Ask the Expert: Modifying a Standard Flattop for Lap-Style Playing

Modifications like this can be a nice way to add some variety to a collection, bring some excitement back to an underplayed guitar, and open up fun new musical horizons. However, not all modifications end well, and some cause damage that could easily have been avoided.

In the late 1990s, I bought a guitar that was built as a prototype. It turned out to be improperly intonated, and even after sending it back to the maker it’s never sounded right. As a person with too many guitars anyway, I’ve let it languish in the closet for many years. Meanwhile, I’m regretting selling my beautiful 1935 Dobro Model 37 Squareneck a few years ago and am now thinking about converting the prototype for lap-style playing. Will I be putting the guitar at risk if I raise the nut and saddle high enough to play it with a bar?—David L.

This is a great question—and especially a great question to ask in advance. It’s quite possible to safely modify this guitar for playing with a bar, like a lap steel or square-neck resonator. It will of course have a different sound than the classic metal-bodied slide guitars, but with the right strings it should have something interesting to say. To begin, let’s take a quick look at what mods need to be made, and then we can discuss the potential pitfalls.

As mentioned in your question, the bridge and nut both need to be modified. Bar-style playing usually involves a flat plane across the strings, as opposed to the radiused arc typical of most steel-strings. Since both the nut and saddle on a standard guitar are cut to create this radiused profile, both will need to be replaced. Installing a taller nut and saddle will also raise the action, which is what you’re after.

Typical flattop guitars, especially those that are built lightly enough to sound satisfying, are designed to withstand a certain range of torque on the bridge. This torque is a function of the string tension and the overall height of the bridge and saddle—the latter create a lever that translates the linear pull of the strings into a rotational force on the top. It’s common for saddles to get cut lower and lower over time, to maintain playable action on guitars whose tops are bulging forward. Many players note the reduction in volume, power, and responsiveness when the saddle gets too low. This is because the lever action of the top is getting gradually reduced, so it is being driven less effectively by the vibrating strings. After a neck reset, which permits the reinstallation of a saddle at the proper height, these guitars wake back up quite noticeably.

By contrast, an excessively tall saddle can present more torque than the top is designed to withstand. A few potential issues could arise as a result—first and foremost, the top is more likely to bulge or distort from the extra stress. Due to this deformation, the braces are more likely to come loose or even crack, which in turn will allow the top to deform even further. Finally, it’s not uncommon to see tall saddles that have tilted forward until they crack through the front of the bridge. 

Strings for resonators tend to be gauged more heavily than typical acoustic sets, with an aggregate tension sometimes above 200 pounds (versus about 160 for a typical bronze acoustic set). For all of these reasons, I advise being moderate with adding saddle height. You can accomplish most of the change in the overall action by elevating the nut, without opening the door to these potential major issues. Raising the nut also does more to make the strings parallel to the neck along its full length, which is a standard component of a good resonator setup.

Unfortunately, elevating the nut is not without its own little risks. In the same way that a tall saddle can add torque to the top, a raised nut can cause the neck to bow forward more than it normally would—the strings have more mechanical advantage to deflect the neck. This should be easy enough to counteract if the guitar has a healthy truss rod, but it will still be worth keeping an eye on the neck to make sure it hasn’t bowed forward. The action change from forward bow won’t be as noticeable with bar-style playing as it would when playing normally, and long-term bow can become permanent if left uncorrected. The raised nut will also create a much steeper break angle from nut to tuner. You may find that the guitar becomes a bit more difficult to tune accurately, because this steep angle considerably increases the friction between the string and its slot. Making sure the nut is cut correctly, with properly sized and shaped slots, will help considerably here.

Finally, take stock of how much elevation you think you’ll need to play comfortably. Resonator guitars frequently have the strings quite high above the fretboard, but achieving a similar height on this flattop may push you close to some of the risks described above. I’d recommend keeping the overall string height as low as comfort permits for bar-style playing, and not any higher than necessary, even if this means getting accustomed to a slightly different playing feel. 

Sometime down the road, you or someone else may wish to convert this guitar back to a standard setup (keep the original nut and saddle, of course!), and it would be great to do this conversion in such a way that the guitar’s overall health will allow restoration to a normal setup.