Locking Mechanism?

Hey guys,

Was wondering if anybody knew how to construct a locking mechanism that can preferably be toggled. I am thinking of using a notched system where it clicks in, and then you pull on a string to let it move up/down.

I’m building a (kind of like a hidden blade from assassin’s creed) device that attaches to the arm, so I can have 2 types of screwdrivers pop out for easy access when I need to do quick repairs on my robot.

If anyone has ideas or have done them before, let me know! I’m going to use those weird drawer pieces as the sliding mechanism, but am stuck on how to lock it in place.

I’m just going to say it now, this sounds extremely unsafe and you should make sure that what you do end up making will not be harmful to yourself or others.

With the being said, you could just jam something into one of the holes of the slide to stop it from moving or make a latch that holds it once it has moved past a certain point and then a physical button to release that latch.

Thanks for the input!

Yes i am making sure safety is of most importance. Don’t worry though, this will only just be dangerous as pneumatics haha.

If this lock + drawer + rubber tubing mechanism works well, provides enough force, and is easily toggled by a motor movement then I am thinking of using this system to replace them because running out of air is bothersome.

sounds very cool. and unsafe at the same time … look forward to seeing it when it is working :slight_smile:

only idea i have is some sort of motorized locking via rotation device … or a worm gear brake ?

I made this once for fun, except not with VEX parts.
Why don’t you just do it with pneumatics? With my extending blade, I only almost lost a finger. :slight_smile:

Well for one if I can get this to work without pneumatics, I will be able to control how forceful it will be through the tension of surgical tubing (which is safer than pneumatics) and I won’t have to constantly refill it with air making the screwdriver more portable/viable. It’s also just my curiosity because I have no idea how locks work, and Vex would be a great platform for me to learn. Plus I am only one year into Vex so it’ll get me more familiar with my parts. I don’t even know how the drawer-esque pieces work!

At the moment I *don’t *want a fast extension speed (like your example is) I just want a locking mechanism so I can just slide a screwdriver out conveniently when I need it and slide it back in when I don’t. If I feel comfortable and safe with the whole thing I will make it automatic but I doubt I will want to. This is also something I want to toy with so I can add to my future robots when I need to toggle lock something.

If I do, I am planning to make it so that surgical tubing pulls on the screwdriver constantly in a retracting fashion so there aren’t any potential dangers that come with mechanisms that extend it like yours. Also this way, I can extend the screwdriver with gravity + unlock which will make it lock extended, and retract the screwdriver by simply unlocking the lock. Finally, this will also easily solve the eternal question of “how do I retract *and *extend it?” I don’t think Vex parts are enough to build a pulley system but I’ll see.

Also yeah your example is why I am trying to get this to work without pneumatics. I don’t want to lose a finger because it goes too fast or it goes off in on accident! Making sure this is going to be 100% safe, go safety :slight_smile:

If you are using only vex parts, try the rack gears. A pair on the end of a beam pivoting on pillow bearings, squeezing more rack gears on a sliding mechanism will lock it. Also a ratcheting screwdriver might be in order since screwdrivers need to spin freely in order to work.

Try gravity driven if you can lower the friction enough. Holding your arm at your side and unlocking it, will slide the screwdriver in to your hand. Reverse to put the screwdriver away. Also you won’t skewer your hand/leg/friend.

we made a locking mechanism out of the plexi glass with a axle and some rubber bands. It rotates on the plexi glass then the axle pushes through the hole when it gets to the place we want it to lock. I would be glad to share pics with you when we get back from worlds.