Skipping! How could I forget the skipping?!

Hubris, I haz it

Hubris, I haz it

Mr. Noble is not the only one prone to hubris.1 After taking into account every post on ideal drawing robot pen holder criteria, I found one more post that I should have read first.  Dan Royer of MarginallyClever.com suggests2 as good pen holder should:

  1. A single cord convergence point.  “Have the two strings meet at a single point, or as close as possible.  The moment they separate the math gets really ugly.”
  2. Deal with friction.  “Friction causes the pen to drag and lean.  If I tell the robot to draw a square corner and it comes out rounded then I know my pen is dragging because it never reached the corner.  The pen has to stay at a right angle to the drawing surface.  So far I’ve found that having at least three points of contact is enough to eliminate the problem.  That’s why I tape my business card to an eye bolt on the bottom of the ring – the bottom edge of the card forms a large contact area with very little friction.”
  3. Be well balanced.  “If the pen is balanced wrong it may point up or down.  If it points up then it might go dry.  If it points down then it might have extra friction when moving downwards, causing the pen to skip and create a dotted line.”
  4. Have an easy way to switch pens.  “Not only should it be easy to replace a pen but every pen should “lock” into the pen holder at the same distance and angle from the drawing surface.  In order to simplify this problem I only use one kind of pen that comes in many colors.”
  5. Works on a slanted surface.  “Works on both vertical and slanted surfaces up to a maximum of 10 degrees.”

My own prior post on ideal characteristics in a pen holder took into account Dan’s number 1, 3, 4 and considered 5.  What I failed to consider was how friction can cause the pen to skip or stutter when the pen is mounted at an angle and the pen travels upwards.

Although I started diving into this consideration, but I’m putting all that over-pontification into its own post.  This post is really about (a) Dan considered a very important factor in pen holder construction which I neglected and (b) how awesome open source is.  My own pen holder would be a terribly complicated mess doomed to multiple revisions had I not had the benefit of being able to review a veritable legion of pen holders used by many many other people in their many many different kinds of vertical drawing robots.

So – Yay Dan!  Huzzah open source!

The next post will be about whether this consideration would cause me to change my existing pen holder design.

Posts in the DrawBot Adventure Series
  1. Wanna make a DrawBot?
  2. DrawBot Resources and Links
  3. DrawBot, the Adventure Begins
  4. DrawBots for the slow learner
  5. DrawBot - The Breakdown
  6. DrawBot - Parts Shipped!!!
  7. DrawBot - The Plan!
  8. DrawBot - The Hacks
  9. DrawBot - Giant Unicorn?
  10. DrawBot - The Delivery?
  11. DrawBot - The Delivery, Part II
  12. DrawBot – The Delivery, Part III
  13. DrawBot – The Assembly, Part I
  14. DrawBot – The Software, Part I (and an existential conversation)
  15. DrawBot – The Assembly, Part II
  16. DrawBot – The Assembly, Part III
  17. DrawBot – The Assembly, Part IV
  18. DrawBot – Design Considerations
  19. DrawBot – Halp!!! No - seriously, a little help?
  20. DrawBot – The Face Palm
  21. DrawBot – The Delivery, Part V
  22. DrawBot – The Silver Lining of Failure
  23. DrawBot – The Delivery, Part VI
  24. DrawBot – The Assembly, Part V
  25. DrawBot – The Assembly, Part VI
  26. DrawBot – Printed Parts
  27. DrawBot – The Assembly, Part VII
  28. DrawBot – The Operation, Part I
  29. DrawBot – The Breakdown, Part II
  30. DrawBot – Printing!
  31. DrawBot – Printing, Part II
  32. DrawBot – Why are you crying?
  33. DrawBot – Calibration
  34. DrawBot – Pen Selection
  35. DrawBot – How to Recover from a Stalled Print!
  36. DrawBot – Drawing Success(ish)!!!
  37. DrawBot – Pen Selection, Part II
  38. DrawBot – Onwards and Upwards!
  39. DrawBot – Another Successful(ish) Drawing!, and an Update
  40. Restarting a Stalled DrawBot Drawing
  41. TSP FTW!
  42. Speedier DrawBot Drawings
  43. Two new DrawBot links! And an update!
  44. Excellent DrawBot Slides
  45. Another Drawing Robot!!!
  46. The biggest inkjet printer ever
  47. Why do DrawBots draw on walls?
  48. All New Polargraph on the way!!!
  49. Ideas for improving my DrawBot
  50. DrawBot Aesthetic Re-Design Ideas
  51. The Eagle Has Landed
  52. I think I know what I want to draw next...
  53. Overengineered Spools
  54. Overengineered Stepper Motor Mounts, Filament Guides
  55. Overengineered Bolt Endcaps, Case Holder
  56. Sourcing DrawBot Parts
  57. DrawBot - A Tour!
  58. DrawBot - A Preview
  59. Arduino Powered Drawing Robot Poll
  60. Building an Arduino Drawing Robot - On The Cheap
  61. DrawBot - Printed Parts Tour
  62. Unidentified Foam Object
  63. Arduino Powered Drawing Robot - Take 2 (Or 3)
  64. DrawBot, now ACTUALLY wall mounted!
  65. A Study of Drawing Robot Pen Holders and Design Considerations
  66. Drawing Robot Pen Holders, Calligraphy Pens, and Thought Experiments
  67. Ideal Qualities in a Drawing Robot Pen Holder
  68. Enough talk! Finally a pen holder!
  69. DrawBot Pen Holder Post Mortem
  70. To Maker Faire!!!
  71. Skipping! How could I forget the skipping?!
  72. Drawing Robot Penmanship
  73. PlotterBot at Maker Faire Bay Area 2013!
  74. PlotterBot.com - a new site dedicated to drawing robots
  1. Photo courtesy of Markus Krispler []
  2. I’m keeping all of Dan’s words, but reformatting them []
April 5, 2013 | Comments Closed

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