Top bulge and string gauge

[dropt]

I am wanting to lower the action a bit on my dreadnaught. But I am also considering changing from medium to light gauge strings.

I know a truss rod adjustment will be required after changing the string gauge. But will the top bulge diminish much (and the action decrease) when going to the lighter string gauge?

[redir]

Originally Posted by dropt

I am wanting to lower the action a bit on my dreadnaught. But I am also considering changing from medium to light gauge strings.

I know a truss rod adjustment will be required after changing the string gauge. But will the top bulge diminish much (and the action decrease) when going to the lighter string gauge?

Only one way to find out

In some cases yes, in others no. Top bulge BTW is typically not a problem and in fact can be indicative of a responsive guitar IMHO. But if you are concerned about it pics with a straight edge across it would help. Top buldge becomes a problem when it starts to loosen the bridge and or cave in the sound hole area.

[John Arnold]

The standard measurement for top belly:
Put a straightedge on the top crossways next to the lower side of the bridge. Measure from the straightedge to the outer edge of the guitar on both sides. Add the two measurements together. If the total is less than 1/2", the belly is acceptable.
The belly may or may not be reduced by changing to light gauge strings. For example, if the belly was caused by overheating the guitar, the top may have taken a 'set'. That means it is unlikely to be reduced unless repairs are done to the guitar.

[mirwa]

Originally Posted by dropt

I am wanting to lower the action a bit on my dreadnaught. But I am also considering changing from medium to light gauge strings.

I know a truss rod adjustment will be required after changing the string gauge. But will the top bulge diminish much (and the action decrease) when going to the lighter string gauge?

I have a simple way of measuring the bridge rotation, same can be achieved with your mobile phone and an angle app and some blue tac to hold your phone steady.

If bridge rotation is greater than 1.5 degrees, from detuned to tuned, then consider having a luthier look at it to see if you have any brace issues that can be rectified before it becomes too bad.

If the top is already deformed (as John puts it - heat set) then bridge rotation may be good, but starting and finishing points of rotation are unfavourable, so likely you may need the bridge removed and the top steamed flat again to get a lower action



Steve

[JDaniel]

Originally Posted by mirwa

I have a simple way of measuring the bridge rotation, same can be achieved with your mobile phone and an angle app and some blue tac to hold your phone steady.

If bridge rotation is greater than 1.5 degrees, from detuned to tuned...]

Steve

Very clever idea, Steve. Thank you! I had just discovered that my phone has that capability this past weekend.