[GarrettF2395]

Originally Posted by cbale2000

Neat concept. Do you have a particular gearbox configuration in mind, and if so, any idea what kind of speeds you'll get in either mode?


My only complaint is that it looks like the mecanum wheels interfere with the belt run, but that's an easy enough problem to fix by shifting things around or widening the frame a bit.

This is the setup I originally had in mind, but really almost anything with a 0.5 hex output shaft would work with this.
Thanks, I actually hadn't caught that yet. There is enough room on the mecanum shaft to scoot things over a bit and put a spacer on either side of the wheel.

Originally Posted by Skywalkar

In addition to the above interference issue, I also don't see any way of retaining the axle bearings between the two side plates. These look like flanged bearings, in which case the easy fix would be to flip them around so that the flanges are inside the module instead.

Seeing how compact you've gotten this thing already, I am also led to consider the possibility of ditching the outer branch of the mecanum side of the module... Doing so would require screwing into the outer end of the axle to prevent the side plates from pulling apart from each other, but swapping out that bearing for an X-type (4-point contact) or conical bearing aught to do the trick. (The robot frame would support the opposite side panel, so you'd only need to swap out the one bearing.)

I was actually just thinking retaining clips on the ends to keep things in place.
Also, could you post an example of one of the bearings you mentioned?

Originally Posted by Ty Tremblay

Looking awesome! It might be a little late to ask this, but why the 6" mecanum wheels? If you're going for compact, you could use a 4" mecanum wheel and change your ratios to achieve the same speeds.

Well, my team already has a pair of 6" mecanums in stock, as well as a full set of 6" Omnis. I'm just trying to save some money there
That being said, a 4" model is on my list to design next.

Originally Posted by Hugh Meyer

It looks like you are planning to move the traction wheel up and down with the mecanum wheel fixed. If you switch that and float the mecanum wheel you can use air pressure to create a suspension system and set the pressure to assure you have all four wheels in contact with the floor. This makes a much better driving mecanum if the floor is uneven. When one wheel goes off the ground driving goes bad.

I probably wouldn't want to have the main drive wheel utilizing system pressure most of the match unless there were large field obstacles (like 2010).
My team ran no suspension mecs this past season and almost never had a problem.

Originally Posted by Electronica1

Personally, I would keep the mecanum wheels fixed, you probably don't want a wheel that is constantly applying side load to be on the end of the module. Also, if you are primarily in mecanum mode, then you probably want that to be stable and not be affected by how much pressure you have.

To counter slide load from the mecanum wheel you can use a thrust bearing, but my team has found plastic spacers on the axle do fine (ex: vex spacers)

On another note, I see you decided to double up the colson wheels. Do you feel this is still considered oct octcanum, or is it dodecacanum? (since you have more than 8 wheels now)

Interesting... I think I'm going with a Duodēcim drive!
Maybe Duodec-drive? Not quite as elegant sounding as nonadrive.

Originally Posted by cbale2000

I'm guessing the idea was to have the mecanum mode drive faster than the traction mode (different size wheels is a quick way to do that). Of course, you could also accomplish this by creating reduction between the belt sprockets.

This is true, but it also helps make the speeds vastly different.
I re-worked some math from the last set I posted and made the mecanum run at 13.4 Ft/s and the colson run at about 5.5 ft/s

Originally Posted by asid61

Why the dual colsons? And why not a smaller mecanum? This could be a lot lighter if you removed a colson and just used 4" mecanums.
Why are there two standoffs almost next to each other in the middle of the module?
Apart from that, this looks very neat. The lightening pattern is perfect and it all looks quite clean. The pivot looks very nice too, and should let you use a smaller piston. However, this could be a good chance to put the mecanum wheels on a suspension by maing those actuated instead of the traction wheels by swapping the two.

The added Colson is just to increase the amount of ground contact. The extra colson is easily removable from the system, I was mostly just testing to see if I could fit both on there.
The added spacers is just me trying to over-engineer this thing to make sure it's rock solid. I could probably get away with removing it.