for a project I calculated a moment of force of 0.5 Nm, not considering friction, so I would like to have a 0.7 Nm bipolar motor to have some buffer. For my project the motor must lift a 1 to 1.5 kg peace of wood for approximately 30 cm.
Since I'm not the electronic professional himself, I wanted to ask you for recommendations regarding the motor and if you can recommend a step-by-step tutorial or introduction, how I can get this motor to work with my arduino. How to set the cables,... the software itself should not be an issue and something I can do on my own.
Can you help me and recommend a motor I can get working with an already existing step-by-step introduction? Perhaps a strange question, but I'm really bad in doing such things out of my brain. If I have a guide I can follow, I should get it work.
As far as finding a suitable motor is concerned, most suppliers list the holding torque of the motors. You should probably be looking for a motor with a holding torque at least twice your measured torque. The net torque of stepper motors declines significantly as speed increases.
The better manufacturers post graphs showing how the torque varies with speed and motor power supply voltage.
You will also need a stepper motor driver and the cheap (and effective) DRV8825 driver should really only be used with motors having a coil current of 1.7 amps or less. That may influence your choice of motor.
You don't really want a stepper for a coop door, a standard small DC gear motor and two microswitches should be fine and smaller/cheaper and consume less power.
Small motors have little torque, which is why we use gearmotors most of the time. High-ratio reduction gears (and worm gears) prevent back-driving of the motor too.
If you do use a stepper you'll need to provide constant power all the time.
A friensdof mine used a cheap car window mech from e-bay - a scrap yard may be cheaper, but maybe that's not solving the problem in the manner that is desired.
Does such a dc motor have enough torque to raise approximately 1 to 1.5 kg (so that foxes and martens cannot come in) and "drive" it down smoothly, so I don't have a chicken guillotine at the end? I calculated 0.5 Nm, not respecting friction, so I would prefer a little buffer.
If so, great. Can you recommend a motor with a driver (a package or both separately or don't I need a driver at all)? The car window motor sounds like a cool idea, but since I don't have the experience I would prefer something "out of the box" where I can find introductions for, how to run them on the arduino.
BLU1:
Does such a dc motor have enough torque to raise approximately 1 to 1.5 kg
You can get DC motors with as much or as little torque as you require by choosing appropriate gearing. For an up-down door it would be best to use a worm reduction gear because it cannot be back-driven, even when the motor is off.
If you need more help please post a diagram of the mechanism you are planning to create.
Here a small description, how the chicken door shall work:
On the left, you see the chicken door closed, on the right, you see it opened.
Motor: I guess it's clear, that this is the motor we are talking here in this topic. Arduino, power supply,.. are not part of this picture.
"Cylinder": This has to be connected, by a screw, e.g. so that the fishing line can role on and role up, so that the chicken door moves up or down.
Fishing line: The fishing line is rolled on and rolled up, depending if the door is opened or closed. I would choose that type of line because it's very strong.
Chicken door: The "door", a peace of wood or aluminium or something like that, that is moved up or down.
Slides: They are used, so the door keeps the direction and no fox or marten can push up the chicken door, wenn it's closed.
I hope, it got clear a little bit. Otherwise, you can see the general functionality I want to have here: Automatic Chicken Door - YouTube
You'll need a solenoid lock, and an alarm if it doesn't reach the bottom of the slides. Depends how clever your foxes are, but they can slide up such doors.
@Robin2: Thanks for adding the graph. Today in the evening I'll search for a "DC motor with a worm reduction gear" and let you know, what I found / ask, if this really is, what I need and want.
@raymw: Yes, I want to extend the door also with two sensors, like those you know from home automization for windows. One part of the sensor is on the window, the other on the windows frame and when the magnetic field isn't there, this means, the window is open. In my case, when the door shall be closed but the magnetic field isn't there, I know, the door didn't close completely or on the other hand, if the door shall be open but the "close state sensor" has a magnetic field, I know, it's still closed. Additionally I would add the same sensor at the top of the door and its "open position" on the outer wall of the coop, so I know, it's open. All this information will be sent via mqtt to my openhab2 "home automatization" (I don't really have home automatization except some temperature/humidity sensors and an irrigation) raspberry pi, which will evaluate the sensor data and the desired value of the door and let me know via telegram messenger, if the desired value and the current state are not equal.
To be honest I don't think foxes can / will come on the property, as it is completely surrounded by a 1.9m wall. My "fear" are martens and 10, 15, 20 years ago there was at least one in the barn. This one will not be alive anymore, I guess, but no clue, if there is a new one or a new one will settle down as soon as chickens are available for dinner.
As last words: I didn't add the sensors in the graph, because I think I can manage it on my own to add them and read their state and to concentrate on the details.
I used the last two evenings to search for a motor. What a pitty, it's not that easy (for me?) to find a motor with about 0.7 Nm / 70 Ncm that does not cost some 100 €.
But it has no driver card included, so I would need an additional driver card. This motor looks massive, but aren't there any cheaper good solutions "in a box" with the right driver card?
I used the last two evenings to search for a motor. What a pitty, it's not that easy (for me?) to find a motor with about 0.7 Nm / 70 Ncm that does not cost some 100 €.
BTW a regular addition of some WD40 to the motor and gearbox would be wise in an outdoor environment even if well protected from rain, electric motors are very prone to rust...
thanks a lot for your response. They don't send to germany, nevertheless, I now have a lead where to look for and that there are quite cheap motors out there. I'll immediately have a look into that.
The hint regarding WD40 is great, thanks. I'll keep this in mind.
thanks for your response. To be honest, no clue, yet. Of course not so fast the chickens could be injured if they are trying to get in or out while the door is closing. How fast this exactly is, I don't know. If the door is closed within 20, 30 seconds, I guess this should be slow enough?!
