pic: Team 973 2009 Robot - RAPTOR
 

Re: pic: Team 973 2009 Robot - RAPTOR
 

this bot is disturbingly beautiful. i just spent 10 minutes staring at it and appreciating it.

Re: pic: Team 973 2009 Robot - RAPTOR
 

There is a slightly simpler version :p , check out ours:
http://www.thebluealliance.net/tbatv/team/245

There is also another robot out there that is similar:
http://www.thebluealliance.net/tbatv/team/121

The different variations of this design seem to be winning a lot of competitions this year. :)

Re: pic: Team 973 2009 Robot - RAPTOR
 

This pic just made my favorites list ... I was wondering whatever came of your request for inexpensive tight-tolerance aluminum rods.

How badly does the ABS fatigue, and is this pic of the bot after a competition? It looks like the lower front pulley of your exhaust is bending inward a bit.

Re: pic: Team 973 2009 Robot - RAPTOR
 

My favorite thing about Raptor are the 28 (I think there are 28) RC Car tires on the 2 ABS intake pulleys.


Oh and the black Garolite.



Great job in LA guys!

Re: pic: Team 973 2009 Robot - RAPTOR
 

I really like ya'lls rollers , made from ABS eh?
care to mention where you got the material and how you machined them so nicely?:D

Re: pic: Team 973 2009 Robot - RAPTOR
 

eh, it's not too orange Adam.

Can never have too much orange... :rolleyes:

Re: pic: Team 973 2009 Robot - RAPTOR
 

I second that... Although some teeth and eyes would be nice. You can't have a raptor without teeth :)


What exactly are all the holes in the frame for? Did you drill all those yourselves, or was it some type of extrusion that had holes in it already?

Re: pic: Team 973 2009 Robot - RAPTOR
 

I believe those were for weight savings.

Re: pic: Team 973 2009 Robot - RAPTOR
 

Trust me, we drilled them all ourselves. And then we deburred* them...
It took FOREVER. :ahh:

*Spelling?

Re: pic: Team 973 2009 Robot - RAPTOR
 

The holes are something I invented a while back to irritate the kids use as a standard mount. It's a #7 (.201) Hole on a 1/2" hole pattern. It actually hasn't been used much so far, as we got close on weight we started welding things on (and haven't had many last minute additions) along with the fact that because the kids were whining, we didn't do every face, so we mounted to some faces lacking holes. #7's are great as they are a #10 bolt clearance, tap size for a 1/4-20 and work fine with normal 3/16" rivits.

Some were done on a drill press with a jig, some were done on a manual mill.

If it were done for weight, it wouldn't be worth it, as each .201 diameter by 1/16" long disk removed must be extremely light. .0002 pounds actually.

As for the RC car tires, we use 28 on the intake, 14 per pulley, and an additional 14 on the exhaust pulley that touches the hopper. With the 6 in drive, that's 48 "wheels".

We never actually bought precision shaft, just ended up using rod and polishing it.

We haven't noticed any ABS fatigue, and the intake pulley doesn't bend at all in that picture, probably an artifact of the cropping in photoshop. There is a 1" OD, 1/8" wall 6061 tube running down the center of him that does a pretty good job of keeping him straight. However, any pulleys without such a sleeve put under high tension do bend, so most pulleys on the competition robot have at least a 1/32" wall thick sleeve.

Thanks for all the kind words.

Re: pic: Team 973 2009 Robot - RAPTOR
 

One of my favorite robots this year, if only because it rivals Team 100 in orange-ness :p

I have couple basic questions about fabrication, it seems like you did some of the same things we did, but much better. How did you join your urethane belting together? Where did you purchase the ABS tubing, and why go with ABS instead of PVC? Judging off of McMaster's prices PVC seems like a much much cheaper material choice. And last question, how deep are the grooves in your ABS, and have you had any problems with belts skipping off?

I love the design, any tips you can offer would be appreciated, our only belt system doesn't look remotely as good as the 5 you guys have on this bot. Excellent job 973!

Re: pic: Team 973 2009 Robot - RAPTOR
 

After looking at all the material properties, we chose (guesstimated) that ABS was the best material to go with.

We actually bought 2.5" OD ABS and had it turned to 2" OD. A local machine shop specializes in tubing and it was no problem at all for them. They were turned to 2" OD, cut to length (they held 29.5 to 3 thou!), gundrilled at 1" thru, and finally bored to 1.125" for 1/2" on each end. After all that, a 1/4" round grooving tool was used to groove 3/16" deep. In hindsight 1/4" would be better, as we've had some small issues with belts jumping, but most jumping issues were solved when we used properly tensioned belts; I think I only saw 2-3 belts jump at LA.

In terms of price, it's not cheap stuff exactly, but we always do our homework and shop around. We think if you're buying massive amounts of material from mcmaster, you're doing something wrong. I think we ended up going with Interstate Plastics, who had it for somewhere around $16-19 a foot after haggling.

We weld our belts with a soldering gun with a spade tip and a jig we bought on ebay for specifically welding round belt. Works great. In terms of strength, there is no difference between that and a Jig would made that was basically two plates with matching slots, but it's certainly easier to use. We initially trimmed them with dykes that were custom ground to have no back angle, but while being lazy I found that a table belt sander works great (not sure if fine grit is required, it's what we used and it worked great for us).

Re: pic: Team 973 2009 Robot - RAPTOR
 

Wow, thanks for the detailed response! Seems like you were fortunate to have that machine shop with tubing capabilities, probably not something a lot of teams could pull of with a basic lathe. In any case, thanks a lot for the insight! Good luck at Las Vegas and Champs!

Re: pic: Team 973 2009 Robot - RAPTOR
 

In 2006 we turned the rollers for our practice bot on a 13x40 lathe (fairly common size for any kind of school machine shop with lathes) without much difficulty.

As long as you have the travel it's not too hard to do it manually. Takes a long time though.