What Is Tube Notching (Fishmouth)? Preparing Tube Ends for Tube-to-Tube Welding
When two round tubes are welded in a T or at an angle, a square-cut end leaves a large gap. Tube notching (coping, fishmouth) cuts an arc in the tube end that matches the mating tube's OD, so the tubes fit tightly – a stronger weld, less filler and a cleaner look.
Typical uses
Furniture and chair frames, bed frames, motorcycle racks and bumpers, fitness equipment, playground equipment and tool handles.
Punching vs milling
| Method | Description |
|---|---|
| Punch notching | A die punches out the arc – fast |
| Mill notching | A cutter mills the arc – suits thicker walls or tighter fits |
Quality points
- The arc must match the mating tube OD for a gap-free fit.
- When both ends are notched, the notches must be aligned.
- No heavy burrs that interfere with welding.
Related machines
| Model | Description |
|---|---|
| WHC hydraulic tube notching machine | Arc notch on tube ends |
| WHC-88-29 double-end notching machine | Both ends notched in one clamping, aligned |
For small quantities, contract tube processing is also available.
Why TONG DA
- TONG DA has designed and built tube processing machines since 1989 and runs contract processing on its own machines.
- Tooling is designed to your tube and drawing; sample trials available.
- CE certified; machines sold to the USA, Germany, Turkey, the UK, India, China and more.
FAQ
Can one machine handle different tube sizes?
Yes, by changing the cutter or die for the mating tube size.
Can you make a trial first?
Yes, please send the part drawing and tube specification.
How do I request a quotation?
Send the tube OD, wall, joint angle and quantity to sales@tdco.com.tw and we will reply promptly.