Was just looking over 5 of my cbgs that I built for myself over the last couple of years and noticed the necks have all started to bow. The necks are all thru the box oak with poplar fret boards and they are strung with light to medium gage strings. I use 1x3 oak and they are all 3 string. Wondering if cutting a slot down the middle of the neck and inserting a piece of flat steel would stiffen the neck and prevent bowing. Anyone tried this? Any thoughts?