What is the best mechanism for controlling a mouse-size door on a tube?

I'm thinking about building what would basically be a tube similar to the picture of this humane mouse trap, but the doors would be electronically controlled. The idea would be I could push a button on the arduino, and it could send a signal to close a door, and then push it again, and it could open the door.

The only issue is I haven't been able to find any examples of a very small electronically controlled door. The chicken coop doors are all basically like sliding barn doors, but that wouldn't work in my case. I'm unsure which opening mechanism to use, or the best way to attach a motor to drive it. Would anyone have any ideas or suggestions around approaching things on this scale?

I would use a small servo. Use with an Arduino using the Servo library. You will need an external power supply for the servo. A 4 AA cell battery pack or a 5V 1A cell phone charger to plug into the wall make good supplies.

Thanks; any ideas on which door-hinge mechanism to use that would connect well to the motor? Ideally it would be able to close the door pretty tightly

Do I understand that you are going to set there and wait for your mouse to go into the trap.

Well, that’s not exactly it but it was the closest analogy I could think of. I was hoping to build an amateur de-lousing chamber for a home mycology kit. The idea is that the tube would be vertical, implanted in the lid of a bucket, and the hobbyist could drop their mycelium chunks into the top of the tube, with the bottom door closed.

Then some UV lights can come on, disinfect the air and mycelium, and then the hobbyist could push a button to open the bottom door and let the mycelium fall into the substrate in the bucket. It’s possible that a non-round tube would be a lot more difficult to work with in terms of putting it through a bucket lid. Here’s a very amateur design.

Sorry, these mind games are not for me. Good night.

You'll find that you get much better help if you just ask for what you need instead of making analogies to something else. In your case, the answer of "use a servo" was appropriate, but for a door on a mousetrap it probably wouldn't be because mice are pretty damn fast. See why the analogies throw us off?

When you do that it just makes people feel like you're wasting their time.

True, I guess I figured it’d be harder to convey the exact requirements. Do you think I’d be better off creating a new thread?

Do not start a new thread.

If you want actually useful answers to your questions, provide the essential details. You are expected to do the preliminary work, and most likely you will have to experiment with several possibilities before arriving at a workable solution.

Furthermore, it is completely pointless to ask for something like the "best" mechanism, without defining "best".

I'll edit the original post with details shortly. "Best" would be a mechanism that could seal or close the door against the bottom of the tube to prevent airflow, while still holding a few grams of weight.I understand a perfectly airtight seal would not be likely but that is not necessary for minimizing airflow.

Please so not change the original post. We lose continuity and subsequent replies can look stupid.

I've never seen an XY problem involving mice before, so +1 for the novelty factor!

@piney_mountains Are you sure you even need an arduino at all for that thing? If I understand correctly, the prototype will be operated manually and not automated. What about a couple of springs and a couple of levers/strings?

I’m not actually sure I need an arduino, I would actually prefer to go with a mechanical solution. But what I can’t figure out is how to mechanically open the door to release the mycelium without introducing contamination.

ie, if I have a stick built into the top lid, and push down into the tube to push a spring-loaded bottom lid open, that stick may introduce contaminants as it slides down.

If the tube is filled with UV-C LED’s it may potentially be a non-issue though. The most important aspect of mycology is preventing contamination and UV-C isn’t instant; ie it needs a few seconds to fully kill mold and bacteria.

If you are going to use an RC servo to control the door, then the RC model aircraft world has all sorts of RC servo attachments and accessories. You could possibly attach a control horn to the outside of the bottom door (similar to ones used on RC aircraft control surfaces etc). You could then run a push rod to a bell crank (I think that's what they are called to change the direction by 90 deg to a second push rod running up the outside of your chamber to your RC servo.

What about actuating mechanical leverages through an airtight membrane? What about some small hydraulic actuators with the pipe passing through a sealed enclosure? Or a well-lubricated Bowden cable? What about magnets, if the distances permit it?

I think a linear hydraulic actuator could work very well, though it seems most are very large and relatively expensive for what's actually needed. This one seems like it could be good though:

I also think a magnet could work well. The only thing I'm still struggling with is how I could mechanically seal the bottom lid again. Technically, the user might never need to reseal the bottom lid until the mycelium has already fully colonized the bucket and it's time for them to open it up, so leaving the lid open until it's manually closed again may be a non-issue.

The only part I need to figure out now is how to add a hinge to a circular lid that attaches to the circular tube. The closest thing I can seem to find is this, though the way the hinge attaches to the tube might be a little too flat:

NVM, I actually think these clasp-tops for mason jars would work perfectly. Just would need to get PVC that matches the width:

You may be able to repurpose a new exhaust flapper or rain cap. Smaller ones (around 2in) seem to be called rain caps for tractor exhausts.

Either I don't understand the problem or you are overcomplicating it. As I understand it, you have this tube/flap in a closed environment. If the servo motor is also in that environment and sterilized before being placed in the container, where would any contamination come from?

As for the seal, as long as its made with a material that has some compliance, a servo motor should be able push it tightly enough against the end of the pipe so that even with power off, you'll maintain a seal. There's enough gearing in a typical servo that it is very difficult to turn the shaft by hand.

If you want a completely manual solution, two cheap syringes connected by a tube of water make a pretty good hydraulic actuator. One syringe on the outside, one on the inside connected to the door and the tube passes through a sealed opening on top. It may need to be spring loaded to work well though.