StringBand Manager Light

© copyright: Joseph Jourdain, Josephus Harps, 2019

Latest Update
-Version 20-04-01: (meaning year-month-serial number)
-Redo string for faster data entry 
-Linear Mass string calculation included
-Resizable program window for larger display
-Spreadsheet templates for Libre Office and Exel 97-2003
-Musical notation used in porgram
-Some cosmetic details for easier usage

Overview

StringBand Manager Light is a freeware you can download to compute string characteristic for harps and other stringed instruments. . It is compiled (using QB64) for running in Windows 64 bit. It is a calculator that does single string evaluation for single strings (one at a time). You can choose either the metric or imperial unit system for your analysis. Results can only be saved to the clipboard as a screen shot or CSV for spreadsheet use. Below are two screen shots showing the calculation logarithms available, the report display and the spreasheet view using clipboard function to import data to the spreadsheet template. The link to download it is at the end of this page.

It is a light version of StringBand Manager written in the 1990’s which is still available on my website. It runs on older versions of Windows 32 bit.

 

   

 

Documentation/Tutorial

The light version of StringBand Manager “SBM” is a calculator that does single string evaluation. 

You can run many instances of the program at once so you can easily compare various calculations for the same string. It must be run on a Windows 64 bit operating system. 

You have access to all the advanced calculation methods of my earlier program SBM. There are 7 choices. For each method you will need a different set of information to give to the computer before it can process your data. Below is a summary of the data you will need to know for each one of these methods.

For monofilament strings:
1 - Find/calculate the tension of a monofilament. You need to know:
     - the note that the string will be tuned to
     - the length of the vibrating string
     - the diameter of the string 
2 - Find/calculate the Length of a monofilament string. You need to know:
     - the note that the string will be tuned to
     - the tensile strength ratio of the string in percentage
     - the diameter of the string
3 - Find/calculate the diameter of a monofilament string. You need to know:
      - the note that the string will be tuned at
      - the tension / length ratio of the string
      - the length of the vibrating string

For Core/Wrap strings:
4 - Find/calculate the tension of a wrapped string WITHOUT bedding.You need to know:
     - the note that the string will be tuned to
     - the length of the vibrating string
     - the diameter of the wrap 
     - the diameter of the core for solid core
     - the diameter and the number of fibres for a fibre core string
5 - Find/calculate the wrap diameter of a wrapped string WITHOUT bedding. You need to know:
      - the note that the string will be tuned to
      - the length of the vibrating string
      - the tension / length ratio of the string you want to have
      - the diameter of the core for solid core
      - the diameter and the number of fibres for a fibre core string

For Core/Bedding/Wrap strings:
6 - Find/calculate the tension of a wrapped string WITH bedding. You need to know:
      - same as number 4 plus
      - the effective diameter of the bedding
7 - Find/calculate the wrap diameter of a wrapped string WITH bedding. You need to know:
      - same as number 5 plus
      - the effective diameter of the bedding.

INPUT, ESCAPING, EXITING THE PROGRAM & ERROR MESSAGES

Stringband Manager Light has a multiple choice menu system. All screen displays will ask you for some inputs. There are four types of input:
1) - Choose an item from a menu
2) - Answer a question to input data
3) - Press any key to continue
4) – Exit your task. You can only exit when the screen displays the "Q = Quit" option. If you don't see that option, proceed with your session until you see one, then press the "Q" key.

All input data from the keyboard can be typed either lower case or upper case.

To exit the program, return to the main menu and press the "Q = Quit" option key for Ending the program and returning to Windows.

Error messages: 

There is one type of error message that you will see on the screen. It is: WRONG INPUT DATA: You have either pressed the wrong key or the input data is not valid. In these cases the computer will beep and you will see a message on the screen for 1 to 2 seconds, instructing you what the problem was or what to do next. JUST WAIT. You will be returned to the beginning of the task you were in before the mistake happened.

INPUT DATA:

The program is interactive and the user must provide a series of values that become data to the computer. The formats and the units used are critical to the smooth working of the program. FOLLOW INSTRUCTIONS CAREFULLY. Here is a reminder. For the Imperial unit system you will use inches in a decimal form to express diameter and length. For example, 1/2 inch is written 0.5 inch. For the Metric unit system length will be expressed in centimetres and diameter in millimeters. Note names refer to the letters of the alphabet from A to G as used by the English speaking countries (C = doh in a "fixed doh" system). The number after the letter refers to the octave. Middle C is C4 with 261.630 cycles/second. Octave above is C5, below is C3 etc. The octave number changes at C. For a sharp note you put the # between the letter and the number, (C#4 for a sharp Middle C). You can also see how  notes are characterized in the TOOLS options under Scale/Frequency table. 

Copying report to clipboard:

Results can only be saved to the clipboard as a screen shot or in CSV format for spreadsheet work. Pasting ( Ctrl+V ) should be done with a mono-space font such as “Courier New” so character spacing is constant for proper display of text. After importing the CSV data into a cell,  that cell will need to be formatted to convert the Comma Separated Value (CSV) text to columns. In your spreadsheet it may be found in the Data menu at Text to Column option. Select the comma as the separator. You will need to make your own labels for the columns. The order of the CSV data is the same as displayed on the screen. If you want to add a string number to your spreadsheet you will have to do it manually as you can import only one string a time. When selecting the copying to the clipboard options you will hear a beep telling you it is done. Paste to your application using CrtlV.

 TOOLS MENU:

Here are 5 utility programs that will help you in your decision making while designing or analyzing a string instrument. These routines are:
1 - Tensile Strength Table. Using Metric or Imperial Unit System, this tool will calculate the breaking point of any string. 
2 - Flat and Sharp Length Table. Using Metric or Imperial Unit System, this tool will calculate the shortening or lengthening of a string necessary to produce a flat or a sharp. It will calculate the sharps and flats for 45 instances evenly spaced between the two given lengths (shortest to longest strings). Use this to evaluate the position of sharping apparatus.
3 - Scale/Frequency table. This tool will display the frequency for a note series in the range of C0 to B8, C4 being Middle C. It also shows you how to enter the note into the program.
4 - Bedding Table. Using Metric or Imperial Unit System, this tool will alculate the Bedding Effective Thickness for up to 30 strands of "X" diameter for a specified core diameter. Remember that for a same number of strands of the same size but with a different core diameter you will get a different bedding effective thickness value.
 5 - Fibre diameter table. Using the Metric or Imperial Unit System, this tool will calculate the core diameter of a string made of up to 45 fibres. You specify the diameter of the fibre.

TECHNICAL INFORMATION:

Accuracy of calculation is 0.05% due to computer rounding of decimals. Numeric displays are to 3 decimal points, however the data saved and the computations are to 7 decimal points or more.  When entering input value with more than 3 decimal points the computation is done with the full value but will be displayed to the third decimals.

British units refers to Imperial units

Use the period (.) as the decimal place indicator and not the comma (,) as some countries do.

REFERENCE TO MATERIAL SELECTION: 

MATERIAL CHARACTERISTICS USED IN THE PROGRAM:

Name: Density Lb/in2; Kg/cm2;
Nylon* 1.067 44600 3135.674
Fibre* 1.140 52000 3655.943
Gut 1.300 52000 3655.943
Steel 7.830 325000 22849.643
Bronze 8.870 125000 8788.324
Brass 8.437 110000 7733.725
Copper 8.930 61000 4288.702
Silver 10.474 41000 2882.570
Aluminum 2.700 20400 1434.255

The 2 left columns refer to tensile strength. 
* Nylon refers to Tynex from Dupont Corp. which is different from nylon guitar strings.
* Fibre refers to synthetic silk (nylon)
- Steel refers to piano string
- For metals the value used should be checked to the sample you have, values here are for pure or traditional alloys. Tensile strength for silver and aluminum are theoretical. 

The Material selection has a user defined material option where you can input your own material. You need to give a different name than the ones above, know its density and tensile strength. For wrap material the tensile strength reference is not used so it does not need to be accurate.

 BASIC STRINGING TUTORIAL

This basic tutorial should give you a basic understanding of the processes that are involved in stringing an instrument. With the help of Stringband Manager your tasks are reduced to thinking about stringing instead of being bogged down by the complexity and tediousness of the mathematics. However, to take full advantage of Stringband Manager your conceptual understanding of string instruments must be sharp. Let's review the fundamental law that masterminds all string instruments:

Here are the definitions used throughout our mathematical analysis. They are :

- BREAKING POINT = tension at which a string under stress will break. For example a nylon string of 0.05" diameter will break at 87.572 lb of stress.

- TENSILE STRENGTH RATIO: This is the ratio of the string tension to the maximum load capacity (breaking point) of the string. For example the same nylon string of 0.05"diameter whose tension is 30.917 lb and breaks at 87.6Lb load,  has a tensile strength ratio of 35.305 percent.

- TENSION/LENGTH RATIO = the value when the tension is divided by the length.

- IMPEDANCE = sqrt(mass * tension) or the measure of how much force must be applied to create a vibrational velocity. In other words a greater mass and a greater tension will give a greater impedance; a thick string has a larger impedance than a thin one.  This value, like the Tension / Length Ratio help us to compare one string to another.

- BEDDING EFFECTIVE THICKNESS:  String bedding is the material that is sometimes put between the wrap and the core of a string in order to maintain the flexibility of the string while increasing its mass. Effective thickness is the value by which a string has its overall diameter increased due to the bedding. For example a string with an overall diameter of 0.07", a core diameter of .03" and a wrap diameter of 0.01, has a bedding of 0.02". [0.07-0.03-(2*0.01)=0.02]. Remember that for a same number of strands using a different core diameter will give you a different bedding effective thickness value. As the core diameter increases it will take more strands to increase the overall diameter by the same amount than it will on a smaller core.

- FIBRE CORE DIAMETER = Sometimes the core material of a wrapped string is made of fibre. Therefore, the core diameter needs to be calculated. The number and size of the fibre used determine the core diameter of the string.

One more thing to remember throughout your string evaluation is the format used in the input and output data. For the Imperial unit system you will use inches in a decimal form to express diameter and length. For example 1/2 inch is written 0.5 inch. For the Metric unit system length will be expressed in centimetres and diameter in millimetres.

 
FUNDAMENTAL FORMULA FOR VIBRATING STRING SYSTEM

The simplest mathematical expression of string behaviour is as follows:
                   \        ----------
F = 1/(2L) × \     /  T/M          or   T = M × (2LF)^2
                      \  /
                       \/
Where F = frequency in cycles per second
L = length in metres
T = tension in Newtons
M = Kilograms per meter length

From the above we can deduce a few basic maxims that will help us to think clearly about strings. That is : For a SPECIFIC FREQUENCY RATE OR NOTE increasing the:
LENGTH will increase string tension
DIAMETER will increase string tension
MASS will increase string tension

Given that the above three factors remain the same, increasing the string's tension will raise the frequency rate. The mass can be increased by making the string bigger, by using a material that has a greater density, or by using bedding and wrap material. Wrapping is a technique used to increase the mass of a thin string, while keeping it playable.

For a monofilament string the tensile strength ratio is directly proportional to the length of the string, its diameter and its density. Therefore, there exists only one correlation for each value of tensile/strength ratio for each type of string material. For example a 24" nylon string tuned at C4 (middle C) will have a tensile strength ratio of 35.305 percent regardless of its diameter, whether the diameter is 0.001" or 3"; the difference in characteristics are found in the impedance and the tension/length ratio.

Okay, we are now ready to work. Basically there are two scenarios which one can use for the analysis of a string instrument. 1)You already have the instrument and you want to find out or change its string configuration. 2)   You want to design a string instrument from scratch. This requires some previous knowledge, experience or reference to work from.

STRING CONFIGURATION FOR A KNOWN INSTRUMENT

The first thing you need to do is to record the vibrating length of each string for the entire instrument and what notes they are supposed to be tuned at. Record also the diameter of every element of each string (core, wrap, bedding and overall diameter). Determine what material the string is made of (core and wrap material can be different). Now that you have gathered all of your known data you are ready to use Stringband Manager Light. Do each string and paste the result into a spreadsheet so you can find out the total tension and how smooth the transitions are from one string to the next and make changes if needed.

STRINGS AND COMPOSITE STRINGS:

While stringing an instrument keep in mind what strings are available on the market. Ask your stringmaker the range of strings sizes they carry as well the range of composite strings they make. You may also ask for the strings characteristics (density, tensile strength). If these characteristics vary greatly from the default values then use the "User defined" option when you are prompted to choose the string material for those strings.

The purpose of composite strings is to increase the mass of the string while keeping the core strong (holding) enough to carry the vibration in a nice way. As the core gets thicker it requires more energy to vibrate the strings. Choosing a series of composite strings is not as easy as one might think because there can be so many combinations of strings that can give similar results. Factors influencing string composition include cost, durability, availability, aesthetic, string overall diameter (it has to fit in the hole), string spacing, special effects, personal preferences and the general design of the instrument.

StringBand Manager Light can evaluate 3 kinds of composite strings:
- solid core + wrap (for metal and non metal string)
- fibre core + wrap (for metal and non metal string)
- solid core + bedding + wrap (for metal string only)

When monofilament string's percentage of tension ratio falls below 40 to 20 percent (according to what you want to achieve) then you may have to use a composite string. First start with the smallest wrap size available, decrease the core diameter by the size of the wrap or more. The objective here is to make the transition between types of strings as smooth as possible. Although the percentage tension ratio may vary significantly at these transitions, you should however try to keep the tension, tension/length ratio and impedance at about the same relative progression between the strings. If you are not sure what is the smallest core size you can start your composite strings, use the tensile strength table in the tools menu. It will give you a table of string breaking point for a specific diameter. For solid core + wrap strings for nylon the core diameter should be at least twice  as thick as the wrap diameter otherwise your string maker may not able to wind the wrap. Never reduce the size of the core within the range of composite strings of the same type for a lower note. For metal strings you can increase the mass of the strings by just increasing the bedding size.

To Down Load SBM-Light click here: SBM-LIGHT    Updated version: 20.04.01  Size: 3,099,648 bytes 

To Down Load Icon save this picture 

Spreadsheet Template for SBM-LIGHT. In Libre Office HERE.  In Exel 97- 2003 HERE

Musical Notation used in the program.

 

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