My team this year has decided on mecanum wheels and after some research AndyMark wheels seemed to be the obvious choice if your team had the money, which we do. Sadly other teams seemed to have come to this conclusion as well because 6" wheels and 8" wheels are both out of stock. Either we roll the dice and hope the AndyMark wheels come in stock in the next two weeks or we buy the VEXPro wheels. There is nothing wrong with them just the fact that rollers seem to have the nasty habit of breaking off. I know there have been improvements made to them this year but we are still unsure what to do. Answer above on what you think we should do: Wait for Andymark wheels or Get VEXPro wheels now.
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VexPro wheels are significantly improved. In one of the other mecanum threads, someone posted a spec showing that the plastic part that was prone to breakage last year is now steel reinforced.
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This year is not last year. You’re going to be traveling much slower with (hopefully) many fewer impacts, especially impacts where your whole robot is thrown up in the air.
OTOH, this year you might be toting around an extra 60 pounds at some points, but again, that should be much more of a static load, rather than a dynamic stress.
*Why not omni wheels?
In addition to this you can get three sets of VexPro mecanum wheels for less than the cost of two sets from AndyMark allowing you to have spares in case of a failure.
Presumably because of scoring platform crossing (which I still have my concerns with regarding many mecanum drives). Possibly frame shape requirements as well.
I’d almost certainly go with the Vexpro Mecanum wheels. Even though VEXPro products have had their share of stability issues, we used their 3-CIM ball shifter gearboxes last year [link]](http://www.vexrobotics.com/3cimballshifter.html) on a tank drive with absolutely no problems whatsoever.
See the bottom section from Vexpro’s Mecanum page.
What does the reliability of the 3 CIM Ball shifter have to do with the mecanum wheels? I could see if you were comparing it to another Vexpro gearbox offering, but in this case they are unrelated products.
If you have any concerns about the VEXpro Mecanum wheels, shoot an email to [email protected] and our engineering team can help answer them.
Andy said the AndyMark wheels would be back in stock within a few days, it sounds like they are waiting for parts. Look at the comments and watch the video I linked above.
I personally trust the AM wheels more as we used them on our robot last year without issue and I don’t really trust plastics at critical points on a robot. I would consider a wheel a critical point. Last year we used some plastics on other portions of the robot and by halfway through the season we switched out for machined aluminum parts.
Even with the improvements, I would still be hesitant on VexPro mecanums. I would rather wait and pay for a product that I know will work based off of experience.
We just ordered the VexPro wheels today. I am personally extremely confident in the people at Vex, and in their wheels. I understand that it’s difficult to overcome public perception based on last year’s product, but that problem was addressed a long time ago, and there have been NO problems with the improved wheels. If we are going with mec, we will be riding on Vex. Not knocking AM at all, either; they are also excellent. How far we have come in the last decade!!
I know the 6 in vex mecanums we’re designed differently this year, but I haven’t heard anything about the 8 in. Were these also improved? We used 6" vex mecanum last year and ran into all sorts of issues. We are interested in the 8" if they are modified.
We were a team that suffered the VEXpro Mecanum woes in 2014, but are very happy and impressed with the VEXpro customer service. They were very upfront and open about the situation and did everything to help us through the situation.
I have full confidence that the proper testing was conducted on the new roller tab design.
I do believe that all the wheels use the same roller tab, just the rollers themselves are different. I’m trying to find the email from Aren last year to confirm.
Edit: After reviewing the VEXpro product page, it appears that only the 4" and 6" wheels have been revised. But I was able to find the email last year and confirm that during the 2014 season, all the wheels used the same roller tabs.
We have some VEXPro 6" mecanum wheels on order. The price and availability is attractive, and I’ve been impressed with the manufacturing quality of other parts of theirs I’ve played with. I think last year’s rough game was a good test environment to find the failure points, and with the new improvements and lower stress game this year we shouldn’t see many issues.
Given that, we’re still going to test the daylights out of them. I’ll be mildly disappointed if we don’t manage to break one during practice, just to see how much effort it takes.
I emailed Aren of Vexpro about the 8" and if it wasn’t updated, if it was still reliable.
This is what he said:
“The 8” Mecanum wheels experience significantly less roller deflection when rotating, we have not applied this update to our current inventory.
In terms of reliability the 6" wheel is your best bet.
-Aren"
We have used both the 6in andymark HD and the 6 in vex. I highly recommend the andymark. We have not used the new vex so I can’t tell you how much they have improved but last yer the vex worked ok on a low speed robot. The rollers became loose and the robot bounced a lot as we drove around because the wheels were no longer round. After the season ended we uped our robot speed. after that all the rollers started to break off. Vex was very helpful and replaced about half of the rollers for free. The improvements on the vex wheels look good. They are also lighter then the andymark. We never had any problems with the andymark. I don’t remember exactly how well they worked I just remember we had no problems. This year we are using the andymark 6in HD. We are using vex gears to gear the CIM down 12.5 : 1 projected speed to be 9.33 ft/s. I do like the vex gears very much. I emailed andymark about the availability and they said they will ship early next week. If you want a wheel to last you multiple seasons get the andymark.
Thank you for looking into this…I guess we’ll hold off for the andymark wheels.