Hi, I have a question. I have been doing a lot of reading here and other sites and I have learned quite a bit, but I am still not sure about what I need to do for my application. I am building a simple halloween prop and I want to use something like a wiper motor to rock it back and forth. I already made a 3d model including the motor and built a linkage system so the rotation of the motor would provide the back and forth motion I was looking for. I know I can throw on a speed controller and then control the speed. the problem I have is Now I also need to control the degree of back and forth motion too. I am not sure how to do this with a linkage mechanism. it seem like I would actually need to not use a mechanical linkage and just auto reverse the motor continuously. this also seems possible. however I want the degree of rotation to be adjustable at any given time. Example I want the motor to be turning 60 degrees back and forth then be able to adjust it to turn say 30 degrees or 90 or anywhere in between at say 10 degree increments. does this make since? I sometimes have a hard time explaining things. it does not need to be real strong or atleast i dont think so. if it can move 3 or so lbs in either direction that would be fine. speed I want to be able to control. it can have a slight pause if needed but less than a second pause would be ideal otherwise i think it is going to look funny. I am open to using a mechanical linkage system still, but i don't know how to do it without making the hole thing really complicated.

thanks

 

If the directions/distances were fixed, I would say mechanical.
But if you require the ability to vary the movement, I would think a stepper system with a step/dir controller would be the simplest, just dial in the amount of pulses.
Either that or a simple DC motor with adjustable limit switch to control reverse and degree of movement.
Max.

 

Thanks I was looking at a stepper motor, but I know even less about that type of set up. I understand mechanical systems alot better. I don't even know what torque I need to look for in a stepper to do what I need. from what I have read a NEMA 23 or higher would be required. but i might be misunderstanding what I am reading. I even looked at the NEMA 42 but I think that is overkill, but i do even know that. plus they are more expensive then what I was looking for. I would like to stay under $50 for the stepper motor if that is possible. I could go a little higher but I am on a budget. Thanks for the fast reply

 

The design was made using a wiper motor for the power. I am sure it would have the torque and rpms capable of doing what I want and that with a speed controller seemed to be a good option. then I thought about needing to change the distance of travel on the fly. thats when i thought of using a stepper or controlling the movement on the wiper motor. If someone here can point me to a stepper motor that would perform closely in torque and speed of the wiper motor that would be awesome. stronger and the ability to go faster is ok as long as the speed can be controlled.

Thanks again