13-06-2008 01:15

Re: pic: 968's 2006 practice bot chassis

Gorgeous system. We can all learn so much from this drive base. It doesn't matter who built it, students or mentors (yeah, I know some people would complain about it being made by some mentors... but that's not the issue I'm talking about here). What does matter, however, is that this is (nearly) perfect engineering. The West Coast Drive is essentially the penultimate drive base, in my opinion. 254 and 968 have boiled out any unnecessary material and structure.

Hey, while I'm at it, does anyone from either 968 or 254 happen to know how much that base (as pictured) would weigh? I'm doing some design work, and it would be nice to have something to compare to.

13-06-2008 01:43

Pat Fairbank

Re: pic: 968's 2006 practice bot chassis

I just have to ask, then, what do you consider to be the ultimate drive base?

13-06-2008 01:45

Re: pic: 968's 2006 practice bot chassis

Judging as FIRST never stops, and teams keep getting better, I'd have to say we haven't seen it yet, and every time we think we have, it will get topped.

EDIT: removed something that apprently ticked someone off...

13-06-2008 06:10

waialua359

Re: pic: 968's 2006 practice bot chassis

I keep forgetting to find out where they chrome the wheels. No one locally does it here in Hawaii. Liking the "bling bling."
Sorry 968, we really are not trying to look more and more like your bots.

13-06-2008 09:18

cooker52

Re: pic: 968's 2006 practice bot chassis

I have to say that that's one of the best parts of FIRST, you can always use ideas from other robots, but they'll almost alway look completely different.

13-06-2008 10:11

Jonathan Norris

Re: pic: 968's 2006 practice bot chassis

I agree that this is a very good drive base that has really become the signature for many westcoast teams. But I still wouldn't build one for any of my bots, still don't see any point of exposing my wheels like that... (I know because I saw my team knock two of 254's wheels off in 2005)

13-06-2008 11:48

cooker52

Re: pic: 968's 2006 practice bot chassis

What's that aluminum on the back for?

13-06-2008 11:49

Madison

Re: pic: 968's 2006 practice bot chassis

It's a roller that helps to keep the chassis from riding up onto balls.

13-06-2008 11:54

cooker52

Re: pic: 968's 2006 practice bot chassis

Thanks.

Did you guys also have another piece to this? I see nuts that look like they're for an expansion.

13-06-2008 12:09

Cory

Re: pic: 968's 2006 practice bot chassis

Yes

http://www.chiefdelphi.com/media/photos/23983

13-06-2008 12:11

acdcfan259

Re: pic: 968's 2006 practice bot chassis

We've got these bumper things now...

13-06-2008 13:07

Lil' Lavery

Re: pic: 968's 2006 practice bot chassis

Yet they still made the finals on Einstein...

13-06-2008 13:09

JesseK

Re: pic: 968's 2006 practice bot chassis

Eh, the shiny wheels are protected (heh, and covered up) by bumpers nowadays. If I remember correctly, there were no bumpers in 2005. It's still a great solid drive system.

I have to admit I can't figure out how to elegantly mount an AM super shifter to it, but I figure there's still plenty of time to work it out.

13-06-2008 13:22

Re: pic: 968's 2006 practice bot chassis

Mounting a SS should be pretty "simple." Just make your own symmetrical side plates, assemble with standoffs, and have two holes designed in that are co linear with the output shaft of the center wheel. Those two holes allow the gearbox to bolt to the chassis member.

13-06-2008 15:14

EricH

Re: pic: 968's 2006 practice bot chassis

And 968 did the exact same thing the next year...

13-06-2008 15:29

sgreco

Re: pic: 968's 2006 practice bot chassis

Now I know where the expression "solid as a RAWC" comes from

13-06-2008 18:09

AdamHeard

Re: pic: 968's 2006 practice bot chassis

If you line up your cross members right, you can bolt on the SS's without any modification to them (besides longer bolts). 973 did that this year as we didn't have the resources to make our own gearbox plates. I'll take pictures when I can.

16-06-2008 10:30

JesseK

Re: pic: 968's 2006 practice bot chassis

We did something similar this year with the SS's. We used an exactly dimensioned (with 1/16" tolerance) wooden block with manually CNC'ed holes to represent the SS to get the exact spacing correct while welding. The SS was positioned above the inside frame rail on either side. However, the output shaft wasn't inlined with the middle wheel.

During the design phase it appeared to be more weight to put bearing blocks for direct drive than it was to run more flat AM sprockets & chain, so I went with the 2-chained approach with tensioners directly mounted to the transmission (another bad idea). In hindsight, complexity of maintaining the chain system was what hurt us most this year, so it would have been much more simple to directly drive the middle wheel. We saw 254 & 233's bots in Vegas '07, and saw the simplicity of direct-drive on the middle wheel yet we didn't heed the reasons why. Coulda-shoulda-woulda's aside, maybe it's better we made our mistakes ourselves?

The good news is, we didn't modify our SS's so now we {should} be able to use them again next year if the rules don't change. Now if we could only figure out where this little plastic washer goes on the SS that appeared out of nowhere on our table...

16-06-2008 21:25

AdamHeard

Re: pic: 968's 2006 practice bot chassis

Pic 1
Pic 2
Pic 3

04-07-2008 22:20

team2061

Re: pic: 968's 2006 practice bot chassis

i could never understand how the wheels stay on. could someone please explain this to me

04-07-2008 22:25

Cory

Re: pic: 968's 2006 practice bot chassis

We use snap rings to hold the wheels on.

You can see this here , sort of. There's a groove in the shaft outside the sprocket. The snap ring expands to fit over the shaft, and then contracts when it is seated in the groove, and then keeps the wheels/sprockets from sliding off.

06-07-2008 01:17

Cory

Re: pic: 968's 2006 practice bot chassis

For some reason I can't edit my post. Here's the right link

07-07-2008 00:50

team2061

Re: pic: 968's 2006 practice bot chassis

but how is the wheel attached on the other side

07-07-2008 00:59

EricH

Re: pic: 968's 2006 practice bot chassis

I believe that the sprocket is on the other side. It's a live-axle setup, so the sprocket is attached to the axle via keyway or hex, probably with a setscrew to keep it from sliding sideways.

07-07-2008 01:24

Cory

Re: pic: 968's 2006 practice bot chassis

Exactly the same way. Both sides have hexes (that screenshot is of the 05 bot, and it used woodruff keys), and both sides have a snap ring groove in the shaft to retain the sprocket/wheel axially. They butt up against a shoulder in the shaft where the hex ends.

07-07-2008 15:59

team2061

Re: pic: 968's 2006 practice bot chassis

oh ok thanks now i understand