Protel 2.8 to G-Code to drive a CNC Router

Create G-Code for CNC Router from Protel 2.8

Not that hard once I spent a couple of weeks researching the subject.

In Protel 2.8.

I will cover single layer first.

Open the pcb you wish to use.

From the menu select File then Gerber.

In the Film Sizes set the Border Size to zero.

In Batch Mode select Separate File For Each Layer.

In Plotter Type select Raster .

In the Options block tick Use Software Arcs and Embedded Apertures

but centre plots on film must be unticked the G54 on Apertures Change seems to not matter.

I left the format set to 2.3.

Next click the Aperture Button then click Create List From PCB.

My Maximum Aperture Size was set to 250mil (Yes I am still using Imperial not metric).

The Generate Relief Shapes and Flash Pad Shapes were both ticked.

Click Close takes you back.

Then click the options button (bottom of window).

Check that only the Copper Trace Layers(Bottom or Top) and Mid Layers(Include Unconnected Pads) are ticked.

Click OK to return.

Click OK to create the .GBL(bottom layer) or .GTL(top layer) file.

I create a directory Named Gerber inside my project file and save the above output there.

Next from the menu select File then NC Drill and save the output to the same directory.

Click OK to create the .TXT file.

This file is of no use until you run GerberFix a Program I created.

Load GerberFix.

You can download it by clicking on the image below.

Run the program the file is then fixed.


Next download FlatCAM software.

Start FlatCAM.

From the menu select File then Open Gerber.

Select from the directory where you saved the gerber files (Your Project).GBL or GTL.

From the menu select File then Open Excellon.

Select from the directory where you saved the gerber files (Your Project).TXT.

You should now see a mirror image of your PCB with the drill plot overlayed.

Next click on the Project tab and select your .GBL or GTL file.

Now click on the Select tab and scroll to the bottom.

If the drill plot and the copper plot are not aligned exactly you can adjust the alignment using the offset.

Just above this is the Bounding Box click on Generate Geometry.

If you are using the bottom layer do the 5 extra steps.

    1. In the main menu select Tool then -> Double-Sided PCB Tool.

    2. In the Tool tab you should see in Bottom Layer your .GBL change Mirror Axis to Y and Axis Locator to Box.

    3, Click on Mirror Object.

    4. Click the dropdown on the Bottom Layer box and select the .TXT and Click on Mirror Object again.

    5. You should now see your plots with correct bottom view now to setup cutout.

Select the Project tab and select your .GBL again or .GTL.

Now click on the Select tab again.

See the Board Cutout I set the Margin to zero.

Set the gaps to 4 and click on Generate Geometry.

When my CNC router kit arrives I will complete these instructions.

The total cost of my CNC and tool bits is under AU$350.

My appologies the kit arrived with two broken sliders.

I assembled it assuming I would be able to get replacement parts.

I was able to test the software and it worked perfectly.

I got stalled and given the run around and after several months I finally gave up.

I disassembled the CNC packed it up returned it at a cost AU$100 my expense.

About another month latter I received a refund of the AU$350 but not the return cost of AU$100.

Lesson learned! Make sure you are dealing with a manufacturer who will supply spare parts.

I have now found a supplier who will produce a small run of PCB's cheaper than I can purchase a blank board and I get them back in about a week even in these difficult times.

I will purchase a replacement CNC but now have no urgency.