Linear Actuator for Door Lock Demo

[RishabhG]

Hi,

A part of my project involves unlocking a door upon a receiving a certain command. The project is part of my undergrad curriculum. One of the ways to demo a door lock is to use a linear actuator. I worked on a linear actuator project last year and it turned out to be an arduous task; built a linear actuator using a stepper motor.

What is the easiest and best possible way to build a linear actuator using a DC motor? How do I attach a bolt and nut onto the shaft of the motor?

Any new ideas for a door lock demo or linear actuator are also welcome.

Thank You
Rishabh

 

[BradtheRad]

Apartment buildings have a door-unlock mechanism. It buzzes loudly for a moment when the resident presses a button.

The only device which can do that is a solenoid (I think).

If you use a motor, consider having it spin a threaded shaft. That will provide linear motion.

 

[RishabhG]

If you use a motor, consider having it spin a threaded shaft. That will provide linear motion.

Unfortunately, I don't have a with a threaded shaft. Is there a way to attach a threaded bolt onto the shaft?

 

[BradtheRad]

Any kind of threaded bolt, threaded screw, threaded block, worm drive, etc., that you can attach.

This sort of thing is not easy (as you have discovered). It requires ingenuity.

Access to a machine shop will be invaluable. Or perhaps a 3-D printer, a recent technology that creates plastic parts from a computer data file.

 

[RishabhG]

This is the image of the motor with shaft that I managed to build.

 

[BradtheRad]

Good work.

That appears to be epoxy joining the bolt and motor shaft, I think? Excellent inventive use of materials at hand.

 

[RishabhG]

I do not know how to proceed further. The rotation of the motor simply moves the nut linearly along the shaft given that I fix the two ends.

How do I get a push/pull motion like that of a solenoid actuator?

 

[BradtheRad]

The linear motion works best if it is on the same axis as the rotational motion.

A length of pipe/tubing becomes a homemade deadbolt. Attach it to the nut by solder/ epoxy/ welding. You can crush the pipe to a hex shape snug around the nut, then fill in the crevice with epoxy.

A 'deep well socket' is ready-made for your purpose. (The kind found in a socket wrench set.) Costs a few dollars. It would not need any epoxy/ soldering/ welding.

 

[KeepItSimpleStupid]

These http://www.aapexonline.com/universal-power-door-lock-actuator-motor-12-volt-8-8lb-torq-7-8.html are basically 12 V motors.

 

[BradtheRad]

I forgot to state that the tube must be prevented from turning. If it is free to turn then the nut will not travel back and forth on the threads!

A rectangular shape is typical for deadbolts.