pic: FTC Custom Drive Train

[carpedav000]

Those white wheels are illegal for FTC. AM designed stealth wheels to take their place

[Jeremy Germita]

Looks great! I love how flexible the FTC rules are getting and I'm excited to see how teams are taking advantage of those rules.

Remember that FTC fields are 12' square(thus far), 6-7 feet per second would clear the field in about 2 seconds. That's ridiculously fast for this scale. Scaling that up to FRC field sizes, it's like gearing for 30+fps free speed.

Here is a custom FTC drivetrain I built a couple of years ago. I clocked it at just under 3 feet per second without any mechanisms on the robot, but it ended up being about 2.5 f/s during competition. I found it was on the cusp of controllability on an FTC field. When 72 made v2 of that drivetrain last season, they geared it for 4fps and the NXT loop execution rate was definitely too slow to control the drivetrain without lag. It would travel about 4-6" between motor controller updates.

Just a warning. These may or may not be valid concerns for the 2015-16 game and control system .

[hectorcastillo]

Do you have a weight estimate?

As of right now it weighs around 13.25 lbs.

Those white wheels are illegal for FTC.

Those are actually 4" VersaWheels from VexPro. Although the color and tread pattern does look similar.

Remember that FTC fields are 12' square(thus far), 6-7 feet per second would clear the field in about 2 seconds. That's ridiculously fast for this scale. Scaling that up to FRC field sizes, it's like gearing for 30+fps free speed.

Thanks. When I was deciding on my gear ratios I knew I wanted something fast, but I wasn't exactly sure how fast was fast and how fast was too fast. But I figured that someone here could point me in the right direction so that I can make the right adjustments.

[ehochstein]

First off - I love the look of this chassis. My students put something together something that looks similar to this last year. I'll see if one of them can send me a photo and I'll post it.

How do you plan on attaching the motors to the gearboxes? I would assume the 6 mounting holes on the face, loctited?

[Fusion_Clint]

I love it, we are going to try incorporating the FRC Texas tubes this summer on the FTC scale.

I have a question, FTC normally requires the robot to pick up something, how to you plan on this drive-train allowing that? I would suggest leaving the "front" somewhat open.

[hectorcastillo]

Originally Posted by Fusion_Clint

I have a question, FTC normally requires the robot to pick up something, how to you plan on this drive-train allowing that? I would suggest leaving the "front" somewhat open.

I originally had the front left open without the front tube. I made it so that you can open up the front and back to fit the needs of the game. Removing the top tubes would make it a little less sturdy, but there are plenty holes along the top of the drive modules to mount whatever structure you need to provide stability and not be in the way. I wanted this design to be as dynamic as possible since we don't know what the next game is going to be.

[Nemo]

Two things:
1) Very cool looking design. I hope you folks end up building something like this.
2) Thanks for bringing my attention to those BaneBots 6mm adapter hubs! That removes a pretty significant barrier to some of the FTC ideas we've tossed around on our teams.

[hectorcastillo]

Originally Posted by ehochstein

How do you plan on attaching the motors to the gearboxes? I would assume the 6 mounting holes on the face, loctited?

There are holes in the gearbox plate that line up with two of the 6 mounting holes on the motor, and yes, I would probably use a little loctite, but not too much in case I need to remove a motor later.

[ehochstein]

Originally Posted by hectorcastillo

There are holes in the gearbox plate that line up with two of the 6 mounting holes on the motor, and yes, I would probably use a little loctite, but not too much in case I need to remove a motor later.

I would suggest using more than two of those holes, we found that using a minimum of 3 worked best.

The gears you are using don't appear to be tetrix gears, what are you plans on mounting them to the output shaft? We've been looking for alternatives to the tetrix gears and would be interested if you found a solution! Currently, we are looking at manufacturing our own solution.

[hectorcastillo]

Originally Posted by ehochstein

The gears you are using don't appear to be tetrix gears, what are you plans on mounting them to the output shaft? We've been looking for alternatives to the tetrix gears and would be interested if you found a solution! Currently, we are looking at manufacturing our own solution.

Good to know about the mounting holes. Thanks! I'm using BaneBots 1/2" hex hubs for 6mm bore to mount the VexPro gears into the motors.

Here's a link:
http://banebots.com/c/WHB-HM-HS4-M6

[IceStorm]

Originally Posted by hectorcastillo

Good to know about the mounting holes. Thanks! I'm using BaneBots 1/2" hex hubs for 6mm bore to mount the VexPro gears into the motors.

Here's a link:
http://banebots.com/c/WHB-HM-HS4-M6

Do you by chance have a close up view of just the gearbox with the Banebots adapter or be willing to share your CAD file. were needing to use a 1/2" sprocket for our drive train this year and having a hard time understanding how I might be able to make one of these adapters work.

[Knufire]

Originally Posted by IceStorm

Do you by chance have a close up view of just the gearbox with the Banebots adapter or be willing to share your CAD file. were needing to use a 1/2" sprocket for our drive train this year and having a hard time understanding how I might be able to make one of these adapters work.

What size sprocket? AndyMark recently released this: http://www.andymark.com/product-p/am-3185.htm

[hectorcastillo]

Originally Posted by IceStorm

Do you by chance have a close up view of just the gearbox with the Banebots adapter or be willing to share your CAD file. were needing to use a 1/2" sprocket for our drive train this year and having a hard time understanding how I might be able to make one of these adapters work.

I couldn't find the CAD file for them while I was designing this, and I was kinda lazy so I didn't bother making my own. So there isn't actually an adapter in the CAD, but it's designed to use them.

It's a pretty simple set-up, though. The adapter should tighten right onto the 6mm shaft. You can then slide your sprocket onto there. The adapter has a lip on one end so your sprocket doesn't slide off that way, and it has a groove to add the retaining ring for the other side. You could probably put some spacers in there to get the sprocket into the right position. You could also cut it to length and machine your own retaining ring groove if you have access to a lathe.

If you send me a picture or a better description of what you're trying to do, I can probably be of more assistance.

[cadandcookies]

Here's a CAD file of the 6mm to 1/2" hex banebots adapters that I whipped up. Both in Creo and STEP flavors. Feel free to use however you want-- this is as close to the technical drawings as I think I can get.

This one is three wide, but I can make a 1 or 2 wide if you'd like. It's a real shame that it looks like BaneBots is going to stop selling these.

[hectorcastillo]

Originally Posted by cadandcookies

Here's a CAD file of the 6mm to 1/2" hex banebots adapters that I whipped up. Both in Creo and STEP flavors. Feel free to use however you want-- this is as close to the technical drawings as I think I can get.

This one is three wide, but I can make a 1 or 2 wide if you'd like. It's a real shame that it looks like BaneBots is going to stop selling these.

My brother managed to make one out of a piece of VEXPro Thunder Hex by drilling out the bore to 6mm on the drill press and drilling a hole in the side through which he tapped the threads for a set screw. It was pretty cool.