DMBot Calibration Guide

Proper calibration is essential for high-quality drawings. The DexArm needs to know exactly where the paper is and how high to hold the pen. This guide covers all calibration procedures.

When to Calibrate

Calibrate your DexArm:

• First time setup -- Always calibrate during initial installation
• After moving the robot - Any change in robot position requires recalibration
• After changing paper size - Different paper sizes have different surface heights
• After replacing the pen - Different pens may have different lengths
• After changing the drawing tray surface - Any modification to the tray affects Z-height
• When drawing quality degrades - If lines appear too light (pen too high) or too thick/dragging (pen too low)

Z-Height Calibration

Z-height calibration sets the exact distance from the robot's home position to your paper surface. This is the most critical calibration.

Procedure

1. Place paper on the drawing tray in the correct position
2. In DMBot, select the robot to calibrate
3. Enter Calibration mode from the robot settings
4. The robot will move to the home position first
5. Use the on-screen controls to gradually lower the pen toward the paper
6. Lower slowly -- you want the pen to just barely touch the paper surface
7. When the pen tip rests on the paper with light contact, confirm the Z-height by pressing "Set Work Height"
8. The calibrated Z value is saved for this robot

Signs of Incorrect Z-Height

• Pen too high -- Lines are faint, inconsistent, or missing entirely. Pen lifts off the paper during fast movements.
• Pen too low -- Lines are thick and blobby. Pen drags and may tear the paper. Robot sounds strained during drawing.
• Correct -- Clean, consistent lines with uniform thickness. Pen glides smoothly across the paper.

XY Offset Calibration

XY offset calibration ensures the drawing is correctly positioned on the paper.

Procedure

1. Enter XY calibration mode
2. The robot draws reference marks at known positions
3. Compare the drawn marks to the expected positions
4. Adjust X and Y offset values (in mm) until the drawing is centered on the paper
5. Save the calibration

Per-Paper-Size Offsets

Each paper size has default offsets that center the drawing area. You can fine-tune these:

• 4x6 -- Default offset centers a 90x90mm drawing area
• 6x8 -- Default offset centers a 120x120mm drawing area
• A4 -- Default offset centers a 270x191mm drawing area

Custom drawing dimensions will recalculate offsets automatically.

Pump Bot Calibration (Auto Paper Replacement)

If using the pump bot for automatic paper replacement, additional calibration is needed:

Tray Position Calibration

Each tray side (left and right) has adjustable offsets:

• Tray X adjustment -- Fine-tune the horizontal position where papers are picked up and placed
• Tray Y adjustment -- Fine-tune the vertical position
• Tray Z adjustment -- Fine-tune the height for pickup and placement
• Rotation angle -- Adjust the angle for paper placement (default: 72 degrees per side)

Magazine Calibration

• Magazine base Z -- The Z-position of the bottom of the paper magazine (fixed at -98mm)
• Page thickness -- Set to match your paper stock (default: 0.32mm). This is used to calculate the Z-height for picking up the next sheet as the magazine empties.
• Magazine pages -- Set the current paper count (max 220). DMBot decrements this after each swap.

Testing After Calibration

After calibrating, always run a test drawing:

1. Set a robot to "Available"
2. Send a test photo
3. Watch the drawing to verify:
   • Lines are clean and consistent
   • Drawing is centered on the paper
   • Pen lifts cleanly between strokes
   • No scraping or dragging sounds

Safety Notes

• Never manually move the DexArm while it's powered on - This can damage the motors and lose position reference
• Always move to the "Home" position before drawing -- DMBot homes the robot on connect, but if anything seems off, re-home manually
• The DexArm has a maximum Z-height of 160mm -- never exceed this in manual commands