MakerBot Industries

As a special treat this week while we compile and film follows up to your questions from earlier in the week, we share a quick mini-doc featuring a project MakerBot Operator Michael Felix created with the assistance of the MakerBot BotFarm and MakerBot BotFarm guru Herb Hoover.

Michael, “Principal of Effalo,” was commissioned to create a gigantic geodesic dome for a high-energy music video directed by Emily Wormley for the song “Fireball” from upcoming album “Flux Outside”¹ from the band Royal Bangs. MakerBot Operator community members Mark Cohen, Aaron Double, and MakerBot staff members Herb Hoover, Keith Ozar, and David Neff helped Michael print and assemble what has to be, to date, the largest thing build mostly from MakerBot printed parts to date.

UPDATE: Rumors have it that this dome will find its way into the luggage of the MakerBot team heading over to MakerFaire Bay Area 2011. And Matt, who created the first video, already has a draft going for a supplementary video going into more of the practical how-to elements so you can build your own geodesic domes….

1. which probably raises different associations for this readership than elsewhere [↩]

M8 CableClippy by elk

Tired of zip tying things, cutting those ties, and the re-zip tying them?  How about trying to reuse those nearly useless grocery store twist ties to organize cables?

If you’ve got a 3D printer like elk’s RepRap, why not just print up some of his CableClippies?  Simple, quick to print, reuseable, and even cheaper than any alternative – they’re exactly the sort of thing at which  DIY 3D printer excels.

M8 CableClippy by elk

This is a clip to fit the M8 studding / rods of a reprap mendel machine and hold any wires / cables down to the rod. It can be used instead of zip ties (I had to cut many zip ties again during my mendel build). The CableClippy can be re-opened with ease and helps to keep your cable chaos neatly arranged :)

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Suzuki by jyro

Thingiverse citizen jyro used the “Import” function on 3DTin.com to have it import an image into the super-user friendly online solid CAD program.  When you import an image, it will pixelate the image, and then turn it into a huge slab of voxels – essentially adding a uniform depth to the entire image.  What jyro must have done is carve away at the parts around the image and sculpted it to have a more rounded appearance.  The result is probably the best looking model out of 3DTin I’ve seen uploaded to Thingiverse.

Rubber-Band Escapement Test Jig by syvwlch

I’ve been really hoping someone would design a printable clock for a while now.  I need hope no longer!

Syvwlch has been long absent and long missed from Thingiverse.  After a sabbatical of about two years, he’s back and posting parts for a printable clock.  He’s making copious use of math, science, and OpenSCAD in the process.  I’d also point out that in the span of about 24 hours he went from just one component to three in three versions – and I can’t wait to see what’s next!  Click through to his offerings and leave a comment of encouragement or some feedback on how these parts printed for you.

Rubber-Band Escapement Test Jig - Maker Block Edition by syvwlch

Maker Block asked if there was a way to have fewer, larger teeth on the escapement wheel, and thanks to the power of parametric design in OpenSCAD, the answer was a resounding yes! With the larger teeth, this should be much easier to print. (EDIT: added a beefier, thicker version, slightly smaller so the pendulum fits inside the build platform. Duncha love parametric designs?)

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Another kind of feed rate

I’ve been a MakerBot operator for about 18 months now, and only just now am I really coming to understand Skeinforge’s nomenclature. ¹  Dave Durant did an excellent job of explaining the most important settings and terminology for Skeinforge in his series on configuring Skeinforge.  “Flowrate” is the rate of plastic exiting the extruder’s nozzle.  With a little math and science the flowrate is a function of the extruder motor speed and the volume of filament.  “Feedrate” is the rate of speed of the XY platform.  There are several different methods proposed on Thingiverse for configuring Skeinforge, and most of them involve solving for the proper flowrate or the proper feedrate for a given profile.

When using a MK5 or other DC motor powered extruder, there’s a very narrow range of reasonable flowrate settings.  The MK5 DC motors had a maximum speed of 255 PWM and a functional minimum of around 230-240. ²  Much less below 240 or so and the motor just wouldn’t turn.  The MK6 stepper motor extruder, on the other hand, has a much wider range of speeds – from around about 0.0 to up to about 3.0 RPM or so. ³

What values, then, is a 3D printer operator supposed to modify to get the best profile?

If you’re using a MK5 or DC motor extruder, I would recommend calibrating Skeinforge as you hold the DC motor speed at 255 and the maximum reliable flowrate you are able to obtain.  You’re going to want to adjust the other variables that are easier to control – the feedrate⁴ , the layer thickness⁵ , and thread width⁶ .  Since I like choosing my resolution and there’s not much choice in flowrate, I like to vary the feedrate since it’s easier to control.

If you’re using a MK6 or other stepper extruder the flowrate, feedrate, layer thickness, and thread width are all easily adjustable.  I prefer to choose the layer thickness and thread width, hold the feedrate at a level I know my robot can handle without problems, and vary the flowrate.

Here’s the interesting thing about solving for flowrate: the nozzle size ends up not being super critical.  As long as you’re choosing sane numbers for layer thickness and thread width, the amount of plastic going in will always equal the amount of plastic coming out.  While a 0.5mm nozzle would be capable of up to about 0.36mm thick layers and 0.75mm wide threads⁷ , these numbers might not make sense for a 0.4mm nozzle⁸ but could still work for a 1.0mm nozzle.

What settings do you like to vary when you’re configuring Skeinforge?

1. Photo courtesy of MadBuster75 [↩]
2. My understanding is that a PWM of 255 equates to about 2 RPM [↩]
3. A few disclaimers are in order.  You can set your RPM in the control panel to whatever you want and try to extrude – with no guarrantee it’s actually going to extrude at the mathematically calculated flowrate.  Additionally, the maximum effective RPM will be a function of the nozzle aperture. [↩]
4. XY platform speed [↩]
5. The thickness of each layer as it is laid down.  0.25mm/layer to 0.36mm/layer are reasonable ranges [↩]
6. This is the width of the filament as it comes out of the extruder nozzle. [↩]
7. Since they’re getting squished as they’re laid down [↩]
8. Since it would be tough to squeeze a 0.75mm thick layer out of a 0.4mm filament [↩]

This has graced the front page of Thingiverse for some time now, but just in case you haven’t seen it, behold this wonderful, potentially useful, MakerBotted gearbox…and check out that ratio.

Oh wait, you don’t like that ratio?  No problem — it’s a parametric design.  Cheers to emmett for this useful, multi-part, parametrically customizable design…use it next time you need to get your SUV up the driveway in an ice storm using an ABP motor.

1:246 Gearbox by emmett

Have you ever wanted to turn a CD-ROM motor into a winch? I decided to see how much gear reduction could be fit into a small space, so I came up with this differential planetary arrangement. This is a well-known design, but now you can use the parameterized OpenSCAD version to customize this to your needs and include it in your mechanical designs. The version shown here is less than 60mm in diameter and 13mm thick, but achieves a 1:246 gear reduction, all with teeth printed on a TOM. The input is the small shaft to the sun gear, the output is the smaller ring gear, and the larger ring gear is to be held fixed. If you stacked two of these units you would have a ratio of 1:60516!

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