Starvin Larry

by stuartChilds

Think of the possibilities,this isn’t all that difficult. Tabletop milling machines are available for a reasonable cost,and are easily upgraded.

 

Compact CNC machines have been around for a long time and there are affordable and often well built units available to buy from surplus suppliers and via auction. Provided a machine is of good quality and has not been abused the hardware will likely work for many years to come.

Though the mechanical side may be serviceable it can be a different story when it comes to the software; the machines may not come with their original control computers, if they do this may not boot or may be missing the security ‘dongle’ for the control software. In addition there have been numerous improvements in motor drive technology in recent years.

We have a Denford Novamill 3-axis mill that came with a rusty old computer that did not boot up. From initial inspection the mill itself looked promising, leaving us with the challenge of connecting a new computer with new software to run the machine.

In this first post we will determine how our machine is wired and bring it up to date with new stepper motor drive electronics, and with a brand new embedded control computer.

Note that CNC machine control cabinets often have dangerous voltages present so care must be taken when working on them.

Out with the old

Inside the control box

Fortunately for us, Denford provide plenty of documentation for their old machines, facilitating modification and repair. They also have an active forum where people discuss their machines and changes they have made. This was incredibly useful when researching updates for the Novamill.

The original control board was removed as it is designed to work with the original, proprietary software via an RS232 connection. This sits on top of a larger board with the electronics to drive the stepper motors. Whilst it would be possible to interface with the old driver board, it was instead replaced with modern higher performance driver modules, the Geckodrive G201X.

The original control board

Next it was determined that the control PC was to be replaced with a much more compact solution: a BeagleBone Black and Probotix breakout board. This will allow use of LinuxCNC, an open source machine control software. It also has the added benefit that the control computer can be placed inside the cabinet.

Fitting the stepper drivers

Read the rest here

Part II here

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