pic: My First WCD
 

Re: pic: My First WCD
 

I hate to say it but this definitely isn't a West Coast Drive (WCD).

That being said it looks incredibly solid for a first drivetrain. Adding a bellypan on the entire bottom would greatly strengthen things. Also how are you planning to tension the chains and what wheels are you using?

Re: pic: My First WCD
 

What do you mean? I thought west coast drive was just a dropped center wheel:confused: . if there are other requirements, what are they?

from the picture it looks like the center wheel is dropped but its hard to tell.

Re: pic: My First WCD
 

A west coast drive typically infers that the outer most point on your chassis are the wheels.

Re: pic: My First WCD
 

The ones that come to mind are:

Live axles
Typically 6wd dropped center (or 8wd in some cases)
Direct drive from transmission to center wheel
Dropped center wheel
Cantilevered wheels

Re: pic: My First WCD
 

Thanks I did not realize that.

Re: pic: My First WCD
 

Looks good! What is the total weight? And are your center wheels along a line perpendicular to the side plates, or are they slightly offset from each other?

Re: pic: My First WCD
 

Has anyone else noticed that the teams who developed the so-called "West Coast Drive" rarely ever refer to it as such? Strange how the name kind of took off.

Re: pic: My First WCD
 

Maybe cause they are used by teams on the west cost, so the east coast calls them west coast drives, thus, it just hasn't reached them yet. ;)

Re: pic: My First WCD
 

Yup that sounds good to me. Im glad this one is not a WCD though per se. It seems that everyone has been jumping on the wcd bandwagon possibly without considering other styles of drive all the while neglecting to implement many of the key benefits of west coast drives.

Re: pic: My First WCD
 

I agree with you, but I am one of those people on the west coast bandwagon. It's a great system. It combines ease of maintenance, light weight, and depending on how you make it it can be fairly low intensity on the machining end. (of course other drives have their advantages too.)


Back to the drawing....That is a really nice sheetmetal drive. I'm guessing the middle is driven via hex and from their power is distributed to to the outer wheels which rest on dead axles. Are they custom wheels? The gearbox looks custom two, or is a standard andymark gearboxbox modified for mounting purposes?

Great design though, the whole sheetmetal thing is taking off...

I personally owe a thanks to team IFI for some inspiration with sheetmetal fabrication...I love seeing all the new with sheetmetal.

Re: pic: My First WCD
 

I believe that this is in fact not part of the sheet metal bandwagon... To me this looks like C-Channel is designed to be welded... Hopefully Stephanie will elaborate further on her drive system and it's components.

Re: pic: My First WCD
 

This is the most famous example of a "West Coast Drive".

http://www.chiefdelphi.com/forums/sh...c+968+practice

Looks really nice! Any idea on weight or thickness of the metal. Also what kind of transmission/gear ratio is that?

Re: pic: My First WCD
 

I observe no flanges where the apparent bends would be which would make you correct and it not a sheetmetal frame, or it could be a lack of detail by the designer by simply extruding off of a preexisting plate rather than actually putting in a bend.

Re: pic: My First WCD
 

I'm interested about a couple of things.

1. Are those custom gearboxes? Or are they specific ones you found online?

2. What is the weight of the frame?

Other than that, this is not w WCD, or the definition of WCD that I am familiar with. But the frame looks nice. I'm worried that some of the extrusions in the frame leave the the metal between a little thin, but it looks excellent.

Re: pic: My First WCD
 

I'll try to answer most of your questions here.

I apologize I got the terminology a little mixed up.

Dave is correct, this is not a sheet metal drive, it is 1/8" 3x1 C channel. It is a little difficult to see in the picture, I apologize. If I have some time later, maybe I'll render a few other perspectives and post them.

It is all C channel. The idea I took was to make things easy to manufacture and easy to get to. All four side rails are completely identical. Front and back are identical as well.


Everything except the outermost side rails would be welded together, and the outermost rails are bolted on via standoffs and brackets at the ends/corners. This would make the outer rails easy to take off and maintain the drive, if necessary. If weight became a concern, these would be replaced with polycarb, as many teams have done previously.

The outer rail channel has cutouts around each of the wheels.

Inventor says the frame is around 10 lbs. Like I mentioned before, there are things that could easily be changed if weight became a concern.

As far as the trussing and cutouts go, there is at least 1/4" material between every cutout, often more.

The wheels are 50 durometer Banebots wheels with the unfinished hubs. There are custom hubs that interface with the wheels after they have been modified to have a larger hole. Outer wheels are dead axle, center are keyed.

There are vertical slots in the side rails that hold a chain tensioner.

I'm not really sure what you're asking 548swimmer, but the wheels are all inline with each other and the center wheel is exactly in the center of the robot.

If I missed a question, or if you have more, feel free to bring it up again, or ask.

Re: pic: My First WCD
 

If all your wheels are in line with each other you will not be able to turn. you need to lower the middle wheel so there are never more then 4 wheels on the ground at a time.

Re: pic: My First WCD
 

By inline I was trying to address the question that swimmer posed, but I'm not really sure what he was getting at. If you'll notice in the description of the picture, the center wheel is dropped 1/8".

Re: pic: My First WCD
 

:ahh: Sorry I assumed that was what he was referring to. I did read you OP but is was a few days ago and I totally forgot. I have no idea what swimmer meant, he is hard to follow at best.

Re: pic: My First WCD
 

Really Cool Chassis and a great start.

A Few Suggestions:

-Ever thought about riveting it all together and then adding a few welds? It would help make it easier to assemble and easier for our welder. We did that this year with our bottom part of our chassis.

-I would honestly pocket less. Its often way stronger to leave it unpocketed. I mean your only losing so much weight. Around the wheels and gearbox I would honestly unpocket it.

-Also wheels selection, why banebot wheels. We bought some a few years ago and the tread seems to wear very easily unless you get a high durometer. They are cheap, but I would switch to pneumatic wheels or Colsons. I'm sure Sean (1771) or someone can elaborate on Colson wheels.

A Few Questions:

-What gearbox is that: ratio, output speed and weight?

-Are you planning to mount electronics somewhere?

-For the chain tensioner, are you pinching the chain down or stretching it up?

Good Job and keep having fun.

-RC

Re: pic: My First WCD
 

Colson wheels are very cheap (usually between $5 and $7 each), and can easily be adapted for a live axle drivetrain. The stock Colson wheels usually have a large ID shaft hole in the center that needs to have an adapter made to fit 1/2" or 3/8" shaft. We use 6061 aluminum for this adapter plug. Simply turn it on a lathe to a slight interference fit, and knurl the outside. Drill out the center and broach with either a keyway or hex broach. Use an arbor press to insert knurled plug into wheel. Done.

Re: pic: My First WCD
 

I would definitely recommend colsons as well. We did the same thing as art this year. Bought stock colsons and put hubs in them. They work great and are designed for durability whereas the banebot wheels are basically childs toys. I've seen and heard of way too many failures/manufacturing inconsistencies with the banebots to ever consider them.

Re: pic: My First WCD
 

With the holes on the side plate, it looks like you have two holes to press-fit bearings for the center wheels into. This led me to believe that your center wheels were not on the same line in the center of the 'bot. Also, from this render it looks they don't quite line up (again with the two bearing holes). I trust you that they are in the center, but it was just a concern I had at the time.

Re: pic: My First WCD
 

Ditto on the Colsons, they are very robust wheels, and have a great grip on the carpet. However they do become pretty heavy when you start adding in the additional parts needed (ie: plug adapter for each wheel). Just another thing to consider in wheel selection.

-Brando

Re: pic: My First WCD
 

I've never seen Banebots wheels used successfully in a robot. I've heard of teams getting them with the bore off center by as much as half an inch. I've seen teams make them fail with only 3 seconds of load. I would go with AM, Colsons, your own wheels, etc. (or if you want to be super cool, take a scooter wheel and put it on your robot!!! no traction but who cares, they're awesome!)