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### Topic: 8 turns (???) Beginner needs help. (Read 452 times)previous topic - next topic

#### projecteinsteinvr

##### Jan 14, 2018, 05:38 am
Hello and thank you.

I am not even sure where to post this.  I need to turn a screw or knob 8 times (8 x 360 degrees).  The knob has very little drag or resistance and I only need to be accurate to plus or minus 30 degrees.  I must keep track of the knob's position.

An stepper motor only does one 360 correct?  A continuous rotation servo will not keep track of it's position.  Not sure how to proceed.

Thank you again.

#### projecteinsteinvr

#1
##### Jan 14, 2018, 05:57 am
How about a continuous turn servo hooked up to a 10 turn pot???

#### outsider

#2
##### Jan 14, 2018, 09:28 am
A stepper motor can turn as many revolutions as you want (until it wears out), if the motor is a 200 step per rev, send it 1600 steps for 8 revs.

#### slipstick

#3
##### Jan 14, 2018, 10:41 am
Or you could get a sail winch servo that does 8 turns under full positional control. E.g. https://www.servocity.com/hs-785hb-servo But they are usually fairly big and expensive.

But check the specifications carefully because not all winch servos can do a full 8 turns.

Steve

#### Robin2

#4
##### Jan 14, 2018, 11:04 amLast Edit: Jan 14, 2018, 11:06 am by Robin2
Linking Replies #1 and #3 maybe a sail-winch servo that can do 3 turns linked to 1:3 gearing would work.

If it works it would be much simpler than a stepper motor because stepper motors don't know where they are unless you have code to move the motor to trigger a limit-switch to identify the zero or home position and then count all your steps from that point.

If you are competent and like tinkering with things you could possibly replace the function of the internal potentiometer within a regular servo with a multi-turn potentiometer connected to your knob.

...R
Stepper Motor Basics
Simple Stepper Code
Two or three hours spent thinking and reading documentation solves most programming problems.

#### projecteinsteinvr

#5
##### Jan 14, 2018, 08:27 pm
you guys are the best and thank you so much.  What help!!!!!!
anybody know Unity, Processing and wants a job???

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