convert a rotational motor to a linear motor.

hello, any body got any ideas on how to easily convert a rotary motor to a linear motion ? are there any existing motors? im trying to make it simple and avoid gearing. im planning to make a door lock. thanks in advance for the advice!

A crank or a cam? Lead screw?

right gotcha thanks

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Pulley and belt (toothed for high traction), or pulley and string.

pulley and string in what arrangement ?

rack and pinion? nick one of a cd drive

thats a good suggestion thanks =) ill see if i can find one laying around the house

do you think this will work http://www.ebay.com/itm/Car-Auto-Plastic-Universal-Heavy-Duty-Power-Door-Lock-Actuator-Motor-2-Wire-12V-/181064113119?pt=LH_DefaultDomain_0&hash=item2a28431bdf? i actually have one laying around my house. just that i have not really tried and use it

If im not mistaken that is a solenoid, basically your gna give it a current and its gna give you linear actuation, your not gna be converting any rotation to linear, simply give linear. If all you want to do is give linear actuation I would suggest solenoids. Just make sure they meet your requirements.

http://www.ebay.com/itm/DC-12V-1A-4mm-100gf-Actuator-Linear-Pull-Solenoid-Electromagnet-/321058230726?pt=LH_DefaultDomain_0&hash=item4ac08fd1c6

take care of the amount of force you need and the distance the piston pushes outwards, if you use a solenoid go on the arduino website and look them up there are model codes and schematics because you have to be very careful when interfacing with the arduino, if you are not careful you'll burn the arduino

DMond:
do you think this will work http://www.ebay.com/itm/Car-Auto-Plastic-Universal-Heavy-Duty-Power-Door-Lock-Actuator-Motor-2-Wire-12V-/181064113119?pt=LH_DefaultDomain_0&hash=item2a28431bdf?

It’s pretty obvious from looking at it that it is a rack and pinion actuator, and very much like what I had in a Ford Fairlane. I suspect it would be a better bet than a solenoid as it is likely to have a longer travel, thereby making installation easier, and less current demand

really? sorry if i misled you i was looking for solenoids on my last project and someone referred me to just that! must have misunderstood him he was probably just indicating me towards a linear actuator! live and learn thanks anyway and sorry again!

DMond: pulley and string in what arrangement ?

There are loads of different arrangements depending what sort of movement you're trying to achieve. If you want to move the motor relative to something else then attach one end of a string to a fixed point, wrap it around a pulley connected to the motor shaft a few times, attach the far end to another fixed point. The motor will winch itself along the string. If you want to move a push-/pull-rod relative to the motor, tie one end of the string to one end of the rod, wrap around a pulley attached to the motor, attach the far end to the other end of the rod. The motor will winch the rod in either direction. If you don't want a rod between the motor and the part being moved by the motor, mount the motor+pulley at one end of the range of movement and mount an idler pulley at the far end. Wrap the string around both pulleys in a loop, attach the part to be moved to the string.

thanks for the advice. i am planning to make a door lock actually. if i am using a pulley system, wouldnt i only be able to perform one action? pull or push? unless i use a rod. but i have been making some tests and i found that its hard to calibrate it properly. im using a servo, and a round plate connected to it. the system is similar to a crank system.