String Design

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

BALL-END STRINGS

Brought to you by ProfessorString.com

 

One of the most overlooked components, in terms of guitar, is the ball end of a string. The concept of a string’s ball-end is simple. Its purpose is to anchor the string to the body, bridge or neck of the instrument. Are all ball-ends created equal? At a glance they all look alike, but they are not. Let's take a look...

Perhaps the most common ball-end has a barrel shape with a groove in the center. They are often made of brass.

  There has been a series of manufacturers who have used stainless steel ball-ends, or chrome plated ball-ends. The purpose of this is more cosmetic, than functional. In some instances, this can be a cost reduction for string companies. The cost of raw materials such as steel, brass, and copper has sky rocketed in recent years. This has been due to world market demands created by many countries continuing to enter the market in manufacturing and free trade. The trend is likely to continue.
As an effort to eliminate the "loop" commonly found on ball-ends, the bullet shape gained popularity amongst tremolo bridge users. The loop often contributed to tuning issues. The bullet shape was a break through in traditional thinking about string termination. It eliminated many of the issues with the ball-end loop. The selection of strings with this type of termination is still fairly limited on the market.   In more recent years, manufacturers have powder coated and painted the ball-ends. This allows for various color coding schemes. In some cases, this enables brand recognition for string manufacturers. Notice the inside of the barrel is lacking pigment as it is difficult to get full coverage into the barrel. This is purely a cosmetic issue, and has no effect on the string’s performance.

 

Sloppy workmanship, poor tooling, and cheap materials are apparent in this unrefined ball-end. This is how the ball-end looked, brand new, out of the package. This was part of a free set of strings a major guitar retailer was giving away. This particular string was made in Korea. String sets given away for store promotions will have this type of low quality ball-end. When we checked the material hardness of the brass ball-end, we found it to be considerably softer than most other ball-ends we checked. Notice the wrap termination was not secured. Upon further examination under the microscope, we found the outer wrap-end to be "pinched" off rather than a clean sliced cut. This is an indication of a dull, or worn cutter needing replaced or sharpened. Everything about this string screamed cheap and low-buck.

 

This string is brand new, and demonstrates another ball-end loop with poor workmanship. The ball-end is contoured brass that has been nicely powder coated black. This is a string that was made in the USA by a very well known string company. Notice the excess string winding resting against the ball-end. This is perhaps one of the worst types of errors in terminating the outer winding. In this case, the ball-end potentially will never seat properly in the bridge due to the excess winding being in the way. As a result, the string may not stay in tune properly. In short, this string should have been rejected at the factory. Unfortunately, we have found many string companies are not inspecting for this type of error.

 

This ball-end is from a string set made in China. It is a low grade brass that allows for ultra low cost strings. Although we found this particular string to have other issues, the twist in the loop is fairly tight and well done. This makes it friendly to bridges with narrow string channels.

As you can see there are many differences in the ball-end. What does a ball-end accomplish in terms of tone and playability? The answers can vary as there are many things, bridge related, to the performance of a ball-end. The first place to look is the loop and twist.

 

Loop Patterns

The loop is the portion of string where the wire has been looped back onto itself and “twisted” around the ball-end. The loop pattern has always been a point taken for granted by the majority of musicians. Many glance at the twist and visually acknowledge whether or not there is enough wrap to hold the ball-end in place while the string is under tuning tension. Take a look at the two twists below. Notice how the Loop Pattern 1 on the left is tighter than Loop Pattern 2 on the right. In Loop Pattern 3, there is no loop. The ball-end loop has been eliminated in this particular design. Depending on the bridge or tailpiece design, the ball-end loop will have a profound effect on tuning.

 

Loop Pattern 1

Loop Pattern 2

 

 

Loop Pattern 3

 Spring Effect

As previously mentioned, the loop can have a profound effect on tuning. Some bridge/tailpiece designs require the ball-end and twist to be completely cut off. Such tailpieces eliminate the issues found with ball-ends and loops. The majority of tailpieces and bridges on the market utilize the ball-end and loop. When dealing with a loop such as Loop Pattern 2 (above), there is a drawback to having excessive tangential slack in the loop. To illustrate how the loop effects tuning, we are going to examine one particular scenario we call the "Spring Effect" in the loop.

 

Figure 1

 

In this illustration we are seeing a cross sectional view of the bridge or tailpiece. We are also seeing a properly seated ball-end. The ball is resting on the bridge as it is under tension. Notice how the string loop is not in contact with anything on the bridge. The loop is isolated via suspension from the instrument. In effect, the loop and string are floating.

Figure 2

 

In this illustration, again we are seeing a cross sectional view of the bridge or tailpiece. In this design, the string channel is much narrower. The loop is about to touch the bridge, before full tension is reached. In this situation, the loop is not going to be floating.

Figure 3

 

As the string is tensioned to a tuned state, the loop begins to compress. The compressing of the loop makes the ball-end want to spring back against the string. We call this the Spring Effect. It effects the tuning of the string.

Figure 4

Once the string is fully tuned, the ball seats against the bridge. At the same time, the loop retains its Spring Effect. In some cases the Spring Effect is so strong; the ball never anchors to the bridge.

 

Results

In the figure Loop 1, below shows a brand new string with a fairly loose ball-end loop. This is a string from a company with a very well known brand in the industry. The core string has good uniformity in its shape. In addition, you can see the normal extrusion marks, or lines, from when it was drawn into the proper gauge diameter and hex shape. In Loop 2, the same exact string was installed on a guitar. The guitar had a tailpiece bridge with narrow string channels. As you can see, there were dig marks created on the core string from the Spring Effect. In fact, a small tiny metal burr has developed on the string. The marks are created by the bridge digging into the ball-end loop. This occurs once the string has been tightened to tuning tension. Additional micro-movement by a string being bent or stretched can create deeper marks potentially creating a stress point that can cause the string to eventually break at the loop. Aside from poorly twisted ball-end loops, bridges and tailpieces that have narrow string channels, without good chamfering and port holes, some string brands are notorious for causing the Spring Effect. If you are interested in knowing how to diagnose this problem, and finding the right strings without the potential Spring Effect problem, check out Professor String's new eBook.

 

Loop 1

Loop 2

 

Thanks to our friends at Professorstring.com for letting us share this information with you. Please visit professorstring.com for more information on string design.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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