How to Generate NC Drill Files in DipTrace: Complete Guide for PCB Engineers

DipTrace handles drill file generation separately from Gerber export, which catches many first-time users off guard. Unlike some tools that bundle everything together, DipTrace requires you to explicitly export N/C Drill files as a distinct step. After working with DipTrace across multiple projects from simple two-layer boards to complex multilayer designs with blind and buried vias, I have found that understanding the separate export workflow prevents the most common manufacturing rejections.

This guide covers everything you need to know about generating NC drill files in DipTrace that manufacturers will accept without revision requests.

Understanding NC Drill Files in DipTrace

DipTrace exports drill data in standard Excellon format, the industry-standard format that nearly all PCB manufacturers accept. The software names this export function “N/C Drill” in its menus, with the slash indicating Numeric Control drilling operations.

An Excellon file is essentially a text file containing tool definitions (drill bit sizes) and coordinate data (where to drill). DipTrace generates clean, well-formatted Excellon files with embedded tool information, which most manufacturer systems parse correctly.

What NC Drill Files Contain

Element	Description	Example
Tool Table	Drill bit size definitions	T01C0.0354 (0.9mm drill)
Header	Format and unit declarations	M48, INCH or METRIC
Coordinates	X and Y hole positions	X+017315Y+009190
Tool Changes	Commands to switch drill bits	T01, T02, T03
End Command	Program termination	M30

DipTrace automatically generates properly formatted headers with tool definitions embedded, eliminating the common problem of missing tool tables that plagues some other design tools.

DipTrace Drill File Export Location

Unlike Gerber export which you access through File → Export → Gerber, drill file export has its own menu path:

File → Export → N/C Drill

This separation exists because Gerber files and drill files serve different purposes in manufacturing. Gerber files describe image data for photoplotting copper layers, masks, and silkscreen. Drill files provide coordinate data for CNC drilling machines.

Many new DipTrace users forget this second export step and submit incomplete manufacturing packages. Always verify you have both Gerber and drill files before sending to your manufacturer.

Step-by-Step NC Drill File Generation in DipTrace

The drill export process in DipTrace involves accessing the export dialog, configuring tool assignments, and selecting the appropriate options for your design.

Accessing the N/C Drill Export Dialog

Open your completed PCB design in DipTrace PCB Layout. Before exporting, verify your design passes DRC by running Verification → Design Rules Check.

Navigate to File → Export → N/C Drill. The Export N/C Drill dialog opens, displaying a preview of your drill hits and configuration options.

Understanding the Export Dialog Options

Option	Purpose	Recommended Setting
Objects	Select which hole types to include	Pads and Vias enabled
Manufacturing	Through or Blind/Buried selection	Based on design type
Plating	Plated or Non-plated holes	Export separately for clarity
Units	Inch or Metric output	Match your Gerber units
Layer Pairs	For blind/buried via designs	Select appropriate pairs

The preview window shows all holes that will be included in the export based on your current selections. If the preview appears empty, check that you have not inadvertently filtered out all hole types.

Assigning Tool Numbers

DipTrace requires tool assignment before export. Each unique hole size in your design needs a tool number (T01, T02, T03, etc.).

Click the Auto button to automatically assign tool numbers to all hole sizes. DipTrace sorts holes by size and assigns sequential tool numbers starting from T01.

The tool list displays all unique hole sizes with their assigned numbers. You can manually adjust assignments if needed, though automatic assignment works correctly for most designs.

Generating the Drill File

After configuring options and assigning tools, click Export to generate the file. DipTrace prompts you for a filename and location.

By default, DipTrace names the drill file “Through.drl” for through-hole designs. For designs with blind or buried vias, additional files generate with layer pair indicators in the filename.

Save the drill file in the same directory as your Gerber files to keep all manufacturing data together.

Drill File Format Settings in DipTrace

DipTrace exports drill files in standard Excellon format with sensible defaults. Understanding these format settings helps when troubleshooting compatibility issues.

DipTrace Default Format Parameters

Parameter	DipTrace Default	Notes
Format	2:4 (inches) or 3:3 (metric)	Standard precision
Zero Suppression	Leading	Most compatible option
Coordinates	Absolute	Easier verification
Units	Matches design units	Inches or Millimeters
Tool Definition	Embedded in header	TnnC format

DipTrace handles format specification automatically based on your design units. If your PCB layout uses metric units, the drill file exports in metric with 3:3 format (three digits before decimal, three after). Imperial designs export with 2:4 format.

Matching Drill and Gerber Settings

For proper alignment between drill hits and copper pads, your drill file units must match your Gerber file units. DipTrace typically handles this automatically since both exports derive from the same design file.

If you encounter alignment issues, verify that both exports use the same unit system. Mixing metric drill files with imperial Gerber files causes scaling errors by a factor of 25.4.

Working with Plated and Non-Plated Holes

Most PCB designs contain both plated holes (for electrical connections) and non-plated holes (for mounting hardware). DipTrace allows you to export these separately or combined.

Separating Hole Types

Hole Type	Typical Uses	Export Recommendation
Plated Through	Component leads, vias	Export as plated file
Non-Plated Through	Mounting holes, tooling holes	Export as separate non-plated file
Plated Blind	Layer transitions	Separate file per layer pair

In the Export N/C Drill dialog, use the Plating dropdown to select which hole types to include. Export plated and non-plated holes to separate files with clear filenames.

Example filenames:

• Through_Plated.drl
• Through_NonPlated.drl

This separation helps manufacturers process holes correctly since plated holes require electroplating while non-plated holes skip this step.

Pad/Via Holes Option Importance

DipTrace has a critical setting that affects whether holes appear correctly in manufacturing. The “Pad/Via Holes” option in Gerber export determines copper removal under drill hits.

Ensure this option is configured correctly:

• For plated holes: Copper should remain under the drill hit
• For non-plated holes: Copper may be removed depending on design intent

Incorrect settings here cause manufacturers to plate holes that should not be plated, or leave unplated holes that need connections.

Handling Blind and Buried Vias

Multilayer designs with blind or buried vias require special attention during drill export. Each unique layer pair generates its own drill file.

Understanding Layer Pairs

Via Type	Description	Drill File Naming
Through	Spans all layers (1 to bottom)	Through.drl
Blind Top	Top to inner layer (e.g., 1-2)	1-2.drl
Blind Bottom	Bottom to inner layer (e.g., 3-4)	3-4.drl
Buried	Inner layers only (e.g., 2-3)	2-3.drl

DipTrace automatically identifies layer pairs present in your design. When you select blind/buried options in the export dialog, the software generates appropriate files for each pair.

Exporting Blind/Buried Via Drill Files

In the Export N/C Drill dialog:

1. Select “Blind” or “Buried” under Manufacturing type
2. Choose the specific layer pair from the dropdown
3. Click Export and save with a descriptive filename
4. Repeat for each layer pair in your design

Alternatively, use the “Export All” button introduced in recent DipTrace versions. This automatically generates drill files for all identified layer pairs in your design.

Common Blind Via Export Issues

Some users report that blind via drill files contain unexpected holes or appear empty. This typically occurs when:

• Via layer assignments are incorrect in the design
• The wrong layer pair is selected during export
• Vias were not properly defined as blind/buried type

If holes appear missing, open the via properties in your design and verify the layer span settings match your intended structure.

Verifying Drill Files Before Manufacturing

Never submit drill files without verification. DipTrace-generated files typically work correctly, but confirming alignment with Gerber layers prevents expensive manufacturing errors.

Recommended Gerber Viewers

Viewer	Platform	Key Features
Gerbv	Windows, Linux, macOS	Free, open source
ViewMate	Windows	Professional features
ZofzPCB	Windows	3D visualization
GC-Prevue	Windows	Industry standard CAM
Online viewers	Web-based	No installation needed

Load your Gerber files and drill file together in a viewer. Enable transparency and zoom into pad locations to verify drill hits center correctly on copper pads.

Verification Checklist

Check	What to Look For
Alignment	Drills centered on all pads
Hole count	Total matches expected design count
Tool sizes	Correct diameters in tool table
Coverage	All vias and pads have drill hits
Scale	No 10x or 0.1x scaling errors

A systematic visual check of several pad locations across your board catches most export errors before they reach manufacturing.

Troubleshooting Common DipTrace Drill Problems

Experience with DipTrace has revealed several recurring issues that trip up users during drill file generation.

Problem: Empty Drill Preview

When the N/C Drill export preview shows no holes despite having pads and vias in your design, check these settings:

Setting	Cause	Solution
Objects filter	Pads or Vias disabled	Enable both Pads and Vias
Manufacturing type	Wrong type selected	Match to your actual design
Plating filter	Too restrictive	Select appropriate plating type
Layer pair	Wrong pair selected	Choose correct layer combination

If all settings appear correct and the preview remains empty, try restarting DipTrace. Some users report display glitches that resolve after restart.

Problem: Missing Holes in Export

When some holes appear in the design but not in the exported drill file:

1. Check each missing hole’s properties in the PCB layout
2. Verify the hole is not accidentally set as blind/buried when it should be through
3. Confirm the hole has a valid size assigned
4. Re-export after verifying properties

DipTrace may not export holes with incomplete or invalid property assignments.

Problem: Manufacturer Cannot Read File

If your manufacturer reports format issues with the drill file:

• Verify they support Excellon format (nearly universal)
• Check for unit mismatch (metric vs imperial)
• Confirm the file extension is acceptable (.drl, .txt, or .exc)
• Request their specific format requirements

Some manufacturers prefer specific file extensions. DipTrace uses .drl by default, but you can rename to .txt or other extensions if required.

Problem: Holes Misaligned with Pads

When drill hits appear offset from copper pads:

Cause	Solution
Unit mismatch	Ensure Gerber and drill use same units
Origin difference	Export both from same design state
Scale factor	Check for metric/imperial confusion

Regenerate both Gerber and drill files from the same design file without making changes between exports.

File Organization for Manufacturing

Proper file organization prevents confusion and rejection when submitting to manufacturers.

Essential Files to Include

File Type	Extension	Purpose
Top Copper	.gtl or .gbr	Top layer artwork
Bottom Copper	.gbl or .gbr	Bottom layer artwork
Solder Mask Top	.gts or .gbr	Top mask openings
Solder Mask Bottom	.gbs or .gbr	Bottom mask openings
Silkscreen Top	.gto or .gbr	Top legend
Board Outline	.gko or .gbr	Board dimensions
NC Drill (Plated)	.drl	Plated hole coordinates
NC Drill (Non-Plated)	.drl	Non-plated hole coordinates

Package all files into a single ZIP archive. Most manufacturers accept this format directly for quoting and production.

Manufacturer-Specific Requirements

Manufacturer	Drill File Notes
JLCPCB	Accepts default DipTrace .drl format
PCBWay	Standard Excellon format works
OSH Park	Prefers .drl extension
Dirty PCBs	Accepts .txt or .drl extension
iTead Studio	May require rename to .txt

Check your manufacturer’s documentation for specific file naming requirements. Most accept DipTrace’s default output without modification.

Useful Resources for DipTrace Users

Official DipTrace Resources

Resource	URL
DipTrace Official Site	diptrace.com
User Forum	diptrace.com/forum
Tutorials	diptrace.com/tutorials
Support Request	diptrace.com/support/request-support

Gerber Viewer Downloads

Tool	Source
Gerbv	gerbv.github.io
ViewMate	pentalogix.com
ZofzPCB	zofzpcb.com

Manufacturer File Guides

Manufacturer	Documentation
JLCPCB	jlcpcb.com/help
PCBWay	pcbway.com/blog/help_center
OSH Park	docs.oshpark.com

Frequently Asked Questions

Why does DipTrace export drill files separately from Gerber files?

DipTrace separates drill and Gerber exports because these files serve fundamentally different purposes in manufacturing. Gerber files contain image data that photoplotters use to create copper patterns, solder masks, and silkscreen. Drill files contain coordinate data that CNC drilling machines use to create holes. Keeping these exports separate gives you explicit control over each file type and helps ensure you do not forget either critical component of your manufacturing package. Access drill export through File → Export → N/C Drill after completing your Gerber export.

What format does DipTrace use for drill files?

DipTrace exports drill files in standard Excellon format, which is the de facto industry standard accepted by virtually all PCB manufacturers worldwide. The files include embedded tool definitions in the header section, so you do not need to provide a separate tool table file. DipTrace automatically formats files as 2:4 for imperial units (two integer digits, four decimal digits) or 3:3 for metric units, with leading zero suppression and absolute coordinates. These defaults match what most manufacturers expect and process correctly.

How do I export separate files for plated and non-plated holes?

In the Export N/C Drill dialog, use the Plating dropdown menu to filter hole types. First, select “Plated” and export with a filename like “Plated_Through.drl”. Then reopen the export dialog, select “Non-plated”, and export with a filename like “NonPlated_Through.drl”. This separation helps manufacturers process holes correctly since plated holes require electroplating while non-plated holes skip this step entirely. Clear filenames prevent any confusion about which file contains which hole types.

Why is my drill preview showing empty when I have holes in my design?

An empty drill preview typically indicates filtering settings that exclude all holes. Check the Objects section to ensure both Pads and Vias are enabled. Verify the Manufacturing type matches your design (Through for standard through-holes). Check the Plating selection matches holes in your design. Also verify you have selected the correct layer pair if working with blind or buried vias. If settings appear correct but the preview remains empty, try restarting DipTrace as display glitches occasionally occur.

Can DipTrace generate drill files for blind and buried vias?

Yes, DipTrace fully supports drill file generation for blind and buried vias. When exporting, select the appropriate manufacturing type (Blind or Buried) and choose the specific layer pair from the dropdown menu. DipTrace generates separate drill files for each layer pair since manufacturing requires drilling these holes at different stages of the fabrication process. Recent DipTrace versions include an “Export All” button that automatically generates drill files for all identified layer pairs in your design, simplifying the export process for complex multilayer boards.

Best Practices for Reliable Drill Export

Following consistent practices prevents problems and ensures manufacturers receive usable files.

Before Exporting

Run DRC to verify all holes have proper clearances and valid definitions. Check via properties to confirm layer span assignments match your intended stackup.

During Export

Use the Auto button to assign tools rather than manual assignment. This prevents errors from mistyped tool numbers. Always verify the preview shows the expected holes before clicking Export.

After Export

Load both Gerber and drill files into a viewer to verify alignment. Check that the drill file is not empty by opening it in a text editor and confirming coordinate data exists after the header section.

Package all files into a single ZIP archive with clear, descriptive filenames. Include a readme file if your design uses blind or buried vias to help manufacturers understand the layer structure.

Generating NC drill files in DipTrace becomes routine once you remember the separate export step and understand the filtering options. The software produces clean, manufacturer-ready Excellon files that work with virtually any PCB fabrication house.