pic: Concept 6W Drive Train

[AdamHeard]

Originally Posted by Infinity2718

You are correct with how we are thinking. I would argue once you add bumper support and interfaces for mechanisms to a WCD, it is more complex. This structure immediately supports the bumpers and provides a little better locations for mechanisms imo. We also try to build as much as we can in house. We are fortunate enough to use the manual lathes and manual mills in the school to build.

We mill our WCD siderails on a manual mill for reference.

Also, bumper support on a WCD doesn't need to be complicated.

As for interfacing to mechanisms, how is it more difficult with a WCD?

[Oblarg]

Originally Posted by AdamHeard

Also, bumper support on a WCD doesn't need to be complicated.

Are there really no problems with only having a bumper support that low off the ground? As far as I can tell, that's going to be contacting the bumper well below-center.

[AdamHeard]

Originally Posted by Oblarg

Are there really no problems with only having a bumper support that low off the ground? As far as I can tell, that's going to be contacting the bumper well below-center.

No problems at all.

We make one piece bumpers with strong corners. Any moment trying to bend the bumper over is reacted by the adjacent section.

[AdamHeard]

Here is a good exercise...

Design a few drivetrains, give them all a good honest effort (otherwise you're just wasting your own time and lying to yourself).

While designing, do your best to optimize all the variants for your resources. Publicly post them for review. Invite BRUTAL commentary, take this in stride and incorporate the feedback that makes sense. If you have enough experienced students, mentors and possible sponsors that can offer review, the public part could be skipped.

At the end do a fair comparison of the different options on the criteria that matter to you; fab time, difficulty, cost, etc...

Going into nearly every season we have designed a swerve, west coast, plate sandwich drive and the last few years butterfly/octonum. We constantly reassess them to better suit our ever changing resources, and compare them on the merits we care about.

It's unreasonable to anecdotally link it to a drive a good team ran. Using that logic ANY drive can be proven to be the best.

[Oblarg]

Originally Posted by AdamHeard

No problems at all.

We make one piece bumpers with strong corners. Any moment trying to bend the bumper over is reacted by the adjacent section.

Ah. We've never done one-piece bumpers. We probably should try it out, it seems. Thanks.

Edit: Out of curiosity, how do you do the corners on your bumpers?

[Deke]

Originally Posted by AdamHeard

We mill our WCD siderails on a manual mill for reference.

Also, bumper support on a WCD doesn't need to be complicated.

As for interfacing to mechanisms, how is it more difficult with a WCD?

We ran bumper supports similar to that and milled the rails manually. Our wc drive performed awesome last year, no issues. By the end of the season the bumpers were all smashed in at the top from no framing support and became more difficult to install, that's my beef with it. It also took a bit to get framing supported for mechanisms, there just isn't alot of framing on a wcd. Most of the framing required alot of attention throughout competitions. It's all fairly minor complaints, i don't have an issue doing a wcd again but i think a different approach could free up resources for us.

Originally Posted by AdamHeard

Here is a good exercise...

Design a few drivetrains, give them all a good honest effort (otherwise you're just wasting your own time and lying to yourself).

While designing, do your best to optimize all the variants for your resources. Publicly post them for review. Invite BRUTAL commentary, take this in stride and incorporate the feedback that makes sense. If you have enough experienced students, mentors and possible sponsors that can offer review, the public part could be skipped.

At the end do a fair comparison of the different options on the criteria that matter to you; fab time, difficulty, cost, etc...

Going into nearly every season we have designed a swerve, west coast, plate sandwich drive and the last few years butterfly/octonum. We constantly reassess them to better suit our ever changing resources, and compare them on the merits we care about.

It's unreasonable to anecdotally link it to a drive a good team ran. Using that logic ANY drive can be proven to be the best.

I'm confused who this information is for, isn't this the exercise we are going through? I enjoy the commentary and feedback, I am hoping it helps. I'd prefer feedback on pros and cons/strengths and weaknesses, versus design process rhetoric.

[AdamHeard]

Originally Posted by Infinity2718

We ran bumper supports similar to that and milled the rails manually. Our wc drive performed awesome last year, no issues. By the end of the season the bumpers were all smashed in at the top from no framing support and became more difficult to install, that's my beef with it. It also took a bit to get framing supported for mechanisms, there just isn't alot of framing on a wcd. Most of the framing required alot of attention throughout competitions. It's all fairly minor complaints, i don't have an issue doing a wcd again but i think a different approach could free up resources for us.

Can you post your frame and bumper setup from season?

Originally Posted by Infinity2718

I'm confused who this information is for, isn't this the exercise we are going through? I enjoy the commentary and feedback, I am hoping it helps. I'd prefer feedback on pros and cons/strengths and weaknesses, versus design process rhetoric.

It's for anyone willing to read it. Is this the only drive you are developing this fall, or are you also re-designing your WCD to have something to compare to?

Maybe look at vexpro drive in a day, and modifications (or stock) you could do there. I know 558 was really happy with, and just posted about it.

[Deke]

Originally Posted by AdamHeard

Can you post your frame and bumper setup from season?

Originally Posted by AdamHeard

It's for anyone willing to read it. Is this the only drive you are developing this fall, or are you also re-designing your WCD to have something to compare to?

Maybe look at vexpro drive in a day, and modifications (or stock) you could do there. I know 558 was really happy with, and just posted about it.

Not really redesigning last year, just adding it to the considerations.

I do like the layout of the day in a drive, and actually all of the cots drives are pretty good. Our team prefers to build as much as we can, and would like some flexibility for perimeter changes.

I did read the 558 beyond the inspection when it came out, and they did say they wished they had more bracing to make the chassis more rigid.

[BrendanB]

Originally Posted by Andrew Lawrence

A full versachassis can get expensive, I'll admit that, but just using some of the parts can greatly simplify this design and make it not only more effective, but more reliable as well. You don't need to buy an entire drivetrain setup, but using what your resources will allow can greatly simplify things.

You don't need to break bank on COTS parts to make a great drivetrain, but ignoring the cost effective resources available to teams isn't the answer either.

I smell no bias here. Nope.

WCD and even the Versachassis is not the answer for every team.

[AdamHeard]

Originally Posted by Infinity2718

Not really redesigning last year, just adding it to the considerations.

What didn't work out well on the framing for bumpers on this?

Hard to tell from just a top down picture, but assuming the supports between the wheels were at the correct height to support the bottom of the bumpers this should've worked out decent.

Was it a mounting issue? Did they have too much slop/play? Was it a once piece bumper?

Were you happy with the drive otherwise, and are just trying to solve the bumper issue?

[z_beeblebrox]

AdamHeard, where can I find good pictures or descriptions of the bumper and bumper mount design that you guys use?

[Deke]

Originally Posted by AdamHeard

What didn't work out well on the framing for bumpers on this?

Originally Posted by Infinity2718

By the end of the season the bumpers were all smashed in at the top from no framing support and became more difficult to install, that's my beef with it.

Originally Posted by AdamHeard

Hard to tell from just a top down picture, but assuming the supports between the wheels were at the correct height to support the bottom of the bumpers this should've worked out decent.

Was it a mounting issue? Did they have too much slop/play? Was it a once piece bumper?

Were you happy with the drive otherwise, and are just trying to solve the bumper issue?

The mounting could have been better, we used wing nuts with bolts through the bumper. It was a one piece bumper.

I have a handful of minor complaints: center live axle getting bent and wobbly a few times (took a while to replace, the dead axles performed better imo), bearing block plates hard to get at to loosen, gear box cantilevering off a few bolts seemed sloppy (, tensioners added construction and wheel maintenance time, if we got tipped the drive would sit on its frame edge and lose traction. Other than that and other things noted in this thread, it was pretty sexy.

[asid61]

In recenty memory, there have been:
2010: Giant bumps made moving fast only possible in the individual sections
2011: Open space for driving. Very fast driving was useful.
2012: Open space for driving, except when passing over the low barrier.
2013: Open space barring the pyramids.
2014: Totally open space. 1678 was geared for 22fps according to their website.
If you feel that the cost/complexity is beyond the team's scope, sigle speed is more than fine. But when running 6 cims, be prepared to add in some kind of anti-breaker tripping code anyway just in case.

[Brandon_L]

Originally Posted by Infinity2718

Center live axle getting bent and wobbly a few times (took a while to replace, the dead axles performed better imo)

Usually you'd use a high strength aluminum alloy here or even steel, what did your team use?

Originally Posted by Infinity2718

bearing block plates hard to get at to loosen

This seems to be a result of where you're running your chains from. On most of the WCDs I've seen the chain runs are actually on the inside of the robot with the chains coming off a sprocket inside of the gearbox itself. Of course you can really do it any way you want, but as a result of sprockets on the outside yes your plates will be more difficult to get to.

Originally Posted by Infinity2718

gear box cantilevering off a few bolts seemed sloppy

What about it seemed sloppy?

With all that being said, 1x1 drives are perfectly valid. The only thing I would comment on is that some of your upper structure seems unnecessary. Maybe you're using the outer upper level for bumper supports, which is fine, but the inner upper level that holds up the gearbox could probably be replaced with something like this. Depends on what you were trying to achieve with it.

Also, I'm not sure if I would trust those vertical gussets you have going on with impacts. But I could be wrong. Who knows.

[philso]

You may want to consider what would happen if this chassis is used in a game that allowed high speed and hard hitting, like this years. There is the possibility that the vertical angle pieces in the corners deform when hit on that corner causing the two outermost side tubes to move backward. Since it looks like your axles are supported by the lower side tube, they may bind in the bearing blocks and/or cause the robot to not drive straight.