Re: 6 Wheel Drive, Wheel/Drive Assembly
 

We avoid breathing the stuff and end up replacing the blades and hole saws frequently. "Fiberglass burn" is a common ailment on the team :(

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

Here's what I've come up with, a 6 wheel drive, the two middle wheels are powered, the wheel on each corner is an omni wheel, even though this is just 1 side, you can see where I'm going with it.

You've all helped me so much already, so any comments/criticism/corrections/suggestions are welcomed!

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

Nice job, looks like your getting the idea. Your wheels may not actually the same size (6 in?) so you may need to offset the traction wheel by a bit.

How are your shafts powered? the omnies will be chained to the traction, right? Also how is the middle axle powered, keyway? I would suggest hex shafts like this one http://www.andymark.biz/am-0520.html No idea if it fits your gearbox, but I am certain you could find one on andymark.biz if those are toughboxes on the drivetrain.

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

This is definitely a good start. In addition to whats already been said, I have a couple more suggestions:

1) you should really try to push the omni wheels as far out as possible without compromising strength. This will improve stability front to back.

2) flip the plates or add fillets on the bottom as well. In my opinion its always better to have the bottom of the plate filleted to help it not catch on something.

3) If using material that thin definitely add flanges to the top and bottom to make it stiff enough.

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

Avoiding this is not good enough. PLEASE use a face mask and obviously goggles while cutting through fiberglass. Glass dust is not Good Eats.

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

I really suggest looking into "Team 221". (Robotics Company, not a team) the universal six wheel drive chassis was designed by some mentors on our team and we have used this system for the last 5-6 years with absolutely no problems with integrity, function, or modularity. Its very simple and maybe would provide you with a couple of ideas. The premiere function on the design is the built in Chain Tension system. All it takes is a couple of turns with an allen wrench to make sure the chains are tensioned correctly. You just set it, and forget it!

http://www.team221.com/viewproduct.php?id=35

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

A big thanks to all who've helped me out here, I've made the following changes:
Changed plate thickness from 1/16" -> 1/8"
Filleted The bottom edges
Moved omni's forward another 3 inches,
and added a top and two separate bottom flanges, extruded 1/2"

I was also going to cut out a few triangular patches to reduce weight, but I was worried about compromising the integrity of the plates. Instead of spamming up the thread, I'll just post a link to the album on photobucket:

http://s919.photobucket.com/albums/a...201%20Rev%20A/


Once again, let me know what you think! Questions/Comments/Suggestions/Criticism, all is welcomed!

Thanks!

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

Get a wet tile saw with a diamond abrasive blade. One can be had for a little over $100 from many places. I got one for cutting carbon fiber tubes, there's very little spray and zero dust.

If you insist on cutting things dry still, or don't have a choice, get a full face mask, preferably of hazmat quality with the appropriate breathing cartridges, and tyvek suits. They will make a huge difference and don't cost too much.

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

We'll look into making our pultruded work safer, but at competitions and for quick jobs, is running a vacuum next to the hole saw insufficient?

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

Well, I think I've got it!

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

The CADs above look legit. I would also recommend added some support bars closer to the omnis. This'll help keeping the drive modules straight when you move.

I'm sure you would've gotten to that sooner or later when you worked on it, but I just wanted to make sure that I put that out there.

Also, just add a couple of cuts on each module. That'll not only help with weight, but also with design.

- Sunny

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

Hmm... Could you go into a little further detail? I'm not quite sure what you mean by support bars...

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

It's certainly better than not having a vac, but the safety guys shouldn't . If you don't have the right tools try to keep everything wet, I used a hack-saw over a sink to cut some pultruded carbon fiber tubes and it didn't kick up any dust. You can get wet tile saws that are very small and portable, some can even be disconnected from their mounting base and used like a cutoff tool. Even a tub of water with a little aquarium pump and hose to squirt water over the cutting area is very useful, and a good Lenoxx blade/hole cutter, even hand powered will make short work of fiber composites. I've used all of these "wet cutting" methods indoors with no detectable air born dust.

A buddy of mine used to do a lot of fiberglass work, even with a face mask (not a hazmat one though) and after a year or two he couldn't exercise much at all, he'd start coughing up blood. Fiberglass and carbon fiber are really nasty if the right precautions aren't taken.

Feel free to send a PM if you have any other questions, I don't want to derail this thread anymore ;) I was responsible for setting up a couple fabrication areas at my college, with a very knowledgeable (read "strict but very correct") safety officer.

/thread jacking

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

Of course. Right now, you have two 80-20 bars spanning across the middle of the chassis and they hold the two drive modules together.

If you can also add bars in front of and behind those bars, that'll provide more support, because when you turn, the modules are going to be torqued about the current middle bars, and the modules are more susceptible to bending.

- Sunny

Re: 6 Wheel Drive, Wheel/Drive Assembly
 

^^ What he said.

Also it doesn't look like there is anything keeping the plates in their proper positions, you need to ad some bolts to keep them in place.