To hold the centerline on the workpiece will help the device shown in the figure.
Recommend to read
MICROPHONE OUT OF SCRAP MATERIALS
It is not difficult to do even the novice hobbyist. And materials needed for this available. The basis of design — a primer of domestic microphone MD-47. The device consists of a...
LARGE IN THE SMALL
— All big things in life starts small. And it's small already in your hands. Because you see a little further and a little deeper than your peers. Do not forget that in any work the main...