OSH Park Docs
GerbV Gerber Viewer
GerbV is a simple, free, open source program that lets you view and edit files in the RS-274X gerber format. In particular, GerbV matches exactly what our system will see, so it’s very useful for troubleshooting when your design is rejected with an error, or something looks wrong on your preview images.
If you’re having trouble, just send us your files at email@example.com and we’ll help out.
The Gerber format is the industry standard way to describe the layers of a printed circuit board. We require files in the newer RS-274X Extended Gerber format; the older RS-274D Standard Gerber format is deprecated and we can’t accept it.
Since Gerber files are just text files, they can be opened and edited in your favorite text editor. The standard does call for all gerber files to end in .gbr, but we have an automated system that depends on the file extensions to detect the individual layers correctly.
Ucamco, formerly the Gerber Systems Corp, maintains the complete Gerber Format Specification (PDF).
Verifying Your Design
Most CAD tools have a Gerber viewer included so you can double check your gerbers, but each program tends to interpret the standard in a slightly different way. GerbV in particular matches exactly how our system will interpret your files, so we recommend giving them a last look using our checklist.
Sometimes, a CAD tool will output the gerber layers with extra symbols, board outlines, or alignment points that can’t be removed by changing a setting inside the tool. In this case, the easiest option is to open your files in GerbV and modify them. You can move and rotate layers relative to each other, and you can delete objects from layers entirely. We have some examples here.
Adding a Board Outline Layer
You can create a board outline layer by copying another layer, deleting everything that’s not the board outline, and saving the file. Here’s a tutorial.
Modifying Drill Files
The most common issue we see with design files is an internal error due to the precision of the drills file. Our system expects to see an Excellon/NC drills file exported with 2:4 inch (3:3 metric) precision, but many CAD packages output with 2:3 or 2:5 by default. Here are instructions to change the precision.
Things that crash GerbV
There are a couple of known issues that will cause GerbV to immediately crash upon opening your design files, which is important because they will also cause internal errors in our system. Check out our list of them with solutions.