Hi All,
I am trying to automate a chicken coop door using Raspberry PI. I am looking for some help choosing a motor that will work for me. I am new at this so please bear with me. The Coop guillotine door is about 2 lbs and needs to raise about 12 inches. Assuming i use a 2" pulley on the drive shaft I am thinking i will need about 223 millinewtons/ meter or 29 Oz/in constant torque. The Motor shied I am looking at is rated for 1.2 amp constant, 3 amp peak draw. I am having trouble finding something that will work. Should I consider a gear box or pulley system? Any suggestions would be appreciated.
Think I found one…
DescriptionSpecificationsUseful LinksDimensionsSupplier Product CodeReviews
Description
DC Gearmotor
Nominal Voltage: 12V
No Load RPM: 4
Stall Current: 0.5A
Stall Torque: 992 oz-in
Shaft Diameter: 6 mm
The 12V 4RPM 992oz-in Gearmotor is a high torque constructed gear motor with oil bearing designed for long service life.
12V 4RPM 992oz-in Gearmotor
Features
DC reversible motors
Solder type terminal
High torque construction
Oil bearing design for long service life
Useful Links
PDF Files
Motor Curves
Specifications
Gear Ratio: 900:1
Nominal Voltage: 12V
No Load RPM: 4
No Load Current: 0.045A
Rated RPM: 3
Rated Torque: 248 oz-in
Stall Current: 0.5A
Stall Torque: 992 oz-in
Shaft Type: D-Shaped
Dimensions
Size: 36.5D x 47L mm
Weight: 133 g
Shaft Diameter: 6 mm
Shaft Length: 18.1 mm
Supplier Product Code
638162
Why not: robotshop.com/en/automatic-c … motor.html
This would save you from having to design, wire, code and troubleshoot a system from scratch.
If you still want to go the custom route, you seem to know the math required… how can we help?
Thanks for the reply but where is the fun in that!? 
I am hoping to use the RPI to add a temp sensor and camera too, maybe even send me a text/email when the door has been opened/closed. I also like I have the possibility of controlling a second door to a fenced in pen down the road.
I wound up purchasing the motor above.
Thanks again!
Very true - sometimes hard to determine who wants a solution vs. who wants to have fun creating one.
Would be great to see what you create!