Re: polyurethane tubing
 

We used 1/4" hollow tubing from McMaster joined with barbs and we've been very happy with it. We've only had one failure, but that was on a belt that had been used for dozens of hours at a very high speed (it was also stretched a little too...aggressively). For a re-fit, I would HIGHLY recommend the hollow tubing, as if you need to adjust the tension you can easily insert or remove sections of belt in seconds.

Re: polyurethane tubing
 

Team 2228 used the hollow yellow polycord from McMaster with the barbs. Package of 25 was about $5 and we reuse them. The polycord was $1.12 per foot. I second the warning on the amount of stretch you apply. We found 8-10% way too much, particularly if you have a lot of belts loading the motor shaft. We found about 3% did the trick and reduced the motor torque load. I would suggest bearings on the shafts, particularly if you have a lot of belts or stretch them aggressively.

Re: polyurethane tubing
 

Fron Anyheck:

Our feed system uses 50 total (10 sets of 5) of the polyurethane belting o-rings to pick up and transport balls. Over 125 FEET of belts. We're using 1 CIM to drive the feed system. We used the 1/8" belting because we had already made all the rollers for a rubber o-ring sytem that didn't work. You'll recognize the robot from the Bayou Regional, team 2992, the red turreted shooter with the flaming ball on the side. Lots of pics of the belts on the website, http://team2992.com







We run the feed system continuosly and it will hold 12 balls. The balls are controlled with belts on both sides so there is no relative motion between the balls. The belts slip until the "gate" opens and allows the balls to feed the turret. Belts are melted together with a cigarette lighter as described by others. We had no jams or broken belts during the Bayou. We were running the feed system at 2 feet/second (600 RPM on 3/4" diameter rollers) to give us a feed rate of 2 balls/second at the Bayou, we're going to double it for the Championship.

Contact me if you need anything, I'm in Slidell.

Re: polyurethane tubing
 

One aspect I never realized before, this is an upgrade to do at champs. No time to really tweak or test.

I'd go hollow with barbs, cut them long, say, for 3% stretch. Test. Need more stretch? try 3.5%. That's a really easy fix with hollow.


You guys are rookies :ahh: :ahh: :ahh:

Keep up the great work, that's simply fantastic.

Re: polyurethane tubing
 

Using the pheumatic tubing would be a much easier change them trying to weld some belting together. Mcmaster sells the barbs needed to connect the end of the pheumatic tubing.

Re: polyurethane tubing
 

We've got you beat at 220 feet of tubing. ;)

Re: polyurethane tubing
 

We've got you beat at somewhere between 300 and 350 feet. We know the exact amount, but are keeping it secret for now.

We'll be having a guessing game in our pit for a prize.

Re: polyurethane tubing
 

The only problem with the peumatic tubing is it isn't very stretchy, so it would be hard to get it to put enough force into roller to have enough friction so it would actually turn with the roller.

An alternative would be surgical tubing. My team did some prototyping with it and it worked very well. We went with the polyurethane belt instead, but I would still say the surgical tubing is a reasonable option.

Re: polyurethane tubing
 

I have used your own tactics against you and have created a spread sheet that gives me an exact number that may or may not be within the range you have stated. Take that, guessing games that I can never win! :ahh:

Re: polyurethane tubing
 

How do you figure? We have two drive rollers in the center, and coming off of them are tubes going up to upper idler rollers as well as lower idler rollers. We have no issues at all driving them. We specifically used the pneumatic tubing because it does not stretch as much as other types of tubing does.

Re: polyurethane tubing
 

I'd have to agree:D Polyurethane tubing stretches after long use(usually goes back to its original form later) and surgical tubing...it's surgical tubing and is not very fun to watch snap during matches because attaching the ends isn't an exact science.

Re: polyurethane tubing
 

I'm curious to how it would perform at speeds many other teams had their conveyors running at. Also, curious about the relative efficiency.

Did you use stock globe gearboxes? and what was your pitch diameter?

Re: polyurethane tubing
 

They use stock globe motors attached directly to the rollers.

I think that if rollers were run at higher speeds, the pheumatic tubing would be less effective due to the lack of stretch that it has. Probably just end up locking up the motors, or the tubing would be too loose.

Re: polyurethane tubing
 

It doesn't perform at speeds similar to other teams.

The Globe's are unmolested and the rollers are 2 inch od. if I recall.

Re: polyurethane tubing
 

This is interesting to me. My team used 5 foot lengths of the polyurethane belt and it needed to be at least cut 5% shorter to have proper tension. We powered the bottom rollers and had a roller at the top and two more idlers in between. The only problem we seriously encountered in prototyping was not enough tension, and with the pneumatic tubing, we simply could not get that tension. It is also important to keep in mind that we were using and FP with a 6:1 reduction. Our conveyor system was very fast and without proper tension it lends itself to belt slipping. We had 2 inch rollers as well.