Scrambler C

[pumptato-cat]

Am I allowed to use 3D printed wheels?

Yes. Make sure you include them in the design log, though.

[BobaTeaTastesGood]

What lubricants would be best for scrambler bearings? Right now I'm running all my bearings without shielding or liquid lubricant, since that's what seems to work best (I've never had issues with this in past vehicle events). Would fine graphite powder improve speed at all? Most of the advice I can find online applies to heavy stresses, temperatures, etc. I have some lying around but I'm scared to add it lol.
If our vehicle was smaller then I'd probably be fine with shielding and protective lubricant, but we built it for accuracy so we're mostly lacking in speed points.

Also, does anyone know where/how I can buy or make a rotary counting device? Counting wheel turns is stressful lol

[BobaTeaTastesGood]

What are you guys using as hooks on the back of the vehicle. We had a dowel glued on but it snapped off just now. What’s a better thing to attach, our comp is Saturday and it was driving really good before it snapped so any suggestions asap would be great. Thanks

We were also using a dowel before, but the only available point of attachment was a circular rod, so even with sanding it was breaking off. We ended up using a trimmed zip tie with glue. If there's an accessible flat surface, though, then drilling a hole would probably be better.

[pumptato-cat]

Can't help with the lubricant because I literally used corn oil in 7th grade, but for counting wheel turns, I don't think you should need a rotary counting device. I count and eyeball after marking the wheel with increments of 1cm, and I never have issues. Sometimes I mess up by one turn(usually count to 30-43 turns) so maybe have a partner watch and count with you? I wouldn't spend money on a counting device, though... you might be better off buying a scope or something.

[ckenn4189]

Hey everyone! I've been watching all the videos, reading the forums, and scouring the web for design ideas and I think I have come down to a general idea of what I want to do:

-Pulley launcher with high-strength braided fishing line
-A carbon fiber body with a wingnut braking system

For wheels, I was thinking either CDs or Banebots wheels? What do yall think would work better?
Also, how does steering the vehicle work after docking? I've heard some mentions about cutting the frame into two parts but I'm confused on how to go about doing that and maintaining stability.

Thanks in advance!

[pumptato-cat]

You should start building--it's rather late in the season so get building asap!! You might want more detail than just "carbon fiber body". CF is expensive, so plan well but don't overthink it.
In my opinion CDs are pretty terrible. They work but have lots of problems. Thin, heavy, large diameter. Thin is bad because CDs are hard to attach perpendicular to the axle, and they're not good for traction, even with balloons(I don't think that'll be an issue this year though, most cars struggle to make it to 11m). Banebots are kinda heavy so you might struggle to reach 11m if you're using small ones. Consider drilling holes to cut weight if you use them. Do you have access to a 3D printer/laser cutter? I'm using 3d printed wheels and they work very nicely. If not, I guess it depends on your design but I'd use Banebots.
I'd highly recommend steering this year. 11m is no joke and the biggest issue I see is getting a car going straight.
Basically you cut the frame into two pieces at one point-common ones are the center of the vehicle, or making an axle on a pivot point. You attach these pieces together with something similar to a screw and nut, and adjust until you find the right setting. There are a ton of other ways but that's the easiest. Not sure what you mean by stability--do you mean how to fix the steering adjustment in place?

[ckenn4189]

Yeah I definitely have to start building ASAP, got a month and change until competition but I've been too busy to start earlier sadly. I can probably find access to a 3D printer but I have no knowledge when it comes to that? Did you make the wheels yourself or did you find a print file online? About the steering thing, I honestly have no idea where to start on that, just trying to see how other people do steering. In my mind, I pictured the a pivot system with one half of the ETV wheels remaining fixed in a straight position and the other half being adjustable so it guided the fixed wheels along, possibly some sort of locking bearing? I appreciate any help with this, this is a whole other beast than gravity vehicle was last year

[pumptato-cat]

I used Fusion360. Steep learning curve but definitely worth it! If you can't get access to/understand how to use a 3D printer, start planning everything out. Fusion360 is still helpful without a printer--I have a file of my car 1:1 scale, and it helped me find any obvious flaws in my design. Also was helpful while building the car. I'm not sure how you'd assemble carbon fiber without a 3D printer(if anyone knows please tell me!)
I can DM some design ideas if you'd like. Not willing to post here because I don't want to share my designs with everyone. Would be willing to help w/ steering, it's not as confusing as it seems. Your idea is basically what most people use, and it works.

[ckenn4189]

Yeah that would be great!

[sneepity]

Yeah I definitely have to start building ASAP, got a month and change until competition but I've been too busy to start earlier sadly. I can probably find access to a 3D printer but I have no knowledge when it comes to that? Did you make the wheels yourself or did you find a print file online? About the steering thing, I honestly have no idea where to start on that, just trying to see how other people do steering. In my mind, I pictured the a pivot system with one half of the ETV wheels remaining fixed in a straight position and the other half being adjustable so it guided the fixed wheels along, possibly some sort of locking bearing? I appreciate any help with this, this is a whole other beast than gravity vehicle was last year

Yeah I definitely have to start building ASAP, got a month and change until competition but I've been too busy to start earlier sadly. I can probably find access to a 3D printer but I have no knowledge when it comes to that? Did you make the wheels yourself or did you find a print file online? About the steering thing, I honestly have no idea where to start on that, just trying to see how other people do steering. In my mind, I pictured the a pivot system with one half of the ETV wheels remaining fixed in a straight position and the other half being adjustable so it guided the fixed wheels along, possibly some sort of locking bearing? I appreciate any help with this, this is a whole other beast than gravity vehicle was last year

Hii!!
Like pumptato said there are a lot of resources to learn CAD! If your school has this, you should try to get the autodesk student license so you can get fusion for free (usually it is almost $600 a year)
https://www.autodesk.com/education/students this should help you access a student license
there are also youtube tutorials to learn CAD
https://www.youtube.com/watch?v=0ByAnvg ... MTutorials
I also suggest wikipedia articles to learn about steering geometry! It will help you come up with system

And also honestly if you cannot get access to a 3D printer, you can always make the parts in a woodshop. It wouldn't be harder, you'll just have just less precision when you're trying to make everything by hand. Alternatively, you can try to make most of the car out of machined parts so it will be consistent ! good luck :0)