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To grid data with faults, you need to have an XYZ data file that you want to grid in addition to a BLN file that defines the fault traces.

There are many ways to create a BLN file of the fault traces:

1. If you have them already saved in another format (ie. SHP or DXF), you can use the Map | New Base Map command to load the faults as a base map, then turn off the axes in the Object Manager by unchecking the check boxes to the left of the axis name, and use File | Export to export to a BLN file.
2. If you know the coordinates of the fault traces, you can type them in the Surfer worksheet, be sure in include a header row above the coordinates for each individual fault trace (the header row only contains the number of points in the following polyline in Column A), and use File | Save to save to a BLN file.
3. If you can visually pick out where the faults should go on the map, create the map, then right click over the map and go to Digitize. Digitize the starting and ending points (and any points in between) of each individual fault. The coordinates of each click will be entered into a text editor window that appears. After digitizing one fault line, and before digitizing another one, insert an empty space in the text window. Therefore, the digitized data for each fault is separated from other faults with a blank row. When you are done digitizing the faults, go to File | Save As in the text editor window and save the coordinates to a BLN file.
4. Some more instructions on how to create a BLN file can be found here: http://www.goldensoftware.com/activekb/questions/674
5. Be aware that faults can greatly increase the gridding time. We recommend that as few points as possible exist in the fault BLN file, preferably under 100 points. The more points you have in the fault file, the longer it will take to grid the data.

Once you have a BLN file that defines all the fault traces, you can grid the data with the fault file:

1. Go to Grid | Data.
2. Select your XYZ data file and click Open.
3. In the Grid Data dialog, select the X, Y and Z data columns.
4. Choose a gridding method that supports faults (Inverse Distance to a Power, Minimum Curvature, Nearest Neighbor, or Data Metrics). I recommend starting with either Inverse Distance to a Power or Minimum Curvature.
5. Click the Advanced Options button.
6. In the Advanced Options dialog, go to the Breaklines and Faults tab.
7. Click the open yellow folder icon to the right of File Containing Fault Traces, select the BLN file created above, and click Open.
8. Click OK to get back to the Grid Data dialog.
9. Specify any settings you wish in the Grid Line Geometry section and click OK to create the grid file. The grid file will contain the fault data and you can use it to create maps in Surfer.