If the outside of the scale is flat and in line with the center line (on same plane) I put it on my drill press table after drawing the tang outline. I chuck a small mill head (from a Dremel tool actually) and set the depth stop for 1/2 the thickness of the tang. If the tang is tapered, I block up the front of the block with a paper/cardboard shim so it cuts a bit deeper there.
Pretty crude, I know, but for someone like me who works in 1/16ths instead of 1/10,000s like some of the guys on here, it gets the job done.