Original Japan BIG DAISHOWA SMB-20 High Rigidity Anti-Collision Chuck Holder for Deep Mold Machining Tool Extension Shank

The BIG DAISHOWA SMB-20 is a straight-shank slim-type Baby Chuck tool holder independently manufactured by BIG DAISHOWA Seiki (Japan). It is a dedicated anti-interference extension holder designed for small-diameter end mills, equipped with interchangeable BC series precision collets (BC-6, BC-8, BC-10). With an ultra-slim small-diameter clamping head and Φ20 standard straight shank, it effectively avoids collision interference during deep cavity, narrow groove and internal mold machining. Made of high-rigidity alloy steel with full quenching and precision mirror grinding, it maintains ultra-low radial runout and stable clamping rigidity under long overhang cutting, widely applied on machining centers for mold, automotive and precision component high-precision milling.

Brand

BIG DAISHOWA Seiki (Japan top high-precision tool holder manufacturer)

Full Model Code

SMB-20

Series Name

SMB Slim Baby Chuck Straight Shank Extension Holder

Shank Specification

Φ20 standard straight cylindrical shank

Overall Length

150 mm standard length

Matching Collet Series

BC miniature precision collets (BC-6 / BC-8 / BC-10)

Clamping Tool Shank Range

Φ6 mm, Φ8 mm, Φ10 mm straight shank cutters

Locking Accessory

Dedicated Baby Chuck lock nut (matched with BC collets)

Body Material

High tensile alloy steel, fully quenched HRC 56~59

Surface Treatment

Black oxidation anti-rust finish, mirror ground inner taper

Runout Accuracy

≤3μm at 4xD cutter extension after assembling AA-grade BC collet

Core Design Advantage

Slim compact chuck head for anti-interference deep machining

Max Applicable Spindle Speed

Up to 30,000 RPM high-speed milling

Standard Package

1 holder + 1 lock nut per original box, collets sold separately

• Pre-hardened mold steel: P20, 718H, NAK80 (HRC30–55)
• Fully quenched hardened steel: S136, STAVAX, Cr12MoV (HRC55–65)
• Stainless steel: 304, 316 duplex stainless alloy
• Aluminum alloy, graphite electrode, copper alloy
• Titanium alloy and heat-resistant superalloy

• Deep injection mold cavity, narrow deep slot anti-interference fine & semi-fine milling
• 3D contour profiling with small-diameter ball nose end mills for complex mold inserts
• Precision automotive miniature fitting, hydraulic component long overhang machining
• Graphite electrode high-speed finishing requiring slim holder to avoid sidewall collision
• Five-axis machining deep recess, inner fillet small tool precision processing
• Batch automated mold production with consistent high dimensional accuracy requirements

• Ultra-slim compact chuck head design: Significantly reduces outer diameter of clamping section, solves interference issues in narrow, deep mold cavities that standard thick holders cannot reach
• Φ20 universal straight shank: Compatible with all standard ER32, ER25, hydraulic and NEW BABY chuck bodies for easy installation on all machining centers
• Matched high-precision BC miniature collets: Delivers ultra-low runout, improves workpiece surface roughness and extends carbide cutter service life
• High-hardness quenched alloy steel body: Excellent anti-bending rigidity, suppress cutting chatter during long 150mm overhang operation
• Integrated anti-rust black oxidation coating: Resists long-term coolant erosion, stable precision under continuous wet cutting
• Single wrench locking structure: Simple fast tool replacement, saves production setup time for mass mold manufacturing