How do you build a lock for hanging? I know there are different kinds, such as a Stanley lock, but that is all I know.
We don’t really require a lock for hanging, we have a ratchet and pawl so when the motors stop turning, the robot doesn’t go down.
The old post poked through a hole in polycarb to lock in place generally works. Rubber band pushes it through once the polycarb is out of the way. Gravity takes over once power is cut and you sty in place. With larger shaft options you can probably hold some serious weight now like this.
Look up Green Eggs robotics for their Fred 3 bot.
https://vexforum.com/t/team-44-green-egg-robotics-reveal/23578/1
Theirs was horizontal to hold their wheels in an outward 45 degree angle for their X drive. Wheels drive them into place then the lock slides in. Pure brilliance.
Worm and Wheel, you can bend an I beam using it as a lever trying to get it to move, and if its geared theres no way you will move.
You first need to figure out your hanging mechanism. There are dozens if not hundreds of ways to build a lock. Do you know your lift system or a few ideas of possible ones?
I thought it would be cool if you’re doing a scissor or some other lift and you’re using a claw to put a hook on the bottom of the claw and have that hook hook onto the bottom of your robot
We are using either a 4 bar or 6 bar. For grabbing the bar we are using a passive hook.
Thanks for the help guys, this gives me some great ideas.
I caution against the 1x25 standoff scissor method for hanging. In Toss Up, one of our teams 81J ended up with a mangled mess when attempting the lift. The metal is far too soft in this geometry to attempt such a lift. A c-channel scissor would work better. The wreckage reminded me of Sauron’s helmet crumpling inward when he was defeated in LOTR.
If you have a high enough torque ratio(and a light base) you may not need one.
Look at Stanley Shi’s locks from toss up. I’m too lazy to find the video but it’s on his channel.
Not to sound cocky, but he stated that he already knows of Stanley’s lock. I believe he was trying to find an alternative lock that could be achieved without pnuematics.
Also something really easy to do (though not super practical), is having a rich and pinion as an alternative to pneumatics. Its slow, and requires a motor, but if you don’t want to put too much time into it, its great.
Also, depending on if your bots tilts back whilst hanging, then you could use this
Correct, we are looking to do something that not only doesn’t require pneumatics, but is completely passive.
Rubber bands might be your best bet. We used them as a lift assist in Skyrise, and they were really helpful. You might look into a constant force elastic system, which maintain constant elastic force at different arm positions. They’re not all that complicated.
I don’t know how to make a passive lock that works twice for an autonomous hang. The best passive lock that I know of is just a piece of metal running along a very shallow drop off cam. Once the joint is turned far enough, the metal locks into the cam and doesn’t allow the joint to rotate back.
That’s along the lines of what I was thinking.
I was thinking something like this:
Maybe if you want to hang twice, you could move the robot somehow to loosen it and be able to come back down.
I would use stanley’s v2 lock and use a rack and pinion instead of a pneumatic actuator, the force of the gears trying to move in reverse should hold everything in place.
I think the point of his question was to come up with a totally passive lock, without pneumatic OR motors.