We'd like to know some parameters or design targets for your system. Do you currently have a motor? What does the pot do? Thanks for providing the link, but let's keep it optional, please post all the info here.
Some initial questions I would ask:
RPMs?
traverse mechanism geared or servo/stepper driven?
Just to verify that I understand what this does, it sounds analogous to a bait casting reel in the sense that it has a brake and a "drag" adjustment and the traverse is like the gadget on a fishing reel that creates the smooth layers of line. Correct?
So a guitar pickup needs between 7000 and 1000 wraps depending on the the tonal qualities you want. The reason to use an arduino is to count, but the motor has to be able to spin 6 - 8 magnets mounted on a bobbin and 7000-1000 wraps of 22-42 awg wire.
you need to be able to adjust the speed, and for the wrap, you want a random scatter that is done by hand. I need a pickup winder for building guitars, but I thought this would also be a good starting point for dipping my toes into making 3d-printer / engraver.
Motor speed adjustment you can buy off the shelf. For rotation count, most setups use a reflective dot on the spindle, and an optical sensor to detect that for counting pulses.
I was thinking a max rpm of 1000 but mostly keep it between 400 and 600 rpm . maybe I don't need a high torque motor.
I thought the pot was for speed control? as for the reflective dot, would I use a photo-resistor and a npn transistor to detect and amplify it in the circuit someplace?
Photo resistors are too slow for that, a phototransistor or photodiode is the way. You can get an integrated sensor that includes IR LED and IR phototransistor.
Having built a coil winder, but not nearly the number of turns you are planning on. There are three important things you need to consider before beginning.
How will you attach the wire to the form before the actual winding begins?
How will you handle the situation when you MUST stop the process during the winding?
How will you attach the wire to the form when the winding has completed.
In all cases, do you need to firmly hold the form in position or do you need to make it freely turn?