Dual action truss rod install

**thistle3585** · Jul-15-2021, 10:02am

I am looking for help on installing a dual action truss rod on a 14.5" scale set neck in an electric mandolin. It joins at the body at the 15th fret then there is a 2" long pocket. I can't find any dual action truss rods that are the correct length, so I'm wondering if I can use a standard mandolin truss rod which is 3/4" shorter than if I made my own single action rod? Where does the "action" of the truss rod need to be placed? Would it be the center of the fretboard or the center of the neck that extends beyond the neck pocket?

In the photo, the red line represents my current homemade single action truss rod location and the green shows the location if I used a standard mandolin dual action truss rod. Do you think the standard, mandolin sized rod would work?

**sunburst** · Jul-15-2021, 10:46am

I'm, not sure I fully understand the question, but...
The rod only needs to, and only can affect the length of neck that is not attached to the body so a standard length truss rod will be as effective as it's design and installation will allow, if it is positioned like your green line. The center of the neck is the proper placement. I'm not sure what the result would be if it was placed to the side like your red line but I would suspect the possibility of uneven bow if the rod needs to be adjusted near it's extremes of effectiveness.

**j. condino** · Jul-15-2021, 11:47am

For years I used most of the commercially available dual action truss rods, with mixed results. The mass and weight always bothered me. After about 20 years of that, I was having a conversation with a well known old timer and he casually looks over at me and said, "Just install your single action rod and give it a few turns before you install the fingerboard. Level flat, glue on the 'board, and now you have a lightweight dual action rod...."

I fabricate all of mine from titanium. I like the snappy response compared to steel and the weight saving is huge.

**pops1** · Jul-15-2021, 11:48am

John, I think the lines represent length only and not position. Still the green rod is plenty long, and of course as John says it should be in the middle, but I think you know that.

**thistle3585** · Jul-15-2021, 11:52am

John,
Obviously, I didn't explain it right. Its not that I'm putting rods off center in the neck. The two colored lines represent the length of the truss rod in comparison to the length of the neck. It would be installed along the centerline. I just didn't know what the ideal length would be with this kind of neck construction.

James,
I agree and I've always done a single action as described but am routinely getting requests for dual action rods because people want adjustability even though I doubt they've ever adjusted a truss rod.

**sunburst** · Jul-15-2021, 11:58am

I thought that was probably the case, but as I was once advised when writing copy for my website; "assume nothing".
If you buy a standard Martin guitar truss rod these days it will probably be much shorter than the neck. Many rods don't extend toward the peghead past the first fret, and as long as they get reasonably close to the neck heel they work fine. In other words, the length of the green line is plenty long. (Making the adjustment accessible is another thing.)

**John Bertotti** · Jul-17-2021, 7:23am

Do you make your own titanium rod?

**j. condino** · Jul-17-2021, 12:13pm

Well... I don't forge the raw materials. I buy commercially available rod stock & then thread, mill & manipulate it into all of the specs I want. 'Been doing that for about six + years now and will not go back, regardless of the extra work. It has been discussed many times here.

Here are a few old photos that were in my profile folder; guitar rods, but you get the idea: