pic: Team 1388: Secret Weapon

So we smoked a FP motor today … this morning actually. Our mechanicial team worked for about 9 hours straight figuring out, designing, building and testing different solutions. We tried just about anything 6 people could come up with on a sunday morning. As a result, heres the final solution. Now the programming team will work all night (starting at 9PM PST) to have the robot programmed for the drivers training on Monday.

Yes, It is a ratchet. Yes, there are 3 holes drilled into the side. Yes, there is a servo that controls which direction it drives. And finally, yes, it works.


That thing is awesome! I couldn’t stop laughing when i saw it and figured out how it works. Its certianly an interesting and very innovative use of your tools.

Good Job, wish we’d thought of something like that :slight_smile:


not sure if it quite matches the dominate switch :ahh:
i’m not quite sure what it does now… it looks like the leverage is a bit little… but i’m not really sure

All it does, is keep that gear from backdriving, which keeps us from having to keep the FP motor at a stall. Simply move the motor up, and the servo locks in the “up” position. The shaft with the gear on it, is threaded at the end and has a jam nut on it which the ratchet fits over. The ratchet is bolted to the frame using a piece of 1x1 tubing and some grade 8 bolts.

When you want to lower the arm, pull the stick down. The program sends a small pulse to the FP motor to raise it up (since you cant change directons on a ratchet under load). The servo then puts the shaft into neutral and allows the arm to be lowered. When you let go of the stick, the servo shifts back into the up posititon, making it ready for the next lift.

As for the dominate switch … heh. This is actually useful :slight_smile:

We’re predicting judges/field officals at the events telling us we left a tool on the bot before the match starts, one thing is for sure … it isnt coming off any time soon.

that’s pretty cool-- not backing driving is a good idea-- we did that and sorta bent somethings but it’s all fixed–good job guys

Oh, our dominate switch has a use…but it wouldnt be a Secret weapon if we told you :smiley:


Haha, that looks almost exactly what we used as part of our winch last year to hang on the bar! Nothin like good ol’ socket wrenches :smiley:

Posting messages that just say “Cool dood!!3!! I rilly rilly like it!3!!” is usually just a waste of bandwidth. I try to avoid it.

But in this case I can only say, “Cool dood!!3!! I rilly rilly like it!3!!”

We threw this baby together in about 3 hours, two days before ship when we burnt out the FP. Can you say desperation.

we had a closed 7/16th wrench once on our robot to guide rope…but I am sorry that is so funny/awesome…one of the most funny/awesome things in just about forever. How much can that hold?

Our arm is only designed to lift one tetra at a time, so we haven’t tried any more than that. It already has a little trouble shifting to go down with only one tetra on there, so I wouldn’t dare try two. Nonetheless, it achieves its intended purpose.

So if I’m looking at this right, does that servo let the wrench fall backwards so you can lower the tetra.

I love the ghettoness of it.

Basically, yes. The servo shifts the wrench between clockwise and counter-clockwise rotation, depending on what the driver is doing with the controller.

So do we. :stuck_out_tongue:

very creative good job

I agree. It looks like you guys took apart a chainsaw and re-assembled it to fit into your robot =p.

Well … the ratchet didnt perform as we anticipated at Sac, and neither did the FP. On a side note, we were unable to control our lower boom and ended up locking it, thus freeing up the van door.

Since we didnt get into the finals :frowning: we spent about 4 hours working on the arm, using the stuff we had for the VD, and ended up mouting, and getting it all chained up (ironically we took an extra sprocket for something completely different, but didnt end up needing it, so we had everything we needed to convert it.

A special thanks to the 2 guys at the 254 Machine shop (cant remember their names, but they were both machinists for NASA) for all the work they helped us with this weekend.

If you were hoping to see the ratchet, stop by the 1388 pits in Atlanta, I’m going to see about making a little jig to show other teams how we mounted it and used it.

For teams that wanted to use the ratchet idea on their bot, I would suggest prototyping it and testing it heavily before you send it into a match. It requires alot of tweaking, but if you can get it dialed in, it works great. It isnt just hardware, theres alot of software r&d for getting the servo to lock in at the right times.

If you guys have any questions, feel free to PM me or the other active CD member from 1388 - jgannon. Good luck, hope to see you guys in Atlanta.

never trust big sprockets

If you had used a Craftsman wrench, you could take it back to Sears when you were done, and they would replace it, no questions asked.

BTW, what does it take to drill a 1/4" hole through a wrench handle? Arnt those things made of hardend chrome steel?

We actually thought about that, but we wanted to keep our Craftsman stuff, and we aren’t planning on removing it any time soon.

It took about ten minutes on the drill press, with two people. The first to hold the wrench and the other to put on some oil every three seconds or so. It was very tedious. (As a rookie I was assigned to the oil).

Care to explain why big sprockets are bad?

Back on subject, great robot 1388! Thank you so much for coming to our aid at the Sacramento Regional. You guys are terrific!