pic: West Coast Drive: Spokane Style

[CraigHickman]

[cdm-description=photo]32123[/cdm-description]

[gorrilla]

if you were thinking about climbing, why not use a 2 speed?

i like this design escpecially the bumper mounts

[AdamHeard]

2 CIMs geared for 10fps doesn't seem traction limited (assuming roughtop/wedgetop tread).

[Akash Rastogi]

if you were thinking about climbing, why not use a 2 speed?

i like this design escpecially the bumper mounts

Don't see the correlation between the two things...care to explain? Plenty of 'bots did just fine w/o any shifting in 06, so I don't see what you mean by that.

[sdcantrell56]

You definitely do not need a 2 speed transmission to climb things. All a 2 speed would really help with is allow you to be a bit more precise in maneuvering. The important things to consider when having to climb are approach/departure angle, breakover angle, center of gravity, and traction.

I do really like this design although I do favor 2 speed transmissions for the ability to push and to be agile when you want. I'm glad Ive inspired a little West Coast off of sorts. Who's next?

O and how much does it weigh?

[Akash Rastogi]

Who's next?


Soon my good man, soon :cool:

[MrForbes]

Just guessing...the frame is made of 1/8" wall 1x2" aluminum tubing? welded together?

Looks very orthodox, and a good design!

[CraigHickman]

I do really like this design although I do favor 2 speed transmissions for the ability to push and to be agile when you want. I'm glad Ive inspired a little West Coast off of sorts. Who's next?

O and how much does it weigh?

I hate to say it, but this design was cooking long before you brought it up. It was you bringing it up that inspired me to post the render. Weight is around 35 for the entire assembly, and that's with chain (not shown in the render)

if you were thinking about climbing, why not use a 2 speed?

i like this design escpecially the bumper mounts

The bumper mounts aren't actually finished in this render. The final versions will have 4 .25" thick plates welded to each of the jutting extrusions pieces on each side. Each plate will have two 1/4-20 holes for mounting the bumper lock bars, something I've been cooking up to allow easy to swap bumpers. Imagine something akin to a door hinge, that allows a bolt to be put in the top on each peg to secure the side bumpers.

EDIT: Yeah Squirrel, it's all 2x1x.125 wall extrusion. The goal was to keep the chassis to only one material to keep the cost down, and the BOM simpler

[sdcantrell56]

O I know it's been cooking for a while. You've had a design similar to this floating around for a while now. It's good though to see how different people change and interpret a well known design.

[CraigHickman]

Actually, after reading over what you said, let's see how many iterations of the West Coast Drive there are out there! If you've got one designed, put the render up on www.tinypic.com and throw it up here!

[s_forbes]

Nice design, that kind of set up has been proven to work tons of times. What kind of guts do you have in the transmissions? Are they completely stock components (minus sideplates), or do some of the shafts/gears need machining?

2 CIMs geared for 10fps doesn't seem traction limited (assuming roughtop/wedgetop tread).

It certainly isn't, the traction limit for roughtop or wedgetop drivetrains (2 CIMS) is closer to 6.5 ft/sec for a full weight robot. Still, we ran wedgetop tread on our single speed robot last year at about 11 ft/sec and didn't have any problems. Of course, we didn't have to push anyone either...

Actually, after reading over what you said, let's see how many iterations of the West Coast Drive there are out there! If you've got one designed, put the render up on www.tinypic.com and throw it up here!

I made one a little while ago that's similar to yours in that it is just a small single speed drive base, but uses cantilevered dead axles instead of live axles. Not really west coast, but still... :rolleyes: Comes in to about the same weight as yours, too, about 35 lbs with chain (says inventor). The transmissions are about as itty bitty as they can be.

http://img407.imageshack.us/img407/2878/smalldrive2lf0.th.jpg (http://img407.imageshack.us/my.php?image=smalldrive2lf0.jpg)

[=Martin=Taylor=]

Actually, after reading over what you said, let's see how many iterations of the West Coast Drive there are out there! If you've got one designed, put the render up on www.tinypic.com and throw it up here!

Ourselves and team 368 built one with 80/20 (or Bosch). Team 100 (http://www.chiefdelphi.com/media/photos/29071). Team 368. (http://www.mckinleyrobotics.org/2007/gallery/week3/images/0124-03.jpg) 368's actually had a really cool pneumatic break that shot into a hole in one of their drive sprockets.

Why is cantilevered better than non-cantilevered? Beats me. We won't be doing this again.

[CraigHickman]

Why is cantilevered better than non-cantilevered? Beats me. We won't be doing this again.

Chassis weight. You need less chassis material for a cantilevered drive base. There's no need for an outer frame rail, which definitely takes weight down.

[Akash Rastogi]

Chassis weight. You need less chassis material for a cantilevered drive base. There's no need for an outer frame rail, which definitely takes weight down.

Hate to be uninformed, but what exactly is a cantilevered wheel/frame?:confused: Pics of specifics would greatly help.

[MrForbes]

Cantilevered means the axle is supported at one end or a the center, non-cantilevered the axle is supported on both sides of the wheel.

[Akash Rastogi]

Cantilevered means the axle is supported at one end or a the center, non-cantilevered the axle is supported on both sides of the wheel.

Thank you very much :)

[Brandon Holley]

Thank you very much :)


just to clarify a little more for you akash...

If you look at pics of our bot last year that is a good example of non-cantilevered....254/968 are a good example of cantilevered

[Joe Finkel]

I don't think you will climb anything over 20 degr. with bumpers mounts in front of the wheels.

[CraigHickman]

I don't think you will climb anything over 20 degr. with bumpers mounts in front of the wheels.

You're assuming that this is the complete assembly for climbing. It was mentioned that some small changes in the event of climbing being required are easily doable on this design. One gear change per box, and 6 inch wheel instead of 4 inchers. Or, I could leave one side open and put a roller on the front, much akin the 254 during raising the bar (I think theirs was to stop them from rolling over balls, but a few small mods and it would work for ramp climbing).

EDIT: I never sleep.... I need to stop forum lurking....

[jwancura]

ok, so I've been looking at these West Coast drives forever, but I still can't figure out where the bearing blocks for the wheels come from. Are they an off the shelf part you can get from mcmaster by any chance? My team has no milling whatsoever so I'm stuck with finding parts from a store.

[sdcantrell56]

In all of the west coast designs I know of and all of the ones I have designed, the bearing blocks are custom machined parts. There really aren't any good off the shelf parts that I know of to accomplish this. You could always look around for a machine shop to donate some machine time. Many shops are very receptive to robotics stuff. You could also use some of the bearing blocks from team 221 although I don't know if they would work for what you want to do.

[billbo911]

ok, so I've been looking at these West Coast drives forever, but I still can't figure out where the bearing blocks for the wheels come from. Are they an off the shelf part you can get from mcmaster by any chance? My team has no milling whatsoever so I'm stuck with finding parts from a store.

There are options for teams with limited machining capabilities. This link (http://www.robotmarketplace.com/products/MB-UCFL201-8.html)will take you to one option from Robot Market Place.

I am not advising either way with these. There are many more options like these, but it might get you headed in the right direction. A pair of these per axle should do the trick.

[s_forbes]

ok, so I've been looking at these West Coast drives forever, but I still can't figure out where the bearing blocks for the wheels come from. Are they an off the shelf part you can get from mcmaster by any chance? My team has no milling whatsoever so I'm stuck with finding parts from a store.

The best off the shelf bearing block I have found is this one (http://hnsparts.com/) (top of the page) used for front hubs on jr. dragsters. The bearings are a little big, but the assembly looks like it could work for wheel axles. I haven't gotten to play with one... I've only seen them online. They are probably way bigger in real life than they look in the picture. :)

[AdamHeard]

ok, so I've been looking at these West Coast drives forever, but I still can't figure out where the bearing blocks for the wheels come from. Are they an off the shelf part you can get from mcmaster by any chance? My team has no milling whatsoever so I'm stuck with finding parts from a store.

If your team has no machining resources a West Coast Drive is not a good option. If you have even basic manual mills available, it can be done very easily and simply; but if you don't have that, it will be much more difficult than other possible base designs.

I'd suggest looking into using the KOP frame (it really is awesome) if you have no resources, or try finding some resources. Opening a phonebook/google maps and calling machine shops will surprise you with the results. You'll see that there are both more local shops than you probably think, and more are more willing to help than you probably think.

[EricH]

Adam's right. I just did a quick Google Maps search for "machine shops Kansas City" (noting your location) and came up with quite a few.

[AustinSchuh]

Looks good.

Is there any reason that you have the frame extending in front of the front and back wheels? I know that in the past, one reason for this part has been so that when you ram something, you can't hit it with your wheels. But we now have bumpers, so that isn't necessary. And by removing it, you can move your front wheels up 1 inch, making it easier to climb stuff.

[AdamHeard]

Looks good.

Is there any reason that you have the frame extending in front of the front and back wheels? I know that in the past, one reason for this part has been so that when you ram something, you can't hit it with your wheels. But we now have bumpers, so that isn't necessary. And by removing it, you can move your front wheels up 1 inch, making it easier to climb stuff.

You can also make the bolt tensioners work off of little end plates. This simplifies the machining of cross members as now don't have two holes ~24" apart that have to be relatively accurate.

[CraigHickman]

Looks good.

Is there any reason that you have the frame extending in front of the front and back wheels? I know that in the past, one reason for this part has been so that when you ram something, you can't hit it with your wheels. But we now have bumpers, so that isn't necessary. And by removing it, you can move your front wheels up 1 inch, making it easier to climb stuff.

It makes the mounting of side and front bumpers with a part not yet in CAD much easier. Once I get the bumper mounts finished I'll upload them and you can see why it needs the front chassis extending all the way out. (all four bumpers can be attached and removed with 8 1/4-30 bolts, all vertical facing and easy to access.)

[AdamHeard]

It makes the mounting of side and front bumpers with a part not yet in CAD much easier. Once I get the bumper mounts finished I'll upload them and you can see why it needs the front chassis extending all the way out. (all four bumpers can be attached and removed with 8 1/4-30 bolts, all vertical facing and easy to access.)

If you are designing a bumper system that is easy to install and remove, why not use cotter pins?

[EricH]

If you are designing a bumper system that is easy to install and remove, why not use cotter pins?
They weren't allowed last year. It had to be a bolt system.

[AdamHeard]

They weren't allowed last year. It had to be a bolt system.

973 has been using a bolt system that is retained by cotter pins the last 3 seasons. Super easy to take on and off, and it still uses a nut and bolt as per the rules. No inspector has ever had a qualm with it.

[James Tonthat]

Can you post a diagram of the nut/bolt cotter system?