Category: Miscellaneous

Miscellaneous

Drawbot at the 2012 Seattle Mini Maker Fair

2012-06-04 Dan

Seattle Mini Maker Faire was fantastic! I talked to over 2000 people, most of whom asked the same question: “How does it work? Magnets?”

Maybe at the next fair I should use colored string so people grok it. I stayed overnight at the famous Green Tortoise across from Pike’s Place Market and met all kids of interesting people.

For instance, I’ve been admiring this Delta robot (called ‘Rostock’) for a while now. Turns out I’ve known the creator for years, and he’s even couchsurfed with me! What a tiny, tiny world.

Have you ever seen the gear heart? Emmett redid it with the Colbert head, just for fun. He had a good time teasing me about how gently I treated his ABS creations.

finally, here is a gallery of other things that were drawn at the Seattle Maker Faire, mostly on Sunday.

Miscellaneous

Drawbot: much better TSP solving

2012-05-31 Dan

Optimization is the name of the game when attempting to solve the Travelling Salesman Problem (TSP). I’ve figured out most of what Lin/Kernighan is saying and then implemented it to run as fast as I can get it to go. Here’s the progress since the last picture I posted.
Here’s one of the Seattle skyline for the Seattle Maker Fair

It helps if you back up and squint. No really, it’s like pointilism paintings. Ever heard of the Group of Seven? Like that.

Here’s the results of the Drawbot working on the above image done by the TSP solver last night.

It ran for three hours and then failed when the laptop went into sleep mode while I was at the VHS. The mess in the top left is because I tried to draw the picture twice – once it failed when the stepper motor got warm and caused the bobbin to slip off the shaft. In a future version of the drawbot I’d like to try bicycle chain and sprockets instead of bobbins and thread.

Got any suggestions for pictures I should draw? Post ’em below!

Miscellaneous

Drawbot: checking out the competition

2012-04-10 Dan
  • Drawbot: No pen up.  Not self-calibrating.  Interesting path planning (circular halftones?).  Very slow.
  • Hektor: Pen up.  Spray paint plotter.  Self calibrating.  Terrible path planning.
  • Smooth Octopus: Pen up.  Nice plotter.  Not self-calibrating.  Java path planning.
  • GarabatoBot: No pen up.  Nice plotter (motors integrated!).  Not self-calibrating.
  • http://www.as220.org/labs/drawbot/
  • http://www.muralizer.com/blog/
  • http://www.unanything.com/

Do you know of any others?  Please comment!

Miscellaneous

3D Printed Thrust Bearing

2012-04-04 Dan

http://www.thingiverse.com/derivative:25706

When two objects are moving together they can have two kinds of contact: sliding or rolling.

  • Sliding produces a lot of friction which leads to extra work, heat, wear, and damage. Sometimes this can be overcome by using two different types of materials: brass slides easily over steel, but steel doesn’t slide well over steel.
  • Rolling is smooth and (nearly) frictionless. Bearings are like wheels on a car: they turn as much sliding friction into rolling friction as possible. Did you know there are bearings inside most of your moving household appliances?

      What makes Thrust Bearings special

      Thrust bearings work like normal bearings except they can take more axial load. (force in the direction the center axis is pointing). Put two of them back to back and you get a Slew Ring, a bearing that can take a great deal of force every which way.

Miscellaneous

Building a Delta Robot: 3D model version 1

2012-01-25 Dan


Now that I’ve defined what success should look like, I have to start putting the pieces together.  This started as a set of pen & paper drawings in my sketchbook.  Then I had a friend model the entire thing in Solidworks.  This model uses

  • Some sheet metal or wood for top & bottom plates (blue)
  • Some 3D printed brackets (green)
  • 24 3D printed ABS bearing mounts
  • 12 3/8″ OD bearings (between the bearing mounts)
  • Three pieces of 16mm hollow square aluminum bar (grey)
  • Three NEMA17 stepper motors
  • Six pieces of 4mm threaded rod
  • Six 1cm rods (attaches bearing mounts to square bar & bottom plate)

Before I could say this design is finished I still need to do a number of changes and tests, based on my previously stated goals:

  • The 1cm rods should be supported on bearings to make movement nice and smooth.
  • Bearings means a redesign of the square rod, the 1cm bar, and the bottom plate.
  • The legs that will hold up the delta robot haven’t been designed yet
  • Length of the 16mm square bar, length the 4mm threaded rod, and size of the plates will change once I calculate the correct numbers for the work area and accuracy that I want.  I just hope the motors I have will be up to the task!
  • Solidworks can simulate material stress and do other kinds of performance analysis.  I should be able to test how much weight the machine can carry before I start making anything, which will help me make sure my targets are being met.