Hello everyone, our team is currently facing an issue with the elasticity of the rubber band we are using to hold the intake frame with rollers for the purpose of intaking purple blocks. The height of the intake is critical for our robot, as even a slight decrease of 1 inch can make it difficult for the purple blocks to reach the elevator where they are stored. Despite releasing the rubber band when not using , it quickly loses its elasticity after only 6 rounds in the competition. We are seeking advice on how to effectively address this problem, as switching to a new rubber band during competition may result in it being too tight, and fine-tuning its position will require significant time and effort. Any suggestions would be greatly appreciated.
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Look at the video by the Flying Cheese robots. They did an analysis of rubber bands, and they give you a link to where to buy them.
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Design with replacing rubber bands as a consumable part. Local teams have figured out how to build the rollers so they can be popped out, re-banded and then put back into the robot fairly quickly.
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Get into the routine of replacing 1/2 of the rubber bands out of sync with the other 1/2. For example, you get 6 rounds of life out of a rubber band. So replace 1/2 at 3 rounds, 1/2 at 6, the first group at 9, second group at 12. So you always have a mix of worn / new bands on the robot. That way your driving experience does not change wildly from old bands to new bands.
Good luck.
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What rubberband are you using and what is your back wall configuration? Do you tie bands? We use #117B Non Latex Rubber bands and they work well.
Hopes this helps and appreciate if you could get back to me!
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The rubber bands causing issues are the ones on the sides that assist in bringing in the purple blocks.
We were using the #64 non latex rubber bands from Amazon. I checked it’s half of the length to the one you mentioned. (3.5 “ and 0.25”)
- I appreciate the advice you gave. I watched Flying cheese’s video on rubber bands and we were using non-latex rubber bands from Amazon instead of the Vex store (which is currently out of stock).
- We didn’t encounter any issues with the rubber bands on the rollers. It was only the rubber band supporting the intake frame that needed to be replaced, causing the problems.
- That suggestion is feasible at the moment. Thank you once more.
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You might want to try the 117B bands for the front. You will need to do the loop and twist double / triple to make them the right size. What you end up with is a multi strand rubber band, this spreads the tension across the strands. It may help your wear issue.
Thank you . You are right. I just arrived at the same conclusion by applying Hook’s law. Connecting the rubber bands in parallel will result in less variation in length due to wear. Our team currently uses the wrapping method depicted in my picture and sketch (orange color). However, if we were to follow your suggestion (green color), the k value would double and the length change would be halved under the same force of gravity, F.
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Please make sure that that this and the picture makes it into your notebook! Judges like this science stuff!