stepper motor and raspberry pi

My question doesn't have to do with thecircuitry, but it's related.

I want this to work for the Raspberry Pi, controlled by python.

I am looking to control a stepper motor for 2 positions on a hatch that weighs about 4lbs.

However, I don't know what to buy. I have looked at Adafruit, and the only thing I know that I have to get is the Hat, however I don't know which one.

What kind of hat do I buy? What kind of stepper motor do I buy? What lever should I get? What power supply do I get, to work with the entire setup? Did I miss anything?

As you can see i'm completely clueless as to how to begin.

I am looking for the simplest setup that works on my bare raspberry pi, preferably without soldering.

This is the setup I have in mind:

https://i.stack.imgur.com/55IC9.jpg

If there is another place where I go with this question, please suggest it.

by basviccc
February 11, 2018

This looks simple, but soon becomes complicated. Perhaps a first approach is to assess how much counterbalance and gearing can be applied. It would be advantageous if the hatch were well balanced and tended to remain in the fully open or fully closed positions once there, and if the gearing were low enough to make the stepper motor torque quite low. This will minimise the stepper current and cost. With motors running at typically twenty pounds, cost would seem to be a major issue. Once you have made a satisfactory mechanical assembly, you will be able to measure the torque requirement and choose a motor and drive circuit.Typical motors are here: http://uk.farnell.com/c/automation-process-control/motors-drives/ac-motors-dc-motors-servo-motors/stepper-motors Alternatively use an ordinary dc motor operated by a simple switch, and save your pi for other duties,

by mikerogerswsm
February 11, 2018

ps - Watch out for high current demands, early pi used more than the half amp normally available from one usb, and connecting usb in parallel is illegal. You will need a separate somewhat beefy power supply for this project.

by mikerogerswsm
February 11, 2018
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1 Answer

Answer by basviccc

Thank you for the quick reply, but this is going to be controlled specifically for the raspberry pi, and everything has to be raspberry pi specific

+1 vote
by basviccc
February 11, 2018

If you wish to attach a stepper motor without counterbalance or reduction gearing the hatch weighs 40 Newtons and this is at 0.5 metres from the axis. You will need to provide 20 N-m of torque. This is really hefty and requires a really big motor and lots of amps. Are you sure this is the way you want to go?

by mikerogerswsm
February 12, 2018

As long as it can be controlled by the raspberry pi in python programming language that is all I care about.

by basviccc
February 12, 2018

There's none so blind as those who won't see.

by mikerogerswsm
February 12, 2018
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