Aug 3

So updated to windows 10 before I realized that they had switched to the google / facebook business model (ie you pay with letting them have all your data).  If you upgrade be sure to read about what you are actually paying for the ‘free’ software.  Unlike a social media site or an email your operating system knows absolutely everything about you.  Their new feature gives away your wifi password to everyone you every ‘connected’ with online. You know so that old ex-boyfriend can sit in front of your house and use your wifi.  Not sure I trust them with my password, if they can’t even make a feedback form that works…




Sep 24

I have been working on a Arduino Shield to run my Reprap CNC, egg-bot and etch-a-sketch bot.  It is a mount for 3 Pololu stepper drivers, 2 power MOSFETS, and two servo connections, or 6 end stop connections.


IMG_5226[1] IMG_5231[1]

The schematic of the board is here: Schematic.

PCB Layout: PCB

KiCad files are here: arduino_rev2 – Copy  (note that this might require some KiCad library’s that are not standard)

KiCad output files: output

Sep 23

After making a couple of 3D printers I thought it would be fun to make a CNC machine.  I liked the idea of using the reprap software tool chain (I hate the word tool chain, but you know what I mean, series of software and firmware) to run my CNC.

If you think about it a CNC is very much like a 3D printer, in the sense that it is a simple 3 axis bot.

The idea is to build a machine that other people can also build easily.  So I didn’t want a lot of measuring, or cutting, and no machining.  I wanted to print all of the dimension critical parts.  That way I can use the 3D printer for all of the hard parts.  And I wanted it to be cheap.



This is the first version I built.  It uses a Dremal as the spindle.  Notices that the work pieces moves, like a Mendel 3D printer.  I found that this setup doesn’t work very well.  I have an excessive amount of play in both the spindle and the bed.

The dremal also seemed under powered, and had a lot of trouble cutting.  Maybe I was using bits that were too cheap.

I upgraded to a real router, and fixed the bed.  I also moved to roller bearings on a fixed support to improved the rigidity of the whole structure.  One of the problems with this design is it uses a LOT of plastic.  Also some of the prints are like 8 hours long.  That can cause problems if you have a printing glitch.



IMG_5216[1]IMG_5218[1] IMG_5222[1] IMG_5221[1] IMG_5220[1]


Jul 5

I have always hated etch-a-sketches.  There I said it.  It is impossible to draw anything good on one.  Well I can’t.  Just google “etch a sketch artist” to see the truly amazing things other people can do.

I decided I wanted to be that good too.  So I made a robot to do it for me.

More information at thingiverse.

Basically it is just a egg-bot hooked up to a etch a sketch.





May 4

This weekend I am  participating in the Austin mini maker fair, with a booth called “How to make a 3D Printer”.   So how DO you make a 3D printer?  I am glad you asked.   I think the first step is to understand how a 3D printer works, and then we can go from there.

What do you mean by 3D Printer?

While there are a number of different types of 3D printers, I  will be talking about Fused Deposition Modeling (FDM) only.  There is a bunch of good information here:

From wikipedia (FDM_by_Zureks.png)


Fused Deposition Modeling (FDM) is an additive manufacturing technology commonly used for modeling, prototyping, and production applications.

FDM works on an “additive” principle by laying down material in layers. A plastic filament or metal wire is unwound from a coil and supplies material to an extrusion nozzle which can turn the flow on and off. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism, directly controlled by a computer-aided manufacturing (CAM) software package. The model or part is produced by extruding small beads of thermoplastic material to form layers as the material hardens immediately after extrusion from the nozzle. Stepper motors or servo motors are typically employed to move the extrusion head.

The Brain

Arduino Mega (wikipedia)

The brain of my 3D printer is an Arduino Mega.  The Arduino Mega is based on an ATmega2560 microcontroller.  From the microcontroler site:

The high-performance, low-power Atmel 8-bit AVR RISC-based microcontroller combines 256KB ISP flash memory, 8KB SRAM, 4KB EEPROM, 86 general purpose I/O lines, 32 general purpose working registers, real time counter, six flexible timer/counters with compare modes, PWM, 4 USARTs, byte oriented 2-wire serial interface, 16-channel 10-bit A/D converter, and a JTAG interface for on-chip debugging. The device achieves a throughput of 16 MIPS at 16 MHz and operates between 4.5-5.5 volts.

The Arduino mounts the microcontroller on a board and adds the necessary components (i.e. voltage regulator, USB plug, etc) to make it very easy from the hobbyist to use.

There are a great number of 3D printers out there, but they mostly use the same microcontroller, so they are functionally the same.  Same speed, same memory, etc.  I like the arduino because it is built to be accessible, and there are a lot of online support (forums) for any trouble you have.

The Extruder

In order for the 3D print to build a part from plastic is must extrude molten plastic.

More to follow… 



The Motion of the extruder nozzle powered by a stepper motor and pulley system.  The stepper motors used in my printer are size Nema 17 (1.7 inch face).  They are rated at about 1.2 amps.  Note that the NEMA rating is a size not a power rating.  The stepper motors are powered by a controller that limits the current, not the voltage, so the current rating on a stepper motor is the number you are most concerned with and you can mostly ignore the voltage rating on the motor.

Stepper Motor (

GT2 Kit from

The pulley I use in my printers are GT2.  Which means the teeth are 2mm apart.  This is a metric timing belt.  There are english unit timing belts out there, but the GT2 is pretty standard on 3D printers.

Apr 24

I just wanted to remind myself of projects I am currently working on. Note that all of these projects are meant to be open-source (I just need to get around to writing them up).  When they are release they will be licensed as CC-SA-BY which means basically that you can use and modify the design even commercially as long as you attribute the work (I am so vain) and keep the project open source (see Creative Commons site for details).

  • Finucane Derivative 3D printer – All of the build information will be mirrored here
  • Finucane Derivative Eggbot – I will be updating the project information here
  • Self Watering plant – I haven’t posted anything on this project yet.  It is a bot that uses a arduino + Wifi + temperature, water level, and light senors to keep a house plant alive.
  • Wifi rover bot – Arduino + Wifi to control a little bot around you house (well at least within wifi range).  I have a Python script to feed controls use UDP protocol.
  • 3D image capature – An ardunio controled rotating bed which rotates a small object. Then using opencv capatures a series of images to be uploaded to 123D

Projects that are in the planing stage

  • Wifi Ramps – Wifi adaptor for a 3D printer.  It plugs into the RAMPS Arduino Mega Shield. PCB project here: (link may not work)
  • Wifi + SD card shield for arduino – Once the wifi ramps project is done I am planning on making a shield with the wifi and a micro SD card.  The idea is kind of a Internet-of-things shield

Projects not yet in the planning stage

  • Arduino Venting machine  
  • Arduino Mega pinball machine
  • Arduino powered toy excuvator – Uses hobby serveo and hobby dc motors
Apr 4

I am mechanical engineering by trade, and do this as a hobby on the side.  I recently moved to Texas.  In Texas you can’t use the word “Engineer” to describe yourself or your business until you are registered by the state.  Which requires a bunch of paper work and a long test that is only offered a couple times a year.  So until I do get registered in Texas, I had to change the name of my LLC.

It is now call Finucane Design LLC.

Mar 29

1. Arduino Fireware –

Things for you to update:
Double check your pins:



*/#define XAXIS_DIR_PIN 7

#define XAXIS_STEP_PIN 8

I updated the fireware so that a step of the motor is a pixel from the artwork in inkscape. A couple of issues make this confusing.  First not all stepper motors have the same step size.  Typically motors have 200 steps/rev or 400 steps/rev.  For a 200 steps/rev (aka 1.8 degree) motor the steps per px (px are from inkscape) is one to one.  But if you have a 400 steps/rev (aka 0.9 degree) motor then you need to take 2 steps per px.  I set this in the firmware with the following line (It was originally used to set the number of steps per mm).

  steps_per_mm = (int)(kStepsPerRevolution/200);

You can see that setting KstepsPerRevolution = 200 the steps_per_mm come out to = 1.  Or set KstepsPerRevolution = 400 for a motor that takes 0.9 degree steps, so the steps size per px with match with both a 0.9 degree motor or 1.8 degree motor.

But after playing with it I found that for the aspect ratio on the image to work, I needed the px’s to be twice as wide as they were tall.

The printing area on the egg uses about a 1/4 turn of the pen motor and a complete turn of the egg motor.  So for a 200 steps/rev motor that works out (with the 16x mircostepping) to a  800 steps tall and 3200 steps wide (around).  I found that if you match 1 px to 1 step the image on the egg comes out tall and skinny.  But if you use 2 steps for every pixel around the egg (the egg motor), then the image on the egg looks about right.  But now your image needs to be 800 px by 1600 px, otherwise as you take 2 steps per px around the egg it will spin twice with a 3200 px wide image.

For my setup with one 400 steps/rev motor, I set both motors to 2 steps per px, by setting the steps per rev for both motors to 400.  This isn’t a great way to do it.  I will update this soon.  This works because the pen motor in my step up really has 400 step/rev, and the egg motor is 200 steps/rev but steps twice per pixel.



2. Inkscape Gcode Exporter –
(Updated to export gcode in px (use 800 x 1600 for best results))

3. –
(Updated for Com 4 and baudrate to match arduino firware)

You will need python to run the file

I used pololu stepper drivers (like from a mendel). More information can be found

You can look in the firmware for the pin outs. Each driver gets three pins: step, direction, and enable. More information can be found Note that I found that for 16x mircostepping the MS pins needed to be pulled high, not low.

Unlike other eggbots I found mine works better at 800 px by 1600 px, using two px in the X for every one px Y. X being the egg motor, and Y is the pen motor.


Mar 25

So just in time for Easter this year I put together a egg painting robot, aka “Eggbot”.  The original idea comes from, and was created by Bruce Shapiro in 1990.

Eggbot original from

Eggbot original from

They sell kits for about $200.  Unfortunately they are not open sourceI wanted a open source version to play with, so I thought I would put together my own.   (sorry I didn’t realize it was opensource, source files here).  It turns out a couple of people beat me to it. 

The sphere-bot is a project at Pleasant Hardware.  There are designs and software posted so it is basically open source  which is great.

Sphere bot from Pleasant Hardware

Sphere bot from Pleasant Hardware

There is a post at thingiverse for the sphere bot by Zaggo.  It is a good design, it uses an Arduino (which I like) and pololu stepper drivers (which I also like). Unfortunately is made primary from MDF.

Zaggo original firmware for the Arduino is posted on github.  I have added a fork / branch here.  (this is my first github branch, so I hope I am not doing it wrong)

A printable version of the spherebot created by Glasswalker is on thingiverse.

Image from

Image from

This design uses 8mm (5/16″) threaded rod and bearings, 3mm and 4mm bolts.  This is similar to the design fo the mendel reprap 3D printers.

There are a couple of problems I found with this design.  The first problem is that the center of the latitude motor (the one that only goes back and forth) is in line with the center of the egg. That works fine for a real sphere, but causes problems for a egg.

The second problem is that there is no linkage between the servo motor and the pen mount.  My sevro arm was too short to even touch the pen mount, so the servo wouldn’t disengage the pen.

I used the sketchup files provided on thingiverse to make updates to the printable design.

Sketchup Model

Sketchup Model

I added a mount for a prototyping board that I used to mount pololu drivers.

 See thingiverse for more information on printed parts.




Please excuse the Texas text, it for my in-laws.

Jan 24

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