Chain Breaking

Is it just me or are the chains in the chain and sprocket set real whimpy? I have broken at least 10 links on my past few robots and it’s driving me crazy :mad: !! So I think that there should be a new set of stronger chain maybe made out of alluminum or something that is at least stronger than the current chain.

I havent had any problems with mine and i have used mine for high stress gears as long as your careful unhooking them from each other i havent had trouble but i think alumium ones would be great because the plastic stretches a little.

NR i know exactly what you mean, every time i try and use them, at least one of the links breaks.

yea that would be pretty awsome but how would you connect them then. alluminum doesn’t stretch so there would have to be another design for the gears and everything.

I agree that the chain seems to be rather weak. I have successfully loaded the chain with about 3 lbs without breakage. (I didn’t want to stress it to breakage). In all my designs now, assuming the motors have a stall torque of 5-8 lb*inches, I try to use sprocets big enough to avoid chain tensions above 3 lbs. Sometimes, that also means running higher sproket speeds and using gears at the load to reduce speed / increase torque.

I think aluminum would be quite expensive and would make lengthening / shortening the chain very tricky. On the other hand, how about re-designing the tank-tread link mold to give us a beefier chain link? The sprokets already exist in the tank tread kit. I would imagine the tank tread can hold over 20 lbs.

I didn’t mean it to be just aluminum, just something that is stronger than the plastic chains.

yea, i like electronjohn’s idea of modifying the tank treads, those are pretty strong.

i sorta like that idea, but they would have to be scaled down. the tank tread sprockets are huge compared to the chain srockets. I would rather see the old chain made with something stronger, not necessesarily something metal,but certainly something stronger than the current desgin.

that is eaxactly what I thought. The chains shouldn’t get any bigger just stronger

Yea. There has got to be stronger plastics out there that are still flexible enough to adjust the chain length (even if I had to use a little tool to break the chain apart).

The Vex chain is plenty strong enough, as long as it is tensioned properly. If your chain is too tight or too loose, it will snap much easier. Always remember, the Vex Inventors Manual is your friend. If you look in the Chain and Sprocket pages (that came with the chain and sprocket kit) it will explain how to use the chain properly. :slight_smile:

Just to prove that the Vex chain is very strong if used properly, look at these next pictures of a double stage elevator built out of Vex parts, using only a single loop of chain to lift it.

It weighed several pounds, and I had a 99.9% reliability of the chain. (It only broke a few times in some fluke chances.) And it was not like I used this rarely, as I used this at several conventions as a public relations tool for FIRST and Vex. (I eventually logged over 1,200 miles traveling to all of the conventions that I demo’d it at.) I let hundreds of random people drive it, and it was virtually impossible for them to break or tip over.

okay, you have a point. but have you used the chain for high tension driving? as in putting the motors to a chain to the wheels.? thats how i tried it and it broke. i dont think it can handle jerky movemments.

The FVC team I mentored last year used the Vex chain for driving their robot, and they did not any problems with it breaking. Over the course of two competitions (in which they placed 2nd in both) they only broke the chain once, and that was because another robot rode up onto the frame of our team’s robot, and the wheels of the other robot became entangled with the chain on ours.

Although I was a mentor for this team, I only helped them with any issues that came up, and the students did 100% of the design work. When I showed them how to properly tension the chain, they never had any problems with it, even though their robot was quite big and heavy.

Here are two pictures of their robot (We were FVC Team 59 last year, and we are FVC Team 228 - to match our FRC team number - this year). The first photograph is when it the robot was still half completed (there is a lot of chain there!), and the latter is the finished robot with our coach from last season.

So yes, even when used for driving big heavy robots the Vex chain is still plenty strong enough. :smiley:

P.S. Hahaha! I just noticed that the elevator from my Vex ‘Space Elevator’ robot is in the top picture. That was the meeting I brought it in to show them the possibilities of the Vex chain and sprockets. :smiley:

At the NJ regional, i was talking to a member of a VEX team and he said that the chain always broke for a robot.

also, can you help me with proper tensioning facts? any help would be appreciated.

Usually I try to have about 1/4"-3/8" of give (if you push the chain with your finger) for about every 4-6 inches of length between sprockets. Over time the chain can stretch a little (all chain stretches, even steel chain), so I would suggust that you experiment with different tensions until you find a good one that works.

A good way to tension the chain is to use a long bolt and those black spacers. By using these, you can put the bolt in different spots where it can rub against the chain to give it tension. As long as the plastic spacers are what makes contact with the chain, there will be very little friction.

thanks for your help.

what about PVC?:smiley: :smiley:

mine allways slips:mad:

why don’t they use a bycicle chain design?
it is made of aluninum and they hook like a hook and a bar, and it is scaled down to the old chain size…

basically if you use chain that is stronger its a pain to use. i learned from my rookie FRC year all about master links and chain breaks. trust me, the weaker chain is worth the convience of not having to deal with that at all. think about it, if the chain was stronger could you just snap it together or apart? what I like to do is power one wheel on a chain drive either direct to the motor or with a gear so if the chain does break it will still drive. but if you are really desprate for strenght use tank tread as a chain.