The shop owner Mr. Jude Reveley located where the bridge pins shall be according to string locations, speaking length, and spacing. Mark bridge pins with customized punch. Set drill bit to go in deep enough but leaving 5mm space for bridge pins to stay out of bridge surface.
The drilling jig is set at a 17 degree angle. When drilling, make sure the bubble is always staying in the middle of mini level. The front and back row of pins go in at different direction. Double check the direction before drilling.
After drilling, sand bridge top with sanding blocks from 150 to 400 grid. Apply graphite (process pictures not shown), notch off wood outside of bridge pin holes (process pictures not shown), then install bridge pins.