My Physics final project (custom puller)

This is something I have been working on this week. This took me two days to build. It's finally moveable. It is my final physics project and is going to be in a competition with different groups in my class and other classes. It still needs some tinkering to the gearing to lower the temps for normal conditions as it will be in a tug-o-war competition with other groups' cars. Also, the front tires lack traction, so I will need to find something with more grip...preferably something with spikes.

                               
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And here's the tires ballooning at full throttle

                               
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Wow...that's cool.  I wish I had some sort of project like that back in school.  

The ballooning is pretty serious for a tug-o-war car, you might wanna gear it down to get some additional torque outta it.

Oh....your front end might be too light, the car might just flip over under heavy load.  Either that or lengthen the chassis.

Very nice DIY.............  
Don't get me wrong, I am not making fun of your truck or anything, but it looks like a Tractor....

I have seen those shows about Robot Wrestling and it looks like the heavier it is, the better chance to wins.....  plus speed is not an issue, it's the torque that makes the difference!

Good luck with your project dude!  SURE WIN!

Thanks guys!

mike, my plan was to make it look like a tractor! I guess I succeeded!

There is a size limit to how big the RC can be. Mine is already a little oversized in width, length is probably at its max. And ya, I really need to gear it for more torque. I tried to run it and acceleration wasn't too good, but it was FAST! Now the gearing is at 19/83, I used Tamiya gears. I am thinking of changing it to 13/83, I think Tamiya makes a 13T pinion for the Clod. Anybody know if there is lower teeth pinions by Tamiya? The 83T spur is fixed, so it can't be changed.

The wood steering piece in the front is getting weak. I am pretty sure one hard hit and it will snap. I will need to increase the bracing for it.

After I change the gearing, if the front lifts, I will add some lead weights onto it to weight it down. Not sure what else I could do, maybe move the battery forward.

Btw, the qualifying tasks are:
1. 30m in 10s.
2. Climbing slope of 30 deg up pinewood surface.
3. Pulling 5N.
4. Launching a ball to hit a target 7m away. (Still gotta work on this)

Competition:
1. 30m dash
2. Highest slope climb.
3. Tug-o-war between the RC's.
4. Hitting target 6m, 7m, and 8m.

I am estimating there will be about 10-15 groups.i

Ever thought about using steel to make a bumper?  That way you can put some weight in the front for your 30 deg climb and pulling (prevent flip over) Or better yet a wheelie bar?
Also, your front wheels, can a original Grasshopper/Hornet/Frog front wheel help with minimized frickion in the front for your drag race?
What kind of motor you are using?  How about a 25T from Tamiya?  I find the 25T motor has good torque and speed....
Good luck dude... and make sure you post photos of all other challengers!

Hey, I also just thought about your rear diff.  Are you locking the rear diff since your front wheels are going to be off the ground during tug-o-war anyways... so a locking diff I think it's better.....
(Holy crap... I guess I have been watching too much Junkyard War......)

Jack,

1st Get some bearings man!!
2nd Kimborough make a 12T pinion (48pitch) so should fit electric trucks
3rd How many cells are you using?
4th Moving the battery forward will be a good idea to put weight down
5th Is that servo really nessesary?
6th If you make the wheelie bar quick low down on the chassis, whenever the front flicks up it should be quick to push it back down, it will also won't effect your pulling if its placed quite low

oh and put some grasshoper wheels on the front like brother mike said

but these are my ideas only

Mike, i think he is running a Graunper 600 already, which is pretty damn torquey!! unless you get a 55T Lathe motor and it doesn't look like it has a diff lol

mike, the rear is a solid axle. I made the whole transmission except for the spur gear. The axle is just a solid rod of aluminum with the ends tapped for the wheels to mount on. I had plans to make the wheelie bar too, but at the moment, the front end does not lift. I guess I will have to see after I change the gearing. For the front, I am going to try a set of Tamiya rally blocks since I already have a few spare set.

Prince,
1. If I could find where to buy at least 3/4" thick lexan here, I will remake the transmission with bearings. But I am not really sure how I could put bearings in the transmission right now, the plates are only 0.120" thick I think.

2. I always thought Tamiya gears are different pitch, I have a whole bunch of pinions in the workshop that I
will try tonight.

3. 6 cell stick pack.

4. Yup, I am going to do this.

5. The servo is there as a backup. Since I made the rear axle, it does not spin true, it is not perfect. And since the event is going to be on carpet, most likely it will go to one side. The steering is there allow the truck to move in a straight line. I remember last semester, some cars went straight on concrete. But on carpet, their paths were slanted to one side. And without steering, some ran into the wall and did not qualify (0%).

It is still hard to get grasshopper wheels here. I want to use something readily available. But I will try the rally blocks first.

Just changed to Tamiya rally blocks for the front. Steering is a lot better now. Also changed the pinion to 17T from 19T. Increase the acceleration a little, but I would like more. The pinions are definitely not Kimbrough 48P, I got a few of those and they don't mesh. Maybe something with standard and metric...not too familiar with that, but I will check the LHs next week to see what they have.

hmm i am sure tamiya pinions are 48pitch sorry man, try 32 pitch but i think 19/83 gives you a very good gear ratio for acceleration i tried a 25/84 on my traxxas rustler before (running on a 'sport tuned' stock tamiya can) and it did rolling wheelies! until be idler gear gave way

i think changing to bearings will require rebuilding the whole thing, so its best just t leave it as it is and just lube the friction points every time you run it to prevent wear, just outta intrest jack, what surface are you running the tractor () on?

For drag race?

原帖由 Jackson 於 2006-3-18 11:11 發表
This is something I have been working on this week. This took me two days to build. It's finally moveable. It is my final physics project and is going to be in a competition with different groups i ...

Hi Jack, I have nothing to say but what U have built is EXCELLENT !!    Surely get a very high mark, and I think U are a real RC genesis ....  

python, ya it's pretty much for drag racing. Drag racing, pulling, climbing

Prince, the gear ratio in your rustler is different compared to mine because mine is a direct drive system. Meaning the only gears it have is the pinion and spur(with is directly on the axle itself). The rustler transmission has internal gears that changes the gear ratio, it is not simply the ratio of the pinion to spur itself, but have to factor in the idler, diff gears too. I don't really remember how to calculate that...but it took a while to do.

Skyline, thanks man! When I finished building this one, I had the urge to build another one because I thought of a totally different design that might work better than this one. If I have a long weekend, I think   I will make it.

Ok just destroyed the spur gear today. I will have to think of another way to fix the gear onto the axle...

原帖由 Jackson 於 2006-3-20 05:53 發表
Ok just destroyed the spur gear today. I will have to think of another way to fix the gear onto the axle...

no worry la, keep up with the good work buddy ..  

Thanks. I already thought of a way to keep the gear on the axle. But this piece is going to take a while to make. Another project for next weekend.

Sorry about the spur gear man but think of it this way -

now you can fit a different teeth spur gear on hope you fix the problem soon

So what happened in the race???  It has been a while now...

lol the competition is on May 9th. Still a few weeks to go. I am going to be fixing it up on Thursday. Have a few plans in my head, we will see if they really work

Another update!

Qualifying is on the coming Wednesday. This is where most of the marks are given. Competition is on the coming Friday. The event is going to be broadcast live on the internet. I will post the link here in a few days if anybody is interested.

As for my car, I actually decided to make a whole new chassis because the first one was a little on the heavy side. My main goal on the new chassis is to be lightweight. I started last night and this is how far I got after a day. It's pretty much finished. This time the axle spin a lot smoother and the gear mesh is pretty close to perfect. Very happy with that. The final process will be to cut away any part of the chassis that is not needed. I am also going to be using 2/3A's for the speed and climb event to cut down on weight. For the tug-o-war, I am going to be using a 3000mah 7 cell pack to increase the weight and power. V2 is a lot more sturdier than V1, but I will be adding a little more bracing before the qualifying.

I still have to remake the catapult. I have searched on the net and have decided on a Trebuchet. Some ancient roman weapon. I will be making that on Tuesday. Hope it works lol

Here's a pic of it I just took. The chassis is made of 5mm polycarbonate, pretty strong stuff

                               
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