in but before it was all the way in it would get pushed back out. Try it though see what happens.

Re: Tank Track
 

If you use something attached to a servo to cause the cube to stay in contact with the tread, the tread's friction should soon pull the cube into your system.

The cubes are very light, so you don't need much friction from the tread. Just a little force will be enough to lift the cube up and over your lump.

Use the servo to cause a "hook" to flop down an press against the cube. I say "flop" because you want this hook to "float" and allow the cube to move the direction the tread is trying to take it. The hook needs to be flexible, not rigid.

Sound feasible in your design?

Blake
PS: Yes - A 36 tooth gear mounted on a servo and turning a 12 tooth gear will rotate the 12 tooth gear nearly full circle.

Re: Tank Track
 

This is great, sounds exactly like what we were looking for. thank you

thanks for all the help everyone, we really appreciate it. wish us luck for saturday

Re: Tank Track
 

Cubes aren't cylindrical or spherical.

Consider this: if you look at pickup mechanisms for FRC for 2006 (or 2004, or 2002, or any other FRC or FTC or VRC game involving balls), they were developed for spherical objects, which a flat plate works for. However, VRC's Elevation uses cubes, which aren't spherical, though they could become that way after going through a flat-plate pickup system!

Other ideas could easily be derived from some of the above teams.

Re: Tank Track
 

Glad to help - Try combining that idea with one of the tread arrangements (in the photos in the other post) that eliminates the need for a sprocket at the intake end of your system...

Time to get some sleep over here on our East coast - Don't forget you owe us all some photos :)

Blake

Re: Tank Track
 

Forget the tank treads -- I see you use the same black boxes with yellow trays that we do. Good taste in parts bins, my friend. :)

Re: Tank Track
 

We used tank-treads-and-a-plate to pick up softballs in the 2006 VRC game, too. Cubes and foam balls were a lot easier. :)

Our team 575 uses rollers to pinch cubes against a flat plate for lifting. It makes use of a Top Sekrit feature which makes it possible for the cubes to ride smoothly up without getting stuck diagonally. I'll post a picture when I download our pics from the Vancouver tournament. Dromedary (the 575 robot) was 4th after qualifying and lost in the semifinals. This is the robot that won the "Amaze" award.

Re: Tank Track
 

If the problem is that it is too tight for the cubes to get picked up you could do what many teams do and move the treads farther apart and just put zipties on the tread like paddles and then those would pick up the cubes. I've seen a couple robots do this and it seems to work.

Re: Tank Track
 

hi, the tank tread idea seems to be a good idea but in the competitions in NZ they don't seem to be working that well. I think for the idea to be reliable you would need to create some sort off suspension between the treads, i had an idea of using slotted plates and standoffs with rubber bands around them to create floating rollers that would let the treads expand to hold the cubes securely (i would like to prototype the idea but unfortunately my team doesn't have a set of treads yet). BTW i really liked your pneumatic claw set up, using steel cable and attaching the cylinder at the end of the arm, i thought it saved a lot of weight at the end of the arm where it counts good luck for Saturday and see you then.:)