FUTURE BLINDNESS

First cuts on Zen Toolworks CNC Mill

AKA — Sun, 06 May 2012 21:42:52 +0000

After months of insecurity and confusion, I finally completed the first cuts on my mill today. The piece didn’t come out perfectly (in fact, I kind of destroyed it as I was removing it), but I feel like I have a much better handle on what I’m doing now.

Much of the confusion was due to my stubborn insistence on using a couple tools I like (and I like these tools at least in part because they run well on OS X). I’ll run through the workflow from design to wood and provide any commentary/helpful links as I go.

Design

The piece doesn’t have any particular purpose except to be a good test of the mill’s performance. I used the free version of Sketchup, because I’m familiar with it, it’s easy to learn, and well, it’s free. One issue is that the free version does not let you export your 3d design into any useful formats. Luckily, Sketchup has a pretty full-featured Ruby API, and some kind soul has written a Sketchup-to-STL exporter that you can download here.

Mesh cleanup
The plugin works quite well, but it’s always worth the extra step of cleaning up your STLs, either by hand in Meshlab or (my new favorite) automagically via the Netfabb site. Why do you need to clean up your meshes? I’ve found that the simpler your model can be initially, the fewer little quirks you’ll run into down the line. Additionally, it’s relatively easy to go into Meshlab or Sketchup to simplify our model or remove a feature that taxes the resolution of your printer or mill. It’s much, much harder to simplify your model once it’s been sliced into GCode!

Slicing

Here’s where I was stuck for quite awhile. I really wanted to conserve mental energy here and remain within the workflow I’ve been using at my job (which involves fairly-complex 3d printing on a MakerBot Replicator). This means using Replicatorg, which I’ve found to be quite comprehensible (partly because I’ve been reading much of their sourcecode on Github because it’s in Java, which is much easier for me to understand right now than Python or other languages).
Replicatorg provides a wrapper for Skeinforge, which is a suite of Python programs that slice a 3d model file (STL) into a series of layers of GCode.

Once the GCode is generated, I use Pleasant3d to view the toolpath for each layer. This serves as a little sanity check to make sure the GCode generation process produced an output that looks like it will work.

Machine Control / Wiring
Wiring up the mill wasn’t very problematic for me, possibly because I have more experience with this part of the process than others. I’m using an Arduino Mega board broken out to a breadboard housing three Sparkfun EasyDriver stepper control boards. While this setup isn’t permanent enough to be proud of, it’s proven very reliable and easy to modify. One of the first things I’m planning to mill now is a single-sided PCB shield (based on the RAMPS boards by Reprap) to clean this part of the operation up!
For the Arduino’s firmware, I very slightly modified Triffid Hunter’s awesome Teacup firmware.

Custom Configurations
To use Replicatorg, I had to make a custom machine description file for my mill. This was so Replicatorg knows the dimensions of the axes, whether or not there are endstops, and so forth. Since the Zen is a pretty popular mill, I thought I’d share my machine file.
The most recent struggles I had (struggles which I finally overcame in order to make the cuts today) had to do with possibly the least-wise part of my workflow: using Skeinforge to generate the GCode for the mill. Skeinforge was developed mainly for 3d printing, which I’m sure you can imagine is a pretty different process to model. Though pretty well-known for being tricky to work with, I like Skeinforge because all the variables are broken out for you to edit and tweak – this is also true for the milling plugins it includes.
That said, this post was extremely helpful in providing me with some baseline values from which to begin. The biggest error I made today was improperly measuring the diameter of my endmill (I bought it as a surplus package, and it didn’t come labeled). I have my Skeinforge settings zipped up and saved here.
As for the hardware, I forked the excellent Teacup_Firmware for the Arduino and my version can be found here. The only change I’ve made is to the config.h file, and this might change as I consider moving some pin assignments around to fit a custom shield.

Conclusion
Though I’ve only just started actually making things, I’ve put a fair bit of time writing this in the hope that others who want to go this route will have this post as a reference. If you have any questions, please leave a comment!

First 3d printed Polytopes joints

AKA — Tue, 01 May 2012 14:23:31 +0000

Yesterday I printed out the first joints for my long-dormant “Polytopes” work – you can see some photos of the results above.

The end goal is to allow anyone to design a polyhedral light fixture like this via a web interface, and then order the printed parts and other components necessary to assemble it.

The source (along with the .stl file for these tetrahedral joints) is here.

How to gets Inkscape DXFs into OpenSCAD for 3d-printing/milling

AKA — Fri, 20 Apr 2012 19:06:33 +0000

I had a devil of a time getting Inkscape to export readable DXFs for use in OpenSCAD. Hopefully the time I spent figuring this out can save you some effort and frustration.
In a nutshell, the issue is that OpenSCAD cannot process curved lines (SPLINES), and Inkscape doesn’t have a straightforward way to export DXFs without splines if they exist in the graphic. So before exporting, you need to convert all curved lines to straight lines by adding enough nodes along the curve to roughly preserve its curvature.
This link contains all the actual steps to follow – disregard any talk of an Inkscape extension called Better Better DXF Export, as I was unable to get that package to be visible in multiple installs of multiple versions of Inkscape over multiple machines…

Getting PCB-GCode working in Eagle 6

AKA — Tue, 17 Apr 2012 23:14:14 +0000

One of the first things I want my CNC mill to be able to do is mill PCB boards – I am working on a couple single-sided boards that I’d like to use around the house for the solar setup, the garden, and even the mill itself.

I’m feeling pretty alone, though, as a Mac user who wants to mill PCB boards…it really seems like the major tools out there are Windows only. I know, you’re going to suggest I use cad.py from the Fab Lab folks, but I have seen that in use enough to know it’s too much trouble; I’d love to find an easier workflow that doesn’t go from Eagle to image to gcode (especially because I’ve heard many users remark that cad.py is also imperfect).

PCB-gcode looked like an ideal solution but I had a hell of a time getting Eagle to recognize it properly. The trick ended up being discussed here, although it took me several reads through for it to sink in.

The trick is, you need to unzip your PCB-gcode folder into the first folder listed in your PATH variable in the Eagle ULP line in the “Directories” dialogue. I’ve been really busy at work recently (just started a new job), so I haven’t actually milled any boards yet. But soon! I’ll post an update when I do.

As always, no original content here – I post things like this to summarize hours of forum lurking, highly-specific Googling, and sourcecode study. I hope it helps!

Custom machines in Replicatorg

AKA — Tue, 17 Apr 2012 20:33:19 +0000

I had a tough time (heh, I bet a lot of my posts are going to begin like that…) getting Replicatorg to see my custom machine file in recent versions of the software. Previously, around version 22, I had no problem dropping my machine_name.xml description file in a Replicatorg directory and then restarting the app to get it recognized.

Due to some recent updates on the way to the current version (034, as I write this), this process no longer works. After some headscratching, I arrived on this process, which has not failed me yet (although it is quite a pain if you change your machine.xml file regularly!). Basically, you need to reinstall Replicatorg and add your machine.xml file before your first run of the software.

In other words, follow these steps:

Download Replicatorg
Install the app (I’m on OS X 10.6.8, so I mount the DMG and drag it to my Applications folder. For easy versioning, I put it inside a folder identifying which version of Replicatorg it is, ie “Replicatorg 034″)
Unmount the DMG
Right-click on the app, select “Show Package Contents”
Add your custom_machine.xml file to Contents/Resources/machines
Start Replicatorg

I’m using a custom machine definition file for my Zen Toolworks 7×7 CNC mill running a RAMPS board powered by EasyDriver stepper drivers. If you’re interested, leave a comment and I’ll post the file.

Resuming this, probably.

AKA — Tue, 17 Apr 2012 20:00:25 +0000

Hi, I’m starting this site back up again – the goal is to provide a place where I can share what I’m learning at my job and in my spare time hacking on various projects.

I’m not going to philosophize often (I hope), but I wanted to begin by explaining what’s motivating me to resume blogging:

I’ve been a passionate hobbyist all my life. I love the communities that can form around almost any practice, from the arcane (gemcutting) to the revolutionary (3d printing, resilient communities). I think one of the more profound impacts that the internet has had on my life is that it can connect me to the state of the art in almost any of these wonderful communities.
I have a few people online who I really admire, and one trait they all share is their openness: they develop a rich presence online not just by posting but by helping. They share their work and thoughts, but take pains to make sure others can join in.
While I can’t purport to be the community leaders, software whizzes, or mechanical geniuses that my role models are, this blog is a step towards opening up and giving back to the communities I appreciate so deeply.

Here I’ll write about:

CNC build started

AKA — Sun, 05 Dec 2010 01:59:40 +0000

I’m building a 3d CNC mill, here is the (somewhat familiar) skeleton being assembled.

Thanksgiving brewing in NH

AKA — Fri, 03 Dec 2010 00:30:46 +0000

Dennis and I brewed a batch of 80/- ale this past Thanksgiving weekend. This is the recipe we used (the ingredients were my birthday present—thanks Dennis!). I wrote a small thermocouple datalogging sketch that would let us see the exact temperature of the brew throughout the process. Dennis made a quick graph in R:
As you can see, we were able to chill the wort quite quickly under the circumstances by continuously running cold water past the brewpot in the bathtub. The initial temperature change you can see between 170 and 180 minutes is a false reading, though, which we think happened because the thermocouple was touching the pot (which is metal and would cool much more quickly) rather than fully immersed in the wort.
After an always-tense 24 hours of no activity, the brew started bubbling away at a good pace by the time we left.

Here’s a timelapse of the brewing. It’s not too interesting. I took it because I thought we might be able to correlate the frames with temperature readings, but I never ended up setting up a good shot that would let us capture details like exactly when certain ingredients were added, etc…

Voronoi video v0

AKA — Sat, 20 Nov 2010 00:35:33 +0000

Voronoi video v0

Originally uploaded by AKA MEDIA SYSTEM

Quick update of what I did today after a lot of stalling.

Advertiser survey

AKA — Thu, 18 Nov 2010 17:47:20 +0000

Hulu’s survey just yielded me this gem: