Saturday 31 March 2007

Chicken and Egg

The problem with making machines that make themselves is how to make the first one! A bootstrap machine has to be made by hand first. This has come to be known as a RepStrap machine in the RepRap community. Lots of people are trying different approaches using whatever materials are easy to come by locally. Wood, Lego, Meccano, copper pipe and drawer slides have all been used by different RepStrappers. The machine needs three axes of motion and an extruder head to extrude molten plastic filament. Most RepStrap machines use threaded rod as a means of creating accurate linear motion from a stepper motor for the axes.

This was the approach I was planning to take when I started looking at this in mid January. I had a look at how professional CNC machines are put together and saw that the prices are a lot more than I wanted to pay but the accuracy and speed was a lot better than I could hope to achieve with drawer slides, etc. I had a quick look around to see if I could get anything second hand or from the surplus market. To my surprise I found an XY table on ebay for $400 which has a super small step size of 6 um but is able to move quickly and has very high stiffness.

This gave me the idea that I could make a very accurate machine that is also stiff enough to do milling. I found a Z axis on CNCzone for $150 and the project was born.


  1. Hi nophead,

    I have some question about controller table.
    1/ If you rebuild it from scratch ?
    2/ Use an alternative model (I think so)
    3/ Coil impedance of stepper motor, max current ?

    All these question because I can buy one but shipping is very expensive with original controller.

    Please reply to my email nplanel a t gmail dot com.

    PS: Great blog very useful experience feedback and very precise !

    Best Regards,

    Nicolas Planel

  2. Hi Nicolas,
    The XY-table came with stepper motor controllers that take step and direction signals details here. I connected them to a microcontroller details here

    The motors are 5V 1A so the coils are 5R.