Key Takeaway: This DIY quick change tapping attachment for CNC lathes replaces the tedious process of manually changing drill chucks and tap holders with a simple slide-lock mechanism. The design is fully open source with downloadable CAD files for 3D printing or machining.
Table of Contents
Why You Need a Quick Change Tapping Attachment
If you do production tapping on a CNC lathe, you know the bottleneck: every tap change requires stopping the spindle, walking to the tool cabinet, finding the right tap collet, and resetting tool offsets. For small batch runs, the setup time often exceeds the cutting time. A quick change tapping attachment solves this by letting you swap taps in seconds without tools.
Design Overview
The attachment uses a spring-loaded sliding collet mechanism. The tap holder slides into a tapered receiver and locks with a quarter-turn of a locking ring. To release, you pull back the locking ring and slide the tap out. Total change time: about 5 seconds versus 2-3 minutes with a conventional setup.
Key design specifications:
- Compatible with ER11 and ER16 collets for tap sizes M3 through M12
- Maximum RPM: 1500 (limited by balance, not mechanical strength)
- Material: 6061 aluminum body with hardened steel collet
- Weight: 180g (light enough for most CNC lathe turrets)
- Repeatability: ±0.02mm measured over 100 change cycles
Fabrication Guide
Option 1: 3D Printing (Prototype) — Print the body in PETG or ASA on a standard FDM printer. Use 0.2mm layer height and 100% infill for strength. The steel collet must still be machined or sourced separately.
Option 2: Machining (Production) — Machine the body from 6061-T6 aluminum on a CNC mill. The tapered receiver bore requires a reamer for proper surface finish. The locking ring can be turned on the same lathe the attachment will be used on.
Required hardware: 2x M6 socket head screws, 1x compression spring (12mm OD x 1.2mm wire), 1x ER11 or ER16 collet, 1x retaining ring.
Installation and Setup
Mount the attachment in your lathe’s tool turret or quick change tool post. Set tool offset using the same method as any other tool — touch off on a reference surface and record the Z offset. Because the attachment uses a fixed-length collet, the Z offset remains constant across tap changes, eliminating the need to re-set offsets for each tap size.
Download
The complete design package includes STEP files, STL files for 3D printing, and a Bill of Materials. The design is licensed under Creative Commons Attribution-ShareAlike — free for personal and commercial use with attribution.
Frequently Asked Questions
What sizes of taps does this attachment support?
Using ER11 collets, it supports M3 through M8. With ER16 collets, it supports M4 through M12. You can use any tap with a cylindrical shank that fits the collet range.
Can this be used on a manual lathe?
Yes. The attachment works on any lathe with a quick change tool post. For manual tapping, you will need to engage the half-nut or use the carriage handwheel for feed control.
Is the design compatible with live tooling?
The current design is for static tooling only. A live tooling version would require adding bearings and a driven coupling, which significantly increases complexity.
Related Reading
External Resources
Sources: Independent design, field-tested in production environment
