Rules of the Road

by Bob Pederson

On your mark, get set, GO!

According to Grammarist.com, these words are traditionally used to start a footrace. The Great Marker Competition was previously described. Here is the start of it!

“Nib is an industry standard term for the tip of the marker used to write.

Felt Ink Reservoir (FIR) is a term this team made up to describe the internal ink storage reservoir consisting of fibers similar to the fibers used in the nib.

Competition in this document is defined as Expo, EcoSmart (also known as AusPen), and the Pilot V Board Master. Although there are many brands of whiteboard markers, we limited the competition to these three markers in order to focus our efforts where they would be most potent. Expo is the most common brand, so it represents the standard marker experience. EcoSmart is rebuildable. Pilot uses a cartridge to refill, which is quick and clean.

Because of the effects of lighting and nuances in subjective user preferences, “marker depletion” will not have an objective definition. We will define it as the point at which the user of the marker considers the marker marks to be of insufficient visibility. From the color quality data we will be collecting, a more objective definition can be determined for the given controlled lighting conditions we will be using.

To get the grayscale color value from an RGB color value, multiply the red value by 0.2989, the green value by 0.5870, and the blue value by 0.1140, and add up those three values.

53 kPa absolute pressure (-14 inHg gauge pressure) was chosen as the pressure for the vacuum testing because that is the air pressure at 5,100 m above sea level, which is the altitude of the highest permanent human settlement. This is less than the pressure in a commercial airplane at cruising altitude in both the cabin and cargo hold.

In the event of a tie in any category in the marker scoring, any better non tying markers will get the lower ranks, the tying markers will share the lowest rank not taken, and then a number of ranks equal to the number of tying markers minus one will be skipped for any markers which are worse than the tying markers in that category. Example: If our marker is the best in a category, Expo and Pilot are both tied below us, and EcoSmart is below Expo and Pilot, then our marker would be ranked 1, Pilot and Expo would both be ranked 2, and EcoSmart would be ranked 4.

Marker Scoring Rubric:

 

  Weight
Color Quality 15%
Uncapped Color Quality 5%
Cost per Distance 15%
Distance per Refill 15%
Leak Volume 5%
Waste per Distance 10%
Refill Time 15%
Nib Replacement Time 5%
FIR Replacement Time 5%
Ink Level Indicator 10%
Total 100%

 

Implementation

Repeated failures of developing mechanical prototypes of marker bodies and components led to the perusal of various types of retailers that carry markers and marker supplies of every type. A blank marker body, was found on 19 March 2017. This seemed as a possible carrier for the minimum required components: ink, nib, and cap.

 

A first, casual experiment, to see if this marker body would have a good ink flow and not leak was conducted. It worked!

A trial fitment of dry erase designed nibs was conducted. They flowed ink and wrote well, but there was no stop feature and the nib did not seem sturdy. 

Next, nibs were developed with a stop feature (nib/FIR combination) and fit to the marker body, along with their drawings, to work with the valve system.

Upon further examination, and encouraged by our research, the figure below shows a concept capillary fluid delivery system with nib/FIR combinations. These were developed to potentially replace the spring-loaded valve ink delivery system.

Blank marker with concept capillary fluid delivery system and concept nib/FIRs

Time ran out for further design work, the testing of the competition and our prototype began, along with finalization of drawings and then analysis of the testing.

Writing test methods:

The color quality, cost per meter of writing, and meters of writing per refill data for each marker came from experiments in which each marker tested went through the following test procedure:

  1. Weigh the marker.
  2. Write a test line with a length of approximately 50 cm.
  3. Take a picture of the test line and process the image data to get the color quality.
  4. Weigh the marker again.
  5. Write with the marker in test conditions approximating a typical academic use case as closely as possible.
  6. Repeat 1 to 5 until the user of the marker considers the marker marks to be of insufficient visibility and then perform 1 to 4 one more time.

The color quality data was found from the test line image in a manner described in further detail in the image processing section.

From the test line data collected, the distance of writing per weight of ink used can be found as a function of the current weight of the marker for each marker. This function can then be integrated to find the distance written as a function of weight. From this, the meters of writing per refill can be found from the starting and ending weights of the marker. The cost per meter of writing can then be found from the cost of the marker and the meters per refill. The waste per meter of writing can be found from the waste over the life of the marker divided by the meters written in the life of the marker.

The uncapped color quality was found by performing the following procedure:

  1. Weigh the marker.
  2. Uncap the marker for 10 minutes.
  3. Weigh the marker.
  4. Write a test line.
  5. Take a picture of the test line and process the image data to get the color quality.
  6. Weigh the marker again.
  7. Write with the marker in test conditions approximating a typical academic use case as closely as possible.
  8. Repeat 1 to 7 until the user of the marker considers the marker marks to be of insufficient visibility and then perform 1 to 6 one more time.

Image processing:

To perform image processing of the test line images, the following procedure was followed:

  1. The image was imported into MATLAB.
  2. The image pixels were converted into HSV.
  3. For each pixel, a distance was found between the pixel and a pure blue [H=240, S=255, V= 29]. The distance is the antiblueness of the pixel.
  4. The image is blindly cropped to only include the approximate area of the test line image with the test line, the blue tape around the test line, and some whiteboard space around the blue tape.
  5. The image is further cropped based on the antiblueness of each point in the image in order to only include the area inside the blue tape.
  6. The average grayscale pixel value was found for the cropped image of the area inside the blue tape.
  7. Based on the size of the cropped image, the average grayscale intensity of the cropped image, the thickness of the marker stroke, and the average whiteboard grayscale intensity (found by sampling images of the test whiteboard), the grayscale intensity of just the marker stroke line could be found. This relationship is shown in Equation 1 and the variable names and meanings are explained in Table 1.
alpha = (T-L*Beta*(w-a))/(a*L)

Equation 1

Table 1: Variable names and meanings for the previous equation.

Variable Name

Meaning
Alpha

Average grayscale intensity of only the marker line

T

Total of the grayscale intensity of all pixels

L

Length of the image
Beta

Average grayscale intensity of the whiteboard

w

Width of the image

a

Marker stroke width (in pixels)

 

Vacuum testing:

The leak mass data was found by performing the following procedure:

  1. Weigh the test and control markers.
  2. Place the test marker tip down with the cap on in the vacuum chamber.
  3. Place the control marker tip down with the cap on in an environment with atmospheric pressure (“atmospheric pressure” refers to the air pressure in Twin Cities Engineering).
  4. Set the vacuum chamber to a gauge pressure of -14 in Hg.
  5. Leave the test marker in the chamber for one hour.
  6. Remove the test marker from the chamber.
  7. Weigh the test and control markers.
  8. The change in the mass of the test marker minus the change in mass of the control marker is the leak mass.

Refilling and component replacement tests:

The ink refill time, nib replacement time, and FIR replacement time were all found from each operation being performed once by three different users.”

 

If you would like to see the Final Design Report (FDR) in it’s entirety, please send a self-addressed, stamped-envelope with a cashier’s check for $3,000,000.00 to the EnduraMark world Headquarters, in Brooklyn Center, MN.

Ganzer, M., Lindquist, B., and Pederson R. (2017). Documentation, Research and Experimentation, Business Plan and Marker Score, Remarkable Final Design Report. Unpublished bachelors’ dissertation. Minnesota State University Mankato, Mankato, MN.

Back to News