Trust Rod Fitting

Now is the time to fit the truss rod (or trust rod, which I feel is more apt, as I am really hoping it is going to work!). The aluminium anchor piece needs to sit under the fboard near the headstock. A hole was chiselled out for it carefully. I have to remember that the neck will be shaped later, and that getting carried away with chiselling could result in a weak end, which is the sort of thing to be avoided at all costs.

The anchor piece slots in OK.

The same sort of thing was done for the adjustment end. This one had to be done even more carefully as it will be visible after the fboard is stuck on. A couple of 30mm screws hold in the nylon bearing block. This had to be penned black as it too will be just about visible. The trust rod was covered with some 6mm heatshrink sleeving and a little oil before it was commited into the chamber of doom, er, the truss rod channel.

Everything was checked & double checked and then it was time to fit the wooden fillet that has a curve that matches that of the (chamber of doom) channel. Lots of glue and clamps as per usual.

Put to one side and allow to dry - and here's one I made earlier. Aaah a Blue Peter dream sequence!

When the glue had dried, I cautiously wound up the tension, looking for a bit of backwards curving. Disaster! As I wound the tension up, the neck started to show a small amount of forwards bow, ie in the same way that would be caused by a set of strings.

Smeg!

Due to the amount of tension I put on the neck, the anchor piece had also started to migrate south for the winter. Whilst I puzzled over what seemed to be a loophole in the laws of physics, I thought I had better strengthen the anchor piece to neck connection with some additional blocks of wenge. This meant losing a small amount of the channel intended for the carbon stiffening rods, but this was more essential. Some M5 washers were also 'drifted' into place just to help out.

Well, here's my theory. Ahem.

The neck currently is not shaped, it has a rectangular cross section. Because of the amount of channels cut into the top, the absence of the fboard and the extra thickness and girth of the neck it is not only much stiffer than a standard neck, but the stiffness is predominantly underneath the trust rod. When the rod is tensioned, although the curved channel should cause a backbow, at the present time with the greatly increased rigidity of the material under the rod, the top of the neck is more likely to be compressed causing a forwards bow.

This seems to make sense, but I cannot do much about proving it until the neck is a lot closer to being finished (ie back coarsely shaped, fboard stuck on). This is another reason why we all have to Trust In Rod.