Chief Delphi - Mystery Sprockets

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Re: Mystery Sprockets

Many wonderful ideals have been expressed here. I, for one, agree with them fully. I also know from first (not FIRST) hand experience that those ideals are not reachable for all teams in all locations. Although I much prefer to teach the "Give a man a fish and feed him for a day. Teach a man to fish and feed him for a lifetime" principle, I think for the sake of the teams that exist outside the "ideal" world I will give an answer to the original question.

Drive sprocket:
McMaster part # 6280K371 $8.23 ea.

Wheel sprocket:
Get it from IFI.
IFI-SPROCKET-35A24 $9.99 ea.

Re: Mystery Sprockets

Quote:

Originally Posted by dlavery (Post 561360)

Some have already commented that they are upset they cannot just purchase the exact part they need and bolt it on their robot. What ever happened to the idea that part of the challenge (and part of the fun) of FIRST was creating your own design out of raw materials? If we do nothing but rely on bolt-on solutions, then we are largely relying on the engineering efforts of others, and doing little true engineering of our own. And that, I submit, lessens the experience for all involved.

The real world does not go together like an Erector set. FIRST robots should not either.

I realize that part of my inspiration was getting my hands dirty on the mills or lathe, drilling holes etc. Personally, I hope we never see the day that you can just bolt together an arm from XYZ company, a drivetrain from ABC company, and a ball collector from DEF company. However, I am a systems engineer, and a lot of our stuff is short turn around, just like FIRST. When you work in those conditions and you work in a HS shop that in total has a band saw, a table saw and a drill press, you look for the way to spend more time on certain parts of the design while taking shortcuts on others. To me, milling out a sprocket is not that exciting, and I would bet that in 80% of the teams, the kids dont do that (its probably sent to the sponsor, to other teams or anything of the like). So whats the difference if you find a resource to buy it from (wisely using your time like a systems engineer would) or you send it off to your sponsor to do for you? Its the same to the kids... but maybe they learn or get inspired by designing in inventor, or putting the transmissions together or putting on the chain.

The entire reason FIRST gave us the "kitbot" in my understanding is so that the disadvantaged teams would be able to make more than just a box that sat on the floor. They could focus more on arm design than just making something that could move around the field. I dont see how buying a sprocket with holes takes away from the design process. If Dean really wants a FIRST team in every school, and everyone has to do their own broaching or steel drilling, he had better buy a full machine shop for every school, or FIRST needs to allow more "system" style designs.

But anyways, sorry Im a bit off topic, although I think the question has already been answered. The IFI sprockets are probably closest. We use McMaster Carr to buy ours and then add broaches or keyholes (at our sponsors place). I think Ben's idea is the best... if you can find a team near you willing to help, or even one that would be willing to overnight parts they did for you, that would probably be the easiest if you dont have the machining resources.

Re: Mystery Sprockets

In the past Team 104 has had no money and only hand tools. That didn't stop us from making adapters for IFI AL sprockets last year for the KOP wheels. We found a LDPE 5/8" cutting board at BED BATH and BEYOND, using 2 hole saws made some donuts. Drew some lines for the spoke slots and cut with a hack saw with 3 blades on it. Problem solved for about 8$. 2 sets from IFI would have cost 44$. The IFI AL sprockets were 1/2 the cost of the custom steel sprockets and less than half the weight. Some times your have to practice the fine art of kluging. In past years I submit that Team 104 has been the King of Kludge. There should be an award for the cheapest kludged bot that places highest in the rankings.

Re: Mystery Sprockets

Quote:

Originally Posted by Gdeaver (Post 562161)

In past years I submit that Team 104 has been the King of Kludge. There should be an award for the cheapest kludged bot that places highest in the rankings.

I don't know, Team 306 might give you a run for your money :D

Team 306 was staying at a mission building in downtown Pittsburgh for the regional because our mentor's friend was looking forward to meeting us, and it proved to be a cheap alternative to a hotel :rolleyes:. Anyway... the 'bot broke, and I had to make a hacksaw out of what the mission house had in its shed, It was interesting. I'd say that is pretty kludge :)

Re: Mystery Sprockets

That is so ugly, it's beautiful.:confused:

Re: Mystery Sprockets

Quote:

Originally Posted by Richard (Post 562210)

That is so ugly, it's beautiful.:confused:

I agree

warning: way off topic -

and...I once found an old dog that I could have named Kludge. I didn't know at the time so I named him Farfle, instead...he lived to be somewhere around 25, looked a whole lot like Cody's hacksaw, kinda.

Re: Mystery Sprockets

OK, I concede, you get the McGiver award.

Re: Mystery Sprockets

Quote:

Originally Posted by squirrel (Post 561754)

One untapped resource could be a "KOP sprockets wanted" post on CD....my guess is many teams are not using them, and there are literally several hundred of those sprockets sitting on shelves and in boxes going unused, right now, as we speak. I personally know of a pair of sprockets, but I don't have authority to give them away.

You migth check the rules first though, as the parts might not be available for sale anywhere, so using "free" ones might not be allowed.

As I read <R43> it would prohibit the use of extra "kit" 24 tooth sprockets obtained from other teams, since that part is apparently not a COTS component. A team that is considering using more than two of the "kit" 24 tooth sprockets (i.e., using more than the quantity included in the 2007 kit) should post a question on the official Q&A site to see if this will be allowed.

Re: Mystery Sprockets

Wow, it's nice to see I could come up with a tough question, without even trying :)

Re: Mystery Sprockets

Quote:

Originally Posted by Richard (Post 563482)

Good catch, Richard.

http://forums.usfirst.org/showthread.php?t=1834

Quote:

Originally Posted by Official Q&A

The sprockets provided in the 2007 Kit of Parts were custom manufactured for FIRST and are not COTS parts. As such, only the two 24-tooth sprockets received in the Kit may be used on your Robot. Teams are welcome to fabricate equivalent parts from COTS items.

Looks like any teams who have borrowed kit sprockets from others are going to have to find an alternate solution.

Re: Mystery Sprockets

Quote:

Originally Posted by billbo911 (Post 562032)

What every you do, do not order these from McMaster-Carr unless you have a way to broach in a keyway. Just because the description on their site includes a keyway doesn't mean that is what you get. Mine delivered today without a keyway. Now it is time to do some calling around. Thank goodness this isn't a last minute discovery.
Sorry for any problems my advice may have caused.

Re: Mystery Sprockets

Quote:

Originally Posted by Karthik (Post 565316)

Good catch, Richard.

http://forums.usfirst.org/showthread.php?t=1834

Quote:

Originally Posted by Official Q&A

The sprockets provided in the 2007 Kit of Parts were custom manufactured for FIRST and are not COTS parts. As such, only the two 24-tooth sprockets received in the Kit may be used on your Robot. Teams are welcome to fabricate equivalent parts from COTS items.

Looks like any teams who have borrowed kit sprockets from others are going to have to find an alternate solution.

When did you see this, Karthik?

I just tried the link above and got "you do not have permission to access this page".

Re: Mystery Sprockets

Quote:

Originally Posted by Richard (Post 565347)

When did you see this, Karthik?

I just tried the link above and got "you do not have permission to access this page".

Weird, I got the same message. I saw it just after 9:00 pm.

Re: Mystery Sprockets

Also, it seems that what Karthik pasted is directly in contradiction with another Q&A, which asked where to obtain KOP sprockets.

Quote:

Altenately, you may want to check with some nearby teams and see if they will be using these parts. Many teams choose not to use the Kit Of Parts-supplied drive system, and may have them as spares (note that if you do obtain them from another team, they still must be fully accounted for the in Robot Bill Of Materials).

I don't think I'm reading between the lines here... that definitely would mean to me that you could use additional KOP sprockets, so long as you accounted for them.

http://forums.usfirst.org/showthread.php?t=1508

Re: Mystery Sprockets

Just a tip we found out today:

When using the IFI sprockets on the kit wheels, make some type of spacer to have the sprocket jut-out a bit. Otherwise the chain will rub against the tread of the tire. The sprockets in the kit have spacers machined into them, and we didn't notice until today when we actually assembled them.