How to properly rubber band?

Hello, so I have been seeing a lot of robots that use an insane amount of rubber bands/ elastics on their robots and then will only use 2 motors on their DR4B lifts and seem to have no issues with burning out, while using a 1 to 5 ratio. While, my team will use a 1:7 gear ratio and 4 motors on the DR4B and occasionally burn out. Is there a certain way to make the triangles on your lift, and if so can someone please help me to understand. (structure and math kinda of thing) Thanks for the help.

If it is your first time using rubber bands on your lifts or in general just stick to a straight line of bands, opposed to a triangle as the concept is a little hard to wrap your head around if you don’t already understand how normal straight rubber banding works :slight_smile:

So for example our RD4B has two screws poking out of it and we have elastic tubing running between the two points. 27606330_751378941721882_1827771473_o - Copy.jpg

We have 1:5 on 2 motors(speed) and this works well. What is your internal gear ratio?(in the motors). The two screws are moved away or closer to eachother to adjust the power the bands give. The bands should be put on in such a way that they are pulling the two bars of your 4 bar together.

Hope this helps a little, anymore questions are fine :slight_smile:

Here is a link to the Uniformly Tensioned Rubber Band System Analysis/ Guide post from team 599D that does a great job of explaining the use of elastics.

on an unlrelated note, why are you doubling up on so much of your c-channel?

Because it makes the bars more strong basically. Go grab a full length bar when you can and try to bend/warp the bar by holding both ends of the bar. It should warp pretty easy, so having two bars counters this problem. There is probably a guide on the forums about this somewhere, however I am too lazy and I think that’s an alright bit of basic reasoning on why. Boxed bars = strong and straight bars :slight_smile:

Pretty unnecessary…

Ehhh We found the RD4B would swing around a lot the higher the lift went. So this was the only solution we could see viably working. :slight_smile:

You could use cross bracing. If you are using axle joints on non-gear arms you can change them to screw joints.

We are using screw and we have a good amount of bracing. We just prefer that yummy stability :stuck_out_tongue: