Description
Product Overview
The Toyo Seiki Boring Head is a high-precision Micro Boring Head equipped with an integral MT3 (Morse Taper 3) shank.
Designed for tight-tolerance finishing work, this head features an ultra-fine graduation of 0.005mm (5 microns). This level of sensitivity allows machinists to “sneak up” on a final bore dimension with confidence, making it far superior to standard “roughing” heads that use 0.01mm or 0.02mm graduations.
- Capacity: Effectively bores from 3mm to 20mm (depending on the boring bar used), making it ideal for small, intricate work on instrument parts or bushings.
- Tooling: It accepts standard 12mm shank boring bars, giving you access to a wide variety of aftermarket carbide or HSS tooling.
- Integral Shank: The MT3 shank is built directly into the body (not threaded on), ensuring maximum rigidity and low runout compared to modular systems.
Condition
Used (Working Condition / Bars Included).
The boring head is in used condition and functions correctly. The dial moves smoothly, and the locking mechanism holds tight.
Included: It comes with 2 x HSS Boring Bars. Please note these bars are in “various” conditions (used) and are included as a starter set; you may wish to grind them fresh or replace them with carbide for serious production work.
Brand Information
Toyo Seiki (Japan) is a legacy manufacturer of precision testing and measuring equipment. Their machine tooling from this era is built to classic Japanese standards—hardened, ground, and designed to last a lifetime if cared for.
Specifications
| Feature | Specification |
| Brand | Toyo Seiki (Japan) |
| Shank Type | MT3 (Morse Taper 3) |
| Boring Range | 3mm – 20mm |
| Tool Holder Size | 12mm |
| Graduation | 0.005mm (Fine Feed) |
| Type | Micro / Fine Boring Head |
| Included | Head + 2 HSS Bars |
Keywords
Toyo Seiki, MT3 boring head, micro boring head, fine boring head, 12mm boring bar holder, Morse Taper 3 tooling, Japanese milling tools, machinist tools.





