Hi all,
as a new rookie team for the upcoming 2025, we are releasing our robot CAD for for our offseason 2024 event.
any feedback is welcomed!
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It’s fantastic to see you working on your design skills ahead of the season! (Something I wish I had focused more on last year!) Your design shows a lot of creativity and effort, which is always exciting to see. As a rookie team, tackling CAD is a huge step, and you’re already off to a great start.
First, some things done nicely:
The belly pan is cool, the access hole for the kraken is well thought out.
Your electronics mounts are impressive, especially having everything organized together. While 3D printing a battery mount can be challenging in terms of strength, the concept is neat and shows great foresight.
The choice of gearboxes for pivot power is solid! Max Planetaries are a reliable and nicely packaged option.
The note skirt is pretty smart! Another option is to have your bumpers only raised on the side that you intake the note to use the bumpers as a skirt, but what you’ve done is an equally viable option.
Now here’s a couple points of improvement:
While T-slot aluminum is common in general robotics, within FRC, 2x1 aluminum box tubing is much more popular. It’s stronger, easier to integrate with FRC-specific parts, and widely available from vendors like West Coast Products and REV Robotics. Transitioning to this material could make your robot sturdier and more adaptable… I would strongly recommend using this instead of T-slot extrusion.
The gear choice here is intriguing, but the pitch seems quite large. The FRC standard is typically 20DP gears, which you can find through suppliers like West Coast Products. Additionally, switching to hex shaft (1/2” or 3/8”) over round shaft would make your robot more compatible with standard FRC parts like pulleys, wheels, and hubs while also improving power transfer.
Using a 3D-printed mount for the Kraken motor might not provide the durability you need. Extending the side plate up and using the hole pattern to secure the motor directly would be a stronger and more reliable solution.
I’m not quite sure where you would get these rollers or what material they are supposed to be. You can buy different wheels & rollers from andymark and West Coast Products and they work wonderfully.
This almost definitely would not work. There will be a lot of torque transferred through any pivot especially as the robot bumps around, and half inch hex is definitely not going to hold up well at all, as well as add a ton of backlash/wiggle to the pivot which is not fun to program. Instead, I would use a large sprocket and chain or a sector gear to actuate this.
It’s amazing that you’re already diving into CAD, and I’d like to share a resource that has made a huge difference for my team: FRCDesign.org. This platform is maintained by experienced designers and provides an excellent workflow using Onshape, which I highly recommend as a rookie team. Onshape’s collaborative tools and parts library are invaluable for teams just starting out.
If you’re looking to connect with more experienced designers for feedback and advice, I’d also recommend joining the unofficial FRC Discord and David’s Design Server. Both are welcoming communities full of talented people willing to help.
If you need to convince mentors or teachers to explore these resources, feel free to direct them to the Discord servers or Chief Delphi. Speaking from experience, transitioning to Onshape with FRCdesign has been a huge leap for our team.
I hope my feedback is helpful and not overwhelming. Its really awesome to see rookie teams connecting to the wider community for help!
Best of luck to you and your team this season!
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To add onto this, what you guys have created is called a “Live axle” pivot, meaning the shaft your shooter/indexer is rotating on is transmitting the torque to rotate it. Most teams nowadays use “Dead axle” pivots, meaning the shaft is not transmitting any torque at all, and the thing being rotated is often actually rotating around the axle.
As you can (maybe) see in this picture, we have our intake driven by a neo motor(through a max planetary like you guys), then a chain reduction to a sprocket directly bolted to our intake. This means the axle the intake rotates around doesn’t transmit any torque or add backlash to the system
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I would guess it’s cats tongue tape wrapped around a 3d print or polycarbonate shaft with a plug
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They are 3d printed ABS with rubber spray coating
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Hmm, even the long ones? I would recommend going with a tube like approach, as although not important for this application, polycarb tube on something like an over the bumper intake withstands impacts better than a 3d print. I can provide more details or link to a relevant thread if you would like.
As for the spray coating, its not super common, but I would be interested in seeing how it actually performs. Most teams use a silicone tube or cats tongue tape to cover their rollers, or they go with a compliant/stealth wheel.
We did actually have some issues with the pivot, we reinforced it with a REV hex thingy, but it uh, didn’t survive.
Definitely something we won’t be doing again.
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I mean I can’t speak to its longevity, but during our games at least we had no issues with the rollers or the coating.
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I noticed that it looks like you are using aluminum as the shooter body, is that just what you had on hand? I would expect to see polycarb used there.
I also noticed that you have the gears on both side of the shooter is that just for reliability/durability? and if so did you have any failures related to that before you added them?
Also do you know what the wight ended up being of the full robot?
I also quickly threw together an Onshape file and here is a link for anyone interested:
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I noticed that you are using 3d printed gears to transmit power from your motors to your shooter and feeder wheels. You have the gears attached to the motor and I would be concerned about how well 3dp spline would hold up to the torque put on it. I would recommend using some type of adapter to help distribute the torque. You can find these from venders like Thriftybot and WCP. Although for thriftybot you would have to use a Kraken Spline to 1/2" Hex Adapter and then the Aluminum Insert for 3D Printed Parts.
Or you could use COTS gears instead that can handle the torque.
Edit: I would also be concerned about the gears themselves holding up. 3d printed gears don’t tend to do well.
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When we used 3d printed pulleys on the motor shaft, we printed them with a 8t 10dp gear profile bore, so we could slide that in the pulley, allowing it to be an interface between the spline XS shaft and the pulley (more surface area). It worked great throughout the season, would highly recommend. We found it didn’t have to be heat-set or inserted mid print, just putting it in would be fine.
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