RepRap Wally: Turtles all the way down

A plastic Wall-E

A plastic Wall-E

RepRap Morgan was recently awarded the Gada prize, which was the first time I had seen a “SCARA arm1 robot.2 Reading Hackaday lead me to read about RepRap Wally, another SCARA based robot.3 Anyhow, My favorite part about this robot is that it boasts it can print parts for larger versions of itself.

While building more 3D printers is, perhaps, a noble goal – democratizing production and all that – actually working to churn out parts is a dull business.  On the other hand, the idea of a robot capable of building increasingly larger iterations of itself is incredibly amusing.  As is the idea that a robot could build smaller and smaller versions of itself.4

Of course, this then makes me think of a chain of robots – one set making ever larger and another set making ever smaller robots… robots all the way down.

  1. Yes, I know that’s redundant []
  2. Photo courtesy of Haceme un 14 []
  3. Watching this orange plastic robot in action, it’s easy to imagine they gave it the name “Wally” for looking somewhat similar to Disney’s Wall-E. []
  4. Of course, smaller versions would really only be more useful if they printed with greater precision []

Have you turned your MakerBot or RepRap into a robo-cutter?

I’m curious – has anyone out there retrofitted their MakerBot Cupcake CNC, MakerBot Thing-O-Matic, or RepRap1 with a cutting device?  I recall seeing an example of someone creating a laser cutter, but I was particularly interested in whether someone had made a cutting device using a blade.

If so, what kinds of blades did you use?  Did you create your own?  Did you use off-the-shelf replacement parts for a commercial robo-cutter?

  1. Or other DIY 3D printer, for that matter []

I had a dream last night…

And, it isn’t the first time.  I was going into excruciating detail about calculating and calibrating a good Skeinforge profile.  Well, we can use a thread thickness of such-and-such, a layer height of such and such, oh, and what plastic are you using?

Admittedly, just before bed I had chatted with several MakerBot/RepRap guys and was tinkering with ProfileMaker v3.0, so math and SCIENCE must have been dominating my thoughts.

New affordable 3D printer – the Ultimaker



Update 3/28/2011:  The Ultimaker is available for pre-order!

Erik de Bruijn along with a newly formed Dutch RepRap group have put together this new design for a low cost RepRap alternative.  The stated goal of their blog is “designing/developing an easy to build low cost 3D printer with a small form factor but large build envelope.”  Erik has invited everyone to comment on this beta design.  It’s interesting to see their progression of prototypes in their second blog post.

The interesting thing about this model is that it combines some of the best parts of Darwin and MakerBot and what appears to be a Bowden extruder.

The very nature of FDM1 means that the robot will only move the Z axis a little bit every once in a while.  One of the design drawbacks to the Darwin was that the heavy extruder head (motors, gears, heating elements) were so heavy that the entire robot would rock or vibrate with the lateral XY movements.  MakerBot got around the heavy extruder head problem by moving the platform in the XY and moving the extruder head only up and down.  This design decision isn’t without it’s tradeoffs, however.  One downside is that their build area is much smaller than a Darwin.  Another downside of the MakeBot design is that once the object being built reaches a sufficiently large volume or height, moving the object around quickly on the XY platform causes it to vibrate, shake, and become somewhat unstable.

One of the main improvements inherent in the Bowden extruder is that it allows you to take the heaviest parts of the extruder head, separate them from the rest of the extruder head, and move those heavy pieces to a different location.  Using a Bowden extruder makes a Darwin style robot much more feasible – the small moveable print head won’t have the mass to cause the robot to become unstable.

It seems that combining either of the X or Y movements with the Z probably won’t matter all that much, since the Z axis will only move about 0.33mm or so per layer and the Z axis typically doesn’t operate at the same time as either the X or Y axis.  Combining the as the new RepRap version II, Mendel, design shows us that combining the Z axis along with either the X or Y axis, but not both, can lead to a very stable configuration.

What I like about the Ultimaker design is that it would appear to incorporate some of the best parts of the MakerBot and Darwin designs. It appears to have a bolt/nut/T-slot MakerBot style assembly structure using thin lasercut wood pieces for the body.  I found these parts to bolt together very quickly.  Contrast this to the Darwin/Mendel structure using lots of nuts and threaded rod and printed plastic parts to hold it together.  At the same time, by making use of a Bowden extruder and the Darwin body shape, it appears to be able to use most of the interior volume for printing.

I suspect it probably uses fewer parts than a typical Darwin, but I can’t be sure.  I also have to wonder about the cost of lasercut wood versus the cost of nuts and threaded rod.

Nice find RepRap Log Phase!

  1. Fused deposition modeling – basically creating a layer and then fusing a new layer on top of that layer in succession to build up an object. []


Thanks to MakerBot for retweeting my MakerBot poll.  The number of responses basically doubled in a single day.  It’s been a busy day so I’ll go into more detail this upcoming weekend.  For now, I’m going to close the poll and show the questions:

  1. Why are you interested in MakerBot
  2. Have you heard or read about RepRap or
  3. Have you tried to design anything in 3D?
  4. Have you tried to upload anything to Thingiverse?
  5. If you had a MakerBot, what would you want to download from Thingiverse and print?
  6. If you had a MakerBot, what would you want to design and print?
  7. If you had a MakerBot, what would you use it for? (Help starving children, make toys, make tools, etc)
  8. Why haven’t you purchased a MakerBot yet?
    • It’s not worth $1,000.00 to own an awesome robot.
    • It’s not worth $1,000.00 to make my own stuff with an awesome robot.
    • I don’t have $1,000.00 to spend on awesome robots.
    • I’m interested in MakerBots, but not interested enough to buy an awesome robot.
    • I don’t think I have what it takes to build awesome robots.
    • I fear awesome robots.
    • My parents were killed by awesome robots.
    • My friend has an awesome robot, so I just use theirs.
    • I don’t think awesome robots are that awesome.
    • Other (please specify)

Totally unofficial unsanctioned and unauthorized MakerBot survey

If the recent MakerBot competition and media coverage1 and showed us anything, it’s that there’s a lot of people who are interested in getting a MakerBot.

I’ve noticed that all the RepRap and MakerBot polls thus far are really geared towards people who already have such a machine.  But, what if you don’t have an awesome robot that makes other robots?  Well, I’m a curious guy, so I put together this poll. It’s fewer questions than the census and WAY less invasive! 2

So, why not set aside 30 seconds and take this poll about awesome robots?

  1. ABC news story, NBC bit, PopSci, and repeated mentions on the wildly popular runaway hit MakerBlock blog… []
  2. I only ask for your SSN and mother’s maiden name, rather than SSN, mother’s maiden name, and birthday []

Chip off the old ‘bot

Chip off the old 'bot

A handsome family portrait

Okay, I’m liking the MakerBot and it’s RepRap child.  But, check out that work area!

(I have the same 3-in-1 oil for my MakerBot.  :)  )

Circle packing, Origami, and RepRap

Eric Joisel's "Woman in Dress 2008"

Eric Joisel's "Woman in Dress 2008"

One of my interests outside MakerBot/RepRap is origami, the Japanese art of paper folding.  At it’s inception it was really only a hobby for the rich – the only ones who had access to such a luxury as paper.  Modern technical origami restricts one to only a single sheet of square paper transformed only through folding – no cuts, glue, tape, etc.

A lot of very interesting origami models have been developed over the years by some incredibly talented artists through a combination of experience and trial and error.  These kinds of models have so much personality they almost appear to be real – rather than mere squares of paper.  One of my favorite origami artists of this “genre” is Eric Joisel.  I still find it hard to believe his models, such as the “Woman in Dress 2008,” can really be made of just a single square of paper.

There’s been a movement in the last two decades to bring a more methodical and mathematical approach to design, sometimes with the assistance of a computer.  One of my favorite technical origami artists is Robert Lang).  His models tend to the more realistic, rather than representational (as with Joisel).  His insects, such as the stag beetle, are a prime example.

Lang has used his background in mathematics and origami to develop a giant collapsing/expandable lens – so that it could be transported to outer space and then deployed.  This allows a normal space craft to deploy a much larger lens than would otherwise be possible.

Robert Lang's "Stag Beetle BP, opus 477"

Robert Lang's "Stag Beetle BP, opus 477"

Unlike Josiel’s models which are typically totally unique and irreproducible by anyone (including Josiel!) Lang’s mathematically assisted models are usually carefully documented by diagrams or, increasingly frequently, crease patterns.  A crease pattern is what you would get if you totally unfolded a completed origami model.  Typically only the “major” structural folds are depicted in a crease pattern.

Brian Chan's "Attack of the Kracken"

Brian Chan's "Attack of the Kracken"

An interesting intersection between mathematics and origami is the problem of determining the most efficient manner of placing the most number of equally sized circle within the smallest possible area, called, “circle packing.”  The reason this is important to origami is that the center of each circle can be turned into an appendage.  Lang has developed a computer program that allows the creation of truly arbitrary proportions – any number of points with any kind of ratio of one appendage to another.

Brian Chan's crease pattern for "Attack of the Kraken"

Brian Chan's crease pattern for "Attack of the Kraken"

Even to someone who doesn’t have any experience with origami or the mathematics involved, the appearance of circles in crease patterns can start to make intuitive sense.  One of my all time favorite origami models is the “Attack of the Kraken” by Brian Chan.  (Check out the larger pictures of that model.  The entire thing is just one sheet of paper.  If you look closely you’ll see some of the tentacles are grabbing sailors!)  In addition to a picture of his final model he has also posted a picture of his crease pattern for that model, even labeling which parts of the model are derived from which regions of the sheet of paper.

I was reminded by all of this after reading Nophead’s recent post on circle packing as it relates to the optimal placement of resistors on a heated RepRap bed and reading Cory Doctorow’s Makers in which one of the characters is an avid origami folder.  As with RepRap, origami allows the production of complex models through an additive manipulation (layers with RepRap, folding with origami) of a simple material (plastic versus paper) in a methodical and repeatable process.

If you’re the least bit interested in origami, I’d highly recommend (in this order) Peter Engel’s “Origami from Angelfish to Zen,” a documentary on origami called “Between the Folds,” and Lang’s book “Origami Design Secrets.”  The Angelfish to Zen book is one of my favorite books for background on origami and a very accessible introduction to the hidden geometry  underlying even the most simple models (and real life too!).

A complete-ish RepRap sold

A few days ago I posted about a RepRap Mendel for sale on eBay with all electronics, motors, belts, etc fully assembled1  The auction (for a set sold in Ireland) settled at 760.00 Euros or about $1,017.18 USD.

Frankly, I would have thought it would have sold for more.  Printed parts are still selling in the $300-$450 range, electronics clocking in at $250 or so, bearings at $50, and all the other bits probably costing another $100 for belts, rods, nuts, bolts.  This means just the materials would cost $700 – $800.  Then there’s the delay and extra expense of sourcing all of the parts for yourself.

Interestingly, I had thought the bottom had fallen out of the RepRap printed parts eBay market.  However, a set of printed Mendel parts just sold on eBay for $455 on April 5.  I suspect the difference is that these parts are being generated and sold in the US which makes for an easier and slightly cheaper transaction

  1. To be fair, the seller mentioned it would require some adjustment to start printing. []