Need help in deciding the configuration for an off season chassis prototype

[orangemoore]

Originally Posted by lamk

We used the long configuration AM14u for aerial assist. It got us to St. Louis. As an off season activity I would like to prototype a 3 cim 2 speed 6 wheel west coast drive. I am leaning towards a 28 x 28 square configuration. My student wants to stick with the 23x32 long configuration. Any suggestions.

I hope you mean 6 cims in total and not just 3.

[Billfred]

Just a notion: Traditional West Coast Drive is just (relatively cheap) 1x2 tubing, creatively machined and assembled. Do you have the resources to machine the tubing, then transplant the gearboxes/wheels/axles to try it both ways?

[asid61]

Make sure you have somebody who can do the machining. Also, make sure your chain tensioning is good. We had a lot of problems because we did not use screw tensioning or cam tensioning. We did a thing with slots, pulling, and locknuts. Bad plan.

[ehfeinberg]

Originally Posted by asid61

Make sure you have somebody who can do the machining. Also, make sure your chain tensioning is good. We had a lot of problems because we did not use screw tensioning or cam tensioning. We did a thing with slots, pulling, and locknuts. Bad plan.

Have you seen these?

We used them this past year, and were nothing but happy with their performance. Not only do they provide easy tensioning by just sliding the blocks in and out, but they only require a drill press for machining.

[lamk]

Originally Posted by ehfeinberg

Have you seen these?

We used them this past year, and were nothing but happy with their performance. Not only do they provide easy tensioning by just sliding the blocks in and out, but they only require a drill press for machining.

That's exactly what I am planning to use!!

[lamk]

Originally Posted by orangemoore

I hope you mean 6 cims in total and not just 3.

Yes 6 cim total 3 cim per gear box

[DampRobot]

One thing I recommend experimenting with is how easily you can get out of T Bone pins with your drive base. If you're planning on putting up a significant number of points next year, you will get T boned more than you like, and you likely will wish you designed your drive base to make it hard to T bone pin you. Think about what frame dimensions will give you the most turning moment against a pin, and what "add ins" like drop down casters, omnis, etc, can help you get out of pins. Oh yeah, and it's a ton of fun practicing pinning with another robot, so I encourage you to test it after you built the base. You'll get ideas for improvement too.

Test out a bunch of different wheels (VersaWheels, AM stuff, different treads omnis, etc) to see what you like best in terms of traction and turning. With a WCD, it's super easy to change out wheels, and you'll be glad you bought the wheels (even if you don't like them all that much) because they'll be a part of your inventory for next year.

Make your bumper mounts rock solid. So many people (including me) mess this up the first time around with WCDs. Design the side bumper mounts as if the robot will be slammed on the side with sledgehammers during an earthquake. Trust me, this is one of the few things on your robot you will not regret overdesigning. And then test the heck out of them by going to offseasons or by having another robot slam the bejesus out of the bumpers for days in end.

If you can, put some kind of manipulator on top of the drive base you're building and go to an offseason or three. Planning on going to a competition will give you a big motivation to finish, and will be a ton of fun once you get there. Sometimes, grand summer plans can fall by the wayside because there wasn't enough motivation to get them done. Deadlines (and looking forward to offseasons) helps with that.

Oh yeah, actual dimensions. I'd go 28x28 and see how you like it, but it really doesn't matter too much either way.

[aphelps231]

Originally Posted by lamk

We used the long configuration AM14u for aerial assist. It got us to St. Louis. As an off season activity I would like to prototype a 3 cim 2 speed 6 wheel west coast drive. I am leaning towards a 28 x 28 square configuration. My student wants to stick with the 23x32 long configuration. Any suggestions.

Team 1318 is working on a few summer projects, including an 8 Colson wheel, 4 CIM, West Coast Drive using dual speed WCP DOG shifters, and a modified 6 Colson wheel AM14U kit bot chassis outfitted with shifter upgrade kits. I reccomend moving out of the box and trying something new when it comes to summer projects (more below).

1318 (The IRS) has been known through out the PNW for their relatively simplistic, and well performing, designs. Last year we manufactured our own chassis, dimensions were based off of the 2013 kit bot chassis. This year, we decided to use the provided kit bot chassis in a 28x28 configuration, which took us up to Galileo division finals (although the front cross brace extrusion is bent in about an inch after division semifinals). By branching out this summer we hope to educate our team about a higher performing level of drive train, and comparing and contrasting different designs (6 wheel vs. 8 wheel, kit bot vs. WCP drive base, etc.)

[tr6scott]

As another design constraint to consider....

Can it get through your room door with bumpers on?

Being slightly under this dimension when you are driving out the door, saves a lot of time when you want to go show off your hard work in the gym, cafeteria, etc...

(AM14U, two speed upgrade, 28x28 configuration, number 4 alliance captain on Archimedes, 1st year not designing WCD base)

[DampRobot]

Originally Posted by tr6scott

As another design constraint to consider....

Can it get through your room door with bumpers on?

Being slightly under this dimension when you are driving out the door, saves a lot of time when you want to go show off your hard work in the gym, cafeteria, etc...

(AM14U, two speed upgrade, 28x28 configuration, number 4 alliance captain on Archimedes, 1st year not designing WCD base)

IIRC, the rules are designed to make sure any rectangular robot can fit through a door with bumpers on in at least one dimension.

[tr6scott]

Depends on your door... but it is better to be a long bot to drive through the door, as to be wide, and have to pick it up and carry it sideways.

Just saying, it's a demo, make it easy on you....

[Andrew Schreiber]

Originally Posted by tr6scott

Depends on your door... but it is better to be a long bot to drive through the door, as to be wide, and have to pick it up and carry it sideways.

Just saying, it's a demo, make it easy on you....

Y'all need a cart with caster wheels then.

[lamk]

Originally Posted by aphelps231

Team 1318 is working on a few summer projects, including an 8 Colson wheel, 4 CIM, West Coast Drive using dual speed WCP DOG shifters, and a modified 6 Colson wheel AM14U kit bot chassis outfitted with shifter upgrade kits. I reccomend moving out of the box and trying something new when it comes to summer projects (more below).

1318 (The IRS) has been known through out the PNW for their relatively simplistic, and well performing, designs. Last year we manufactured our own chassis, dimensions were based off of the 2013 kit bot chassis. This year, we decided to use the provided kit bot chassis in a 28x28 configuration, which took us up to Galileo division finals (although the front cross brace extrusion is bent in about an inch after division semifinals). By branching out this summer we hope to educate our team about a higher performing level of drive train, and comparing and contrasting different designs (6 wheel vs. 8 wheel, kit bot vs. WCP drive base, etc.)

Agree! That's why I will go with the WCD 28 x 27 to get away from the am14u.
Will also buy different vex wheels and colson wheels to try out.

[lamk]

Update:
We have prototyped a square configuration 6 wheel 3 CIM ball shifter VersaChassis WCD. Haven't done AB comparison driving with our AM14U since it's the summer holiday. Will start AB testing in a few weeks once all the students returns to school.
Our team has made a Step by Step guide to building the VersaChassis. Hopefully it will help anybody who wants to try something different than the KOP AM14U.
http://www.chiefdelphi.com/media/papers/3050

[Monochron]

That is a really awesome paper. It would have really helped me when I was making a parts list for building a WCD with VersaChassis earlier this summer!