Screw Type Linear Motion? Stepper Motor?

sounds like a gun trigger for a drone

...or worse, a "dead-man switch" detonator for an IED. Sorry, I'm not going farther on this one.

How about a window motor or antenna motor as used in cars? Maybe see what your local auto parts store has.

Thank you. I will look into that.

Good God! No, release switch for an animal cage. We do wildlife management. That way I can let skunks out without being right near them. Cages are already rigged with pushbutton releases.

I would tend to think terrorists wouldn't be looking for advice in this venue, but then again, the world is full of whackos. I am sure it won't be long before what you are talking about actually happens. They already have ones that will drop paint balls and whatnot. How long before somebody adapts that to... who knows what.

Thanks for the feedback, you would be surprised at some of the "requests" that come through here! So you want a way to push a spring loaded button? How about a picture or two of the cage and release mechanism? If not then the cage manufacturer and model number would help us understand the intricacies of mounting and controlling the depth of throw, etc.

The reason we ask is because it has already been done recently and reported by the media, so now lots of people know and are likely trying too.

Some of those large RC servos for large model planes may work, and the robotics servos would but the cost and physical size is likely going to be prohibitive for this particular application.

Have you considered just modifying the cage locking mechanism instead? Perhaps changing it to a spring loaded draw out pin that doesn't require a lot of effort to move in and out? Then even a simple solenoid would work.

Maybe you should consider having your assistant perform the animal releases so that they can become fully competent and experienced?

I have had several "assistants" that I would definitely recommend for the job.

Hi. I have a trap I have used frequently for small game transport. Occasionally, wind up with a skunk in it. All I have done is point the trap gate towards the nearest wooded area and opened the trap. The skunk toddles off announcing it's indignation of being in the trap. I have never been sprayed.

Thank you. They don't seem to make one strong enough. The ones for things like airplane ailerons produce only fractions of an ounce of force. I need about 7 pounds. Anything I have found producing that much force then jumps up to things designed to shove auto parts around in a factory. They produce hundreds of pounds of force and cost thousands of dollars. If you know of an R/C supplier who has one suitable I will be grateful for the lead. It is my guess that as the technology for these "drones" grows, and they start making the really big ones for places like Amazon and what not, then parts like this will become available. Scaled up.

Thanks,

TB

How about a small rack and pinion arrangement, driven by a small 12V gear motor?

I guess until the OP responds to a few of our questions, we're just pi**ing in the wind!

A few follow questions too:

• Is there a firm size constraint? I know you stated 2" x 2" but can it exceed those dimensions?
• Can you post a picture of where you want to install it on the cage?
• Does it have to hold the button in or can it just activate it and return to the "safe" position?
• A 12 VDC gear motor with a simple cam may work also?

Tom,

Where are you located?

I do feral cat trap / spay-neuter / release so I understand where you're coming from.

I have seen a lot of stepper motor linear positioning screws drives and they may fit your size requirements.

Let me know and maybe we can figure out a solution?

The motor below is 3" OAL and about 1.5" OD and runs off 5-9 volts but requires stepper motor driver circuitry

What is the source for these? I can think of a couple of applications in my work

Ebay!

http://www.mcmaster.com/#electric-actuators/=ys0hhf

Linear actuator solenoid?

He said he tried a solenoid but it did not have the force required!

I know he could try a different one but he is working with 12 VDC R/C controllers and it may not have the available current needed to push a heavy magnet?

He quoted 7 lbf, the one I linked to gives 9.9 lbf.

I stand corrected. I do know that it takes a bit of current to get those solenoids to fully actuate.

I don't think he has the needed current available with the R/C equipment!

The supplier states 400mA, I don't know if that's high from the point of view of R/C stuff.

I was once a housemate at Cornell University with a guy who was studying skunks. Once in a while he got sprayed. One of the best neutralizers is tomato juice.

Add a second lock to the door in the form of a 12V DC magnet and a manual override mechanism for the existing lock. During transport and normal operation use the existing lock. When the cage is set in position for a release, energize the magnet to lock the door and override the existing lock. Retire to a safe distance and de-energize the magnet to release the door. The magnet is energized for only a short time so can be powered by battery. When the cage is empty the existing lock can be reset manually. A "Single Door Electric Magnetic Lock 350lb Holding Force for Access Control" is available on e-Bay for £22.60 (about $35) + p&p (Seller information " homegarden2012 ") This product was the first hit on Google search engine (no recommendation implied) but there must be many similar products available.

If you enjoy building little contraptions, this might work... You would need a small electric motor (from a hobby shop or your kid's battery-operated toy), a length of threaded rod (a long threaded bolt would work), a nut with the same threads as the threaded rod, and two small gears. Mount one gear on the motor shaft. Drill a hole in the center of the other gear, large enough so it will slide freely on the threaded rod. Mount a nut to this gear. Make sure it's centered. Mount the contraption to the cage so that when the motor turns, it will turn the gear & nut. The gear and nut must be free to spin, but not free to move linearly. The threaded rod will ride back and forth along the spinning gear & nut. When the motor spins clockwise the threaded rod will move one direction (linear) and when it's reversed the threaded rod will move the other direction. (It's hard to describe this in words.)

I coached a high-school Science Olympiad team several years ago. There were events where they had to build things that were powered by mousetraps, battery motors, etc. It really was great fun! I remember several contraptions where threaded rods moved along spinning nuts to convert rotation to linear motion.

LOL, What you are describing it indeed a screw jack. They make these things for all kinds of jobs. I am just looking for one scaled to what I need to do. That was the basis of the original post. What I have come down to is that nobody seems to actually make the size I want. Probably no commercial market. So I think I will try making one, but a little simpler than you describe. I found a plan on some hobby website and did the palm slap forehead thing. Now if I can find a motor already coupled to a threaded rod...

Look on eBay.. I found tons of them!

Check this Site/blog for Electric Linear Motor Information. If not go to Web and look for Electric Linear Motor there are quite a few suppliers for these devices. Address:http://www.designnews.com/document.asp?doc_id=272441&

That's great! Gravity is both reliable and free. Technically, I guess it's not free, since you had to lift the weight up every evening. But it's an extremely efficient and reliable way to store energy!

Try these guys: https://www.firgelliauto.com/