Mecanum Demo-Bot Recommendations?
 

Our team has never built a mecanum drive base.

We'd like to add build one for demonstration purposes.

What is CD reader recommendations for:

-size of wheels
-vendor of wheels
-a frame that can be bolted or riveted - easy to see what is happening when bumpers removed
-a gearbox that makes both assembly and maintenance easy

Looking for a robust solution that can also be visually understood by visitors.

Thanks!

Re: Mecanum Demo-Bot Recommendations?
 

Hey there! Our team has run mecanums for a long time now and here are my recommendations:

Size: 6in wheels (nice in between size)
Vendor: Vex (they make really nice plastic wheels. We even had mecanums this year and didn't have have a single roller break ever. This included going over the Rock Wall full speed.)
Frame: modified kit chassis. We ran a modified kit chassis in 2014 and a modified version of that in 2015. You really want a square base for mecanums.
Gearbox: toughbox nano. These are really nice because they are easily moddable and easy to maintain. They also fit really nice on the kit chassis.

Re: Mecanum Demo-Bot Recommendations?
 

You could try using VersaFrame combined with Clamping Gearboxes, both from VexPro. We used the clamping gearboxes from VexPro in 2015 and they overall worked pretty great. It keeps the base simple, and VersaFrame is a relatively cheap, low resource option.

Re: Mecanum Demo-Bot Recommendations?
 

True. I didn't want to recommend something I had never used. :)

It's probably cheaper and easier.

Re: Mecanum Demo-Bot Recommendations?
 

I would recommend 6 inch VEXpro wheels:
http://www.vexrobotics.com/vexpro/mo...um-wheels.html

The 6 inch variety isn't very expensive but is still big enough to see them working well enough. Also a smaller wheel means less gearing.

I think either a modified KOP chassis or a Versa-frame with the clamping gearboxes would work great. You'd probably need to make a guard around the gears to avoid potential for harm.

You could also try a Andymark Nanotube chassis:
http://www.andymark.com/NanoTube-p/am-0809.htm

Re: Mecanum Demo-Bot Recommendations?
 

Consider using the Tetrix components for FTC. Smaller, typically cheaper, and you can still interface with FRC motor controllers.

Re: Mecanum Demo-Bot Recommendations?
 

Using a FRC motor controller that is capable of 60 amps continuous seems a little wasteful for a tetrix motor that can't even draw 1 amp at max power output

Re: Mecanum Demo-Bot Recommendations?
 

That's what we did for a demo project. We went with 4" AM Mecanums. Ran that drive train for a year of demos, including several sponsor presentations, outreach events, and football games.

Re: Mecanum Demo-Bot Recommendations?
 

We used the Vex products, including the Single Reduction Clamping Gearbox - easy to put together, held up very well and overall very happy with the results.

You can get the Vex BOM and other info here: http://www.vexrobotics.com/vexpro/examples-guides#VC

Here's a video of ours in action: https://www.facebook.com/16737887669...6466343787954/

Re: Mecanum Demo-Bot Recommendations?
 

I remember seeing that picture when you first posted it! If you don't mind me asking, what were the reasons you went with the AndyMark 4" mecanums instead of the VexPro ones? Durability?

Re: Mecanum Demo-Bot Recommendations?
 

I recommend AndyMark Nano Tube for mecanums.
http://www.andymark.com/product-p/am-0968
I also recommend only using your mecanum bot on carpeted surfaces. Sometimes the rollers leave black marks that can be a bit unseemly, and they're aren't too friendly with gravel/asphalt.

Re: Mecanum Demo-Bot Recommendations?
 

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.

Re: Mecanum Demo-Bot Recommendations?
 

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.

Re: Mecanum Demo-Bot Recommendations?
 

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.

Re: Mecanum Demo-Bot Recommendations?
 

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.