New Products for Fall 2010 - PCB Milling Accessories

One of the fastest growing trends we are seeing is the rapid decrease in the cost of hobbyist grade CNC mills and their corresponding increased use in milling custom printed circuit boards. This used to be the exclusive domain of high end equipment manufacturers like T-Tech and LPKF and you would expect to spend upwards of $30-60k for one of these systems.  Now you can buy a small CNC router/mill for less than two thousand dollars and the necessary software for a few hundred dollars.

Having consulted to customers on the purchase and selection of these machines in the past I would usually advise against it. You can prototype a LOT of printed PCBs for that kind of money. There is also the misconception that they are faster and easier to produce a prototype board. When you consider the fact that you are limited to 2 layer boards, have manually solder vias and the sheer amount of time it takes to set up the machine, change tools, calibrate the cut width, watch the milling process, flip boards,  align the back side and do it all over again it can take up the better part of a day assuming you get a usable board out the first time. My feeling is that could be used for other more productive activities while waiting for your ready-to-go board to come back from the vendor. Unless you have interns, that is.

That being said, one of the new toys here at Celeritous is a new 3D CNC mill and we naturally had to experiment with using it for PCB milling. That of course involved finding sources for all the various tools and accessories. When our engineering interns from Texas Tech University saw it they commented that the Engineering department owned a T-Tech machine that students used regularly and that students were responsible for supplying their own tools.  It has been impossible to find tools for the mill locally.  Most online tools suppliers for thing like milling, routing and drill bits had minimum orders or long lead times, so we decided we would start carrying a limited selection of common tools for our local customers and offer them online as well.

As usual one thing leads to another and before we knew it we had a wide range of new tools and accessories for the mill, particularly for producing circuit boards. As with all of our other tools for electronic prototyping and assembly we share not only our knowledge and experience, but also the tools themselves.

Our initial offering falls into 4 different categories of PCB Mill tools, accessories and software. These include:

PCB Milling Tools

Our offering of milling tools include both high-end durable carbide tools for regular users and low cost high speed steel (HSS) tools for occasional users. We have a variety of routing bits for cutting out PCBs as well as routing larger holes. We also have a variety of V-Cutter style milling bits for copper etching ranging from 10 degree angle for very fine cutting to 60 degree angle for wider cutting and copper removal from larger areas.

PCB Milling Setup Tools

There are some essential tools for PCB milling and some that are optional, but make setting up much faster and easier.

One of the tools we consider to be essential is our 25X pocket microscope with reticle scale and LED light. One of the most tedious things in setting up a PCB prior to routing is calibrating the width of the cut. This handly little microscope make this job a breeze and can be used without removing the board or changing the setup. With its built-in 0.5mm scale, a test cut can rapidly be measured in-situ and adjustments made.

A handy, but not essential tool is our pocket digital laser tachometer. This tachometer has a wide (29-99,9999 RPM) range and can be used to measur the spindle speed as well as drive axis speed which helps in calibrating the Mill and cutting speed.

PCB Milling Software

To produce mechanically etched PCBs you must have three key pieces of software:

1. Software to lay out the PCB and produce Gerber files - generally in RS-274X format
2. Software to convert the Gerber files into GCode format for most CNC mills
3. Software to control the CNC mill, generally based on interpreting GCode files

We already use a well known PCB layout program to create layouts and generate Gerber files and a copy of the ubiquitous Mach3 software came with our mill to control it.  Our most difficult task was finding a solid, low cost program to convert the Gerber files to GCode. We finally settled on a program called CopperCAM which we found to be mature, well thought out, intuitive and easy to use. It comes with a demonstration mode that allows the full range of features to be explored with the sole limitation of limiting the number of output paths it will generate , similar to the Mach3 demonstration mode.

We are proud to announce that Celeritous is now a distributor for the CopperCAM program. It is available as a free download to evaluate and when you decide to purchase a license we can process the payment and provide you a license file.

Pre-Plated PCB Copper Clad Stock

If you have done any homemade printed circuit boards, be it by mechanical or chemical means, you know copper oxidizes as fast as you can clean it and soldering fine pitch surface mount components can be difficult whether done by hand or reflow processes.  Anyone who has experimented with the chemical tin plating knows it is almost useless and as messy as chemical board production. We searched around and finally found a vendor that could provide us with solder plated PCB stock so it can be mechanically etched and is immediately ready to solder without laborious cleaning and gobs of flux. We offer a number of standard pre-plated board sizes for you use.