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Stepper driving leadscrew
#1
Hi all, Chris here from Bowling Green, Ky.    Restoring a Rhodes 28' sailboat (tiller) and plan to singlehand a lot.  I'm primarily an electronics guy, but have a small home machine shop.

I've been talked out of the tiller pilots and similar, hearing serious reliability issues.  I have a 5/8" stainless leadscrew, and a bronze bearing.   I'm wondering if anyone has driven this kind of thing with a nema 23 size stepper using a commercial stepper driver?  Would I need an additional arduino to glue the driver to the autopilot's output?  A stepper may not be ideal, but I'm not sure I like a standard brushed motor with gearbox in a marine environment ...
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#2
(11-09-2019, 12:30 PM)trebleplink Wrote: Hi all, Chris here from Bowling Green, Ky.    Restoring a Rhodes 28' sailboat (tiller) and plan to singlehand a lot.  I'm primarily an electronics guy, but have a small home machine shop.

I've been talked out of the tiller pilots and similar, hearing serious reliability issues.  I have a 5/8" stainless
These break usually for:
1) stripped gears/belts broken belts
2) water in electronics

If you keep the electronics below and dry it will solve #2. The motor controller in pypilot has protection from stalling, and soft start which helps a lot with #1 but can still happen with the wrong settings.

Quote: leadscrew, and a bronze bearing.   I'm wondering if anyone has driven this kind of thing with a nema 23 size stepper using a commercial stepper driver?  Would I need an additional arduino to glue the driver to the autopilot's output?  A stepper may not be ideal, but I'm not sure I like a standard brushed motor with gearbox in a marine environment ...

The cheap tiller pilots use this. The better ones use ball screws. Usually there is a brushed dc motor and belt or gear to the lead screw rather than a stepper motor.

If the stepper motor has enough torque (not sure about nema23 if it's enough) it could go directly with a coupling, but then you would need to modify the motor controller sketch to drive a stepper motor.

brushed dc motors are better for this application unless you have a closed loop stepper controller. They are good enough for autopilots and don't require an extra sensor like the alternatives.

A more efficient alternative is to use a brushless motor with sufficient torque to drive a ball screw directly. It should also have angular sensor on the shaft.
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