Mecanum Demo-Bot Recommendations?

[Cothron Theiss]

VexPro has details about a very simple Mecanum drivetrain on their website.
http://content.vexrobotics.com/vexpr...17-8000-MD.pdf

It would meet all of your design criteria, albeit being a bit pricey.

[FrankJ]

We have used the Vex clamping gear box with 6" mechanums. it works well. We used a belt second stage. Detailed on Vex's web site bottom of page. The single stage isn't enough reduction. The cost of the Vex clamping boxes add up by the time you add bearing, gears, belts, and so forth. We have also used Andymark's nano gearboxes with the wheels mounted directly to them. Stock gearing in them is a little slow with 6" wheels.

[mr.roboto2826]

How crazy are you looking to get? Way back in 2010, we build a "demo" bot with 15" mechanum wheels. It was quite the fun project as we had to make everything custom. It even has a torsion beam suspension! It's great in the sense that it's a great all purpose robot, and can climb almost anything (barring you have enough power). Downsides are its expensive, heavy, and requires quite a bit of juice!

TLDR; Big wheels are cool, but expensive.

[Thayer McCollum]

We have had VEX mecanum wheels break on us. It seems like everyone else has had a good experience with them so take my advice with a grain of salt. AndyMark mecanums are more durable. The VEX ones look really cool but the way the rollers attach makes that attachment pretty weak, we busted three rollers off different wheels all in that same spot. So we now have AndyMark mecanums on our bot and they have held up much better. I don't know why the VEX ones broke and I trust VEX's quality in most things but I prefer AndyMark for mecanums.

[James3245]

Thanks for input everyone - very helpful!

[R.C.]

Originally Posted by Thayer McCollum

We have had VEX mecanum wheels break on us. It seems like everyone else has had a good experience with them so take my advice with a grain of salt. AndyMark mecanums are more durable. The VEX ones look really cool but the way the rollers attach makes that attachment pretty weak, we busted three rollers off different wheels all in that same spot. So we now have AndyMark mecanums on our bot and they have held up much better. I don't know why the VEX ones broke and I trust VEX's quality in most things but I prefer AndyMark for mecanums.

Did you get the new updated rollers?

http://www.vexrobotics.com/vexpro/mo...um-wheels.html

Look under Mecanum Wheel update

[Thayer McCollum]

Originally Posted by R.C.

Did you get the new updated rollers?

Yes, R.C. we were using the updated rollers. The robot they were on was from 2015's game. I would expect that they broke because in 2015 my team had a large number of problems, and that directly correlated to how well our robot was built. And so, if we had built our drive-train properly the problem would have been avoided. Let's just say (and OP make note of this) that putting your gearboxes underneath your frame members, held on with 6 inch 10-32s is a REALLY bad idea. So OP when building a mecanum drive give your wheels and gearboxes their needed support, and if you're not going to, give them some kind of suspension. So R.C. we were using the updated rollers but I don't blame VEX at all, and should have made that clear, we were just using them very improperly.

[Ryan_Todd]

I'm surprised that nobody has mentioned this yet, but one of the biggest reasons to use mecanum wheels on a demo bot is for the shock-and-awe factor! In that regard, 4" or even 6" wheels are a bit small-- this makes it harder to see what's going on and how the wheels work.

I would personally suggest 8" wheels for this application, although 10" mecanum wheels aren't a bad choice either. AndyMark offers both 8" and 10" varieties, and I can personally recommend them for their durable construction-- although I will definitely admit that the VexPro mecanums are easier on the eyes.