Servo Motor Sensitivity

hello everyone,

My project is xy plotter with servo motors and i build it based on that page: www.instructables.com/id/Simple-Arduino-XY-Plotter/

But i have that problem where arduino code calculates the right angles and sends them to servos but servos' sensitivities are seem like not enough to move when angles are so close between each other. So to simplify the situation here's the step by step expression.

  • Arduino code calculates the angles based on coordinates (it's %100 right because i tested it A LOT)

  • Sends them to exact servos (no problem either)

  • When angles are between 80 and 90 degrees, it doesnt move even a little bit. But when angles are between 60 and 70 degrees, it moves a little for each angle as it should.

So to sum it all, sometimes they move like they should be to exact location, but sometimes they dont move at all.

I'm using tower pro mg995 servo for each arm, pen servo is not relevant or important for that matter.

So here's what i'm thinking

  • My servos are not sensitive and couldnt move between spesific angles
  • My servos are not digital so it can be a part of the problem (analog servos might be less sensitive)

So if the problem is servos not being sensitive, i'm thinking about buying these motors.
http://www.banggood.com/Power-HD-LF-20MG-20KG-Torque-Digital-Servo-for-RC-Robot-p-1037365.html

What do you think about causing the problem, what could it be based on your experiences?

Should i buy these servos, are they enough for the sensitivity that i want?

That project uses two stepper motors for the position control, and a servo for the pen. There
are no servomotors.

MarkT:
That project uses two stepper motors for the position control, and a servo for the pen. There
are no servomotors.

I have to use servomotors because my lesson's project and my project xy plotter with servos, not stepper motors.

You know the difference between a hobby servo (servomechanism) and a servomotor?
You know a "continuous rotation servo" isn't servo at all, its just a DC motor with a controller.

Please be precise about what you are wanting to use - partnumbers, datasheets, etc.

You cannot use continuous-rotation servo alone for a postioning system.

my servos are not contunious rotation servo..they are 0-180 rotate standart rc servo...

So I don't understand how you can operate a belt-driven XY positioning system! Is your
design rather different then? If so it would have helped to describe it rather than link to
something very different.