Scrambler C

[iwonder]

What you descibed is what I think most people do. Using threaded rod for the axle and pillow block style bearings to hold the shaft. What I think Bernard meant when he refered to the wheels being 'parallel' is that they are at right angles to the shaft and don't wobble back and forth at all, which could happen irregardless of how you mount them.

Also, a 5" inner diameter doesn't quite make sense unless your axle is 5" in diameter, I'm assuming you mean outside diameter, but in either case the servo city rubber probably won't stretch that much. I am curious about what you think you'll gain from covering the sides, it would stop the rubber from rolling off the wheel but if that's happening then it's probably easier to fix by making sure everything is aligned properly (front/rear axles are parallel, the vehicle isn't 'crabbing', etc)

[sciolyscambler]

What you descibed is what I think most people do. Using threaded rod for the axle and pillow block style bearings to hold the shaft. What I think Bernard meant when he refered to the wheels being 'parallel' is that they are at right angles to the shaft and don't wobble back and forth at all, which could happen irregardless of how you mount them.

Also, a 5" inner diameter doesn't quite make sense unless your axle is 5" in diameter, I'm assuming you mean outside diameter, but in either case the servo city rubber probably won't stretch that much. I am curious about what you think you'll gain from covering the sides, it would stop the rubber from rolling off the wheel but if that's happening then it's probably easier to fix by making sure everything is aligned properly (front/rear axles are parallel, the vehicle isn't 'crabbing', etc)

oops sorry i meant 5 inch outside diameter. The rubber bands aren't rolling off the wheel. My front and rear axles are parallel so thats not the problem. I actually had a really cool way to achieve parallel axels. I took a piece of wood and used it to space the distance between my front right and back right AND my front left and back left ball bearing. This made the distance between corresponding front and back bearings exactly the same, so my front and back axis were completely parallel which was nice. what exactly are the servo city hubs for? Do they serve as an adaptor between the servocity wheel and threaded rods? my axels are 5/16 threaded rods, so could i get a 5/16 servocity hub? would i need 8 hubs, (two for each wheel) and would the hubs add any significant weight to the car(since they look pretty big)?

[bernard]

What you descibed is what I think most people do. Using threaded rod for the axle and pillow block style bearings to hold the shaft. What I think Bernard meant when he refered to the wheels being 'parallel' is that they are at right angles to the shaft and don't wobble back and forth at all, which could happen irregardless of how you mount them.

Also, a 5" inner diameter doesn't quite make sense unless your axle is 5" in diameter, I'm assuming you mean outside diameter, but in either case the servo city rubber probably won't stretch that much. I am curious about what you think you'll gain from covering the sides, it would stop the rubber from rolling off the wheel but if that's happening then it's probably easier to fix by making sure everything is aligned properly (front/rear axles are parallel, the vehicle isn't 'crabbing', etc)

oops sorry i meant 5 inch outside diameter. The rubber bands aren't rolling off the wheel. My front and rear axles are parallel so thats not the problem. I actually had a really cool way to achieve parallel axels. I took a piece of wood and used it to space the distance between my front right and back right AND my front left and back left ball bearing. This made the distance between corresponding front and back bearings exactly the same, so my front and back axis were completely parallel which was nice. what exactly are the servo city hubs for? Do they serve as an adaptor between the servocity wheel and threaded rods? my axels are 5/16 threaded rods, so could i get a 5/16 servocity hub? would i need 8 hubs, (two for each wheel) and would the hubs add any significant weight to the car(since they look pretty big)?

The Servocity hubs are screwed onto the wheels and they slip onto shafts or threaded rods. For threaded rods, I recommend buying a hub with a hole size slightly smaller than your threaded rod. Then, hammer down the end of your threaded rod on an anvil so it is flat. From my experience, that helps the screw on the hub get a better grip.

Could you explain why you would need 8 hubs? I've only needed one hub per wheel but perhaps you might be using them differently. Also, if you want pictures of the assembled wheel, hub, and shaft setup I have, I can post them.

[sciolyscambler]

oh ok. i thought that the hubs were designed to clamp on both sides of a wheel. If only one hub is needed per wheel than I think that is good. Pictures of your setup would be nice so i could see what I should expect.

[bernard]

oh ok. i thought that the hubs were designed to clamp on both sides of a wheel. If only one hub is needed per wheel than I think that is good. Pictures of your setup would be nice so i could see what I should expect.

Sure, I'll take some pictures tonight and upload them.

[Spam Tzu]

What is this "Photogate Timing system" all about?

[JonB]

What is this "Photogate Timing system" all about?

Accurate way of timing.

http://www2.vernier.com/manuals/Logger_ ... togate.pdf

They might not be used at all though. We do not see them at the regional or state level in Florida.

[bernard]

What is this "Photogate Timing system" all about?

If you're a competitor, this isn't something you need to worry about. It's just an option for event supervisors if they want a more accurate way of timing. However, if you happen to be an event supervisor, I can describe the photogate timing system in more detail.

[fishman100]

Does anyone have a clue as to what scores may be competitive at states/nationals? For nationals, I'm envisioning that at least 20 or so teams try the bonus. So,what do you guys think may be a competitive time as well as distance score for a run with the bonus?

At an invitational on Saturday we scored ~4800 and placed 10th.

Assuming a team doesn't attempt the bonus, has a run time of 3 seconds, and stops 10cm from the wall, the team's score is 4960.

10 points is very valuable once teams break ~4850 points. I can easily envision the top 10 teams at States/Nats being within an extremely close margin (I'm not that good at estimating, so I won't give a value).

Definitely work on your distance score!

(IDK if any of the teams on Saturday attempted the bonus; we didn't)

[sciolyscambler]

I saw a team on saturday attempt the bonus and still manage to get the car within 10-15 cm of the target. It was really crazy because they had the steering, angle of their launcher, and other factors all thought out and they executed it perfectly. Its gonna be impossible for my car to compete against them unless i get the bonus figured out. All i need is control the over the steering of my wheels, and how to get my car to launch PERFECTLY straight out of my launcher. I'm currently just using a simple string that wraps around the rear of the vehicle and propels it like a sling shot. The problem with this is that it doesn't launch the car completely straight out of the launcher. Do any of you guys have an idea for a launching mechanism to get the car to launch totally straight. I was thinking maybe attaching two tiny eye hole hooks to the bottom of my car, and having a straight rod sticking out of my launcher that kind of holds the car completely straight while it is accelerating all the way until it exits the launcher. Do any of you see possible problems with ideas, or have other suggesting to a launching system? Any opinions on string that wraps around back of car vs hooks that pull the car?

Another question. If i chose to position a pulley in front of my car (but a little higher of course) so that i could run a single string/hook to connect to my car, how would i avoid the vertical wooden dowel from hitting my pulley. I know i could just have the car start in a starting position such that the wooden dowel is in front of the pulley, but then my vehicle would have to be very long in order to achieve max distance over which my car can accelerate, correct? Is there a general consensus over car length? My current car is about .8 ish meters but i have never been sure about the trade off of length over which the car can accelerate, weight, stability, etc.