
Before continuing, ensure that everything is disconnected from your main power source. Remove the clip cord, to be doubly sure. Make sure that when tuning the tattoo machine, the armature bar needs to be held down to set the gapping between the contact screw and the front spring. Doing this will give you the gapping you are looking for. Setting the machine for finer, detailed line work usually requires about a dime sized gap. For shading, you want the gap between the front spring and contact screw on the tattoo machine to be about a nickel's breadth apart.
When you've set the gapping to the setting you need, reconnect everything to check your work. Secure the contact screw to the locking device. Attach the clip cord to the power source and the tattoo machine. Plug the foot pedal to the power source, as well. Remember to keep your workstation as sterile as possible, following the laws and policies governing your profession and the shop.
This can be quite tricky at first, as you have to make the changes on the fly, while working with a client. If everything went right, your tattoo machine should be tuned and ready!