Engineering Project on Mecanum Wheels-Please help me gather input

[BVespone]

Dear FIRST members,

I hope everyone has had a great build season, and I wish everyone luck at the upcoming regional events. Team 3015 decided to use mecanum wheels this year, and due to the limited availability on Andymark, we actually built our own wheels with the help of our mentors and our Sponsor Getinge, which provided some machining capabilities (laser cutting) that are not available in our school. For my Senior Engineering Class, I am researching a method by which high school FIRST teams can fabricate mecanum wheels utilizing only the tools in their school shop, and parts from a hardware store. I am hoping that I can get some help from the FIRST community with my research by having FIRST members answer these quick questions in this thread:


1. Which of the following tools do you have access to?

a. Drill Press b. Band Saw c. Miter Saw d. Lathe e. Welder f. Laser Cutter (please list any additional tools you think are important)

2. If you have used mecanum wheels in the past, have you ever created your own?

3. What do you believe is the most challenging aspect concerning the creation of the mecanum wheels?



Thanks Everyone!

[Racer26]

Well, here on 1075 we have access to everything there except a laser cutter, but we also have a CNC Mill.

We've never used mecanums.

I suspect the most challenging aspect is making sure all of the rollers are properly aligned.

[Jon Stratis]

Like you, we built our own mecanum wheels - for us, it was more about price than anything else - buying 8 wheels (competition and practice robots) is just way too expensive.

In our shop, we don't have a lathe (yet), laser cutter, or welder - but we can get access to those if we need them off site. for our wheels, our primary sponsor donated some machine time to cut out the patterns for us and build up the rollers. All the rest of the work was done at the shop - bending and twisting them into shape, sticking the high traction rubber on the smooth plastic wheels, and assembling the whole thing.

For 1075guy - aligning the rollers is actually pretty easy, if you have everything cut and bent correctly. We built a little jig that let us bend the "spokes" to the correct angle consistently, which helped with that a ton.

I would say the most challenging aspect was simply the time involved. We didn't have all the parts we needed until week 4 or so, and the wheels weren't assembled until week 5. That's a long delay and a lot of work into something as "basic" as wheels.

[Andrew Schreiber]

Originally Posted by BVespone

Dear FIRST members,

I hope everyone has had a great build season, and I wish everyone luck at the upcoming regional events. Team 3015 decided to use mecanum wheels this year, and due to the limited availability on Andymark, we actually built our own wheels with the help of our mentors and our Sponsor Getinge, which provided some machining capabilities (laser cutting) that are not available in our school. For my Senior Engineering Class, I am researching a method by which high school FIRST teams can fabricate mecanum wheels utilizing only the tools in their school shop, and parts from a hardware store. I am hoping that I can get some help from the FIRST community with my research by having FIRST members answer these quick questions in this thread:


1. Which of the following tools do you have access to?

a. Drill Press b. Band Saw c. Miter Saw d. Lathe e. Welder f. Laser Cutter (please list any additional tools you think are important)

2. If you have used mecanum wheels in the past, have you ever created your own?

3. What do you believe is the most challenging aspect concerning the creation of the mecanum wheels?



Thanks Everyone!

Noble goal, not sure but I think you could check out the behind the design books looking for 357 or Jester Drive. (Or in the CDM archives) They might have some interesting solutions. Also search for VEX Mecanums here on CDM too, some people have done some cool stuff with VEX that might be worth checking out for ideas.

397 has: Drill Press, Band Saw, Chop Saw, Lathe, Welder, Mill

2337 has: Drill Press, Band Saw, Chop Saw, Lathe, Welder, Mill (Numeric Control and manual)

The real benefit of these tools is that they must come equipped with an operator who knows how to work them.

2337 has used Mecanum wheels in 2008 and they purchased them from AndyMark. 397 has never used Mecanums but they also purchased a set from AndyMark.

The most challenging aspect of Mecanum wheel fabrication would be making the proper rollers IMHO. This could be overcome by molding your own set using a process similar to 125's wheels this year. This would allow the user to fine tune the hardness of the urethane and thus the "grippyness"* of the wheel to their specific needs. The downside would mean that teams would have to understand not only the process but how an increase coefficient of friction would effect their drive train. I have a theory (that hasn't been proved by me looking at the math) that in the case of Mecanums more grip is not always a good thing and that there is a sweet spot for FRC competition. If this could be experimentally or numerically discerned and an appropriate roller design made publicly available I think the difficulty in manufacturing Mecanum wheels could be drastically reduced.


*"grippyness" is really coefficient of friction but I think I prefer that word because it is very blunt.

[Pausert]

1.) Drill Press, Miter Saw.
Others not on the list: Band saw, Belt Sander.

2.) First year with Mecanums, did not build them ourselves. We purchased 8" and 10" from Andy Mark.

3.) I believe that creating a plate similiar to the 8" Andy-Mark's is practically impossible with our tools. The 10" wheels seem like they could be imitated, but it wouldn't be nearly as accurate and would take ages on a band saw. Also, I think bending the roller holders correctly would be extremely difficult without some specialized tools.

Team 1727 REX out.

[big1boom]

1) Drill Press, Miter Saw, 20 year old CNC that is only able to cut plastic or wood.

2) We have never used mechanum, and instead have gone straight to swerve.

3) Hardest part about custom mechanum is probably the making the rollers.

4) Any team that has enough machining for a custom mechanum can do a custom swerve/crab drive.

[joeweber]

We have built mech wheels using 3/4 HDPE, Rubber stoppers, long 1/4x20 bolts, and brass bearings. We cut the HDPE (high density poly ethalene) close with our ban saw, than lathed it to round. We than set up a jig and using a drill press we first drilled at a 45 using a 1 1/8 paddle bit around both sides and than drilled though with a 3/8 bit for the bearings. If you use a long 1/4 x 20 bolt you can bottom the nut out just shy of the rubber stoppers.

[BVespone]

Thank you SO MUCH everyone. All this input is extremely helpful, and I invite any other teams that may wish to throw their stories in the mix! I may have a nice design plan to share with everyone on CD in a few months, and it is my hope that other teams can benefit from this project in the future.

[Coach Norm]

Originally Posted by BVespone

Dear FIRST members,

1. Which of the following tools do you have access to?
a. Drill Press b. Band Saw c. Miter Saw d. Lathe e. Welder f. Laser Cutter (please list any additional tools you think are important)

2. If you have used mecanum wheels in the past, have you ever created your own?

3. What do you believe is the most challenging aspect concerning the creation of the mecanum wheels?
Thanks Everyone!

Team 2468 has a drill press, band saw and vertical mill. We are currently working on the motors and control software for a table top CNC lathe. We also have a combination metal shear, brake and roller and a belt sander.

We are using mecanums this year for the first time.

I think it would be machining the rollers.

[Jeffy]

We have never made ours, but this might give you some help on what types of machineing capabilties teams have:
1. Drill press, wood cutting bandsaw (also works on aluminium), miter saw, welding machines and a few students who are pretty good at it.
2. We did not create our own mecanums for quite a few reasons.
3. no experience making them

[Rohan J]

In our little machine shop we have a Miter saw, an abrasive cutoff saw, a band saw, a drill press, a table saw, an old imprecise maximat mini lathe, and a full-size jet vertical milling machine.

Our team has used mecanum wheels for three years, though we've always purchased them from AndyMark. This year we used the 8" variety, though my favorite is the 6" due to the closeness to round. I know of quite a few teams that make their own wheels, and it seems to me like getting the plates cut out right, and then bending them would be somewhat difficult. We've played around with polyurethane and silicone molding compounds, which, like epoxy, come as two parts, and after mixing them together, they begin to harden. This would be a good way of making the rollers. If you can spare the change, however, I highly recommend buying the wheels from AndyMark, as you will be sure that they will always function properly. AndyMark has excellent service, and makes excellent products. We have contacted Andy on several occasions about issues and he has always been prompt, both in response and in fixing them.

Good luck!

[JHSmentor]

Um - well. all we had were hand drills, a band saw, some files, and a teeny tiny drill press. Oh, we have a hack saw as well. we sent our chassis out for welding.

Is that enough of a challenge for you? I've thought about giving it a go using these tools and some elbow grease - obviously they wouldn't be very precise but it would be interesting to see how precise was absolutely necessary to make them work respectably well.

team 3210

[viperred396]

Well team 2240 has a Drill Press, Band Saw, Miter Saw, and a Laser Cutter


good luck on your project!

[My-smokepole]

279 Hasn't try any of them yet. Tool wise we have most that was said but for the laser
David/toledo

[BVespone]

The input I have received so far has been great. If anyone else would like to chime in I would really appreciate it.