How does 2910 turn/lathe shafts? What machine do you use?
We use a cheap manual lathe and some knock off 12" digital calipers. https://www.precisionmatthews.com/shop/pm-1022v-pm-1030v/
Here’s the lathe, it doesn’t get too much cheaper
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Teal wheels best wheels
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Looks even more amazing with the climber and 4414 style shooter! The overall compactness of Baby Grond is really mind boggling.
Is the climber rigging routed to the other side of the robot? I can’t seem to find any driving mechanisms in the picture.
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There is a Falcon on a Falcon Sport gearbox on the bottom side of the robot.
Because the robot is small the climber looks disproportionately tall when extended.
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We are very happy with how Baby Grond has preformed at off season events this Fall. Our media team recorded match video at Chezy Champs. Below are a couple of my favorite matches.
Since the pervious CAD release we have added:
- A 4414 Style multi roller hood
- SDS MK4 modules with L4 gearing
- Module mounting reinforcement plates inside of the 0.05" wall 2X1 to spread the load of the bolt heads
- A 4-Stage telescoping climber
The additions (mostly the climber) added about 12 pounds to the robot. It is right at 90 pounds without the battery and bumpers. CAD files of Baby Grond as it competed at Chezy Champs can be downloaded from our 2021 robot GrabCAD partner space.
Thank You Chezy Champs for the really high quality robot photo!
The climber is my favorite addition. It uses 1/16" wall tubing with 1/4" size increments between the tubes. Everything is supported by bearings and there are some clever tricks to make things work with the tight clearances between the tubes. The climber uses constant force springs to extend and a winch to retract. Thank you to our friends on 4911 for the inspiration on the climber.
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Love the climber design, very neato!
Do ya’ll plan to release your code for this season as well?
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Patrick,
Very slick looking design for the climber. I do have a few questions that I was hoping you could answer on some of the finer points of the design:
I notice some loops of black cord of some sort on the side of your climber. Are those to limit the amount of extension of each stage, or is there some other purpose for those cords?
I’m assuming that you used the same winch retraction to hold the climber in the retracted position and then payed out the rope to allow the arm to extend. Is that correct?
It looks like you have a pneumatic cylinder that operates a lock-off mechanism on your winch spool. Can you elaborate on that a bit? Did you just have holes drilled into the face of the end plate of the spool, or was there something more elaborate in play?
What strength were the linear springs that you used? Also, did you use the same strength linear spring for all stages, or did you tailor the spring strength progressively to try to control how the arm extends?
Thanks for sharing this very cool and polished design!
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Yes, those are made of Paracord and limit the extension of each stage. They are not modeled in the CAD. We tried to think of other ways to limit the extension, but it is pretty tricky with the 1/16" clearance between the tubes.
Yes, We use the winch to retract the climber and constant force springs to extend it. When the climber is not moving the motor is not powered and we use the pneumatic lock to hold the climber in position.
The spool has dog features that lock against the shaft of the pneumatic cylinder. We found that it was important to install a long set screw into the threaded hole of the cylinder shaft to prevent it from deforming by the force of the locking mechanism. After we did that we didn’t have any issues with the shaft strength. I think the set screw is not shown in the CAD.
The constant force springs we used were Mcmaster 9293K263 They are 2.3 pound springs. All of the stages used 2 of these springs except for the bottom stage which used 4 of them. This resulted in the bottom stage (stage 1) extending first followed by stage 4, 3, and then 2.
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Your climber is amazing. Couple of questions
- How did you install your Press fit threaded standoffs?
- What keeps the climber from extending during the match
- you have a lot of 3d printed parts on the climber. What material did you use?
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We do!
Our 2021 code is available here: https://github.com/FRCTeam2910/2021CompetitionRobot
Some interesting features of our robot code include:
- Using vision targeting to detect the loading station and dynamically generate autonomous paths for quickly lining up
- Two different 6-ball autonomous modes to ensure a high degree of auto compatibility with our alliance partners
- Comprehensive shooter hood+flywheel velocity tuning so we can shoot from many different distances
- Multi-threaded to perform path following and odometry updates at a higher rate
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We did not actually press fit them. The hole machined in the tubes are clearance fit and the nuts are captured in the assembly process.
During the match the pneumatic lock keeps the climber from extending. The gear reduction of the 12:1 falcon sport gearbox is actually enough to keep it from extending, but the pneumatic lock is easy insurance since we already need it to stay up at the end of the match.
We used Markforged Onyx for all the printed parts on this robot.
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What tool did you use to press fit them. Seems like it would be hard inside the tube.
@Bpk9p4 We did not actually press fit them. The hole machined in the tubes are clearance fit. The nuts are inserted from the inside of the tube by hand.
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Would you be able to elaborate on the beam break sensors. when a power cell breaks the first sensor does the conveyor move the exact right amount till the sensor is no longer broken? If so wouldn’t you not need a second sensor to know when it is full? I think the reason for having the sensor might be because if two balls are picked up in a row the sensor might have only broke once when it should have been broken two times. lastly to pick up a fifth power cell I would assume the top sensor would trigger full and the bottom sensor would be triggered and the conveyor would not advance since the power cell is trapped between the intake and frame.
Never mind I found my answer in one of your posts.
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