This is the next step in my attempt to make a Sarrus linkage based 3D printer. The idea is to have a cartesian mechanism without those long rods and bearings.

I built three of the Mark III and mounted them in a x-y arrangement as shown. They can move over a square about 105 mm wide, and someday may carry an extruder. They are driven by DC motors taken from inkjet printers. These motors are driven in a servo arrangement using quadrature optical encoders and optical strips removed from the same printers.

Since I am giving a presentation at a conference with the subtitle "Here be dragons" I knew I had to print dragons.

I've managed to cut the head off the open dragon from here:http://www.cgarena.com/freestuff/meshes/meshes.html

But it's not a clean cut and I'm not terribly good at editing models so if someone wants to improve the cut, I'll reupload the model.

Update! Nate True fixed up the model. I've added a second file called "dragonheadfixed" that you'll want to use from now on. Thanks Nate!

The base fits a DC motor with 20mm in diameter but its dimensions can be adjusted on the openscad script.

This is a work in progress. The plastic is so lightweight that it doesn't counteract the pull of the motor and I'm hoping it'll eventually work as a mini propeller (test video: vimeo.com/8199151). But for now it really is just a cooling/exhaust fan which can be held still by either bolting it down or using the 9V battery version - the weight of the battery is enough to keep it from moving, specially if placed on a rubbery surface.

Even though there are lots of great gears on thingiverse, I couldn't resist the urge to model some too :)

The combinations of parameters are too many to upload an STL for each, so I just picked a few.

I also made a version for helical gears: thingiverse.com/thing:1339

This is a drag chain for the MakerBot extruder cable (or any other cable/wires).

It keeps your extruder cable out of the Z-stage belt and let your MakerBot look professional (kind of...)

The objects need very detailed printing in order to work. You definitely want a good tuned MakerBot and Skeinforge settings to print this (don't say I didn't warn you!).

The ZIP file contains GCode files for all objects, including 6 or 8 chain links on one raft. It might be the best to skeinforge the gcode with your own, tuned settings. The included GCode files worked for me (resp. my MakerBot), but (again): these are some really hairy objects to print.

A regular polyhedron with twelve pentagonal faces. This one is about about 25mm high and is hollow. See hydraraptor.blogspot.com/2008/11/dodecahedron.html.

This is part 3 of "Pimp my MakerBot" (see thingiverse.com/thing:973 and thingiverse.com/thing:958 for part 1 & 2 :)

I was tired of dragging on the Z belt multiple times to upper or lower the z stage of my MakerBot.

With this crank mounted on one of the 4 M6 threaded rods, I can now easily adjust the height of my MakerBot.

I was inspired by zignig's Printable Desk Clamp thingiverse.com/thing:683 . I used hex nuts instead of square nuts because hex nuts are more common. All the parts are easily available at hardware stores and hobby shops. The total cost is about $4.50 for this clamp compared to $50 ones. It is used for holding circuit boards at comfortable angles, hobby modeling, and holding stuff. Enjoy.


The picture of all parts does not show two nuts that I had already hammered in but I did not want to take them out. Also it does not show 20mm brass tubing as I already hammered some of them in.

This is my second prototype of a Sarrus linkage type linear axis. A Sarrus linkage uses hinged joints to make linear motion. The idea is to have a linear bearing suitable for making part of an x-y cartesian assembly without needing long polished metal rods, thus getting a 3D printer that can make more of its own parts.

Notice that there is a set of 4 holes on the top armature that match 4 hole patterns on the end pieces. This means that one axis could mount on two others at right angles.

Drive system: DC motor from a cheap garage sale inkjet printer, using the timing belt from the printer. The pulley at the other end of the belt is a screw/washer/spacer combination with a skate bearing. The skate bearing is mounted in a flexure plate style mount to give tension the belt.

Optical feedback: I took a optical quadrature encoder and encoder strip from the same printer as the motor. The encoder is mounted on the moving armature, and the strip is anchored at both ends in the end blocks.

Hinges: The hinges on the Sarrus linkage are made with 1/16" diam brass rod as the hinge pins. The holes for the hinge pins were reamed out with a 1/16" drill bit.

Frank Davies

Here is a squeeze buckle like you normally have on a backpack or hiking gear. I removed all of the supports for a strap on the fork part, since it just wasn't printing properly.

Also the fork fits into the sleeve in only one direction, due to the edits I had to make to make it printable.

Enjoy!