Poly Cord

[RoboCat2005]

Where is the best place to get the poly cord that a lot of people used in 2006?


Also:
How well did it work in roller system for picking up the balls in the 2006 game? I was not around for that game to much.

[Tom Line]

Look up urethane belt on mcmaster.

[wireties]

http://www.durabelt.com/roundoringinfo.php

This is the company that makes the stuff. Look for distributors in your area or on-line.

HTH

[mathking]

From McMaster-Carr: link

This is what we used in Lunacy.

[Chris Fultz]

We ordered ours from McMaster. It worked well. There are some guidelines on measurements and what to order and if you follow that it worked very well. (There is a recommended stretch).

[Drivencrazy]

Do you guys order specific lengths or do you order extra and cut to length? If you do the latter then do you use those quick connect fittings or do you weld them together?

[BrendanRadabaug]

Originally Posted by Drivencrazy

Do you guys order specific lengths or do you order extra and cut to length? If you do the latter then do you use those quick connect fittings or do you weld them together?

we used it in 2009 and ordered extra to cut to length (built 4 duplicate robots that year that were all a little off from each other). to hold them together we welded them with a lighter and then used a sander to shave off the excess bumps that formed from pressing the two ends together. if you go with welding the ends let the cord sit for a couple hours after heating to let it fully set.

the extra was used to whip the engineer in charge of designing the robot because of how much "fun" it was to put on the robot.

[Peter Matteson]

Originally Posted by BrendanRadabaug

we used it in 2009 and ordered extra to cut to length (built 4 duplicate robots that year that were all a little off from each other). to hold them together we welded them with a lighter and then used a sander to shave off the excess bumps that formed from pressing the two ends together. if you go with welding the ends let the cord sit for a couple hours after heating to let it fully set.

the extra was used to whip the engineer in charge of designing the robot because of how much "fun" it was to put on the robot.

We have used the same technique on all our robots using round or flat polycord. (04, 06, 08, 09, 11)

[Phyrxes]

We used the solid polycord from McMaster in 2009. We created a jig and purposed an old soldering iron as the heating element to fuse the ends together, as was previously stated the stretch factor is important.

[mathking]

We used a piece of steel angle as a jig, clamping the two ends together. We used a creme brulee torch (a small butane torch) to heat the pieces together. As was pointed out earlier, they then need time to cool completely before they are used. Also, be really careful when you sand or cut off any bubbles or bumps. I recommend practicing on a few short bits. One of our mentors and one student became very adept at the welding, so we had one of them do it whenever we replaced the cord.

Side note: If you use polycord that needs welding, you are going to want to have a bunch of replacement lengths already welded when you go to competition. (In general no open flames allowed in the pit area.)

[IndySam]

We used hollow with connectors for Lunacy and never had a single failure.

[Ian Curtis]

Originally Posted by Chris Fultz

We ordered ours from McMaster. It worked well. There are some guidelines on measurements and what to order and if you follow that it worked very well. (There is a recommended stretch).

The recommended stretch 10% is pretty overkill in my experience with the 3/8 solid. If you have more than three or four belts it takes a huge lever arm to get things to line up, and you take a huge performance hit from the all the friction in your bearings. We found 5% much easier to work with, and we even did 3% with no difficulties. (Though as a precaution we shipped the robot with the 3% belts removed so they didn't stretch over time)

[Tom I]

My team used solid core round belting belting material in Aim High and it worked very well for us, but it was a BEAR to melt together. In Lunacy we switched to the hollow core tube belting and used the metal barbs that came with it, and that worked just as good, no failures.

There's a big discussion about the use of polyurethane round belting here if you're interested.

[chadr03]

Did you use a drive pulley manufactured for poly cord belts, or make one? It looks like some of the drive belts are made out of a piece of pvc pipe with spacers or something similar. It looks like it could get pricy quick to buy multiple drive pulleys.

[Drivencrazy]

What OD's did you guys use in the hollow and solid applications? I would think somewhere around 1/4" would be sufficient but then again I've never used them before.