Mousetrap Vehicle C

[Rêveur]

Is there anything in the rules that disallows our rod from hitting the ground when the vehicle stops? Our rod is a flexible metal so when our car brakes the rod keeps bending and hits the ground but bounces back up. This doesn't actually affect the run of the vehicle in any way, but the proctor at Northview informed us that it's something we might want to watch out for in future competitions. I just want to be prepared in case any other proctors bring this up.

Could be seen as a construction violation b/c of 3i "The only parts allowed to contact the floor during the run are wheels/treads, drive string(s) and those parts already in contact with the floor in the ready-to-run configuration.

[biz11]

What materials have people been using for the lever arm?

Also, if anyone could post what a good weight to aim for for different parts of the car that would be really helpful (drive axle weight, frame weight, power axle+wheels weight, breaking axle+wheels weight.) I ask because my current car is approximately 400 grams and want to know the best areas where I should be looking to cut the most weight. One other thing, I noticed everyone on here has said to use fishing wire for the string. Is there any reason to prefer this over regular thread or some sort of reinforced quilting thread?

[dragonfruit35]

What materials have people been using for the lever arm?

A wooden dowel thick enough to not flex easily (~3/8") has worked fine for me!

What materials have people been using for the lever arm?
One other thing, I noticed everyone on here has said to use fishing wire for the string. Is there any reason to prefer this over regular thread or some sort of reinforced quilting thread?

I think fishing line would work fine- thread seems like it would break too easily, but you could give it a try if you wanted.

[Wabbit]

One other thing, I noticed everyone on here has said to use fishing wire for the string. Is there any reason to prefer this over regular thread or some sort of reinforced quilting thread?

I was having some issues where it seemed like my fishing line was stretching a tiny bit, thereby changing the number of wraps needed on the drive axle. Looking back on it now it may have been me mistaking a slipping knot for stretching, but regardless, I decided to go with a piece of thin metal wire instead and it's been working fine for me.

[19sawickin]

One other thing, I noticed everyone on here has said to use fishing wire for the string. Is there any reason to prefer this over regular thread or some sort of reinforced quilting thread?

I was having some issues where it seemed like my fishing line was stretching a tiny bit, thereby changing the number of wraps needed on the drive axle. Looking back on it now it may have been me mistaking a slipping knot for stretching, but regardless, I decided to go with a piece of thin metal wire instead and it's been working fine for me.

How do you get the metal wire or fishing line to wrap tightly enough around the axle? For me, the wire kept the shape of the original spool it was wrapped around and there was practically no friction between it and the axle.

[Wabbit]

One other thing, I noticed everyone on here has said to use fishing wire for the string. Is there any reason to prefer this over regular thread or some sort of reinforced quilting thread?

I was having some issues where it seemed like my fishing line was stretching a tiny bit, thereby changing the number of wraps needed on the drive axle. Looking back on it now it may have been me mistaking a slipping knot for stretching, but regardless, I decided to go with a piece of thin metal wire instead and it's been working fine for me.

How do you get the metal wire or fishing line to wrap tightly enough around the axle? For me, the wire kept the shape of the original spool it was wrapped around and there was practically no friction between it and the axle.

Maybe I'm misunderstanding your question, but at least on my design, friction between the string and the axle isn't important. I just have a loop at the end of the string (wire) which hooks onto a peg sticking out of the axel. As I turn the drive axle it wraps the wire up around it, like it was being put onto a spool. The mousetraps pull fairly hard on the wire and keep it tight.

[19sawickin]

I was having some issues where it seemed like my fishing line was stretching a tiny bit, thereby changing the number of wraps needed on the drive axle. Looking back on it now it may have been me mistaking a slipping knot for stretching, but regardless, I decided to go with a piece of thin metal wire instead and it's been working fine for me.

How do you get the metal wire or fishing line to wrap tightly enough around the axle? For me, the wire kept the shape of the original spool it was wrapped around and there was practically no friction between it and the axle.

Maybe I'm misunderstanding your question, but at least on my design, friction between the string and the axle isn't important. I just have a loop at the end of the string (wire) which hooks onto a peg sticking out of the axel. As I turn the drive axle it wraps the wire up around it, like it was being put onto a spool. The mousetraps pull fairly hard on the wire and keep it tight.

Do you secure the wire to the axle or tie a knot to attach it to the axle? Because I did not attach it to the axle in any way and it was impossible to wrap around the axle because it wasn't gripping anything and i was thus winding the back axle and the string wasn't winding around it. On the off-handed occasion that the fishing line cooperated, the wire was so loose around the axle and didn't actually spin it. Does this sort of help?

[JasperKota]

Do you secure the wire to the axle or tie a knot to attach it to the axle? Because I did not attach it to the axle in any way and it was impossible to wrap around the axle because it wasn't gripping anything and i was thus winding the back axle and the string wasn't winding around it. On the off-handed occasion that the fishing line cooperated, the wire was so loose around the axle and didn't actually spin it. Does this sort of help?

Most people make some sort of peg the axle - by bending some wire or tying a ziptie and cutting it to the nub, then securing with glue. Then make a loop at the end of your wire by tying a knot, then attach it to the peg. When you wind the axle the string will then wind around it, and then when released will tug on the peg, unwind, and cause the axle to spin.

[bluehorse123]

dumb question - How do you tie the the string to the end of the lever arm without using the locking bar's loop?

[antoine_ego]

dumb question - How do you tie the the string to the end of the lever arm without using the locking bar's loop?

See here.

Has anyone else encountered the issue where as the lever arm slaps down, it jerks the vehicle off course? For me, it results in a 10cm difference which is huge. I've tried using foam to cushion the arm as it drops down to no avail. Any tips?