pic: CV Robotics WCD 6wd Drivebase Prototype

[Adrian Clark]

Originally Posted by Dunngeon

We have a shop that's offered up their CNC Plasma Cutter. We plan to cut it, then check tolerances to see if it's good enough for use. If it isn't, our fallback is to use one of our schools CNC routers to machine a wooden bellypan and paint it black.

I cannot stress enough how important it is to test new fabrication methods before the season. In 2013 I tried to cut a bellypan out of .090 5052 Al on a plasmacam machine, a machine I had never used before. When I came to the shop and showed the staff what I was making they told me it wouldn't work, and they were right. As I was cutting out the profile the sheet began to warp, I had to give up shortly after I started because the sheet bent up and hit the torch. This is exactly what I was warned would happen.

Before you take the time preparing to go to your sponsor and make the test parts I recommend you talk to an operator first. They will know the machine and it's limits and can tell you if your parts can be made on their machine and even give you tips on how to design your parts to be easier to cut. The main things you need to convey to the operator is the materiel, its thickness, and the complexity (run time) of your parts. With that information they should be able to tell you if they can cut them without the sheet warping.

There a several teams with in house CNC plasma cutters, you should be able to find them with a quick search. I would recommend talking to them as well, they can provide you with valuable insight on how to best utilize a plasma cutter for an FRC team.

-Adrian

[Ethroes]

Looks nice guys. Will you have a prototype on your Bunnybot robot or will you be using another drive train? For last year's Bunnybot competition, we field tested our first swerve modules on 2471-A. It was a valuable system for us and I recommend it for you guys if you have the time and budget. Of course, a gen 1 swerve drive is bound to have a few kinks to work out, but you never know. It's just a tip.

[Dunngeon]

Originally Posted by Adrian Clark

-snip-

-Adrian

I hadn't considered that it would warp, thanks for pointing that out! I'll look into it. Our sponsor wasn't sure, they are primarily a steel outfit.

Originally Posted by Ethroes

Looks nice guys. Will you have a prototype on your Bunnybot robot or will you be using another drive train? -snip-

I neglected to mention that we are building this drive right now, the 2x1 entered machining yesterday. Unfortunately for swerve drives, we subscribe to the "swerve is never necessary" ethos. Even though I think your drives are pretty brilliant.

Originally Posted by Andrew Lawrence

I noticed the strand thickness on your bellypan is much thicker than the thickness we usually design for, so you could probably go a lot thinner than you currently do.

I'm assuming you are choosing to use a custom transmission because it fits your resources better than a COTS one, though if it doesn't I could always lead you to some sources about why COTS transmissions are a great solution.

All that aside it looks like a very promising design that will serve you well should you choose to use it for the 2015 season.

The strand thickness was fairly arbitrary, we weren't sure how thin we could go and still have torsional strength, looks like we can scale it down a fair bit (though not to your level....yet)


I'd prefer a COTS gearbox over this one, but we use the gearboxes to teach advanced CNC code to students. All of the CNC code used to mill these gearboxes is handwritten. The only other advantage to this gearbox for us is it sits much lower than a WCP or Vex gearbox in the frame. Personally, I'd like a 2-stage gearbox (16.8 FPS is high) w/ shifters, but team history precludes that effort for the time being.

Originally Posted by dragon_pilot

Why did you guys decide on using chain instead of belts?

It simplifies our drivebase, with belts we would need tensioning blocks and would also run the small risk of snapping a belt. We ran our drivebase without chain tensioners last year, and that's carrying over because it worked so well (71 matches, still within tolerance).

Originally Posted by Dunngeon

It simplifies our drivebase, with belts we would need tensioning blocks and would also run the small risk of snapping a belt. We ran our drivebase without chain tensioners last year, and that's carrying over because it worked so well (71 matches, still within tolerance).

If you are not tensioning your chain, then why do you have bearing blocks instead of just placing the bearings in the tube? If you have milled slots in your tubing and bearing blocks like you mentioned, it is a simple addition to have cam tensioners added in that could easily stop a potential problem from happening. They're no work at all for a season-long reassurance.

[Dunngeon]

Originally Posted by Andrew Lawrence

If you are not tensioning your chain, then why do you have bearing blocks instead of just placing the bearings in the tube? If you have milled slots in your tubing and bearing blocks like you mentioned, it is a simple addition to have cam tensioners added in that could easily stop a potential problem from happening. They're no work at all for a season-long reassurance.

To be honest, we weren't sure how the cantilevered shafts would affect the 2x1 bearing holes. Last year our shooter utilized 2x1 with bearings mounted directly into the 2x1. Over the season, the pressure caused the holes to ovalize. The forces aren't equivalent, but the construction is. I linked a picture of our shooter mechanism (JVN Cam).

I wasn't aware you could add cams to this type of bearing block

Originally Posted by Dunngeon

To be honest, we weren't sure how the cantilevered shafts would affect the 2x1 bearing holes. Last year our shooter utilized 2x1 with bearings mounted directly into the 2x1. Over the season, the pressure caused the holes to ovalize. The forces aren't equivalent, but the construction is. I linked a picture of our shooter mechanism (JVN Cam).

I wasn't aware you could add cams to this type of bearing block

Look at 2791's recent drivetrains. I'm sure Chris Picone can elaborate more on their processes, but they run a C-C WCD variant without blocks and haven't experienced any problems that I'm aware of.

And those cams were invented for that kind of bearing block.

[Dunngeon]

Originally Posted by Andrew Lawrence

Look at 2791's recent drivetrains. I'm sure Chris Picone can elaborate more on their processes, but they run a C-C WCD variant without blocks and haven't experienced any problems that I'm aware of.

And those cams were invented for that kind of bearing block.

This is why I love Chief Delphi, I feel stupid for missing that ... Thanks for pointing it out

[Oblarg]

Originally Posted by Dunngeon

This is why I love Chief Delphi, I feel stupid for missing that ... Thanks for pointing it out

I learned that a month ago, and had the exact same feeling.

[T-Dawg]

Are CIMs glossy or am I clinically insane...

[Merfoo]

Originally Posted by T-Dawg

Are CIMs glossy or am I clinically insane...

I'm pretty sure CIMs are not glossy...

[asid61]

Nice drivetrain! Very clean, looks good. A few questions, if you don't mind:
1. What is the weight with what is shown in the picture?
2. What size wheels are those? Are they custom or COTS? Tread?
3. What is the thickness of the 2x1 and the bellypan?
4. How are you planning on tensioning?
5. Are those gearboxes mounted directly to the 2x1 or via standoffs? If it's the latter, change it to the former.

A small recommendation: Make sure the gearboxes shown have the same mounting hole pattern as either the Vex or WCP gearboxes, just in case. Or both even.

Originally Posted by asid61

Nice drivetrain! Very clean, looks good. A few questions, if you don't mind:
1. What is the weight with what is shown in the picture?
2. What size wheels are those? Are they custom or COTS? Tread?
3. What is the thickness of the 2x1 and the bellypan?
4. How are you planning on tensioning?
5. Are those gearboxes mounted directly to the 2x1 or via standoffs? If it's the latter, change it to the former.

A small recommendation: Make sure the gearboxes shown have the same mounting hole pattern as either the Vex or WCP gearboxes, just in case. Or both even.

Read the thread. Half of your questions were answered within it.

[Dunngeon]

Originally Posted by asid61

Nice drivetrain! Very clean, looks good. A few questions, if you don't mind:
1. What is the weight with what is shown in the picture?
2. What size wheels are those? Are they custom or COTS? Tread?
3. What is the thickness of the 2x1 and the bellypan?
4. How are you planning on tensioning?
5. Are those gearboxes mounted directly to the 2x1 or via standoffs? If it's the latter, change it to the former.

A small recommendation: Make sure the gearboxes shown have the same mounting hole pattern as either the Vex or WCP gearboxes, just in case. Or both even.

1. Mass Properties says 40lbs (which is heavy)
2. 4in, custom, they will be 70a Polyurethane
3. 1/8th and 1/8th
4. In thread
5. The front plate mounts directly, it's already setup for Vexpro IIRC

[T-Dawg]

I just updated the mass properties, and it gave me approximately 40lbs. I'll edit this post if I find any mistakes in the settings.

[StephenNutt]

Originally Posted by T-Dawg

Are CIMs glossy or am I clinically insane...

A matte black dissipates heat faster than a glossy black. (I've even been thinking about painting the CIM coolers matte black )