pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Obviously the electronics are not totally ready to be put in quite yet, but this is the basic design of the drive.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

wow that's crazy any chain slip ???

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

How rough were you guys on the chain when you were testing? We have a very similar setup and were just contemplating moving our Toughboxes further back yesterday to get more chain wrap on the drive sprocket. We wanted to avoid doing so because that would involve replacing the angled braces with another method of holding up the transmissions due to wheel interference.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Would you consider using a floating tensioner on that long front loop?
I wonder what that open front is for....
Be careful with that, you don't want your frame to twist inward there at the front. That will give you horrendous chain trouble.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Sorry to say but your end cap is 5 inches long. It needs to be 6 for a bumper. I hope you have some c channel left over.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

The endcap itself is only 5 inches but depending on how they choose to mount the bumpers some structure above or below the endcap (still in the Bumper Zone) that stretches the full 6 inches could be used to meet the bumper mounting requirements as the "module" is over 6" wide.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Nope, it's still really tight, after an hour or so of driving.

It's been measured, there will be a 6 in bumper segment on the front of the sides, it will be entirely legal.

Our testing used forward/backward quickly, long stretches of driving, and vigorous motions to try to throw the chains. So far, this chain set up has really impressed me, previously I have been told you need 120 degrees of wrap around a sprocket for it to stay on, but this has proven that wrong, so far. Chain tensioners will not be necessary due to the extremely tight chains that are on it currently. The frame is very sturdy, although it appears weak due to the hole in the front, that is conveniently about 24 inches wide, I don't know why it would be that wide? hmm...;)

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

How will you be able to tighten the chain?

We set up our prototype this way to give our drivers a feel for tank drive. The chain will stretch with usage, so you will need some way to re-tention or you'll be throwing the chain.

The team has decided on 4WD/4 motors with gear boxes and tention the chain with the mounting angle (Gearbox Bracket - PN: am-0204) that have the long holes to allow the adjustment.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

He could probably use the new AndyMark Chain tensioner. Simple and inexpensive.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

One way to tighten the chain is to shim the transmission and bracket up, by putting washers between the frame channel and the brackets.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

It shouldn't need tension for a good long while, we will more then likely replace the entire chain with new chain when it eventually fails, it is extremely tight and does not require and sort of tensioning device.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Did you test at full weight?
120 lbs + Battery + Bumpers = ~150 lbs

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Also, did you test stopping quickly (like what will happen when two robots collide)?

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

If weight wont be a problem (at least a big one) I like 2 chains for redundancy. Maybe the chain doesn't fail, but say your wheel sprocket mounting does, etc etc.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Yeah, I realized the bumper piece could be longer a while after I posted but w/e. Any reason you cut it to 5 instead of 6?

We actually did the same thing as you, but we cut ours to length and installed it and then I remembered the 6 inch rule, and measured it, luckily it was 6 inches exactly, so this is why I noticed.

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

I am the coach of a 2nd year team so please take what I am saying as such. This is identical to the setup we used last year and we had HORRENDOUS problems with chain skipping etc. and did not realize the FULL extent of if until we drove on various surfaces. We seemed to have no problems until we had done almost 40 hours of test driving. By then the chain had stretched to the point that we could not move hardly any distance at all without skipping teeth on the sprocket. Once we switched over to the carpet the problem was compounded by the higher traction vs. a tile floor. I know that this year we are running on a "slick" surface however you will still deal with the chain stretching esp if you have it as tight as you say you do. I would strongly encourage you to rethink you're position on the tensioners. At least have them available in case you wind up needing them quickly between matches in case you don't have time to do a full chain swap. Also, another thing to consider is the amount of chain wrapped around the sprocket. Check the recommendations and compare to what you have, we are using a new design (for us anyway)that gives us a 180 degree wrap around EACH sprocket and in combination with the floating tensioner assembly from Andy Mark (6.00 each) we expect MUCH fewer problems with the chain skipping this year!

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

Can those wheels be cleaned up any?

I'd eventually like to know if this is a good example of what a "non-stock", no-go wheel surface would be for inspection. Have you attempted to clean the wheels and restore the tread surface?

Wonder how FIRST will advise inspectors to handle things (sample pics/wheels for reference?) when teams show up with "dirty" scuffed up wheels? Have them fork over $20 per for replacements? :P

Re: pic: Precision Guessworks 1646 - 2009 Drive Teaser
 

See this thread discussing possible ways they can judge "normal wear".