A homemade and computer controlled pen plotter/milling
machine based on a treadmill with stepper motors

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A homemade and computer controlled pen plotter/milling machine based on a treadmill with stepper motors

Report by Stefan Spännare September 6 2016, latest major update November 11 2017.


Contents

1. Introduction
2. Summary of technical components and software
3. Computer program download and instructions New!
4. Some photos of the treadmill plotter/milling machine
5. Some videos of the treadmill plotter/milling machine in action
6. References


1. Introduction

Summer 2016 I came across a defective treadmill (Swe. promenadband) and got the idea
to make a computer controlled pen plotter of it with stepper motors. For some lucky reasons I
had the parts that were needed at home and they fitted surprisingly well to each other. Although
not originally belonging to each other. The resulting treadmill plotter turns out to be an almost
surprisingly well working technical device. Actually the mechanical setup of it was assembled
in less than a day.

I modified some of my old graphical computer programs for mathematical curves (se my old
ssdosmix.zip package for 32-bit OS) so an arbitrary milling machine or plotter can mill and
write them. For example a spiral, the Cocoon curve, a Dragon curve and Lorenz attractor. The
computer programs can soon be downloaded from this web page with instructions how to use
them. Perhaps I should already mention that a very fast PCI-DIO24 24-bit digital I/O board
(bought from JoR.se in Sweden) is used for the output signals from the computer programs
and desktop PC to the stepper motor drivers. The C-programs were compiled using Microsoft
Visual Studio Community 2015 (C/C++) which is very good and free for registred users.

November 2015 I made a CNC milling machine with a small coordinate table and stepper motors.
It has very high precision. Some images of this machine are shown soon below. Summer 2017
I sold these things again because the coordinate table was too small to be really useful.

The PCI-DIO24 I/O card is very good and fast but also quite expensive and a bit specialized.
There are USB 2.0 digital I/O cards available (for example Velleman K8055 and K8061) but
they are a bit too slow for these applications. An attractive approach would be to use a standard
breakout board with the parallel (or printer) port, but I am not so happy to program such a device.


2. Summary of technical components and software

Hardware for the treadmill plotter/milling machine

Software for the treadmill plotter/milling machine


3. Computer program download and instructions New!

Here are now C computer programs (with executables for Windows) for writing or milling
a spiral or a Dragon curve. Other curves will come soon. Read the readme.txt file carefully
as a whole before you start to use the programs. It is assumed that you have a PCI-DIO24
digital I/O card in your computer. And a suitable stepper motor controlled plotter or
milling machine. Treadmills and old electronic typing machines can quite easily be
converted to plotters. An experienced programmer can probably quite easily convert
the computer programs for other types of digital I/O cards.

tmprog.zip (1 MB, version 1.01, latest update 2017-11-11) New!

readme.txt (version 1.01, latest update 2017-11-11) New!


4. Some photos of the treadmill plotter/milling machine

Four photos of the treadmill plotter and the electronics taken with my mobile.

New! Three images of the coordinate table milling machine. The Proxxon KT 150 has
a moving range of 150 mm x 150 mm. The steppermotors and drivers are exactly the
same as for the treadmill plotter band motor (500 steps/rev and 1 mm/rev on the
coordinate axes). In the last image the small extra table is seen that is a holder of
the milling spindle motor. This motor is for the moment on the treadmill machine.


5. Some videos of the treadmill plotter/milling machine in action

Two videos of the treadmill plotter writing a spiral and a Dragon curve of order 8. Here the
machine is still on the floor and with the high handle part not sawed of. The files are large
so perhaps you better download them to your computer desktop.

spiral1.mp4 (50 MB, about 75 seconds long)

spiral1-hd.mp4 (Full HD 154 MB, about 75 seconds long)

dragoncurve1.mp4 (148 MB, about 223 seconds long)

dragoncurve1-hd.mp4 (Full HD 455 MB, about 223 seconds long)


6. References

ELFA A nice electronics component shop in Sweden
JB CNC Everything for your CNC project in Sweden
JoR Measurement A place to buy very good I/O cards for PC and much more in Sweden
Microsoft Visual Studio Community 2015 A very good and free programming environment with with C/C++ and many other languages


Author: Stefan Spännare
E-mail: stefan.sp@hotmail.com
Document created: 2016-09-06
Latest update: 2017-11-18