Sunday, March 19, 2006


So the championship is april 27-29.
I was just thinking about stuff we need to get done (because you guys wouldn't let me start a list last night), and here's a preliminary list:
-pack tools and parts
-buy parts (like more zip ties. Unless we still have the billions that people gave to us)
-make a mobile pit, which we will actually need in Atlanta
-take more batteries
-repair our current bumpers
-make more bumpers (preferably better designed...)
-figure out how to attach bumpers (preferably some method that does not require zip ties, cool as they are)
-figure out how to tension our chain (also preferably some method that does not involve zip ties, because it means replacing them after every round)
-figure out what to do about our HUGE chassis rail bending/crooked wheel problem. We now only have two chassis rails that we can use from Thor, and as we now know, just replacing the ones on Rosie doesn't actually work. Unless maybe we try replacing the inside ones.....? We can discuss this.
-wash our gatorbotics shirts, because I'm sure they all smell.
-What else?

Yay, everybody, we're going to Nationals!!!!!!!!



HomogeneousTransform said...

Hahahaahaha ;) I think I'm going to wear the same shirt from last year's nationals that I haven't washed since . . . last year's nationals.

Let's powwow about the bumpers. There's one way to permanently inset 'nuts' into a hunk of plastic, which means you're not drilling new holes into the material every time you take 'em off. If we find you a hunk of scrap ABS, you can drill a line of holes all one inch apart and use a soldering iron to permanently MELT IN metal 'nuts' (actually, they are called PEMs).

I'll bring a sample and you can decide if this is something you'd like to try ;)

When are you guys meeting next?

Sophia said...

oooooh, and abs is hella heavy

Kersten said...

When did we start allowing you to use that word, Sophia?

Anyway, I don't think we've come up with a plan for meeting the next few weeks. That's on our to-do list, too. I guess... Should we lower it to, like, 3 times a week? More? Less? I'll talk with Chrissy and you guys and figure something out. It might just be easier to keep meeting Mon-Fri.
What does PEM stand for?

HomogeneousTransform said...

Yo kiddos. I re-read the rules and I think we might need to check in with the judges or through the Q&A online before we do this ABS thing.

Actually, ABS is about the same density of plywood, with a density of approximately 0.038 lbs/in3, which means that a 0.5"X28"X5" board will weigh a little less than 3 lbs. There's probably IDEO scrap somewhere of this stuff.

PEM, whoops. Right, a threaded insert. Go to mcmaster-carr and search for 'threaded inserts for plastic and wood'. You drill a hole too small in your plastic usually, and then stick the little metal doodad on the end of a soldering iron, heating it up to 700 degrees, and sink it into the plastic, which means it's really hella hard to pull out. Now you have a permanent 'nut' welded into your plastic and you can put nice metal machine screws into it with socket caps, meaning you can get in there with an allen wrench.

More later. I'm totally slacking. IT's raining and I can't go outside and spray adhesive . . .

juleea said...

Another thing to keep in mind about bumpers:

The layers of plywood on our first set of bumpers (black material) started to rip off and I don't think the wood was cracking just where we had drilled into it. So, I'm all for using abs and threaded inserts...if it's allowed, of course : )

TranquilityBase said...

this is purely random, but does anyone know team 1614? some guy named cody blogged on our gatorbotics blog saying we did really good. umm. yeah. might want to read it? don't know

juleea said...

team 1641 (not 1614) was the third team in our alliance with los altos...

thunder & lightning said...

yeah, they were cool. i think we're meeting 4 times per week, right after school? maybe somedays we can meet later/ earlier.
we hella rock. o

oh and em, sophia is giving her senior talk today at 2:45 if you want/can come see it. (i know you have work... :)

the abs sounds good. i like. woo-hoo!

HomogeneousTransform said...

Dooooh. I think I missed Sophia's senior talk.

I forgot to write this yesterday . . . the chain tensioning thing - perhaps we can bring two long lengths of #35 chain with us, so that we can put in a PVC or nylon rod in the frame and then tighten the chain over it? Right now, I don't think we have slack with the chain on their to go over a bolt. I'll see if there's a nylon bolt or something that's nice and light.

On that note, yeah, perhaps we could do the same with the frame to keep it bend again. I kinda liked how Chrissy went and whacked it with a hammer to straighten things out. If we put a few spacers struts across the offending area, it would probably be less.

We gotta be careful with our weight though . . . . hmmmm . . .

thunder & lightning said...

also remember that we do actully have about 1/2 a pound (8 ounces) to spare after we got rid of the jamming plate and chopping off some of the electronics board

also, the spacers sound good for inbetween the frame, i was just pushing the outside frame back was arcing up as well as in towards the mainframe

HomogeneousTransform said...

Good point Chrissy about the extra 1/2 pound. Let's weigh one of those 3/8-16 5" long bolts that we're using as axles right now.

Oh on a completely different note, I'm in Dallas pretty much all next week unfortunately, breaking furniture, yeeeeeeeehaaaw!!!!!! Butkeep me posted.

Kersten said...

Wow. I hadn't checked the comments here for a while. I see the bracing thing has already been suggested, Chrissy. Anyway, having it as part of the bumper system would still be good. I'm not sure we could get away with putting an actual spacer in there, but I'm sure just the nylon locknuts would do the trick.
Emily and Sophia and Julia: I just talked with Chrissy about a bumper mounting idea that I will share with you tomorrow because I'm lazy and already have to type up the between rounds checklist.


Kersten said...

Things to do between rounds:
-Check electronics board:
-make sure speed controllers are on tight
-make sure board is firmly attached to aluminum plate which should be firmly attached to transmissions
-Make sure PWMs (LED, pinwheel esp) are plugged in
-replace chain tensioners
-check bumpers:
-need patches?
-still on the robot?
-Check turret set screws
-tighten shaft collars on chassis wheel axles
-tighten shaft collars on wheel o' doom axles
-check chassis wheel axles (still straight?)
-replace batteries:
-check voltages
-zip tie 12V
-check wires on turret (not tangled, in chains)
-check PWM jumper for autonomous

juleea said...

for those of you who, too, missed em's previous comment (i didn't read it until after svr!), FIRST provides a preliminary packing list.

here's a link/url (scroll down to the last page):

HomogeneousTransform said...

Yo again kiddos.

So I went back and looked at my original receipt from Minton's Lumber to find out the grade of plywood I got you: CDX plywood (3/4" thick 4X8 foot sheet costs $40.00). Suspicions confirmed. CDX is the crappiest plywood you can get (and since we needed a lot of it for the field elements, I got you the crappiest crap).

There are four grades of plywood (and most of the plywood that you get is douglas fir although you can get hardwood plywood as well). Those grades are A,B,C and D. CDX pretty much means that you have something between C and D, and X stands for GLUE on the surface to fill in knots, holes and splits. Thus, you started off with a piece of wood that wasn't all too structurally sound to start with - my bad.

I suggest we spend a little bit of money and get some high quality hardwood plywood without existing splits and holes, that will bear the weight better. We only need like a 2X4 sheet of it to give us like four bumpers, each 28"X5" right?

Let me check in with IDEO first for scrap, but feel free to go visit Minton's on your own! They are in Mountain View and that would be a really fun trip!

HomogeneousTransform said...

So Kersten ask a question via email to me about traction wheels.

FIRST QUESTON - ask jrock how much money we have in the bank to spare.

SECOND QUESTION - you might want to read up on wheels again - Remember that if you make ALL SIX wheels traction wheels with rough treads, you'll do great pushing people and driving forward, but a much harder time turning. Do you remember that one time I came by during dinner time to talk about this? You need two wheels to have traction and two wheels to slip a little when you turn!

On that note, *if we have the money*, it'd be cool to try two of those traction wheels on the chassis. For two 8" diameter wheels that are 1" thick, along with 2 treads and four sprockets (think what the middle pair of wheels needs), you'll run a price tag of $184.75 if you buy them from IFI robotics via UPS ground. WE HAVE TIME TO SAVE SOME MONEY ON SHIPPING SO THINK about soon!

Getting a set of six and the corresponding sprockets will run you close to $500. We can make our own treads out of some sort of more slippery rubber for the outside wheels so we preserve the turning radius.

But first things first, we really need to get a hand on our financial situation here. I'm not going to spend any more money until I know you've got jrock's approval! ;) yeah?

Kersten said...

Yeah, Aditi was saying that about the traction. I'll go email jrock now about the money.


HomogeneousTransform said...

Hey, I'm here at Casti from 12:15 -1:15 pm-ish right now ;)

I've brought you two pieces of scrap A grade hardwood plywood cut to approximately 28"X5" for the bumpers if you need them.

There's also a flat box with the wheels and a bunch of stuff that belongs to you guys that I cleaned out of my trunk, my desk, IDEO and my toolbox.

This includes: 4" diameter 2" thick wheels (2), the gear puller, miscellaneous lengths of timing belt pulleys, fasteners and a bunch of other stuff.

The box is labelled: 'FOUND BY EMILY'.

Uh, wow. Hahaha. Looks like a tornado went through the science project room . . .