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PCB Milling Updates

My PCB milling work flow is working well for single sided boards with through hole components. I am still working on support for surface mount devices and double side boards but the capability I have now is enough to speed up the progress on my queue of projects. This post is a general update on what I have been doing with that capability. I saw this tip on a blog post mentioned on Google+ but unfortunately I can't find the original link. Essentially you take a block of wood, drill some largish holes partially through it and use it to keep the tool bits you need for the particular task you are…

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Seven PCB Milling Tips

After a lot of weekends of trial and error I finally have my PCB milling process working. In this post I share some things I have learned along the way - hopefully it will make it easier for anyone else trying to develop the same process. 1. Be Consistent This is one of the most important factors to get repeatably reliable boards. It's very tempting to just tape a board down randomly and start milling - but the next board might not be in the same place and you wind up with very different results. Your goal should be to minimise the number of variables as much as possible - use the same size bl…

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CNC Probing

When you are milling PCBs with a CNC having a level surface is extremely important and can be very difficult to achieve. This post describes some of the techniques I used to get a level surface so I could mill PCBs with reasonable quality. Milling a PCB requires cutting away just 0.05mm of copper (or less) from the surface. If you cut too deeply you will damage the cutting tool tip and, due to the arrow shape of the cutting tool, make your isolation cuts too wide - reducing the width of the resulting tracks. If your cut is not deep enough the tracks will not be isolated and your board will hav…

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CNC Updates

It has been a long time since the last post but I certainly haven't been idle in the Lab. Most of my time has been spent working on my larger CNC machine (a CN3020T) including a number of control board redesigns and fine tuning a PCB milling workflow. In my last update I described a simple ATmega328p based board running GRBL. That worked fairly well to control the small linear stepper assemblies I bought on eBay so I decided to use a similar board to control my larger CN3020T machine (which I've been having problems with for a while). To actually drive the stepper motors I bought a set of sing…

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A Simple CNC Machine - Part 3

Another update on my mini-CNC project - progress has been a little slower than I hoped for but I've reached an important milestone now - moving motors! As you can see there are some issues with the precision of the movement - each of those moves is supposed to be 20mm. It doesn't quite make the full 20mm and doesn't return to the same starting point. I'll discuss those issues later in the post but first I would like to talk about the circuit itself. I intended to use the GRBL firmware from the start which requires an ATmega328p with an external 16MHz oscillator. The circuit I used is a basic m…

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