BIG-PLUS Dual Contact Spindle System

Simultaneous Taper & Flange Fit

BIG-PLUS is a dual contact spindle system where the shank contacts the spindle taper and the spindle face simultaneously, resulting in increased tool rigidity. BIG-PLUS surpasses all other spindle concepts while offering interchangeability with existing machines and tool holders.

  • Improved surface finish & dimensional accuracy
  • Extended tool life
  • Prevention of fretting corrosion caused by heavy cutting
  • Improvement of ATC repeatability
  • Elimination of Z-axial movement at high speeds
  • Improved roundness of boring operations

BIG-PLUS vs. Conventional

Minimized Deflection for Maximum Machining Accuracy & Superior Finish

With BIG-PLUS simultaneous contact, machining rigidity is greatly enhanced due to the larger contact diameter of the tool holder flange face. This larger face contact, combined with the taper contact, works together to resist deflection. With less deflection, greater machining accuracy and superior finish can be achieved.

Comparison of Deflection
Comparison of Deflection

Strict Gage Control
Strict Gage Control

Cutting Conditions
Machine: 40 Taper (Horizontal Machining Center)
Cutter: Face Mill Ø5" (6 Cutting edges)
Work Material: A2017 Duralumin
Cutting Depth: .094"

Improvement of ATC Repeatability

The BIG-PLUS Spindle System assures the highest precision location of the tool holder in the spindle when using the ATC for loading tools as a result of the dual contact, which precisely positions the tool holder within 1 micron.

ATC Repeatability
ATC Repeatability.

Basic Concept

The BIG-PLUS Dual Contact Spindle System is based on the most current available standards in ASME B5.50, JIS B6339, and DIN 69871. A conventional steep taper tool holder is supported on a reference diameter called the gage line. On the contrary, a BIG-PLUS tool holder is supported on the flange face, which brings remarkable improvement to rigidity.

Increased Contact Diameter (Example of BT50)
BIG-PLUS vs. Conventional

Taper No. Conventional BIG-PLUS
CV50 Ø2.750 Ø3.875
CV40 Ø1.750 Ø2.500
BT30 Ø1.250 Ø1.811

Strict Gage Control

BIG-PLUS spindles produced by the licensed machine or spindle builders are strictly controlled in dimensions by the BIG original Master Gage. Only the BIG-PLUS trademarked tool holders can achieve the optimal performance fully and safely.

Gages for Machine Spindle
Gages for machine spindle

Not All Dual Contact Tooling is the Same!

The current market contains many suppliers of dual contact tooling who are NOT licensed for BIG-PLUS. Without the license, they have neither the exclusive gages nor dimensions and tolerances for the critical relationship of taper to the flange.

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Condition #1
Proper Fit

  • Dual contact of taper and flange after clamping

Elastic Deformation.

Flange contact only.

Condition #2
Flange Contact Only
Limited or No Taper Contact

  • Poor runout accuracy
  • Severe chatter and vibration
  • Spindle damage

Taper contact only.

Condition #3
Taper Contact Only
No Flange Contact

  • Features of BIG-PLUS are voided
  • Works same as taper-only contact tooling

BIG-PLUS Tooling Licensees

The following companies are licensed for production, sales, and use of the BIG-PLUS trademark:
BIG DAISHOWA INC
REGO-FIX
SHOWA TOOL CO, LTD
BIG KAISER PRECISION TOOLING LTD
KOMET GROUP
SUMITOMO
SANDVIK COROMANT
YUKIWA SEIKO USA, INC

Only select BIG-PLUS tooling from licensed companies and ACCEPT NO IMITATIONS OR COPIES

All products will be clearly marked with the following indications on all parts:

BIG-PLUS® Spindle System
License BIG Daishowa Seiki

BIG-PLUS Spindle System Machine Builders

The BIG-PLUS Spindle System is offered by many of the world’s leading manufacturers of machining centers. Some of the machine and spindle builders who have produced BIG-PLUS spindles are as follows:

ACCUWAY, ADVANCED MACHINE, ALEX-TECH, AMS, ANCA, AONO GIKEN, ARES, ASADA SEIKI, ASA TECH, AWEA, BERG SPANNTECHNIK, BFW, BOST, BROTHER, CERI, CHEVALIER, CHUO-SEIKI, CITIZEN, COLGAR, D.S.TECHNOLOGIE, DAH LIH, DAITO, DAIYA SEIKI, DIXI, DMC, DMG MORI SEIKI AD, DMG MORI SEIKI CO.,LTD., DOOSAN, DYNOMAX, EGIN-HEINISCH, EGURO, ENSHU, FADAL, FANUC, FEELER, FEMCO, FIRST, FIRST, FISCHER, FOREST-LINÉ, FPT, FRANZ KESSLER, FUJI SEIKI, GIDDINGS & LEWIS, GMN, GROB, GTI, HAIDE, HARDINGE, HARTFORD, HEYLIGENSTAEDT, HISION, HNK, HOMMA, HORKOS, HOWA, HST, HURCO, HWACHEON, IBAG, IBARMIA INNOVATEK, IKEGAI, INOUE KOSOKU KIKAI, JHENG TAI, JOBS, JOHNFORD, JTEKT, JUNGWOO M.S., JYOTI, KARATS, KASHIFUJI, KASWIN, KENTURN, KIRA, KITAMURA, KIWA, KMT, KOMATSU NTC, KONDIA, KOYO, KPTEC, KURAKI, LAZZATI, LMW, MAG, MAGNIX, MAKINO, MAKINO SEIKI, MANDELLI, MATSUURA, MAZAK, MECTRON, MILLTRONICS, MITSUBISHI, MITSUBOSHI KOGYO, MITSUI SEIKI, MOTOKUBO, MTE, MYL, N.S.S, NACHI, NAKAMURA, NEWAY, NICOLÀS CORREA, NIIGATA, NIPPON BEARING, NISHIJIMAX, NISSIN-MFG, NOMURA, NORTHLAND TOOL, NSK, NUMEN, O-M, OBATAKE, OHTORI, OKK, OKUMA, OMLAT, OMV, PAMA, PDS, PIETRO CARNAGHI, PMC, QUASER, REIDEN, ROKU ROKU, ROYAL, RS TEC, SAJO, SEMA, SEMPUCO, SETCO, SHAN RONG, SHIBAURA, SHODA, SHW, SKF USA, SKG, SKODA, SKYNC, SMEC, SNK, SODICK, SORALUCE, SPINDER, SPINTEC, SPINTRUE, SPS, STARRAGHECKERT, STUDER, SUFENG, SUGINO, SUNWOO, SUPERIOR SPINDLE SERVICE, SWIFT, TAJMAC-ZPS, TAKAMAZ KIKAI KOUGYOU, TAKISAWA, TANABE, THETA, TONGTAI, TOS KURIM, TOS VARNSDORF, TOYO SEIKI, TSUDAKOMA, TSUGAMI, UGINT, UTSUNOMIYA, VICTOR TAICHUNG, VTEC, VYU CHENG, WALDRICH COBURG, WELE, WIA, YAMASAKI GIKEN, YAMASHINA SEIKI, YASDA, YASUNAGA, YCM, YU HUNG, ZAYER

(as of July 2021)

• Bold company names are North American licensed BIG-PLUS spindle rebuilders

Perfect Interchangeability

BIG-PLUS dual contact tool holders can be used on existing standard machine spindles. Existing standard tool holders can also be used on BIG-PLUS spindles. In this case, however, simultaneous contact cannot be attained. Although other simultaneous contact systems require exclusive new accessories, BIG-PLUS tooling uses existing accessories such as a tool presetter and tool holder fixture as it is based on a conventional steep taper shank. Further, it is not necessary to modify tool magazines and ATC devices of existing machines.

BIG-PLUS compared to conventional.

Existing Accessories Utilized
Existing accessories utilized.

BIG-PLUS spindles have been adopted by licensed machine or spindle builders around the world under strictly controlled dimensions using BIG's Master Gage. In order to protect the spindle or prevent possible accident, only use tool holders with the BIG-PLUS trademark.