As the design lead, I’ve been working on climb ideas. My current idea (and the one we’re currently going with) is using two 775pros to raise an elevator up to the height of the generator switch and making sure we are securely on the bar. We would then have two MiniCIMs pull the elevator down, raising the robot up.
We are planning on using VersaPlanetaries for all four gearboxes involved. The thing is that when a friend of mine got some VersaPlanetary Lites for an off-season project, he had to place three different orders because he kept forgetting to get the parts necessary to put his 775 in his VPs.
I know that the regular versions do come with the 700 Series mounting plates that caused his problems, but I wanted to make sure from someone who has used this system before that this order we may make in the near future includes all that we need.
The current order slate:
775pro gearboxes (2 of each)
- 1/2" Hex Output
- 10:1 Reduction
- 0-2 Stage Screw Kit
MiniCIM Gearboxes (2 of each)
- 1/2" Hex Output
- 90:1 Reduction
- CIM Adapter
- Ratchet Kit
- 0-2 Stage Screw Kit
Let me know if there is another problem here I’m not seeing. I can upload a picture of our (experimental) CAD, too.
You’re using way too many motors for such a task. While in theory you got it right, 1 redline and 1 miniCIM would be enough. However I would probably look at other solutions, everybot is a great solution that only uses one motor. Remember 4 motors means 4 motor controllers + 4 PDP slots + weight.
looks like you are missing the ring gears, and I dont remember whether or not the motor mounting kit comes with output stages (I think they do).
I am also going to add that I dont think its the wisest idea to use that many motors on just raising and the climbing with a mechanism especially when it only needs to go up and down one time a match. by cutting out half those motors you save ~$230 as well (~$420 if you count motor controllers)
Take a look in the docs and downloads on the vex site. 90to1 with a mini cim is not recommend.
Spring load your extension mechanism and just motorize your winch! Stored energy is great for FRC and saves PDP slots.
As others have noted, you are using too many motors and gearboxes for the task. Your design process should always have a step where you analyze your design to see if you can simplify it and use mechanisms for multiple functions.
Piling on - way too many motors, you may break the mini-CIM VPs. If you don’t want to spring load and don’t trust yourself not to pull the hook down with the main lift, ONE snow blower motor should be enough to raise and set your hook unless it’s heavier than it should be. ONE mini-CIM or other CIM-class motor with a more modest reduction should be plenty enough power for the lift.
OBTW, if you use the snow blower or another worm gearbox to set the hook, also run it when you do the big pull. It won’t add much force to the lift, but that way you won’t be trying to backdrive that gearbox.
You might be interested in my design spereadsheet. You can use the mechanism tab to help you choose how many motors and what gear ratios you need to accomplish your task. Then the new VersaPlanetary Calculator will help you make sure the ratios you’re picking are within the rated loads, and it will tell you what part numbers you’ll need to order to make that configuration (and how much it’ll cost).
Thank you all for the help. My team doesn’t really have very much experience not winging the robot design, so having other people to discuss ideas with really helps.
This afternoon I devised an alternate setup based on both our 2018 climber (to help minimize the cost) and the Everybot.
Old VersaPlanetary setup:
Second idea (using just one regular CIM):
The CAD is still missing finer details like the springs, spacers, brackets, and the like.
I remember 2015 doing 120:1 off a minicim. That was fun.
Something I constantly forget until the parts arrive: The base kit includes the screws for 0-2 stages. At least, it did last time I made a VP order last summer. I’ve got so many extras from including these in my order over and over again.
Okay, so we have our everybot-based elevator climbable, but the springs that pull it up are so powerful that it pulls the elevator up past the 45" limit. But if we remove a spring from each side, then it’s not powerful enough to lift the elevator up all the way.
Does anyone have an idea on how to fix it in place for the match but make it still climb to its full ability?
Can you add a short section of rope between the spring and one of its mounting points, effectively shortening how stretched out the spring is (and thus how much force is involved) at full retraction?
We had a similar issue that we solved by lightly powering (.1) the motors in the opposite direction of the climb throughout the match.
In our case the friction from the motor and gearbox wasn’t quite enough to hold the lift down during all the jarring and bouncing resulting in our lift drifting up a few inches by the end of a match.
If you need to significantly power the motors in order to prevent the lift, then you may need a mechanical solution.
Just chiming in to say that for a mini-CIM under the load shown here, this is totally safe to do (at least in terms of the motor itself). The motor will barely even get warm.
Thank you for the help, but we figured outand tested a release system involving zip ties and a screw. We’ll keep this in mind if something happens to this idea
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