VEX Custom machined twoish inch Mecanums

During the summer of 2011 i decided that i would embark on the process of Designing, CAD modeling, and Machining my own mecanum wheels for VEX. I started out with looking to GER for the concept design of the wheels but after that i had to CAD model the wheels in order to make myself able to machine them.I used the two high strength gears and omni wheel rollers to make them (just like GER). I created two Jigs to make them i used one for the Mill and one for the Lathe. i bolt the gear to the Jig in the lathe to take off the teeth and then bolt it into the jig where the gear is mounted at a 45 degree angle, drill down, unbolt, turn one rotation, bolt in, drill down, unbolt and repeat six more times for one half of a wheel. Then you have to change drill bits for the axle hole and do it all over again.

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I really like this mecanum design but I have a few questions.

How are they?
I’m not sure because they are gears but what is the approx. diameter with the teeth removed?
Are there current VEX wheels with the same or very close diameter?
Have you guys used them on a competition robot?
What advantages do you see when compared to the regular mecanum wheels that VEX sells?
Would you suggest making them if a team did not have access to a lathe?
On a scale of 1-10 what was the difficulty of making these?

I thought that they worked very well

I would have to check the wheels to be sure(i’ll do it tomorrow) but they were about 1.7 inches including omni wheel.

There are currently no VEX manufactured mecanum wheels with a diameter close the only ones they have are the 4 inch ones

Yes we are the first team to use mecanum wheels in competion because we used them before they came out and continued to use them in competition even through the worlds competition

I haven’t personally used the mecanum that VEX made but i know that with a smaller diameter there is less torque on the motor but i am 100% on the direct relation we are going to order them soon to compare

I think you could do the work of machining off the teeth in other methods and also that dimension doesn’t need to be as accurate in my opinion

I think that the difficulty would be anywhere from an 8-10 depending on your experience in machining parts i had help from one of our machinist FRC mentors with advise on how to do it and the basic how to get started but it was more that we were working together to figure it out but once we did it wasn’t too much work

In a nutshell most of the difficulty is getting your setup in the mill right and making the jigs.

Vex needs to market these
i spoke to your members at worlds these were genius.
thank you for have exceptional original ideas.

For the record. These were first made by Green Eggs Robotics. VEX already has a mecnaum wheel, and BELIEVE ME they are hard to get really small at any efficient kind of design. Fact of the matter is that these wheels has lots of inefficiencies because they are so small and made with parts already existing in the kit.

  • Andrew

That is not nessecarily true as long as you make them accurately they can work very efficiently. I used them on my competition robot that went to worlds.

I’d like to believe you on that, but the fact of the matter is that there is to large of a gap between rollers to really be ultra efficient. I think that their efficiency in comparison to the actual VEX mecanum wheel will be very poor. But I’m always open to being proven wrong. :slight_smile: If someone wants to test the tiny ones vs. the large ones in a full design comparison I would be quite awesome.

Meaning things like forward backward speed, pushing power forward and backwards. Side to side translastion speed loss. Side to side pushing power. The works.

  • Andrew

Once i get the VEX mecanum wheels i will try to test the wheels but they definitely work very well and i think that the main difference between the two in the end will be that the one is smaller and the other is bigger because in my experience with the wheels i geared them for speed and the strafe is about 70% to 90% of the forward or reverse speed