Truss Rod Routing

[Sevan]

Hey guys, I'm about to route my first truss rod channel and I have a question. I have found no connection as to when one would leave a gap between the channel and the truss rod access. I have seen both straight and angled headstocks with both a gap and routed straight through. What is the benefit of implementing the gap? 

[curtisa]

I'm not sure what you mean by 'a gap' Do you mean this:

Compared to this?:

[Sevan]

That's it.

[mistermikev]

the way I see it... this gap has to be there and a compression rod style truss rod... as the idea is it has to have wood to compress against... but I put that there on a two way rod because I feel it is better to have as little air space around the truss as possible.  I also like the idea that even that small of a piece of wood will reinforce the neck there to some degree so... for those reasons I either drill out to leave that wood or sometimes rout out and then glue a small piece of wood in there.  I want it secured in that channel as much as possible.  I believe some leave it out because of two main reasons: 1 it's easier and 2 in theory you could potentially remove the rod if there is ever an issue.  I don't think there is anything  wrong with either.  ymmv

[Bizman62]

It also depends on the type of the truss rod. A dual action rod doesn't require any support at the end whilst a single action one works by pushing against the end of the neck. Then again the actual channels of the two are different in shape, for single action rods (upper) the entire neck supports the adjusting nut so it actually doesn't matter whether there's a gap or not - other than if you have a bell shaped cover with a screw hole at both ends the gap is needed.