This is a rendering of our 2014 off season drive system. The cad model and info is here
Did you guys make any changes from last season?
The Gearbox is integrated into the frame, we are using 4 inch mecanum wheels, we used two Colson wheels per module instead of one, we are using 8 motors, and we are using retaining rings.
To add on to what John said:
When using 4 motors, it is lighter than last years system (It is actually geared so it will still work if we decide to not use the minicims)
It is now a single stage reduction rather than using a tough box nano.
The modules have gotten smaller because we are using 2 inch colson wheels.
The piston is now a 2 inch stroke rather than a 3 inch stroke with the ports rotated. This actually allows our frame dimensions to be much more flexible than last years design.
We had issues with last years system with the bolts on the modules backing out (especially at the rumble, where we had one bolt back out enough to prevent us from using the traction wheels after lunch). To fix this, we are switching to retaining rings.
The 4 inch mecanum wheel allow us to make the traction wheel even closer to the mecanum wheel, making the chain length even shorter.
The modules are now made out of 1/8th sheetmetal instead of 1/4th plate, allowing us to use our sponsors turret punch. This should be faster and more accurate than trying to manufacture it in house.
The frame has the battery box built in, in order to be more robust than last years system.
What Alex and John said.
Although 1/8" material is pretty hefty, you’re missing an opportunity to add essentially “free” stiffness to your frame members by only using L shaped metal pieces instead of “C” shapes.
I would recommend that you add a continuous bottom flange to every piece of sheet you have in this photo.
Also, if you do what I mentioned above, you could certainly use a thinner gauge of metal (like .090"), which would allow you to have less lightening holes. Your turret punch sponsor will thank you.
With the type of drive we are using, a bit of flex is a good thing. This is the 4th year we have used a frame of this nature without any notiable need for more stiffness.
That’s fair. I don’t have much experience with mecanum. I didn’t think about it initially, but now I recall hearing that having a flexible frame is important to making sure that all 4 wheels are contacting the floor.
Originally it was a C frame that was .09, it was changed later in order to give the frame a bit more ground clearance (the location of the module pivot was determined by geometry, which ended up a bit too low to fit a bend on the bottom of the frame and still have acceptable clearance).
We have found this particular frame style to be more than strong enough for anything we will run into for frc.
You’re right. This is the fourth iteration, so you guys have certainly thought this through better than I originally gave you credit for, my apologies.
It looks really slick, and I like it!
sorry about the multiple replies. We appreciate any extra eyes and comments on anything we post. We have very little professional engineering support. I am always looking for experienced eyes on our projects. It’s just that this was a very large discussion a few years back.
As for the cheese holes. We are Blue Cheese after all, it’s a style thing
Does the extra cim on each of the front wheels provide an advantage over just a 4 cim drive?
I believe there is a miniCIM along with a CIM on each corner.
That’s a great looking chassis.
Do you install your mecanum wheels as rendered? It’s backwards from a normal set up.
Yea, I put them back in when I was trying to clean up our cad model to post it, and mixed it up. We will fix it for the season if we chose to use this system.
Have you seen any issues with dropping the traction wheels instead of the mecanum wheels? You’ll see more side loads with the traction wheels.
Actually, mecanum wheels always apply sideloads due to their nature, and the traction wheels only have a side load when we are being pushed. We also spend most of our time on mecanum wheels, so we wanted those to be the stationary wheels.
Also, if we damage the module, we can remove the module for a match or so and just run a mecanum system.
So, is this drive system an octocanum or a dodecacanum?