Chain Slack-Tower takeover

Just today I’ve moved my drive motor from directly driving the wheel, to driving it from a chain. Whats happened now is that the drivetrain is now being chained in the front. To make space for a tray. But the chain fell off because it was too loose. Will putting some slack by adding an extra link make the movement of the robot imprecise?

What I would recommend is by adding some sort of tensioner that uses rubber bands, that way the chains are always tensioned well. If it is possible, you could also try gearing the wheels to reduce slack


I get the point. However how would you add tension to a chain using elastics bands. Wouldn’t that add friction to the drivetrain.

Ideally no, you shouldnt add so many rubber bands that the chain is hard to turn, it should be just enough to lift up the chain and provide tension, but also should be easy to push back down. It might take some adjusting to work

Is that someone which you have done before, because wouldn’t the chain pull the elastics along with then when being moved?

No, but I’ve seen a team do it in turning point. I’ll draw a quick pic to illustrate it.

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I drew this on my phone, so it isn’t the best

it really hard to depict, maybe if you have a physical example take a picture.

I made something like it what @Railgunawesome is describing, but it is probably not the ideal tensioner, a nylon space on a screw or a idler sprocket would work better.

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Yes, somewhere along the lines of gameoa but more like a c channel with a spacer for the chain to run over. The c channel would be attached via axle or screw joint to the chassis. The rubber bands would be attached to it similar to how the tray foldout is setup. The c channel would rotate and thus tension the chain, and would be pushed down when the chain tightened, ie when. Your bot starts moving.
You could also use what @Gameoa has shown, but mount the sprocket on a c channel or piece of metal, then use rubber bands to push the sprocket down.

I know I posted a picture of a simple tensioner a while ago. Let me see if I can find it.


This tensioner isn’t on a robot (obviously), but it shows the idea of using a spacer rather than a sprocket. When trying to compact a tensioner using sprockets, you’d likely end up with a 6 tooth sprocket, which are if I remember correctly are notorious for breaking chain. A nylon spacer does a better job without even having to rotate. Just let the chain run over it and the smooth surface should take care of the rest. :​)


You could also try moving the motor or changing the size of the sprockets (assuming you kept a 1:1 ratio) to get a better natural chain tension.