2073 is looking into WCD, feedback requested
 

Up until now, we have mostly been a KOP drive base shop. KOP on Steroids has been our main chassis for the last few years. We are now looking into switching it up and moving to WCD.
Here is are a couple of renders of our first attempt.





I am not a CAD master by any means, this is done by one or more of our students. I am going to ask them to follow up on any/all questions and suggestions.

We had originally thought we would try to have a single drive belt contained in the frame rails, but found that a single serpentine belt needed to wrap around idler pulleys that were way smaller than the minimum recommended by Gates. So, now we plan on using one internal to, and one just inside the frame rail.

Any comments, critiques, questions, or suggestions will be greatly appreciated.

Full size images can be viewed here and here.

Re: 2073 is looking into WCD, feedback requested
 

It's a really nice rendering in any case!

I have no experience with WCD, but your design seems pretty textbook - just missing the shaft collars / circlips needed to hold the wheels on to the hex shafts.

Re: 2073 is looking into WCD, feedback requested
 

From what I see it looks good. Like others have said its just missing an clip ring or shaft collars. Everything looks to be functional and it looks beautiful! Best of luck!

Re: 2073 is looking into WCD, feedback requested
 

Howzit!

We started using WCD last year and really like the performance. So unless the game dictates otherwise we will be using it again, though possibly a hex frame 8 wheel WCD.. I posted earlier
..
A few things.. Top render has the transmission constrained on the wrong side of the drive rail.

You will be better off not using the versa blocks on the center and just drilling your center hole to use the WCD gearing block.
http://www.wcproducts.net/217-3634/

You will also need to drill a few holes on the drive rail for the bolt heads on the transmission plate to nest into. This will allow the transmission plate to rest against the drive rail giving much better support. You can run a dual sprocket on the transmission to drive each of the outer wheels.

I suggest #35 chain. We have been using #25 but last year we had to tension the chain more often due to our use of the WCD 3 CIM dual speed transmission. (great transmission by the way)

Also factor in a chain/belt cover. Nothing is worse than an electrical wire getting in there. Most of the time an encoder is mounted to one of the outer wheel shafts. Plus the judges like things to be safe!::ouch::

I am sure I will think of more after I post this..

Good luck with this, looking good!
Aloha

Re: 2073 is looking into WCD, feedback requested
 

Bill,

We should arrange an in-person design review in December. It would be a great experience for both teams. We're not too far away after all :)

-Mike

Re: 2073 is looking into WCD, feedback requested
 

+1. Some inspectors will not like the uncovered chain, but more importantly stuff can get snagged in there really easily.
Also, when doing renders, turn on perspective. It makes it looks a little more realistic.

Re: 2073 is looking into WCD, feedback requested
 

I'm unsure if the little tabs on the edges are for bumpers but if they are I would either come up with a way to support them or a beefier way because I could see though bending easily if a team gets under you bumpers. Aside from that looks good

Re: 2073 is looking into WCD, feedback requested
 

I saw that too, but I think that is just the wheel reflection in the frame rail.

Looks great to me, once you figure out chain/belt runs you should be set. We have had a harder time figuring out chain/belt runs than anything else building our first in house drive train.

BTW, your RSL is hanging outside your frame perimeter...

Re: 2073 is looking into WCD, feedback requested
 

First of all, there is no pulleys on the inside of the gearbox for the two back wheels.

In tube belts is going to be a nightmare to fix. With a regular WCD, the spacers in the gearbox make it harder to fix belts, but doable because you can always just remove the back plate. With this setup, you have to remove the entire gearbox to replace the in-tube belts.

Re: 2073 is looking into WCD, feedback requested
 

Keeping in mind that it has the 2014 controls.... Anything under the CIMs is going to be hard to access. You would also want to make your radio platform easy to remove so you can get to PD board. Depending what ends up on top, you might want to face your pneumatic controls & gauges out. The disconnect switch looks a little buried. You obliviously have a little rearranging to do to make the belts work.

Re: 2073 is looking into WCD, feedback requested
 

Excellent idea! I know we plan on meeting with your team leadership to discuss CCC, maybe we can coordinate both things happening at once?

Everyone else, THANKS!! Please continue the feedback!

Great observations and suggestions so far. Correcting these details will go a LONG way to make this a successful endeavor!

Re: 2073 is looking into WCD, feedback requested
 

It looks like this setup only mounts the WCP gearboxes via 2 #10 bolts. Could you or your students provide an exploded view, or a close-up view, of the gearbox, rail, intended bearings, and all bolts around one side of the bot's center wheel? Making the rail transparent or semi-transparent would also help.

Re: 2073 is looking into WCD, feedback requested
 

I'm working with the student who created this to get his CD account set up so he can respond directly to these questions. The team is out of school this week, so communications are a bit slow. I hope to have him up on the board later today.

Thanks for the request JesseK, we will work on getting that up ASAP.

Re: 2073 is looking into WCD, feedback requested
 

Looks like you have ~1" between the bumpers and the wheels. Consider pushing your wheels out a bit further. That'll give you more room inside the base for your electronics.

Why not stand the battery upright? The bumpers will extend to the top of the battery anyways, and you gain a bunch of space back.

The 20/30 amp fuses are hard to get to and see. Move the radio up a lot, or somewhere else.

Considering that the electronics will change next year, can you get models of them and try fitting them into your base instead? That'll be more valuable (and they are smaller!)

Re: 2073 is looking into WCD, feedback requested
 

Bill,

The things I would change:

-Don't use a full versasblock per gearbox, use 1/2. And mount the gearbox so the face of the gearbox is flush.

-Use the WCD 2 CIM DS and ditch the belts inside the tube. Go to 18T sprockets and run chain, you'll be much happier. If you still want to run belts, I would read some of the posts/docs on here about tooth size and width of belts.

I would comment on the electronics layout but Austin has me beat!

Re: 2073 is looking into WCD, feedback requested
 

It looks like you are using 2 x 1 inch tubing for the frame and the "stubs" between the wheels for supporting the bumpers. If you are anticipating playing a hard hitting game like this years, the bumpers may "pivot" inward on the top edge of the stubs and the front and rear cross members when hit hard. You may want to consider stacking another piece of 2 x 1 on top of the stubs and the front and rear cross members. Some spacers may be needed where you have the gusset plates. Alternatively, use 3 x 1, or larger tubing.


It would be best to locate the battery and input breaker at the end with the PDB and the motor controllers and rotate the PDB by 180 degrees to minimize the lengths of the high current paths. Ensure that you do not cut off access to the battery with your upper structure. Use the space between the CIMs to run wires between the two halves of the chassis. Allow at least an inch of space along each side of the PDB and the Digital Sidecar to allow for the wiring in and out. I would suggest allowing the same clearance around the new RoboRio.

You may want to locate the CRio and Digital Sidecar together on one side, say where you currently have pneumatic valves and compressor. Locate the compressor where the air tanks are now. The air tanks are pretty light so they can be put in the middle or up on the upper structure. You may want to install the pneumatic gauge higher up and turned around (as Frank suggested) so it can be seen over the bumpers.

Moving the radio to the other end will put it closer to the CRio that it connects to and away from potential noise sources (motor controllers). If possible, mount the radio on a light piece of plastic in a space in the upper structure so that it is physically protected and not surround it with metal (for better reception).

Re: 2073 is looking into WCD, feedback requested
 

Thank you for the feedback. Yes the little tabs are for the bumpers. Throughout the 2014 season we used a similar fashion for mounting the bumpers. How do you suggest we support them? I felt like keeping them away from the edge would allow them from being bent by having all the force of impact be disbursed throught the 2x1. Any suggestions would appreciated.

Re: 2073 is looking into WCD, feedback requested
 

Thank you for the feedback. I will work on moving the wheels out more, it will definitely help with getting more space inside the frame. Standing the battery upright was done at first and i simply forgot about it, that will for sure be done. As far as cadding in the new electronics goes i have done that and its simply a seperate render. After putting those in there is alot more space also considering the new speed controllers are stackable. Anything more advise will be highly appreciated. Also the reason for using old electronics is this will possibly be used as a practice run for our first WCD, i dont beleive we will be buying the new control system for it.

Re: 2073 is looking into WCD, feedback requested
 

Thank you for the feedback. At first we were planning on using a single belt that ran inside the 2x1 but were promptly met with many issues. In this render we were planning on having the back to center wheel's belt on the inside of the frame and the front to the middle inside the tubing. We planned on using belts because of their minimal stretching, but after recieving all this feedback to switch to chains, we will probably be doing so. I will be cadding a cover too and will update the render with all the great suggestions. As far as the gearing block goes we have already ordered them before break and i will propose buying those to our instructor. The render issue you saw was simply a reflection issue but the transmissions still need to be editted to include a sprocket on the output shaft. I will hopefully have the updated render in by tonight.

Re: 2073 is looking into WCD, feedback requested
 

The simple things always count! Thank you for your feedback, i will edit that part.

Re: 2073 is looking into WCD, feedback requested
 

Thank you for your feedback. Yes the gearboxes are mounted on by only 2 bolts, i was wonderig of a way to fix that and R.C. has responded with a great idea. I will be editting the cad to allow better contact. If you would still lile to see the exploded view let me know and i will happily render it out with the frame's transparency changed, it just that knowing we will probably be changing to chain it we wont have that issue any longer

Re: 2073 is looking into WCD, feedback requested
 

If you are concerned about running chains inside the frame perimeter you can easily put the sprockets on the back of the wheels and run the chain system that way. It will reduce the interior available space but will eliminate the need for chain covers. The chain covers will reduce the interior space available so in reality it about the same amount of space. If you like I can send you our CAD from last year.

Here is one of our CAD models with chain runs behind the wheels. Pardon the overly large sprockets.. We ended up moving the chain to the interior for that year.

http://www.chiefdelphi.com/media/img...9ae90ccd_l.jpg


Last year we used the WCP 3CIM DS transmission with chain runs inside the frame perimeter. We installed chain covers, like on a bicycle. The chain covers worked just fine but this year we are going to run the sprocket & chains in the frame..

http://www.chiefdelphi.com/media/img...e70e30e9_l.jpg

Keep it up!!

Aloha
Mr H.

Re: 2073 is looking into WCD, feedback requested
 

I would love to see your cad from last year to reference the chain idea. Being our first time with WestCoast, anything will help!

Re: 2073 is looking into WCD, feedback requested
 

Do you have the center wheel dropped lower? If so, how much lower? I think I have seen some teams that did not drop their center wheel, how much of a difference is this? Is it beneficial or not? For those that did not drop the center wheel, would you recommend it?

Re: 2073 is looking into WCD, feedback requested
 

The current design has a .125" drop.

Many of the suggestions here have been incorporated into an updated version. I will see if I can get the improved version up soon.

Re: 2073 is looking into WCD, feedback requested
 

If there is no drop center you will run into scrubbing (robot hopping from the outer wheels having too much traction to allow smooth turning). I have seen the use of Omni wheels to resolve this on a non dropped WCD.

1/8" drop is the norm for the center wheels. If you keep the weight centered well enough, spinning around is very easy! As mentioned, even when weight is not centered, on a drop center drive the robot will rock to one end and essentially be 4wd with a short wheelbase, which will turn much easier with less scrubbing than 6wd non drop..

Yeah robot doughnuts!

Aloha!

Re: 2073 is looking into WCD, feedback requested
 

I'd recommend using colsons and then shaving down the center wheel till happy with your drop. We started out with 3/32 and ended up with 1/16 or none.

Re: 2073 is looking into WCD, feedback requested
 

Did you find 1/8" gives too much rocking of the chassis?

By intentionally shaving down the center wheel, which usually wears down fastest anyway, aren't you introducing a different effective FPS from the center wheels than the front and rear wheels? I know this is done on purpose with some 4x4 vehicles to increase traction on surfaces that will allow slippage, like sand or gravel. Are you suggesting to do this as a way to determine optimum drop, or something else.

Re: 2073 is looking into WCD, feedback requested
 

^THIS ^

We started with 1/8" and kept it. By championship it was worn close to 1/16th and ran like a champ.. Though might of been that WCP 3CIM DS transmission... :D

With the deformation of the carpet and the Colson wheels, it was ready to go at 1/8" !

I will get the CADs up over the long weekend.. like the end of it because the weather is great!

Aloha

Re: 2073 is looking into WCD, feedback requested
 

Thanks everyone who gave suggestions and comments. This is almost becoming a "Design by Community" project.
Here are two new renders. Most of the suggestions have been incorporated now. In the oblique projection, we noticed the tension cam is on the wrong side of the block. Ooops! It is corrected in the overhead render.





Full Res images here and here.

Re: 2073 is looking into WCD, feedback requested
 

The people running the wiring and the pneumatic tubing will be much happier with this version.

You may want to move the solenoids and the Spike a bit so you can move the Digital Sidecar away from the CRio to allow space for PWM cables.

You may want to mount your pressure gauge in a small, protected space in your upper structure that makes it visible.

You may also want to add a voltmeter next to the pressure gauge. We found it handy for knowing when to stop the practice and change batteries.

http://www.amazon.com/s/?ie=UTF8&key...l_4s6cbqg7iv_e

Re: 2073 is looking into WCD, feedback requested
 

I may have to grab a couple of those meters for myself. let alone the robot(s).

Many of the items included in this render will not be located where they are due to the new RoboRio controller and speed controllers. No DSC's with the new controller, so that will give a bit of extra room.

Additionally, the new game will dictate changes that can't be anticipate at this point in time.

Re: 2073 is looking into WCD, feedback requested
 

Is there a Digital Pressure Gauge too by any chance, hopefully we will never rely on air again, but any information during a match is great to know as a driver.

Re: 2073 is looking into WCD, feedback requested
 

With a pressure transducer similar to this one, and a digital display like this one all being driven by our good buddy Mr. Adruino, we can cook up one of our own!
Who on the team would be a good candidate for this project?

Re: 2073 is looking into WCD, feedback requested
 

Tyler 2.0, aka Daniel is amazing when it comes to Arduino, he would be perfect for this project.

Re: 2073 is looking into WCD, feedback requested
 

Another option would be to use wider tubing. If you aren't riveting to the top or bottom of the tube (so clearance isnt' an issue), I would recommend 2x2 tubing and 15mm belts. If you can make your own pulleys, you can fit it in 2x1.5 tubing with some creative counterbores. Since it does seem like you are riveting, 3x1.5 tube is safer, but that's definitely adding some weight.

Honestly, I think some of the feedback against belts is a bit unfair, and maybe not based on hands on experience. If you design your belts right, you should never need to perform maintenance on them inside a tube; we're going into season 5 without a belt failure. Even with an in-tube design it is possible to change a belt in 10-15 minutes if you think carefully and know what you're doing. You do not need to remove the entire gearbox to change an (internal) belt - you slide it out a few inches until the pulley is free, then slide it back in once the next belt is in place. An access window above the middle wheel will help with this. If you leave the ends open you do not need access windows on the outer wheels.

All of this said, there are compelling reasons to use chain over belt, particularly if you are running the power transmission external to the tube. Chain drive external saves weight in using a smaller extrusion profile, and I guess it saves a little space too. In the case of using belts outside of the tube, a belt drive failure would require removal and disassembly of the gearbox, and that's no fun. It's really up to preference, and whether or not you want to tension after the fact or not. If you like tensioners and bearing blocks, chain is a lot easier. If you can machine "exact centers", where your wheels are fixed the exact distance apart that a belt calls for, and you don't mind a "fatter" drive tube, belt drives are nice.

So maybe they weren't wrong... Just thought I'd add some data and explain the logic behind internal belt drives a little bit more.

Re: 2073 is looking into WCD, feedback requested
 

I think a lot of people are debating belts is its possible to put too much load on certain combinations in a drivetrain. The smallest chain system you can buy is #25 chain with 16t sprockets. The torque calculations with 4 inch wheels are still within spec of #25 chain, even with 6 cims. Whereas with 9mm belts and 24t pulleys, you are out of spec for the belts. I saw alot of teams (including us) use that combination this year, and it did not work out well. Had we gone up to 30t pulleys we most likely wouldn't have broken a single belt, but if you have a baseplate mounted under 2x1, like in most WCD's, you actually cannot fit a 30t pulley without pocketing the baseplate, or spacing it out. And inside a standard WCD its harder to fit 15mm belts.

So if you make sure to put the right size belts in, they can be a great system. But I would not use 9mm belts with 24t pulleys. You will most likely have a bad time if you do.

Re: 2073 is looking into WCD, feedback requested
 

We're also looking at WCD this year and doing something similar to your setup. We are mounting the gearbox with the WCD mounting block and then using chains & sprockets to get to the other wheels. Pic show concept - brown items are the chains (not belts).

Definitely planning some sort of chain guard/cover.