Good luck!
(20 chars)
I am still honestly kind of split on the idea of using a CAD though. I guess I should make a thread for that.
Yay. No if you have questions. Sadly I can’t help you there because if use inventor but there are tons of people that use it so feel free to ask.
Yah you can make a poll or something on how many people use cad and ask questions all in the same topic. I bet you could get a ton of info from thsg
2 Likes
there are already a ton of topics talking just about how to CAD, no need to make another.
1 Like
No not how to make a cad
the topic i was going to make would be more about IQ CAD instead of VRC. And not necessarily how to make a CAD either.
Use proper c chanels instead of rails for your chassi space out your wheels and add bracing for your chassi
Another thing is that your indexer and arms are made of steel c channel I think that if you change them to aluminum you will lower the center of gravity of your bot and mitigate tipping
1 Like
Thats a great point, although would it change the center of gravity by much because id have to buy aluminum parts
aluminum is always much better than steel, but it’s also more expensive, so if you are on a tight budget steel is ok.
3 Likes
My thoughts on steel
so a couple questions. obviously I would want to use all aluminum if I had the choice, but what it be smart to use steel for the base and aluminum for everything above it? (To help with the center of gravity) Next question is if I am using steel does that mean I have to box bolt?
First answer. Yes you can make your whole base steel to lower the center of gravity which might help a lot with your tipping. You still might want to move the cortex. Then yes you can make everything else aluminum. And no, you don’t have to box bolt anything. It just makes the connections stronger.
Typically, no. That’s overkill, and you’d be increasing the mass without that many gains. I still would box bolt a few connection points for aesthetic purposes. And for areas with very high loads, I would box bolt it even if the steel can handle it. Better to be safe than sorry.
If I was in your situation (with limited aluminum parts), that is what’d I do. Steel not only helps your center of gravity, but it also gives you more traction because of mass. Traction is defined as coefficient of traction x normal force (this is also referred to as static friction). Traction is needed to transfer the energy from the motors to the ground. You can’t move without traction (unless you have some sort of chemical exhaust which is illegal).
Normal force is directly proportional to weight. So in essence, you gain traction by having more mass (weight is mass * force of gravity) or increasing the coefficient of friction of the wheel material you’re using. Omni-wheels tend to have enough friction for most applications. A set of traction wheels can’t hurt you (but don’t use all traction wheels on a drive).
In general, think of how different mechanisms will logically function. I understand it can be difficult without having taken a higher level physics course. That being said, I highly encourage everyone to take a course such as AP physics as these concepts apply to all aspects of robotics (even software).
4 Likes
Even with a lower center of gravity, you have to account for the balls the robot will store. I’d say a competitive robot can store at least three balls which is a significant amount of mass for a robot. Especially very fast robots. (This is because of momentum which is mass*velocity). Speed is key in this game (imo). So, back to the original topic of this thread. An anti-tip will probably be very helpful.
1 Like
Well actually I do agree with you but I don’t agree because these balls are extremely light.
I’ve taken ap physics so I understand what you are saying (and this is the first time what i’ve learned is useful wow). anyways I understand what you are saying is true, but then you don’t want it to be too heavy because that would put too much strain on the drive base motors right? This is why I made the switch from 2 to 4 motors for the drive base
1 Like
Yes exactly. Understanding the limitations of the motors while also optimizing their functionality through physics is what I’m trying to get at. Friction between axles and bearings and traction are the biggest bottle necks for drive trains. In short, finding a balance is very important. And a 4 motor drive is almost a pre requisite to be competitive,
1 Like