DS Slicer Scaling Guide

How to Fix Resin Shrinkage and Improve Dental 3D Print Accuracy

If your dental 3D prints feel too tight, too loose, or slightly inaccurate, the issue may be resin shrinkage. This guide explains how to use the Scaling function in DS Slicer to perform dimensional compensation and improve fit​

1.What Is the Scaling Function in DS Slicer?

The Scaling function in DS Slicer allows users to fine-tune printed model dimensions to improve fit accuracy and dimensional precision. 

This function is primarily used to: 

• Compensate for resin shrinkage 
• Improve internal fit (e.g., splints) 
• Correct bottom expansion caused by overexposure
• Reduce remake rates

This function is especially useful for splints, surgical guides, and high-precision dental models, to improve fit accuracy and dimensional precision.

When using a Phrozen 3D printer with our validated partner resins, the optimal printing parameters are already pre-configured. For printing standard models or splints, adjusting the Scaling Ratio is usually not necessary.

2.Why Does Resin Shrink in Dental 3D Printing?

During photopolymerization, resin molecules crosslink and form a solid structure.

This causes volumetric shrinkage, typically affecting the XY dimension.1

Common effects include:

• Slight shrinkage in the XY direction
• Bottom layer expansion due to higher exposure (commonly known as the “elephant foot” effect)
• Different shrinkage rates depending on resin type

Therefore, even with high-precision printers, material properties may cause dimensional deviations of ±0.02–0.1 mm.2

This is why dimensional compensation is often required in precision dental printing.

3.Understanding the Scaling Panel in DS Slicer

3-1. Scaling Ratio (X / Y / Z)

Scaling Ratio controls proportional scaling of the entire model.

• 1.000 = 100% original size
• Adjusting this value scales the entire model proportionally

* This setting is not recommended for fine fit adjustment.

* If you are using a Phrozen printer with validated resins, adjusting the Scaling Ratio is typically unnecessary.

3-2. Compensation Mode: Normal vs Bottom 

Normal: Applies compensation to the entire model

Bottom: Applies compensation only to bottom layers

Bottom compensation is commonly used to correct bottom expansion (Elephant Foot).

3-3. Inside vs Outside Compensation (mm)

Outside adjusts external dimensions. Inside adjusts internal cavities or fitting areas. Values are measured in millimeters (mm).

These values control dimensional offset:

Unit: millimeters (mm)

Positive value = hole diameter decreases  
Negative value = hole diameter increases 

Example: 

If you want to increase the inner diameter of a surgical guide sleeve hole by 1 mm, enter -0.5 mm in the Inside field. This is because the hole is circular, and Inside compensation affects the radius on both sides of the hole.

Diameter change = Compensation value × 2. 

When -0.5 mm is applied: Hole diameter change = -0.5 × 2 = -1 mm

The hole diameter will therefore increase by 1 mm.

4.How to Adjust Scaling for Better Dental Fit Accuracy 

Step 1: Open Settings → Print → Scaling section

Step 2: Select compensation mode:

• Normal (entire model)
• Bottom (bottom layer correction)

Step 3: Enter compensation values (e.g., 0.03 mm)

Step 4: Slice and test print

It is recommended to adjust one parameter at a time.

5.Common Dental Use Cases for Scaling?

Case 1 – Splint Is Too Tight

Problem: 
Patient cannot fully seat the splint.

Solution: 
Increase Inside compensation: Normal → Inside: +0.05 mm

Case 2 – Model Is Slightly Loose

Problem: 
Restoration fit is looser than expected.

Solution: 
Reduce Inside value or increase Outside slightly.

Case 3 – Bottom Over-Expansion (Elephant Foot Effect)

Problem: Base layer appears wider due to higher bottom exposure. 

Solution:

Adjust Bottom compensation. Bottom → Outside: -0.05 mm

6.General Guidelines for Dental 3D Printing

In dental 3D printing workflows, final model dimensions may be influenced by factors such as material shrinkage, printing parameters, and post-processing procedures. In some cases, minor dimensional adjustments using the Scaling compensation function may be required.

Inside / Outside compensation applies a surface offset to the model geometry, which modifies the dimensions of the affected structures. When adjusting holes or internal features, it is recommended to start with small compensation values and gradually fine-tune until the desired fit is achieved.

Recommended Adjustment Workflow: 

1. Print a test model using the default parameters.
2. Measure critical dimensions using tools such as digital calipers.
3. Apply small compensation adjustments based on the measured deviation.
4. Reprint and verify the dimensional accuracy.

It is recommended to adjust one parameter at a time to clearly evaluate the effect of each change.

7.Tolerance Compensation for Surgical Guide Sleeves

In dental 3D printing, most calibrated resins already have optimized printing parameters. 
When using Phrozen validated partner resins, additional Scaling Ratio adjustments are typically unnecessary for general models or splints.

However, in surgical guide applications, metal sleeves must be inserted into the printed guide.  
Because sleeve holes require high dimensional accuracy.3 Therefore, minor adjustments using the Scaling compensation function may sometimes be necessary.

When material shrinkage occurs during printing, the sleeve hole may become slightly smaller than designed, which may result in:

• Sleeves fitting too tightly
• Difficulty inserting the sleeve
• Reduced surgical guide accuracy

In these cases, Inside / Outside compensation can be used to fine-tune the hole diameter and ensure proper sleeve insertion.

7.1 Example: Sleeve Hole Compensation

When tolerance compensation is disabled, resin shrinkage during printing may cause the sleeve hole diameter to become slightly smaller than the intended design.

For example, in this case, designed sleeve hole diameter: 7 mm

If Tolerance Compensation “OFF”, measured diameter will be 6.89 mm.

If Tolerance Compensation “ON”, measured diameter will be 7.03 mm.

By applying appropriate compensation values, the printed hole diameter can more closely match the intended design dimension, ensuring accurate sleeve placement.

7.2 How to Adjust Sleeve Hole Compensation

If the sleeve fit is too tight or too loose, the hole diameter can be adjusted using Inside compensation.

Typical adjustment range:

Recommended calibration workflow:

1. Print a test surgical guide
2. Measure the sleeve hole diameter using a caliper
3. Adjust Inside compensation if necessary
4. Record the optimal value for future prints

7.3 Sleeve Hole Compensation Calculation

Inside / Outside compensation applies a surface offset to the model geometry, which affects both sides of the hole radius. Therefore, the diameter change = Compensation value × 2

For example, if you want to reduce the sleeve hole diameter by 1 mm. 

Enter the following value in the Inside field: Inside = -0.5 mm

Because -0.5 mm × 2 = -1 mm, this will reduce the sleeve hole diameter by 1 mm.

Tolerance compensation helps correct resin shrinkage and ensures the printed sleeve hole diameter matches the intended design dimension.

8.Frequently Asked Questions (FAQ)

Q: Does scaling affect layer height?

No. Scaling only affects XY dimensional compensation.

Q: Should I adjust both Inside and Outside?

Yes, but separate testing is recommended.

Q: Why do different resins require different compensation values?

Because each resin has a different polymerization shrinkage rate.

Q: What is the difference between Scaling Ratio and Compensation?

Scaling Ratio changes overall size proportionally. Compensation fine-tunes dimensional accuracy. For dental fit optimization, use Compensation.