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Rossyspsce wrote:

cuber wrote: • A rack and pinion was verry successful, and I came in second despite my alignment screw inexplicably coming loose, and the car veering 5cm. It simplifies the setup massively because you do not need to acomidate for initial angle.

Can someone explain this for me please?

I think I know what Cuber is saying so basically he has a chassis where the mouse traps sit then he has a front piece that can be rotated. So he has screws to adjust it then tightens it to lock the angle of it in place. Correct me if I'm wrong though.

How long of of a rod and string is needed to travel the 8 meters with 3 inch diameter wheels?

cuber wrote:My car fits within the 40cm² box perpendicularly, but I measured it diagonally because i was cutting it close. The ES (who is the ES of the national competition) informed me that while this was currently accaptable, there verry likely will be an FAQ or rule clarification coming out soon that would make this impossible.

You've got to be kidding me...

DarthBuilder wrote:

Rossyspsce wrote:

cuber wrote: • A rack and pinion was verry successful, and I came in second despite my alignment screw inexplicably coming loose, and the car veering 5cm. It simplifies the setup massively because you do not need to acomidate for initial angle.

Can someone explain this for me please?

I think I know what Cuber is saying so basically he has a chassis where the mouse traps sit then he has a front piece that can be rotated. So he has screws to adjust it then tightens it to lock the angle of it in place. Correct me if I'm wrong though.

I proposed this idea earlier in this thread, but I will explain it again. Baisically, the dowel is not fixed to the chasis, but instead a 10cm rack gear. A set of bevel gears transfer rotation from the front wheels 90 degrees to a pinion, which extends the rack as the car travels forward. The dowel touches the cup at first, but extends outward while the car moves straight. This strategy is not practical at nationals because you would need a 50cm rack, but nationals wont be in the cards for me so I tried it. it was not as “easy” to implement as I originally thought, but 3d printed gears do help quite a bit.

dragonfruit35 wrote: Also, @ cuber, do you mean that your car was 5cm off the VTP and you got second? How close was the cup to the CTP?

I was about 6cm off the CTP, with a 9.8 second run.

Going off of your outside the box thinking, You can make it so that when your trap fully clamps down, it clamps onto some accordion-like thing that pushes air into a 25cm long plastic straw with a perfectly fitting magnet iniside. As the magnet gets pushed along, your dowel would also have a magnet (not strong enough to resist the force of the air pushing the magnet along the straw) and it would follow that magnet in the straw to end up 25 cm to the right of your car. This seems pretty simple to make.

cuber wrote:

DarthBuilder wrote:

Rossyspsce wrote: Can someone explain this for me please?

I think I know what Cuber is saying so basically he has a chassis where the mouse traps sit then he has a front piece that can be rotated. So he has screws to adjust it then tightens it to lock the angle of it in place. Correct me if I'm wrong though.

I proposed this idea earlier in this thread, but I will explain it again. Baisically, the dowel is not fixed to the chasis, but instead a 10cm rack gear. A set of bevel gears transfer rotation from the front wheels 90 degrees to a pinion, which extends the rack as the car travels forward. The dowel touches the cup at first, but extends outward while the car moves straight. This strategy is not practical at nationals because you would need a 50cm rack, but nationals wont be in the cards for me so I tried it. it was not as “easy” to implement as I originally thought, but 3d printed gears do help quite a bit.

dragonfruit35 wrote: Also, @ cuber, do you mean that your car was 5cm off the VTP and you got second? How close was the cup to the CTP?

I was about 6cm off the CTP, with a 9.8 second run.

How long of a drive rod and string did you use?

We bought ball bearings that are slightly larger than our rod diameter (about 0.025" or 0.6mm larger). I just tested it and the rod can wiggle inside the bearing. Will this still work? Or is the ball bearing part not even going to spin.

sciencecat42 wrote:We bought ball bearings that are slightly larger than our rod diameter (about 0.025" or 0.6mm larger). I just tested it and the rod can wiggle inside the bearing. Will this still work? Or is the ball bearing part not even going to spin.

If the rod can rotate within the bearing, it won’t work properly. You should be able to fix this by adding a layer or so of tape on your rod over the part where the bearing goes.

Does anyone have any good ideas for mousetrap braking systems?

'JordanC22 wrote:Does anyone have any good ideas for mousetrap braking systems?

There's a forum for it here: viewtopic.php?f=292&t=12731