Mousetrap Vehicle C

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Re: Mousetrap Vehicle C

Postby DarthBuilder » January 5th, 2019, 6:21 pm

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.
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Re: Mousetrap Vehicle C

Postby Zxcvbnm123 » January 5th, 2019, 7:00 pm

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

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Re: Mousetrap Vehicle C

Postby PM2017 » January 5th, 2019, 9:08 pm

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.


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Re: Mousetrap Vehicle C

Postby cuber » January 5th, 2019, 10:00 pm

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.

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Re: Mousetrap Vehicle C

Postby Bitconnect » January 7th, 2019, 6:30 pm

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.

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Re: Mousetrap Vehicle C

Postby Zxcvbnm123 » January 7th, 2019, 9:10 pm

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?

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Re: Mousetrap Vehicle C

Postby sciencecat42 » January 9th, 2019, 10:49 pm

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.

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Re: Mousetrap Vehicle C

Postby dragonfruit35 » January 10th, 2019, 4:54 am

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.

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Re: Mousetrap Vehicle C

Postby 'JordanC22 » January 12th, 2019, 4:56 pm

Does anyone have any good ideas for mousetrap braking systems?

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Re: Mousetrap Vehicle C

Postby Rossyspsce » January 12th, 2019, 10:28 pm

'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

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Re: Mousetrap Vehicle C

Postby sciencecat42 » January 13th, 2019, 11:20 am

dragonfruit35 wrote:
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.


I tested it without any tape and the rod seemed to rotate with the bearing just fine, although I'm not sure what happens when the rod spins past the top of the bearing as gravity would take over.

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Re: Mousetrap Vehicle C

Postby sciencecat42 » January 13th, 2019, 5:05 pm

What has everyone been using to attach the arm to the mousetraps? I've been using wire and tape but these are either super tedious to attach or not very modular.

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Re: Mousetrap Vehicle C

Postby dragonfruit35 » January 14th, 2019, 7:40 am

sciencecat42 wrote:What has everyone been using to attach the arm to the mousetraps? I've been using wire and tape but these are either super tedious to attach or not very modular.


I’ve used mini zip ties both last year and this year and they seem to work fine if you put a few of them.

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Re: Mousetrap Vehicle C

Postby Rossyspsce » January 14th, 2019, 7:40 am

sciencecat42 wrote:What has everyone been using to attach the arm to the mousetraps? I've been using wire and tape but these are either super tedious to attach or not very modular.


I use zips ties and a drop of ca glue. This is what most if not all teams in the area use, besides the one or two teams that have a 3D printed jig

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Re: Mousetrap Vehicle C

Postby sciencecat42 » January 14th, 2019, 8:28 am

dragonfruit35 wrote:
sciencecat42 wrote:What has everyone been using to attach the arm to the mousetraps? I've been using wire and tape but these are either super tedious to attach or not very modular.


I’ve used mini zip ties both last year and this year and they seem to work fine if you put a few of them.


Can't believe that I didn't think of that earlier. :lol: What's the best way to attach the mousetraps to the chassis? I tried screws but I ended up splitting the mousetrap wood so I've been using superglue but then I can't swap them out.


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