So I’ve decided to automate my sliding glass door to let my dog out. I haven’t figured out what I want to use to trigger it yet, a button my dog can push or figuring out where to place an RFID reader. I know they make products that can do this but the cheapest one I can find is $400 and is only meant to work with a glass door that has the sliding door on the inside with the fixed on the outside. The set up I’m trying for I a stepper motor attached to a ball screw mounted to the door. Unless I want to detach the screw every time I want to use the door without the motor, I need a motor that will turn freely when not actively powered. I’ve been trying to do research on stepper motors but I don’t know how torque oz-in relate to how much of a horizontal load the motor can handle. I had a friend who suggested I could use a NEMA 17 or 22, I think I found something that listed the horizontal load of a NEMA 23 is 25kg but I only found that one place and don’t know if it is accurate. https://www.amazon.com/dp/B08JCM2742/ref=cm_sw_r_cp_apa_glc_fabc_FEXEY9GRDCRKJNV5W7K8
I was looking at something like this. Any advice or suggestions are welcome I’m having fun trying to work this out but I will freely admit when I need some help. TIA
Nema 23s are really powerful, I have seen them used with a balls screw move loads upto 40kg.
Why did you want to use a stepper anyway? You could use a standard motor with end stops or even a linear actuator, like are used on automated gates.
From what I can find an actuator long enough would be expensive and I wasn’t sure if the door would still usable with one attached. I was looking at using a dc motor but a co-worker suggested a stepper motor would be a better option.
I think it is a toss up between a stepper motor and a dc motor with limiting switches, if you are only going to implement the absolute minimum. With a stepper motor if you were also to implement limiting switches (a good idea imho) then it would be easier just to implement a dc motor with limiters.
What about getting a sliding glass doggy door insert? Might be an easier plan
Yes linear actuators would probably be expensive and are not usually back driveable.
Stepper motors would work but seems over kill if your not wanting to say half open the door etc ( this could still be done with a dc motor) also you should still fit endstops to prevent accidents.
DC motor probably the cheapest and easiest to set up, would need end stops and could use timing to give part opening etc or even fit with a encoder to report position.
Really the choice is yours I just recommend a DC motor.
Check out this where they use an old windscreen wiper motor.
Thanks I am looking to open the door about half way. I have seen that video and the first time I looked at it I was thinking it didn’t meet my needs but I think I might look into that method again.
Hey guys so my ideas are outpacing my knowledge, I could use some advice.
Question one don’t know if this is possible or not, I was thinking of using a v1 access controller but making a bigger antenna, we scrap a ton of magnet wire at my job and a think I can ask for some without a problem. I just don’t know how hard it would be to tune it or if it would be possible to give it something like a 2 foot read range. If not I’ll probably try a pressure switch or sensor. RFID would just be cooler.
Second I have a lift motor from a treadmill that would work well for this although I don’t know if I need a longer lead screw, anyway it has some kind of sensor built in to read the position but I don’t know what kind of sensor it is or how it reads position.
I’m using a pi zero wh, and in my head it makes sense that I should be able to have the pi read the info from that sensor to open the door a set amount but in reality I have no idea. Any advice or resources would be really great. TIA
That type of motor (usually) uses a small switch on a set of cams that are gear driven. Eventually your motor turns the swirch and kills power to itself.
That type of motor is called a linear actuator.
After further research I now know its a hall effect sensor. On the gear that drives the lead screw there is a magnet, the hall effect sensor reads the strength of the magnetic field and I’m guessing the control board tracks the field strength and therefore the number of rotations it can then tell the location of the actuator. I love learning new stuff.