Mousetrap Vehicle C

[antoine_ego]

what times would be considered fast this year?

It depends. For regionals standards, I think 10 seconds is probably the best that can be done while rationing sufficient string for a decent reversal. For nationals standards, I think maybe 13 seconds is probably the best that can be done. That being said, I wouldn't be surprised if someone exceeded these predictions. Keep in mind however, that fast times often come at the cost of accuracy, so it maybe be better to reduce your speed and instead focus on good accuracy.

[biz11]

Has anyone experimented with docfizzix cd tires? If so, how well do they work? Is it worth getting them instead of balloon tires or 3d printed tires?

[Fridaychimp]

Has anyone experimented with docfizzix cd tires? If so, how well do they work? Is it worth getting them instead of balloon tires or 3d printed tires?

According to Doc Fizzix, his DVD layers are half the thickness of regular CDs, thus reducing rotational inertia, so there might be some advantage over using your own CDs. However, even if you choose to use Doc Fizzix wheels, it's always beneficial to wrap balloons around them to give them better traction. In general, CD wheels are problematic, as their thinness means that they often wobble and have poor traction.

[Wabbit]

Has anyone experimented with docfizzix cd tires? If so, how well do they work? Is it worth getting them instead of balloon tires or 3d printed tires?

According to Doc Fizzix, his DVD layers are half the thickness of regular CDs, thus reducing rotational inertia, so there might be some advantage over using your own CDs. However, even if you choose to use Doc Fizzix wheels, it's always beneficial to wrap balloons around them to give them better traction. In general, CD wheels are problematic, as their thinness means that they often wobble and have poor traction.

The other issue with CDs is that they are simply too large in diameter. Even with something that's thinner than a standard CD, I would imagine that rotational inertia will still be substantially higher than with a smaller wheel (banebots, 3d printed, etc). More over, larger wheels will always be slower than smaller wheels due to decreased mechanical advantage, and while this can be overcome by increasing the diameter of the drive shaft, doing so can be a bit clunky.

As a general rule, the smaller your wheels, the faster and more accurate your car will be.

[PM2017]

Has anyone experimented with docfizzix cd tires? If so, how well do they work? Is it worth getting them instead of balloon tires or 3d printed tires?

According to Doc Fizzix, his DVD layers are half the thickness of regular CDs, thus reducing rotational inertia, so there might be some advantage over using your own CDs. However, even if you choose to use Doc Fizzix wheels, it's always beneficial to wrap balloons around them to give them better traction. In general, CD wheels are problematic, as their thinness means that they often wobble and have poor traction.

The other issue with CDs is that they are simply too large in diameter. Even with something that's thinner than a standard CD, I would imagine that rotational inertia will still be substantially higher than with a smaller wheel (banebots, 3d printed, etc). More over, larger wheels will always be slower than smaller wheels due to decreased mechanical advantage, and while this can be overcome by increasing the diameter of the drive shaft, doing so can be a bit clunky.

As a general rule, the smaller your wheels, the faster and more accurate your car will be.

Yes, but the higher your IMA, the lower your distance travelled. CD wheels should be fine size-wise for this year. I'd just be concerned about the grip.


EDIT: Woot 400 posts!

[biz11]

Sorry, I was unclear, I realize the issue with thickness, although, I feel like CD size is reasonable for this year. I meant the tires for the CD's that they have. Probably should have said "Traction Treads" like what they have here: https://www.docfizzix.com/products/part ... 10df.shtml
One thing with Banebot wheels, how long would it take to ship? I need to get wheels very soon.

Also, and sorry for all the questions, I have two questions with threaded rods. 1. does stainless steel or zinc work better? (rod is 3/16 inch if that matters) 2. Does it work using ball bearings with threaded rods?

Thanks!

[Fridaychimp]

Sorry, I was unclear, I realize the issue with thickness, although, I feel like CD size is reasonable for this year. I meant the tires for the CD's that they have. Probably should have said "Traction Treads" like what they have here: https://www.docfizzix.com/products/part ... 10df.shtml
One thing with Banebot wheels, how long would it take to ship? I need to get wheels very soon.

Also, and sorry for all the questions, I have two questions with threaded rods. 1. does stainless steel or zinc work better? (rod is 3/16 inch if that matters) 2. Does it work using ball bearings with threaded rods?

Thanks!

This is just speculation, but the Doc Fizzix Traction Treads look a lot like cut-out balloons. I don't think there would be any significant improvement over simply using your own balloons because the product description doesn't list any specific beneficial features. On banebots, the website (http://www.banebots.com/INFO_SHIPPING.html) says that they ship within 3-5 business days, so I'd expect them within about a week (?) depending on whether you're willing to pay for express shipping.

[MadCow2357]

1. One thing with Banebot wheels, how long would it take to ship? I need to get wheels very soon.
2. Does stainless steel or zinc work better?
3. Does it work using ball bearings with threaded rods?

1. Takes from 4-7 days for me, but I live in RI so it might be different for you.
2. In my opinion, the difference is negligible
3. Yes, definitely use bearings. Bushings will eventually get torn up by the threaded rod.

[sciencecat42]

1. One thing with Banebot wheels, how long would it take to ship? I need to get wheels very soon.
2. Does stainless steel or zinc work better?
3. Does it work using ball bearings with threaded rods?

1. Takes from 4-7 days for me, but I live in RI so it might be different for you.
2. In my opinion, the difference is negligible
3. Yes, definitely use bearings. Bushings will eventually get torn up by the threaded rod.

Do you know where we could buy such bearings? I'm using a 1/8" threaded rod.

[MadCow2357]

3. Yes, definitely use bearings. Bushings will eventually get torn up by the threaded rod.

Do you know where we could buy such bearings? I'm using a 1/8" threaded rod.

https://www.amazon.com/inch-ID-Ball-Bea ... B00VU5C8Q8
The above should work