Preferred stepper motor type for a door lock

[grandruby]

pls I am looking for a stepper motor type to drive a gear train which in turn drives a rack that drives a bolt to lock or unlock a door.I do not know how to go about the calculations on torque,speed , step angle,back emf, infact everything. I need help.
its about my project:SMS controlled electronic door lock.

pls everyone.say something.anything useful.Thanks.

you can check my intended design.

[tumutbound]

The design seems overly complex.
How about a simple solenoid to operate the bolt?

[packrat]

Look at these; http://www.anaheimautomation.com/pro...ist.php?cID=52

Do a google for linear stepper motor . They are on ebay and some of the electronic surplus stores have them too.

On this type of motor the shaft is threaded and the inside of the motor is a nut. The shaft moves in and out instead of turning.

[grandruby]

Thanks Packrat for the info. Still I like to ask.How would this linear stepper motors fit into my design. Pls I need some explanations if you don`t mind. Thanks.

[Al_The_Man]

I would agree with Geoff, do you really need a stepper motor when a simpler mechanism would do it.
The start and end position appear to be defined and fixed, so why a stepper?
A bit higher cost than a simple spring loaded solenoid is a Shot Bolt, if it is security you need.
Al.

[grandruby]

Thanks Tumutbound for the idea. How and where do you think the solenoid would fit into my design? Please I need your help. Thanks again.

[grandruby]

I have done some calculations but i am not sure if what I did is realistic. Its a bit much but please I just need someone to read it and give me advice. Thanks.

[packrat]

Originally Posted by grandruby Thanks Packrat for the info. Still I like to ask.How would this linear stepper motors fit into my design. Pls I need some explanations if you don`t mind. Thanks.

The bolt would be connected directly to the shaft of the stepper I suggested. No gear train is needed, it moves in a straight line(linear).

A solenoid is usually limited in the amount of movement it can make. Plus a solenoid would have to be triggered both to open the door and close the door. most solenoids are spring loaded so it returns to the extended position when the power is released.

[Al_The_Man]

Shot Bolt lock.
http://www.prosecurityzone.com/Custo...plications.asp
Al.