If a line is printed twice, as part of two different laser tracker placements, and the two lines don’t match, there are two possible groups of causes: Stationing Issues and FieldPrinter Issues. 

Stationing Issues are more common and can occur when the Laser Tracker’s position on site was not established well, either due to physical control point positions not matching layout control positions, or inconsistent scanning methods.

FieldPrinter Issues are less common and can occur if a FieldPrinter is damaged due to inappropriate handling, resulting in deviations relative to the established position of the laser tracker. A printhead calibration process can compensate for small mechanical deviations over the life of the FieldPrinter.

First, check for FieldPrinter Issues. Check that the FieldPrinter is printing correctly relative to the current stationing:

1. Place the Reflector directly on an existing line on the floor printed during this stationing, such as a printed trade line or layout line.
2. On the Dusty app, zoom in on that area of the Dusty app canvas.
3. Confirm that the Reflector icon sits in exactly the same place on the screen as the Reflector on the floor.

If the reflector icon matches the lines from this stationing, the FieldPrinter is printing consistently and is printing where your control point says it should, and the fix is in your control points. Otherwise, follow the steps outlined below on how to run calibration or contact support to assist with recalibration.

If the FieldPrinter is indeed printing consistently relative to the current stationing, there is likely a Stationing Issue. For more, see Best Practices for Recording Control Points in the Field and ensure you are stationing consistently.

The FieldPrinter does not guess or stretch the layout to fit. It uses a best-fit alignment across all recorded control points, which makes problems visible instead of hiding them.

How to fix control point errors

Work through these steps in order. Step 1 confirms the FieldPrinter matches the floor and your control points. Step 2 checks the FieldPrinter's calibration. Step 3 confirms the FieldPrinter prints the same line in the same place. If all three pass, the problem is the way the control points were recorded.

1. Confirm the FieldPrinter matches the floor and your control points

If you've stationed the system and the FieldPrinter still prints "in the wrong spot," first confirm that what's on the floor matches what's on the Dusty app. These two checks take a couple of minutes, and they tell you whether the problem is the FieldPrinter or the control point.

Check each control point:

1. Set the Control Point Target on a control point, with its center crosshair lined up over the mark on the recorded control point.
    

   

2. Seat the Reflector in the target's center hole, and make sure the laser tracker is locked on.
    

   

3. On the Dusty app, zoom in on that control point.

4. Confirm that the Reflector icon sits directly on top of the control point. The lines should overlap and meet at the same center point, like the example below.
    

   

5. Repeat for every control point in the station.

What the results mean:

• Both checks pass: the FieldPrinter is printing exactly where your control says it should. Confirm the FieldPrinter's calibration in Step 2. If the calibration is good too, the problem is in the control itself (the points, the survey, or how they were recorded).

2. Print an overlap test to confirm the FieldPrinter prints accurately

Once Steps 1 and 2 check out, confirm that the FieldPrinter prints the same line in the same place every time. Use the same stationing for the whole test, so the FieldPrinter is the only thing being tested.

1. Pick a new line in a clear area, such as a line that runs North to South. Don't use a line that was already printed, especially one where you first saw the shift.
2. Print the new line North to South with the left printer.

3. Print the same line again with the left printer South to North, and check that the two prints overlap exactly, with no second line or offset visible.
    

   

   
    

4. Repeat the test with the right printer on another new line, also printed North to South.

3. Run calibration patterns on the FieldPrinter

Before you rework your control, rule out the FieldPrinter. Calibration patterns confirm that the FieldPrinter itself is printing accurately. If your error values are low and evenly spread but the layout still prints rotated or shifted, this is the most likely cause.

• Clear a flat, clean, open area for the FieldPrinter to run calibration patterns. 
• To run calibration on the left printer, follow the steps below:
  • On the left side of the Dusty app, click Settings.
  • Toggle off Automatic.
  • Select Left.
  • Do the same for the right printer.
• In the Dusty App, at the top right corner, click your first and last initials, and then click Preferences.
  • Click Advanced Settings.
  • Click Calibration Patterns.
  • Finally, select Calibration Patterns.
• Let the calibration finish without moving the FieldPrinter or blocking the laser tracker's line of sight. 

The example below shows the result of a good calibration. The lines cross cleanly at a single center point, and the square and target print sharp and square. 

The earlier layout was printed from a different stationing, so comparing new prints against it tests the old stationing, not the FieldPrinter. Fresh lines printed from one stationing isolate the FieldPrinter. Testing both the left and right printers confirms that each one prints accurately.

If the lines overlap for both the left and right printers, and the measurements match the drawing, the FieldPrinter is printing accurately and repeatably. 

For more detail, see:  How to Select Control Points for Better Stationing Accuracy, How to Verify Control Point Accuracy After Stationing, and How to Use the Control Point Target to Place the Reflector on a Control Point.