Achieving Precise Stepping for Printer Calibration: A Comprehensive Guide

Introduction

Stepping calibration is a frequently used method for adjusting printers, and its importance is well known among users. In this article, we will explore the reasons for adjusting stepping values and provide guidance on achieving accurate stepping for printer calibration.

Understanding Stepping Values

To illustrate, let’s consider the EPSON printhead as an example. The nozzle width of an EPSON DX5 printhead is 24.5mm, which means that with all nozzles firing, each pass will have a width of 24.5mm. As we discussed in a previous section on inkjet printing principles, multiple passes are required for complete ink deposition. For instance, when printing with 4 passes, the stepping value would be calculated as 24.5 ÷ 4 = 6.125mm (without considering feathering algorithms).

How to Achieve Accurate Stepping?

Step 1: Calibrating Mechanical Gear Ratio

In the printer software, there is a gear ratio calibration option for both the X-axis and Y-axis motors. The gear ratio relevant to stepping is associated with the Y-axis motor. To calibrate it, follow these steps:

  1. Set a known movement distance in the software, such as 1000mm.
  2. Click “Send” to initiate the movement, and measure the actual distance covered using a ruler.
  3. If the actual distance matches the set value, it indicates that the gear ratio is correct. If not, input the actual distance into the software dialogue box, and the software will automatically calculate a matching gear ratio. This allows the software to determine an accurate stepping value based on different pass settings.

(Note: In most cases, the gear ratio is pre-set by the factory, and end-users typically do not need to adjust it. This information is provided to enhance understanding of stepping values.)

Step 2: Fine-Tuning Stepping

While gear ratio calibration is a coarse adjustment, further fine-tuning of the stepping value is necessary before actual printing. What causes the initially calibrated stepping value to change?

  1. Material Replacement: When changing materials, the thickness of the new material can differ, resulting in variations in the pressure applied by the pinch rollers and causing deviations in the stepping value. Thus, it is crucial to recalibrate the stepping value after replacing materials. Some printer software allows the addition of different material types, enabling the selection of corresponding stepping values.
  2. Tension Changes: At the start of a print job, when the roll of material is large, the tension required by the pinch rollers is significant. As the roll decreases, the tension changes, leading to variations in the stepping value. To address this, printer manufacturers may include a tension bar in the material feeding mechanism to maintain consistent tension. It is important to use the tension bar when loading materials, even if it may seem cumbersome. Additionally, some users may start printing without using a take-up system, only engaging it after a certain length of printing. This change in tension caused by the take-up system can also affect the stepping value.
  3. Platform Temperature Variations: It is common for operators to adjust the stepping value immediately after turning on the printer. However, as the platform temperature changes, typically constructed of aluminum extrusions, it undergoes thermal expansion. This can result in slight variations in the stepping value. It’s worth noting that platform temperature changes can affect not only the stepping value but also color matching, bidirectional settings, and other parameters. (We will discuss platform-related details in a future article.)

Conclusion

Achieving precise stepping is vital for printer calibration. By understanding the process of adjusting stepping values and the factors that can cause deviations, users can ensure accurate and consistent print results. Regularly calibrating and fine-tuning stepping values based on material changes, tension variations, and platform temperature fluctuations will contribute to optimal print quality.

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