Roland Modela MDX-20 PCB milling machine is an awesome piece of hardware. This machine can be found in any FabLab around the world. It can be used for scanning 3D objects, making 3D shapes and finally making Printed Circuit Boards (PCB). This machine was recently purchased by our professor Dr. Prabhat Ranjan. As we wanted to use this machine in one of our projects, we had been given the task to run the machine. I had once used this machine in COEP FabLab, but had never used it on my own.So heres how to do that.
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| Modela MDX-20 in the Lab |
Searching for ‘Modela PCB’ gives numerous results and I too found out 4 different methods to do the same, One of the method was to use a .png image and generate a dxf and send it to the printer. Other method used the cad.py script to visually set the parameters and send the file to modela. It used Python Imaging Library.
I used Marc Boon’s method for sending the files to modela and it worked perfectly. The same method is described in http://mlab.taik.fi/paja/?p=1874
Links:
Marc Boon method: http://fablab.marcboon.com/pcb/index.html
Manchester Fablab: http://www.fablabmanchester.org/p66/Eagle-To-Modela-Program.html
Today finally we tested and made a demo board using the above said method. I was happy as this will definitely
help us in our project.
Few important things to be kept in mind:
1. Give offsets correctly. The circuit is mirrored and so don’t mess up the PCB.
2. Set the Z point manually. i.e. Touch the tip of the drill bit on the PCB and then tighten the screw.
3. Each drill size has different Design Rules (.dru) files. So, be sure of the drill bit. Also use proper bits.
4. Always use a sacrificial board beneath the PCB.
5. A particular problem we faced was that the buffer capacity of the machine was less. We were using USB to Serial converter(FTDI chip) and hence the whole file was not completely read. Hence, we had to send the data in small files.
More tips and tricks will be posted soon after we make our real project PCB.
You need to use a real serial port that does hardware flow control (RTS/DTS) properly, otherwise when the roland buffer fills up, commands get lost of the host keeps sending more data. USB serial adapters usually do not do RTS/DTS at all (and the few which do it, still don't do it properly - they send a few more bytes even after the printer says pause)
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