I’m not sure why you guys are having so much trouble with extrusion. For our last two yearsour robot has been built entirely out of extrusion thanks to our great sponsor item mindwest.

You can see our 2003 robot here.

During the entire season we have made zero repairs to our robot structurally. At the Midwest Regional all we had to do was swap out a drill motor as far as repairs go. And then at IRI we never even needed to touch a wrench to the thing.

I am guessing that your problems reside in either using improper construction techniques or inferior extrusion.

We used Extrusion for our frame (#64 Gila Monsters) in 2002. We survived our first regional in Seattle without needing any repairs to the frame, but we needed to replace the front after the LA regional...

Some things to consider though.

a) We seeded first and with team 60 and 330 we ended up winning (so we played LOTS of competitive matches)

b) Mike Rush told me, "In elimination rounds, do what we say we can do or break the robot trying"... needless to say I did, and it worked ;)

So, although it broke... it also went through more than its fair share of abuse :yikes:

On another note, we did not have any 'sliding' issues, and if you tighten everything regularly you shouldn't either. For simplicity, teams that do not have access to welding can benefit greatly from extrusion :)

Yes, that would be due largely in part to us - The Circuit Breakers 696. We were the one with 968 and 294. We had the pink bumpers and tall pink and green flags. Glad to hear we broke ya good. j/k Anyway, we had some great matches there and I hope we play again some day.:)

Except hes talking about 2002 and youre talking about 2003 :)

Cory

I was a field attendant at that competition, and I have a 2.5" piece of extrusion from that robot, sitting here on my desk. It was left on the field, after one of your more violent matches, and I decided to keep it as a souvenier, in honor of the first swerve drive robot I'd seen in real life.

I suppose it was such a great story I thought it could be applied to any year. j/k I had the alliances way wrong for the year didn't I.Anyway, sorry for the mistake. Oops.

Beside that, my team has used extrusion for the past three years with great success. We tighten all the fasteners to where "feel of the hand meter" reads "tight as it can be without breaking or bending or stripping anything" We do regular maintainance on the machine and have never had anything slide or pull out. It's fast to cut and assemble and is very dependable and changeable.

One problem that we had with extrusion was our chains becoming slack, although it was much easier that in previous years to fix because of the slots. One thing that we are planning on doing for Cal Games is making a block that bolts into the 80/20, and has a screw running parallel to the 80/20 that can push up against the pillow plock to tension the chain. After a whole season, we have noticed loosening of bolts and stuff, but its really nothing regular maintenance wont solve.

Cory

We've never had such a problem, and we've been using extrusions since '01. We only tighten then once or twice in competition, with no failure until now. :)

Cool! It was one of the first swerve drive systems I remember too, I was actually surprised when I saw another at NATS that year... I thought we were the only darned creative ones :yikes:

As cool as it was though, it was very hard to maintain. It took 10 minutes to swap out the gears for ONE wheel, and then the motor calibration in the program was insane. That is why I have these nice blueprints on my desk for swerve^2... its motto would be, "All the swerve, none of the fuss" :rolleyes:

Anyway... back on topic. This wonderful story goes to show that even after a year... extrusion from our robot is still around... somewhere at least :D

As far as I know...our team has used extrusion for at least the last 3 years with little or no problems. It does get scratched and chipped every so often with impact but it, as far as I know, it hasn't bent to a big degree unless really hit hard. We use extrusion for our frame every year not to mention other parts. Every so often, we'll just go around and hand tighten everything and it does just fine. I'd recommend it. It is really easy to work with as long as you have the other hardware (t-nuts, gussets, etc.)

Mikes-chassis
 

....Hey,
Extrusoin is great for a rookie team. It's easy to work with, durable, interchangeable and long lasting...... Just keep the bent sheet aluminum parts to a minnimum :)

As far as the power/turning ratio, my team sorta beat the system last year. We used one of the pneumatic pistons to lower a plate on which two casters were mounted. If we needed to turn quickly, we hit the trigger, dropped the plate, and it turned on a dime. For power, and to stay up on top of the ramp and to climb up the ramp, we'd raise the plate. This gave us the maximum power of our drivetrain design, with the added maneuverability of a two-wheel system.

comment on the whole ready-made chassis thing: I believe it takes away from the robotics experience. Part of the fun(and panic) is designing everything from scratch. Only time will tell what they're going to do

The only problem with this is that some rookie teams don't know where to start. I have horror stories about some rookie teams showing up at competition expecting to build their robot AT the competition. Granted that most rookie teams these days are started by experienced FIRSTers, having an already designed base at your disposal is a great learning tool ;)