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Newbie question, but I'd like to know what would be a way to connect a 20 mm auger drill to a standard stepper motor (12v).

enter image description here (from here)

I'd like to try out a pet food dispenser project that involves the use of these two, but I'm trying to figure out a way to connect them. The motor will then be controlled by a microcontroller for rotation. The torque required if it was ok to use these parts would be enough to drive the pet food kernels into a hole (output) using the auger drill.

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    \$\begingroup\$ Details, please: What is your project you have in mind? What is the datasheet for your stepper ("standard 12V stepper" tells us more about your knowledge level than the motor)? \$\endgroup\$
    – dpdt
    Aug 24 '16 at 3:46
  • \$\begingroup\$ Apart from the probability that any stepper motor is the wrong choice for this, a "12v" stepper is typically one with a high inductance winding which means it will have very low torque when turning at more than slow speed. \$\endgroup\$ Aug 24 '16 at 4:42
  • \$\begingroup\$ Why do you think this has anything to do with electronics design, electrical engineering, or anything remotely related? \$\endgroup\$
    – pipe
    Aug 24 '16 at 7:24
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    \$\begingroup\$ I'm trying to do a pet food dispenser that uses the auger bit to be driven by the motor. I'm trying to see if using the auger drill to connect with the stepper motor is feasible. I wouldn't need that much torque, I think, because the concept is that the auger drill would push out the dog food through a hole. So, just enough torque to rotate the drill, I would say. As for the motor, I dont have specs yet and depending on the recommendations, I will look into that soon. \$\endgroup\$ Aug 24 '16 at 18:14
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    \$\begingroup\$ Connecting two shafts together is at best a mechanical design question. Have you looked at the usual sources for such parts, such as McMaster-Carr? \$\endgroup\$
    – Dave Tweed
    Aug 24 '16 at 19:23
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NO!

Driving a drill bit with a stepper is a bad idea. Steppers are built for very precise positioning, NOT torque. The instant you try to drill into anything with a stepper, the stepper will stall.

If you have that stepper, try running it and stopping the shaft with your fingers (or a pair of pliers, if your motor is strong enough) and compare its torque to that needed to drill into wood.

Perhaps a better idea for your project would be a regular motor running that drill bit, and a stepper controlling the position of that bit (but I'm guessing here - we need to know what your project is), like this: https://en.wikipedia.org/wiki/CNC_wood_router

EDIT

Ok, I see what you are doing now. A stepper isn't such a disastrous choice as I thought - it may be able to move the food, unless a piece gets stuck. With such low torque, probably just duct tape will work.

However, remember that steppers are designed for very precise positioning. A DC gearmotor, like in the video, is almost certainly a better choice. Steppers introduce added complexity.

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    \$\begingroup\$ Indeed. It's possibly they are using the auger drill bit for something else, such as a feed auger for moving material, but still a stepper motor is probably not the right choice. \$\endgroup\$ Aug 24 '16 at 4:32
  • \$\begingroup\$ @ChrisStratton Look at the link - looks like a wood drill bit to me. \$\endgroup\$
    – dpdt
    Aug 24 '16 at 4:47
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    \$\begingroup\$ It's sold as a wood drill bit, yes, but I could see someone trying to use it to move plastic pellets through a tube or something like that. Hardware stores are where engineers wander around looking for things to creatively re-purpose... \$\endgroup\$ Aug 24 '16 at 4:52
  • \$\begingroup\$ Thanks for this info guys! I'm actually trying to do one of those pet food dispenser projects. Here's a link from youtube where I saw this particular project that I would like to try out. youtube.com/watch?v=ubpAXMBY5KM \$\endgroup\$ Aug 24 '16 at 17:56
  • \$\begingroup\$ If you were able to watch the link, he was using something called a gear motor and using a coupling, I think, to connect the drill to it. But I'm not that familar with with these types of projects so I'm trying to gauge out some measurements first to reduce costs. \$\endgroup\$ Aug 24 '16 at 18:00

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