pic: 4242 Preliminary CAD 2



Team 4242’s preliminary CAD. Elevator with a ramp on the back for delivering totes from the chute to other bots consistently. Ramp isn’t done yet and there’s an extra sprocket in there. Please feel free to tear it apart or tell us something we haven’t thought of yet!

Have you put into consideration of the CoG? That’s what our team is having issues with right now.

Within the CAD Program’s features, we tested the CoG of our original design and found 2 totes would make it tip over and have a catastrophic failure. Since then we have revised the design.

Yeah, we quickly found out that that design does create some interesting CoG problems as well. I urge you to investigate it now while you still have time to fix it.

Have you put into consideration of the CoG? That’s what our team is having issues with right now.

Within the CAD Program’s features, we tested the CoG of our original design and found 2 totes would make it tip over and have a catastrophic failure. Since then we have revised the design.

Yeah, we quickly found out that that design does create some interesting CoG problems as well. I urge you to investigate it now while you still have time to fix it.

Did you have CoG problems after weighing down the back end or before? The plan is to put around 25lbs back there.

Keep in mind that the battery is ~13lb. That is a free counter balance if you locate it correctly.

It is possible to build a design like this and offset your COG somewhat if you are deliberate about putting all of your extra weight in the back.

My concern would be about the elevator twisting. If I was using the REV extrusion or 80-20, I would consider something like Team Indiana’s elevator which used four posts instead of two for more support.

Fixed that for you.

you could also move your lifting posts behind your front wheel to help with CoG.

Please ensure that your design and your manufacturing methods allow you to adjust the spacing of the vertical rails so that they are locked at the correct spacing for the lift carriage and so that the vertical rails are the same distance apart at the top and the bottom. Otherwise, your lift carriage will not move smoothly or may jam at one end of the travel.

You may also want to consider the various height limitations, direct and indirect, especially if your team intends to do well.

Good insight, philso. We were going to tap the ends of the uprights and fasten them to the top piece but we may go with angle brackets now for adjustability. We also plan on putting a crossmember on the angled supports for rigidity.

You’re right. we’re trying not to bite off more than we can chew. I’d much rather a more limited design that does one or two things consistently.

Thanks

It is not clear how tall your robot is. My comment about the height limitations is a reference to the direct height limitation (see R3 in the Game Manual) which is obvious and one that is not so obvious (see http://www.usfirst.org/sites/default/files/uploadedFiles/Robotics_Programs/FRC/Resources/2015_Shipping_Crate_Construction.pdf). It would be sad to see a team have to take a hacksaw to their robot before bagging it after winning at a regional. The height limits have been discussed in some other threads here on CD.