pic: 6CIM WCD

[Nate Bloom]

Originally Posted by Adrian Clark

looks great!

But it looks like you have some problems with your chain interfering with your gearbox standoff and possibly your belly pan too. I would suggest you downsize to 16T sprockets instead of the larger ones you're using.

Thanks! Nice observation, that's on the change list for the next revision.

Originally Posted by DampRobot

Have you considered how your corner gussets will stand up with significant torsional loads? Or are you using a bellypan? Also, how will you make sure that the two sides of the drives are parallel? Rivets holes usually have enough play in them that locating of them doesn't work super well. Are rivets the only things holding the frame together, or is the tubing welded too?

I only ask because I've recently been working through some of the same design problems myself. It's interesting to see how different people have worked through the same problems.

By the way, I really like those bumper extension tubing thingys that surround the center wheel.

Right now it's just those gussets, but I've been considering adding a bellypan (for both strength and electronics). Would a bellypan also help with keeping the sides parallel or would the play in the rivet holes still be an issue?

I would much prefer welding the tubing but my team has never had success welding aluminum. We have access to a Miller Syncrowave 200 TIG and a Snap-On MIG 300, but no one with much experience welding. Would it be worth having some members learn and practice welding in the off season?

[DampRobot]

Originally Posted by Nate Bloom

Right now it's just those gussets, but I've been considering adding a bellypan (for both strength and electronics). Would a bellypan also help with keeping the sides parallel or would the play in the rivet holes still be an issue?

I would much prefer welding the tubing but my team has never had success welding aluminum. We have access to a Miller Syncrowave 200 TIG and a Snap-On MIG 300, but no one with much experience welding. Would it be worth having some members learn and practice welding in the off season?

Yes and yes.

Bellypans do add a lot of strength (especially torsional, which was partially why I mentioned it to begin with). If you're designing a WCD, you've probably seen some well done bellypans before, but even just for inspiration, take a look at 254's or 1538's. They do a really great job with the elex layout. In terms of keeping the sides parallel, it will definitely help. There will be a lot of rivet holes far apart on a bellypan. Because they'll be separated by a longer distance, small amounts of wiggle in the rivet holes will change the relative angle of the two frame pieces you're joining less than it would witj your gussets right now, where the rivet holes are relatively close together. (If this made no sense, consider the effect of changing the length of one leg of a right triangle a with either a small or large hypotenuse. With a longer hypotenuse, changes in the leg will have less effect on the opposite angle.)

Welding is both a lot of fun and very useful in FRC. I highly suggest that people learn it, especially TIG, during the summer. I've recently taken up TIG myself, and can personally attest to how much results are driven by experience and practice. TIG is generally considered to be better for thin aluminuim (like in a frame for FRC), but if MIG's more your cup of tea, do that, it works fine too. I don't know about your machines in specific, but Miller tends to make nice equipment.

I've changed my mind several times on this, but my current thoughts on welding vs riveting are these: do both. Welding is very strong, but tends to warp frames (and a lot!) if it isn't done with proper care. Even careful tack welding, shimming, and fixturing can leave you with a slightly warped frame. Riveting, on the other hand, is much faster, and of course is less permanent. However, as I touched upon earlier, it isn't quite as strong. My advice at this point is to make your gussets be fixtures for welding. Set up the frame nice and square, rivet it all together, and see how it looks and performs. Then, clamp it to a welding table, and, tack welding first, etc. etc, weld it together. You ideally get the strength of welding with the ease and straightness of a good riveted frame.

As goes with all of my advice on CD, try it yourself and make up your own mind. I'm just suggesting things based on experience. See what works for your team. Follow my suggestions to the letter, mix and match them, or even throw them completely out the window. It's all about you and your team.

[1683cadder]

Adding a plate that links the gearboxes together is great for additional strength.