Our catapults turning point is mounted on a shaft. However due to the tension placed on the catapult it’s causing the shaft to flex which in turn causes our entire bot to flex. How do we prevent this without adding significant weight to our bot?
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I don’t do IQ competitively, so I don’t know how much this would help, but I recommend adding another beam (Like the one you have on the inside of your drive) closer in to the catapult, after switching the axle, because I don’t think that one is still usable.
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You can always use more standoffs and “box around” the axle to keep that end from twisting in. They are pretty light and they will be at the force end of the lever/catapult, so the extra weight will be a bonus.
I’ve built “double axles” Take two 1x2 beams, put the existing axle through one end, pin the other end to the support beam. Put a custom length axle into the center hole, secure on the far side the same way with two 1x2. Now the load is distributed across two axles 1/4" apart. Depending on the span, you can put one or two 1x2’s in the middle. Your span isn’t that far, so it shouldn’t be needed.
Good luck!
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Why isn’t there a shaft that passes through the entire catapult part? That would help significantly . Fix the shaft points and make a proper mounting. Support the sides and brace to be more stronger.
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That is a lot of flex. Our last bot had a similar problem, we fixed it with instead of having the axel bridge the entire bots length, do a smaller catapult with two axels and beams.
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The shaft does go through the entire catapult so I’m not quite sure what you mean.
We’ve tried boxing it in before and it didn’t do much and adding more shafts added a lot of weight but if we have to well go back to it.
Can you build out from the supports so there isn’t such a huge distance between the support and the catapult? From the picture it looks like you have 2" gap on either side.
Like a stack of pinned together 2x2 squares with the shaft going through the middle? That puts the weight on the frame and gives the shaft less distance to flex.
You may need to put two 2x6 then two 2x4 then two 2x2 to give you enough support for that distance.
The bending is not the problem of the axle, but instead the entire robot itself. Use cross-bracing and multiple other reinforcement methods to support the structure. Also place beams at the top of the robot to connect both sides.
Also if you reinforce the robot enough, and secure the axle well (put shaft collars as close as you can to the robot), the axle shouldn’t bend as much.
To avoid this problem entirely, our team simply used a beam in place of the axle. (We placed the beam so the sides face horizontally for more strength).
So you mind sending a photo I don’t quite understand, but yes we will add more cross bracing
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The shafts that are the points where it connects -
What are those? It looks like shafts that go through 1 hole but they do not connect together. Wouldn’t you want the shaft to go through the entire catapult?
It just likes like that it’s actually a 12 inch shaft that goes all the way through you just can’t see it from this angle,
I think what you mean is to bring the points where the axle intersects with its supporting parts closer together so the axle has less room to flex. Am I right in assuming this?
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I also eventually got that and tried building walls on the inside of the drivetrain and fixed it.
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