Chain vs. Belts?!?

Belt and chain weight is the same when you factor in pulleys/sprockets. That being said I 100% agree that #35 is bulltproof and should be used for a “first chassis” sort of deal.

Assuming you are using aluminum pulleys, the pulley/sprocket weight is probably close to a wash. Factor in 35 chain, the chain is a lot heavier.

Polycord will slip given enough torque. That is either a bug or a feature depending on your needs.

That was the 2014 season, Our Jupiter Robot. No real noticeable issues with belt slip.

Here a match from that season with plenty of pushing.

Wow, I never would have thought that polycord would work in a year like 2014. I’m impressed.

I was thinking about #25. For #35 nothing beats it in terms of weight. :rolleyes:

EDIT: InFlight, that is a gorgeous robot and a great performance! I can’t believe polycord drive worked that well.

Our team has used #35 chain with no master links for the past 3 years. Before that we used belts one year and did some direct drive from the gear boxes before that. Personally i dont see us ever moving away from #35 chain. We have never had a problems with it while i have been on the team, however i think that our first year we did break a few chains dew to improperly installing the master links. Since then we just haven’t used master links and it works very well.

How do you avoid using masterlinks? Do you have a #35 chain tool like the Dark Soul one for #25?

This year my team’s robot had 8" wheels and 22t sprockets, which stressed #25 chain more than in any of our previous drivetrains, and had zero issues. On the other hand, we broke our #25 intake arm chains multiple times, and in the future we will likely use #35 chain for arm applications. At least for our team, we have found applications for both #25 and #35 chain.

Where would you go about getting a dark soul for #25. Our team needs one.

221 Robotic Systems recommends here.

I bought one from Dave’s motors earlier this afternoon and it shipped only a couple hours later. So far they seem to be a good supplier, and they take PayPal which is nice.

Ditto here. I’ve bought two from DDM. (Get a spare set of pins when you do; I’m not sure how long they last after you know how to use them, but we had one break under first time handling by a student on Saturday.)

A similar tool for #35 is available here. As it happens, I’ll be ordering a couple this evening, so I can’t make a recommendation.


For the record, the Dark Soul tool requires slightly different usage for standard duty vs heavy duty (e.g. Vex, and I believe also AM) chains. The difference between the two is the “plate thickness”, that is, the thickness of both the inner and outer plates that run from pin to pin. For heavy duty chain, when removing a pin, it is necessary to go to the point of increased resistance, then about another 1/4 turn. For regular duty chain, doing this will result in the pin being pushed completely out of the outer plate, making it essentially impossible to use that link again, at least by using the DS tool.

Also, take care not to over-tighten on pushing pins into the chain; stop just before the screw pin reaches the outer plate of the chain. Even when doing this, I have found it necessary at times to use a screwdriver of just the right width and a hammer to push the outer plates away so that they do not bind on the inner plates – especially when using standard-duty link-and-a-halves.

OBTW, does anyone know where to source a heavy duty #25 link-and-a-half?

The order is placed. I’ll try to remember to post some info back here in a few weeks. If not, send me a PM around 1 August to remind me!

Edit 2:

On the first tool we ordered (all I’ve had in hand so far), the pins were driven perfectly by 5/32" allen wrenches. That was already our most-used hand tool*, so I just bought a couple more!

    • I even have one on my non-car key ring - not only for use on robot stuff, but the “crash door hardware” at the school and church both use 5/32" hex keys to place the hardware in and out of “access from outside” mode. I pretty literally never go more than 50’ from my house without a 5/32" allen key in my right pocket.

I did notice some online directions for using the Dark Soul tool referencing a millimeter-based tool (4mm, IIRC).

While we do have a few hand held chain breakers, what we use most is a custom press pin we made to mount right to a small bench top arbor that we have. On the face of the press there is a piece of steel with holes drilled to align the chain under the pin and then we just press out one of the pins so it is just in one side of the link. Then remove however links we need to and flip the chain and press the pin back in.

I’d love to hear how these tools perform. I want my team to get away fro Master Links in #35 chain, so just some info about how well it works would be greatly appreciated.

I would be really interested in seeing some pictures of this. This sounds amazing, and a clever piece of engineering.

I will try to get some picture in the next few days. It has done wonders for making chain lengths for us.

We bought that exact chain tool from Amazon for this build season. It works, and it does the job, but the quality is not the best. One of the bolts had a hex socket that was ever so slightly too small, and I had to widen it by pounding the 3/8" hex key in and shaving off a thin layer of metal off the bolt. No other hex key, in mm or inches, was as close to fitting as the 3/8" - which works perfectly fine for the other bolt. I was probably just unlucky, but that’s still bad quality.

Both chain and belt are legitimate forms of power transfer and can be used successfully with proper implementation.

My personal preference is chain for low speed high torque applications, such as drive. Chain takes up much less space than an belt with the same strength. IMO chain has more reliability and strength in a smaller package, with less efficiency and more weight than belts.

Belts for high speed low torque application, the gains in efficiency are noticeable over chain. Also, belt for long runs for weight reduction.

The beauty is there is no right or wrong answer, there just has to be consideration for the down selection and performance desired.

We have been using this little guy for years now and it performs very well. It can be a small hassle to get the new pin to line up properly with the holes in the chain as you tighten down the screw, but isn’t as bad as installing a masterlink. Like everything, doing it with the chain untensioned is going to make your life easier, but we have had success even with chain lengths that are technically too short for where we are using them.

We have a chain tool that looks just like that Gee Two linked to. I think we bought from the same place some years ago based on CD recommendation. Works great. The guides line up the chain and help to hold it in place. Assembling/breaking chain takes a bit of technique. Easily learned through practice.

We have also found this tooluseful for putting master links on chains.

For those considering poly cord for drive train, keep in mind that one wheel per side on Inflight’s nicely done robot was direct driven from the gear box which plays into how much torque needs to get transmitted to the other wheels by the poly cord. The pulleys for the poly cord where also large which helps with the force transfer.

I can attest that that tool is approximately 5-10 times faster to use than the one-size-fits-all spring-loaded chain breaker.