8" Mecanum wheels and KOP wheel brackets

[smcmahon]

Can anyone confirm or deny that the 8" Mecanum wheels from AndyMark (AM-0083) actually fit width-wise inside the 2010 KOP wheel brackets (AM-0450)?? We are trying to lay hands on the wheels, but AndyMark isn't quite ready to ship them just yet. We want to make sure they would fit inside the KOP brackets. Looking at the CAD files and stuff, it appears that they will. I just want to make sure there's enough room for a spacer and sprocket as well.

[Bryan Herbst]

Our team determined that the 8" AM mecanum wheels do NOT work with the KOP wheel bracket.

We are working on our own brackets right now.

EDIT- sorry, read your post again. They DO fit width-wise, they do not height-wise. We considered cutting it to accommodate the wheels, but decided that it wouldn't be very structurally sound.

[smcmahon]

We were thinking of just notching out the top, up to where the opening gets larger. We were just afraid of the width, with the wheels being 2.52" wide already and the opening seemingly less than 3"...

[nitbaj]

The width of the KOP bracket isn't really wide enough to hold the wheel WITH a sprocket and chain. We had to cut it wider and also bend it out a bit, which took a lot of the strength out of it. It worked fine for a prototype, but I would suggest making your own brackets for your final robot.

[caffino54]

we made some super-simple brackets : 2 9" pieces of plate aluminum on either side of the area in the kitbot chassis that would attach to the regular wheelmount. drilled new holes near the hole-pair and bolted them on. works brilliantly

[TubaMorg]

From the AndyMark site.
We decided to make our own brackets though since we want to drive the wheels directly and the angled design of the brackets make adding bearings and mounting the transmission more difficult.

[joek]

Originally Posted by Tanis

Our team determined that the 8" AM mecanum wheels do NOT work with the KOP wheel bracket.

We are working on our own brackets right now.

EDIT- sorry, read your post again. They DO fit width-wise, they do not height-wise. We considered cutting it to accommodate the wheels, but decided that it wouldn't be very structurally sound.

wrong, Bryan, they don't fit width-wise, but they do height-wise, believe me, i would know, i tested them in CAD models

[dlavery]

Originally Posted by TubaMorg

From the AndyMark site.
We decided to make our own brackets though since we want to drive the wheels directly and the angled design of the brackets make adding bearings and mounting the transmission more difficult.

I will repeat what I said in another thread about this idea. I would be VERY careful about adapting the KOP wheel brackets in the manner shown in that picture. If you cut away that much material from the bracket, you are severely compromising the ability of the bracket to resist lateral forces in line with the wheel axle. A lot of testing was done with the bracket/KOP wheel assembly. If the bracket is made of thinner material, or if enough material is removed from the bracket, bad things happen. If the wheel/carpet coefficient of friction is high enough, and the impact energy is high enough, the bracket will bend and fold when the robot is hit from the side by another robot. So let me be real blunt here: don't do this. If you do, you WILL regret it.

-dave



.

[GearsOfFury]

Plus, as it's been said, you cannot fit a spacer, sprocket, ANSI 35 chain, and bolts all in there.

If you're just trying to prototype mounting options, here's one that seems to have worked for another team. The brackets are simply shelf cross members you can buy at the hardware store: http://www.youtube.com/user/SteveJes.../1/UQQ67SB8Acc

As another poster said, I would strongly suggest working up some CAD for a sturdy mounting system of your own design, as opposed to planning on using the KOP brackets or something similar to the YouTube video...

[Diminish]

It actually says on the Andymark website that they don't quite fit:

"For Use in 2010 FIRST Robotics Competition
These wheels fit within the AndyMark Wheel Bracket, with a bit of modification for sheet metal removal around the wheel, and if the interior screws on the wheel are shortened to 2.5" long screws instead of 3" screws."