I fit one scale, clamp and drill through the tang. Insert the pins on one side. Fit the other scale and clamp. Remove pins one at a time, drill and replace pins through both scales. With a friction fit I rough shape the handle. When I'm close all around I remove the scales and pin them together to true them up on the sharp end.

I then epoxy the scales and pins in place. When the epoxy is set I do the final shape and poish. Depending on the material, I may use pins, cutler's pins (threaded), or just epoxy. As this is a knife that will see some heavy work I elected to pin it. On large full tang knives I always use cutler's pins.

I have an aircraft rivet gun. I just filed these pins down and finished them with the the gun and a die. This isn't a required step. On smooth finished knives you smooth and polish everything.