What's Required.

A project log for Chalkboard Plotter

Bringing old hat chalkboards into the modern era so I can plot all the sweet drawings I make at Hyperloop.

riskncrisknc 02/26/2017 at 00:210 Comments
I'm chilling at crashspace and diving into this project.

Phase II

Requirements and Metrics

Based on customer needs above I’ve compiled this list of requirements, and the metrics by which to measure them by. I’ve split this into subjective measures and quantifiable ones. Each will influence my concept generation and downselect process.

They are in the format


Requirement-Metric (Best:Better:ok)



Cool to Watch



Capable of Rendering Drawings:

Can print vector format - yes/no

Can operate from computer - yes/no

Can operate without computer- yes/no

Can operate from phone - yes/no


Initialization speed - seconds (5:10:20)

Traverse speed - in/min (600:350:240)

Plot Speed - in/min (250:170:100)


Positional Accuracy- in/3ft (.010:.030:.060)

Line width rendering capability- #ofwidths (8:6:4)

Rendering accuracy of drawing- in/3ft(.020:.060:.125)


Modular - yes/no

Disassembleable - yes/no

Weight - lbs (15:30:45)

Minimum packable volume - in^3 (800,1000,1250)

Setup / teardown time - seconds (60, 180, 600)

Packaged transport volume - in^3(1000, 1500, 2000)

Useable by untrained persons

Ease of setup - 1 to 10 difficulty

Simple interface - 1 to 10 diffficulty as compared to printer

Error recovery ability - 1 to 10 difficulty from me having to fix it to child can fix it

Operates in various environments

IP rating ( IP76, IP 65, IP54)

Max/Min Operating Temperature - F (200/-10)

UV protection - years (10,5,2)

Power options - # (AC/DC, AC)


Won’t bend - Factor of Safety to yield failure (2)

Won’t break - Factor of Safety to Ultimate Failure (3)

Shock Resistant - Factor of safety to impact / toughness (3)

Won’t resonate - natural frequency of cart vs excitation frequency at speed.

Won’t Fatigue - estimated mean time to failure ( 5, 2, 1+ Years continuous operation)


Technical documentation completeness - % of system described (100)

Parts availability- % OTS or printable components (100, 80, 70)

Time to assemble- hours (4, 20, 100)

Difficulty to assemble- 1 to 10 ()

Low Cost

Parts cost - $ (250, 500, 1200)

Tooling Cost- $ (50, 100, 250)

Yearly Maintenance Cost- $ (5, 20, 50)

Open Source

Yes / No

License type-

Able to demonstrate others principles of physics and engineering

Number of documented physical / engineering principles at work - # (5,2,1)

Next week I’ll focus on concept generation (Phase III) and then start to narrow concepts into a system that meets as many of the requirements above as possible. Back to chilling at crash.