Under deployment give 0.05-0.1 mm in diameter.
Sharpened drill on a modern machine gives 0.05-0.10 increase in the diameter of the hole. And with coolant it is necessary to deploy. The essence of the deployment is uniform removal of stock from the bore for highest accuracy and surface finish of the hole.

it Should be noted that the scan goes deeper into the hole, bodies better it is centered. But shallow holes get aboutSTO ugly, especially in soft material.

I’m in the aluminum to put a hole in the piston under your finger. the diameter of the drill bit 12 11.8 took. 11.5 if it was already heavy. 11.8 came out perfectly. Moreover, the increase in precision deployment occurs when reducing back taper, increasing the heating of the tool. Therefore, to increase the accuracy of the obtained holes, you need to take the scan with most lower back and taper to handle at minimum speed with maximum pressure.