It's a long rod lodged up in the neck of a guitar used for keeping the neck of the guitar straight.
The truss rod is used to allow the neck to bend either way in response to the tension of the strings. Without it, there would be no steel string Guitars, the neck wouldn't be able to handle the tension of the strings. Many beginners think that adjusting the truss rod will lower the "action" or how high the strings are from the fret board of the guitar. This is not entirely true and it is probably more of a Nut and saddle/bridge adjustment that is needed.
No, they do not require a truss rod. Some of the Banjoleles have them installed, but they aren't required.
No. Some less expensive guitars do not have truss rods in their necks. Any guitar that is more than a toy should have a truss rod, with out the truss rod if your guitar got into some moisture and the neck bowed,you would not be able to straighten the neck out.
You can't!
In short you can do, but it's a very lengthly process and will cost you a fair bit of cash. Usually the way to do it (assuming your neck is deep enough to accommodate the truss rod) is to remove the fretboard, then route a channel down the centre of the neck under the board, install the rod with the adjustment nut at the headstock end, then reglue the fretboard. Though TRUSS me, it's a lot harder than I made it sound just then! I'd recommend taking it to your local repair place to get a quote and don't try it yourself unless you're a master router. If the problem you're trying to fix with a truss rod is that you're guitar neck is slightly warped, then a slightly easier option would be to get the frets out, plane/sand the fretboard level and then get it re-fretted.
A guitar's truss rod is a long metal rod that runs from the body of the guitar along the back of the guitar's neck all the way to the headstock. It's purpose is to provide strength to the guitar neck against the extreme tension of all the guitar strings. Also, without the stability provided by truss rods, guitar necks would have to be made from much harder and stronger woods to take the tension of the strings, which would in turn raise costs significantly. The use of a truss rod allows manufacturers to make guitar necks out of much softer woods or composite materials. It is also a means to stabilize and adjust the relief of the guitar neck (forward curve).
The recommended truss rod allen key size for adjusting the truss rod on a guitar is usually 1/8 inch or 3mm.
There is no real answer, as anyone could make a new kind of truss rod, for example a licorice truss rod. Perhaps you mean that a truss rod could be under stress or under compression, or be designed for both.
To loosen the truss rod, turn it counterclockwise.
To determine which way tightens the truss rod in a guitar, turn the truss rod wrench clockwise to tighten and counterclockwise to loosen.
Your truss rod may not be tightening anymore due to a potential issue with the truss rod itself, such as being stripped or damaged. It could also be caused by excessive tension already on the rod, or the nut may be worn out. It's important to have a professional inspect and repair the truss rod to prevent further damage to your guitar.
Is the truss rod loose in your guitar and making the neck unstable?
You should use a 4mm allen key to adjust the truss rod.
To properly tighten the truss rod on your guitar to adjust the neck relief, use a truss rod wrench to turn the truss rod clockwise. Make small adjustments, about a quarter turn at a time, and check the neck relief by pressing down on the first and last frets. The goal is to achieve a slight bow in the neck for optimal playability. Be careful not to over-tighten the truss rod, as this can damage the neck.
To properly tighten the truss rod, use a truss rod wrench to turn the rod clockwise to increase tension and straighten the neck of the guitar. Be sure to make small adjustments and check the neck's curvature as you go to avoid over-tightening.
To determine if the truss rod in your guitar is broken, you can visually inspect the neck for any unusual bending or warping. You can also try adjusting the truss rod to see if it responds properly. If the neck remains bowed or twisted after adjustments, it may indicate a broken truss rod. It is recommended to consult a professional guitar technician for a more accurate assessment.
You should use a 4mm allen wrench to adjust the guitar truss rod.
To adjust the truss rod on your guitar, use an appropriate tool to turn the truss rod nut clockwise to tighten and counter-clockwise to loosen. Tightening the truss rod straightens the neck, reducing relief, while loosening it allows the neck to curve slightly, increasing relief. It's important to make small adjustments and let the neck settle before making further changes.