On the What's On Your Workbench tread there is a discussion on truss rods. Although not normally required on a 3-4 string CBG [if the neck material and dimensions are suitable] there are times when one could be of benefit. As Tom says in the discussion he would fit one as he uses heavy gauge strings, and of course with a six string a rod is the norm.
Any way, photo's should tell the story. I'll admit its not my idea I got it from Cumpiano's book back in 1989. My first choice is factory double action rods, but I still use this design for some builds.
You can see the amount of adjustment is available in the completed rod photo, of course it would be bending down away from the pull of the strings. The black rubber spacers were applied to restrict vibration it the channel, but not required with a good tight fit.
I cold bend the rod and then hammer the two legs tightly together at the bend.
You may never need a rod but if you do you know how, and its in the spirit of DIY.
Cheers Taff
Replies
Cool .,thanks for posting., I too have the book that shows how to do this as part of an acoustic guitar build.,.,you could certainly put a serious back bow on a neck using this.,.,
Good pics to help visualize the results.
Sorry my mistake it was ILL Green that commented on heavy strings.
Taff