The World's Most Rigid Dual Contact Spindle System BIG-PLUS was developed to unlock the full potential of spindle rigidity. Both the spindle and tool holder are manufactured to precise specifications, allowing the gap between the spindle face and flange to close simultaneously.
Tool Holder and Spindle System BIG-PLUS DUAL CONTACT
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BIG-PLUS The World's Most Rigid Dual Contact Spindle System
BIG-PLUS was developed to unlock the full potential of spindle rigidity. Both the spindle and tool holder are manufactured to precise specifications, allowing the gap between the spindle face and flange to close simultaneously. This ensures consistent, reliable dual contact every time a BIG-PLUS tool holder is loaded into a BIG-PLUS spindle, delivering repeatable performance. In addition, BIG-PLUS maintains full compatibility with standard tooling, allowing conventional holders to be used in BIG-PLUS spindles when needed and vice versa. The BIG-PLUS Spindle System is an Original Development of BIG DAISHOWA Seiki Co., Ltd.
SIMULTANEOUS TAPER & FLANGE FIT 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
CONVENTIONAL
Basic Concept Conventional steep taper holders are supported at the gage line diameter, while BIG-PLUS holders also contact the flange face—significantly increasing rigidity.
BIG-PLUS
Conventional
Taper No.
Conventional
BIG-PLUS
SPACE
50 ø3.875 The BIG-PLUS Spindle System is based on the most current standards in ASME B5.50, JIS B6339 and DIN 69871. ø2.750
CONTACT
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UNDERSTANDING BIG-PLUS
Standard CAT Holder + Standard Spindle A .125" gap between the spindle and flange face can increase vibration, runout and premature tool wear.
CV50 SPINDLE (CAT50)
CV50 HOLDER
Standard CAT Holder + BIG-PLUS Spindle The BIG-PLUS spindle delivers greater clamping force and improved tool clamping accuracy.
BIG-PLUS SPINDLE (BCV50)
CV50 HOLDER
R
SPINDLE SYSTEM DUAL CONTACT
BIG-PLUS Holder + BIG-PLUS Spindle Dual contact at the taper and flange face provides maximum rigidity, improving surface finish, dimensional accuracy and tool life.
BIG-PLUS SPINDLE (BCV50)
BCV50 HOLDER
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BENEFITS OF BIG-PLUS
High Spindle Speeds At high speeds, spindle expansion from heat and centrifugal force can pull standard tool holders inward. BIG-PLUS holders prevent this by contacting the spindle face, minimizing Z-axis projection variation (variation due to heat exists).
Z-Axial Movement During Rotation (Ex: CV40)
60 50 40 30 20 10
BIG-PLUS CONVENTIONAL
BIG-PLUS
Effect by Thermal Deformation is Included
.0008"
20,000 RPM
0
0
1
5
10
15
20
25
30
CONVENTIONAL
Spindle Speed (x1,000 RPM)
A Vertical Machine was Used in the Test
Improved ATC Repeatability Dual contact precisely positions the tool holder within 1 micron, ensuring highly repeatable accuracy during ATC tool changes.
ATC Repeatability
Machine: Horizontal (4 years old)
6"
ISO40
10 8 6 4 2 0
WITHIN 1 μm
Taper Contact (Conventional) Dual Contact (BIG-PLUS)
Test Bar (Zero Runout)
Pulling Force 800kg
12345678910 No. of Times of ATC
Perfect Interchangeability BIG-PLUS tool holders work with standard spindles, and standard holders can be used in BIG-PLUS spindles (without dual contact). Unlike other systems, BIG-PLUS requires no new accessories or machine modifications, as it’s based on a conventional steep taper.
BIG-PLUS Spindle + BIG-PLUS Holder CONTACT
Conventional Spindle BIG-PLUS Holder CLEARANCE +
Existing Accessories Utilized
Tool Presetter
BIG-PLUS Holder
Tooling Fixture
Conventional Holder
Tool Storage System
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MINIMIZED DEFLECTION FOR MAXIMUM MACHINING ACCURACY
BIG-PLUS simultaneous contact enhances machining rigidity with the larger contact diameter of the tool holder flange face, reducing deflection and improving accuracy and surface finish.
Strict Gage Control
Comparison of Machine Spindle Deflection
BT40
BT50
100
500
CONVENTIONAL
CONVENTIONAL
80
400
60
300
BIG-PLUS
Conventional
40
200
20
100
Cutting Conditions Machine: 40 Taper (Horizontal Machining Center) Cutter: Face Mill ø5" (6 cutting edges) Work Material: A2017 Duralumin Cutting Depth: .094"
BIG-PLUS
BIG-PLUS
H F
0
0
2
4
6
8
1
2
3
4
(kN)
(kN)
F
LOAD: F
LOAD: F
H
A vertical machine was used for the tests.
BIG-PLUS Spindle Principle Increased Contact Diameter = 4x Increased Rigidity
Comparison of End Mill Deflection
50 Taper
ø100
ø69.85
(100.00)4 (69.85)4
= 4.2 Times
Deflection
BIG-PLUS CONVENTIONAL
40 Taper
60 70 80 90 50 40 30 20 10
ø63
ø44.45
(63.00)4 (44.45)4
= 4.0 Times
30 Taper
ø46
ø31.75
0
0
1
2
3
4
(46.00)4 (31.75)4
= 4.4 Times
Radial Depth of Cut (mm)
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Application Examples BIG-PLUS and Standard Tool Holder Comparison Tool Holder: Hi-Power Milling Chuck Workpiece Material: 4140 Steel
STANDARD CAT40
CV40-HMC.750-3.5 End Mill Diameter: ø.472" (12mm) 4-flute Cutting Depth: .157” (4mm) Cutting Speed: 321.5 SFM (98m/min)
Axial Depth (ap): .157" (4mm) Spindle PRM (n): 2600min -1 Feedrate (f): 20.54in/min (520mm/min) MRR (a e x a p x f): 1.523in Roughness (Ra): 198.0μin (5.030μm)
3 /min (24960mm 3 /min)
Cutting Feed: .002"/t (.05mm/t) Radial Width (a e ): .472" (12mm)
BIG-PLUS CAT40
BCV40-HMC.750S-3.5 End Mill Diameter: ø.472" (12mm) 4-flute Cutting Depth: .157" (4mm) Cutting Speed: 321.5 SFM (98m/min)
Axial Depth (ap): .157" (4mm) Spindle PRM (n): 2600min -1 Feedrate (f): 20.54in/min (520mm/min) MRR (a e x a p x f): 1.523in Roughness (Ra): 35.9μin (.913μm)
3 /min (24960mm 3 /min)
Cutting Feed: .002"/t (.05mm/t) Radial Width (a e ): .472" (12mm)
BIG-PLUS CAT40
BCV40-HMC.750S-3.5 End Mill Diameter: ø.472" (12mm) 4-flute Cutting Depth: .236" (6mm) Cutting Speed: 321.5 SFM (98m/min)
Axial Depth (ap): .236" (6mm) Spindle PRM (n): 2600min -1 Feedrate (f): 30.7in/min (780mm/min) MRR (a e x a p x f): 3.427in Roughness (Ra): 41.0μin (1.042μm)
3 /min (56160mm 3 /min)
Cutting Feed: .003"/t (.075mm/t) Radial Width (a e ): .472" (12mm)
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Inspection Results of Non-Licensed Dual Contact Tooling Testing of 25 samples of 40 and 50 taper non-licensed dual contact tooling revealed inconsistent taper or flange contact in 88% of the samples. Only 16% of the samples were within allowable tolerance. For reliable, repeatable dual contact performance, use only licensed systems built to verified BIG-PLUS standards.
44% NOT TO SPECIFICATION Taper Contact Only , No Flange Contact • Features of BIG-PLUS are voided • Works same as taper-only contact tooling
Gap
40% NOT TO SPECIFICATION Flange Contact Only, Limited or No Taper Contact • Poor runout accuracy • Severe chatter and vibration • Spindle damage
Gap
16% ALLOWABLE TOLERANCE Flange & Taper Contact • Dual contact of taper and flange face after clamping
Elastic Deformation
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Strict Gage Control
BIG-PLUS spindles produced by licensed machine and spindle builders are strictly controlled in dimensions by the original BIG master gage. Only BIG-PLUS trademarked tool holders can achieve the optimal performance fully and safely. BIG DAISHOWA Produces and Maintains All Spindle and Tool Holder BIG-PLUS Gages Worldwide For Licensed Companies Only
Gages for Machine Spindle Master Gage
Master Arbor
Measuring Device
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: 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 PRECISION BORING, DMG MORI SEIKI, DOOSAN, EGIN-HEINISCH, EGURO, EMCO, ENSHU, FADAL, ANUC, FEELER, FEMCO, FIRST, FIRST, FISCHER , FOREST-LINÉ, FPT, FRANZ KESSLER, GIDDINGS & LEWIS, GMN, GROB, GTI , HAIDE, HARDINGE, HARTFORD, HEYLIGENSTAEDT, HISION, HNK, HOMMA, HORKOS, HOWA, HSD, HST, HURCO, HWACHEON, IBAG, IBARMIA INNOVATEK, IKEGAI, INOUE KOSOKU KIKAI, JHENG TAI, JOBS, JOHNFORD, JTEKT MACHINE SYSTEMS, JTEKT, JUNGWOO M.S., JYOTI, KARATS, KASHIFUJI, KASWIN, KENTURN, KIRA, KITAMURA, KIWA, KMT, KOMATSU NTC, KONDIA, KOYO, KPTEC, LAZZATI, LMW, MAG, MAGNIX, MAKINO, MAKINO SEIKI, MANDELLI, MATSUURA, MAZAK, MCM, MECTRON, MILLTRONICS, MITSUI SEIKI, MOTOKUBO, MTE, MYL, N.S.S, NACHI, NAKAMURA, NEWAY, NICOLÀS CORREA, NIDEC MACHINE TOOL, NIDEC OKK, NIIGATA, NIPPON BEARING, NISHIJIMAX, NISSIN-MFG, NOMURA, NORTHLAND TOOL , NSK, NUMEN, O-M, OBATAKE, OHTORI, OKUMA, OMLAT, OMV, OVERMACH, 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 September 2025)
• Bold company names are North American licensed BIG-PLUS spindle rebuilders
BIG-PLUS Tooling Licensees The following companies are licensed for production, sales and use of the BIG-PLUS trademark:
BIG DAISHOWA INC SANDVIK COROMANT REGO-FIX
YUKIWA SEIKO USA, INC SHOWA TOOL CO, LTD SUMITOMO
Only Select BIG-PLUS Tooling from These Licensed Companies — 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
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BIG-PLUS FREQUENTLY ASKED QUESTIONS
Answers to the most common questions about BIG-PLUS, including spindle compatibility, tooling performance and dual-contact technology.
Can I Use BIG-PLUS Tool Holders in a Machine that is not BIG-PLUS?
Conventional Spindle BIG-PLUS Holder CLEARANCE +
Yes. BIG-PLUS tool holders will fit into any machine no matter if it is made to the BIG-PLUS or standard specification. The gage plane of a BIG-PLUS tool holder is the same as standard tool holders and therefore seats in the spindle taper only. For this reason, BIG DAISHOWA has standardized almost all of the tool holders produced with BIG-PLUS.
The Tolerances of BIG-PLUS are Very Tight, But it does Not Seem Possible to Achieve Dual Contact Unless the Spindle and Tool Holders Are Nearly Perfect. How is BIG-PLUS Able to Work on any Machine and in any Environment for Dual Contact? All BIG-PLUS tool holders are made to the same tolerance and specification. However, there is a known and repeatable elastic deformation that occurs to the spindle due to clamping. Every machine will see an axial movement during clamping of approximately .0005"-.001". We use this movement to secure taper contact first, followed by face contact second, all within the elastic deformation of clamping. As a result of BIG-PLUS achieving face contact with the spindle, BIG-PLUS is able to control tool offset better than standard tool holders.
BIG-PLUS Comparison of BIG-PLUS Before and After Clamping The clearance is important for face fitting Clearance
BEFORE CLAMPING
CONTACT
BIG-PLUS
AFTER CLAMPING
Clamping
Elastic Deformation
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How Does BIG-PLUS Compare To HSK? Which Is Better? HSK is a dual-contact spindle system that relies on tool holder expansion during clamping. This is achieved through very high clamping forces and a thin-walled, short-taper design that allows the holder to expand elastically during clamping. Extensive testing at BIG DAISHOWA comparing both systems found that as tool holder length increases, BIG-PLUS provides greater rigidity and stability. Also, due to the internal construction of HSK, tool overhang is longer, while BIG-PLUS has better tool holder taper engagement in the spindle. However, for high speed applications, HSK should be considered the better option.
BIG-PLUS
HSK
Tool Overhang
Is it Possible to Rebuild BIG-PLUS Spindles to Original Factory Specifications? Yes, there are several companies who specialize in spindle repair and have obtained the license and gages for BIG-PLUS. Also, these companies can convert a standard spindle to BIG-PLUS by replacing the spindle shaft during the rebuild process at their company.
Gages for Machine Spindle Master Gage
Master Arbor
Measuring Device
Do I Need to Acquire BIG-PLUS Adapters for my Tool Presetter or Tightening Fixtures? No, if your presetter is already equipped with CAT or BT adapters, BIG-PLUS tool holders will fit and measure like a standard tool holder.
Existing Accessories Utilized
Tool Presetter
BIG-PLUS Holder
Tooling Fixture
Conventional Holder
Tool Storage System
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For the Complete Line of BIG-PLUS Tooling, See Our High Performance Tooling Solutions Catalog
BIG DAISHOWA Inc. Tool Holders | Boring Tools | Cutting Tools | Workholding | Tool Measuring 2600 Huntington Blvd | Hoffman Estates, IL 60192 (224) 770-2999 | bigdaishowa@us.bigdaishowa.com | bigdaishowa.com
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