pic: hmmm.

[Chuck Glick]

Lemme guess Cormier... is it a hook?

[EricH]

I hope you guys didn't skip school to make that...

Spoiler for For those that didn't get the pun:

"Skip school" = "Play hooky"

[Josh Fox]

*Groan*

Looks like a pretty good hook to me. Hope it hangs in their under load.

/non-hook based pun attempt

[Isaac501]

Holy cow, you could hang 10 robots off that thing. I hope you guys don't have weight problems, because that's seriously overdesigned. Friggen Awesome, but way overdesigned.

[Brian C]

The Riddler strikes again!

[Taylor]

I don't know if I like the right side, or if I prefer the left.

It looks like it's come to a standoff.

[MrForbes]

Originally Posted by Isaac501

Friggen Awesome, but way overdesigned.

Maybe it's not designed enough? Good design gets the job done with the minimum material needed.

(the "overengineered" or "overdesigned" thing is a pet peeve of mine)

No question that it's strong enough, though

[Wetzel]

The real question is what comes before the question mark.


Wetzel

[billbo911]

Originally Posted by Isaac501

Holy cow, you could hang 10 robots off that thing. I hope you guys don't have weight problems, because that's seriously overdesigned. Friggen Awesome, but way overdesigned.

I think it may actually be under designed. That's right, under designed.

Do you see a cable attachment point? How about a mounting mechanism? All I can say is, without the rest of the lifting system, this is very questionable.



Buuuuwaaaaahaha.

OK, now that the second image is available, it answers my question.


Ohhhh, I did it again!

[Alex Cormier]

Originally Posted by billbo911

I think it may actually be under designed. That's right, under designed.

Do you see a cable attachment point? How about a mounting mechanism? All I can say is, without the rest of the lifting system, this is very questionable.



Buuuuwaaaaahaha.

Actually, yes you are correct. We made some subtle but drastic changes and it's amazing how well it works now. We added two bolts onto the lexan pulley so the cable would not flop around and it hung very smooth and very fast. Too bad we fixed that friday night, not thursday.

Originally Posted by Joe Johnson

I, for one, love this little enigma. Easy to build in a HS shop class, strong light, gives me a real warm fuzzy feeling when I imagine it holding up a very precious cargo of 150lbs of blood, sweat and tears.

Imitation is the sincerest of flattery... ...I stole the entire idea for 2849's hook once we ran out of weight for our pole climbing arm. You'll see something very like it in Baltimore over the next 3 days...

Awesome! We did manage to hang for all of our last 3 matches. It was a beauty and made us all proud. Do you have any pictures of 2849?

[Joe Johnson]

Originally Posted by billbo911

I think it may actually be under designed. That's right, under designed.
<snip>

I get that the tending stress is roughly (Mc/I = 12Mc/bh^3, c=.5, b=.25, h =1, M= 150lbs at 2in = 300in-lbs) = 7200psi add in normal stress of (F/A = F/bh) = 600 psi and you are still under 8,000psi. Well under Aluminum's yield stress.

I don't see buckling being a problem... ...plenty strong for me.

Joe J.

[billbo911]

Originally Posted by Joe Johnson

I get that the tending stress is roughly (Mc/I = 12Mc/bh^3, c=.5, b=.25, h =1, M= 150lbs at 2in = 300in-lbs) = 7200psi add in normal stress of (F/A = F/bh) = 600 psi and you are still under 8,000psi. Well under Aluminum's yield stress.

I don't see buckling being a problem... ...plenty strong for me.

Joe J.

Absolutely no argument on strength. But, if you forget to include a way to attach it to your robot.........


See my edit at the bottom of my post.

[Joe Johnson]

Originally Posted by billbo911

Absolutely no argument on strength. But, if you forget to include a way to attach it to your robot.........


See my edit at the bottom of my post.

I'm still not seeing a problem.

We easily hang 150lbs off a similar hook (only with plastic spacers and the official screw of all right-thinking FIRSTers the 10-24). Our last one is the axle for a pulley with a loop of 1.9mm Spectra from Spearit.com all is well.

The only "tricks" are just to be sure that the axle gets loaded in double shear not in bending because over an inch span the stress can get a bit higher than I'd like and make sure to guide the cable to the middle so that one side doesn't take all the load over the other.

If those are the hardest issues I have to solve in FIRST, I'd be in good shape...

Joe J.

[billbo911]

Originally Posted by Joe Johnson

I'm still not seeing a problem....

Joe J.

My first post was a poor attempt at a bit of humor to go along with the early part of the thread. It came just prior to Alex posting the picture of the hook on the robot.
It was sort of a two part pun.

I think it may actually be under designed. That's right, under designed.

Do you see a cable attachment point? How about a mounting mechanism? All I can say is, without the rest of the lifting system, this is very questionable.





Buuuuwaaaaahaha.

The first part was pointing to the fact that the hook did not appear to have any obvious means of attaching it to a lifting mechanism, be it am arm or cable. The second part was a reference to the fact that it is shaped like a question mark.

Now, after Alex posted the second picture, the design intent became much clearer. Thus my edit with an additional reference back to earlier posts.

OK, now that the second image is available, it answers my question.


Ohhhh, I did it again!

[pfreivald]

Originally Posted by Isaac501

...but way overdesigned.

Our hook is a single piece of 3/4" aluminum, milled out in the shape of a hook. And you think *that* is overdesigned!

Originally Posted by Alex Cormier

Awesome! We did manage to hang for all of our last 3 matches. It was a beauty and made us all proud. Do you have any pictures of 2849?

It was a beauty, and you guys should be proud. Well done, 3181, well done!