Archive for the 'Prototyping' Category

Arduino G-Code Stepper Controller

rStep Project

Reza Naima has been working on an Arduino G-Code Interpreter.  There have been a few other projects like the grbl projects and the rerap type machines have some g-code history to them.  Most of the project is being documented over at the rStep Google Group.

It is nice to see more and more open source G-Code interpreters for micro controllers out there.  In some projects this can free up the PC or at least reduce the need for expensive and or complicated CAM controllers like Mach3.  A quick look at the firmware shows it handles a decent sub set of  G-Code commands including arcs.

rStep Arduino G-code Controller

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Ink Jet 3D Printer

This looks like an interesting hack.  There are not a lot of details, but apparently there is some good information at the Yahoo DIY 3D Printing and Fabrication Group and at CandyFab.org.  It looks like a lot of work and the results are questionable, but if you’ve read any blogs here you know I never criticize people for showing early, but rough results.

It appears he uses paper sheets on the powdering tray to set the height of each pass.  Remove at sheet and the level moved down.  Great, simple, consistent idea.

See video after the jump.

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The Age of the Self Replicating Machine.

MC Escher - Drawing Hands

There is a saying amongst DIY CNC router builders that goes something like this… “You only need to build your first router good enough to build you second one“.  In my case that turned out to be true.

I built a wood, conduit and skate bearing Solsylva router.  I painstakingly layed out the various pieces using calipers, t-squares and compasses.  I cut them out using hand held tools like jigsaws and drills.  It worked remarkably well, but every time I routed out a perfect CAD drawn piece, I always thought “Gee, I wish I had this thing when I built the router“.

It wasn’t too long before I built my bigger, better, more accurate router.  I was able to use tougher materials, hold tighter tolerances and cut more exotic shapes.  It works much better.  A few months ago I finally pulled off all the good bits and Sawzall’ed the old one apart to get more room in the shop…a bitter sweet day.

Most of today’s designs develop inside a computer.  Resolution and accuracy are infinite in this realm.  We expect our fabrication machines to output similar accuracies, but how does one construct a machine with this accuracy with common (analog) tools.

Today’s open source machine are addressing this head on.  There is a big push towards self replication.  Struggle past the first one and the rest will be easy.  It is not just an accidental bonus it is initial design requirement.  It is a lot more work, but I think it builds the strong communities behind these projects that help insure their success.

Here are three examples of self replicating machines…

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D.I.Y. Selective Laser Sintering – Update

SLS Printer XY Stage

Update. Peter is still working on his SLS project.  He is experimenting with a new fully laser-cuttable x/y stage.  He is catching some flack for the ideas in some blog comment sections like hackaday.  Obviously there is some refinement needed for accuracy, backlash, etc, but I applaud his efforts.  I am sure some of his ideas will find their way into the final design and we will all benefit from it for this and other projects.

If he was just building a device for his own use, it would probably be easier and cheaper to use conventional materials, slides and gears, but he is clearing spending a lot of time to design something the budget conscious maker can afford.

Many people put similar questions to me on the design of the open source “self replicating” laser cutter.  I have redesigned and rebuilt constantly to lower the costs, tools and skills required to build it.  I swapped out very robust milled aluminum parts with laser cut Acrylic ones to prove they would work.

His most recent changes area aimed at removing the “shearing/binding issues” from the previous iteration.  He is using Kapton tape (Polyimide-film) to reduce friction and using a four gear contact point.

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Rotational Molder

rotational Molder

I saw this rotational molder a while back on several blogs (Ponoko, Core77, designboom).  Rotational molding is typically used to make large hollow plastic parts.  They make anything from kayaks to gas tanks.  The molds are very simple hollow cavities, that split into at least 2 pieces.

A specific amount of material is placed inside and the mold is heated.  When the material is in a liquid state.  The mold starts to rotate in 3 dimensions so the material evenly coats all the walls.  The material in allowed to harden and the mold is split apart.  You now have a seamless hollow plastic part.  It has a parting line, or flashing, but the part is essentially seamless.

This machine is a beautiful example of flat-pack design.  There is very little waste material.  This version ditches the heating step and uses cold set resin.  They recommend a two part resin called ‘Easy flow 120′.  It is available at Mouldlife.  It comes with a sample mold and you are on your own for the next one.  It looks like the mold was vacuum formed.

It is called My First Rotational Moulder and is available for purchase at StudioMyFirst

(I guess they spell molding differently over there?)

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