• Special Screws
  • Functional Screws


Clamping Screws with Eccentric Head

  • Fixing/Positioning

Hints for Correctly Using NBK Products

The video is an example using SLEC-A-EL(SLEC-A-EL). You can perform the same operation using this product.

Dimension Drawing

SLEC-AClamping Screws with Eccentric Head寸法図



M (Coarse)
Nominal of Thread

Unit : mm

Part Number M (Coarse)
Nominal of Thread
Pitch L D1 L1 e Key Part No. Hexalobular Socket No. t Qty per Pack Mass
SLEC-M3-A M3 0.5 6 6.8 2.5 0.4 SKX-10 10 1 1 0.7 4.36 CAD Cart
SLEC-M4-A M4 0.7 8 7 3 0.4 SKX-15 15 1.2 1 1.6 4.63 CAD Cart
SLEC-M5-A M5 0.8 10 8.5 4 0.4 SKX-20 20 1.5 1 2.6 4.36 CAD Cart
SLEC-M6-A M6 1 12 10 4 0.5 SKX-25 25 2 1 5.1 4.46 CAD Cart
SLEC-M8-A M8 1.25 16 13 5 0.8 SKX-30 30 2.5 1 11 5.09 CAD Cart
SLEC-M10-A M10 1.5 20 16 7 1 SKX-40 40 3 1 22 5.80 CAD Cart
SLEC-M12-A M12 1.75 24 18 8 1 SKX-45 45 3.5 1 32 6.52 CAD Cart

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Main Body SCM435
Ferrosoferric Oxide
Strength Class 10.9

*1: The hexalobular shape is prescribed by JIS B 1015:2008(ISO 10664:2005)“Hexalobular internal driving feature for bolts and screws”.


Fixing linear guideway rails / Workpieces / Jigs


  • When the screw is tightened, the workpiece is strongly clamped by the head, which is decentered from the shaft center of the screw. The wedge effect creates a large clamping force with low tightening torque.
  • The hexalobular*1 shape can withstand high tightening torque.
    ⇒Features of the Hexalobular Socket
  • Use a dedicated wrench SKX for mounting and removing.
  • Use the SKX-N hexalobular wrench for extremely limited access spaces for mounting and removing in tight spaces.
  • Suitable for fixing linear guideway rails. As the decentered head presses the linear guideway rail against the installation reference surface, precision can be easily achieved when mounting. Also, mounting accuracy is maintained by suppressing warping and misalignment caused by long-term use.
  • SLEC-A-EL is an electroless nickel plating type. For applications that require corrosion resistance.

*1: The hexalobular shape is prescribed by JIS B 1015: 2008(ISO 10664: 2005)"Hexalobular internal driving feature for bolts and screws".

Usage Example

Fixing linear guideway rails.

SLEC-AClamping Screws with Eccentric Head

Refer to the s max. dimension in the mounting dimensions; if the clamping screw with eccentric head may interfere with the carriage, etc., avoid interference by lowering its mounting surface.
When using in a rail, press at the position of the rail body's mounting screws.

Mounting Method

SLEC-AClamping Screws with Eccentric Head

Mounting Dimensions

Unit : mm

Part Number Part Number E M Adjustment Range
s max.
SLEC-M3-A SLEC-M3-A-EL 3.10~+0.3 M3 -0.1/0.7 3.3
SLEC-M4-A SLEC-M4-A-EL 3.150~+0.3 M4 -0.05/0.75 4.1
SLEC-M5-A SLEC-M5-A-EL 3.90~+0.3 M5 -0.05/0.75 5.3
SLEC-M6-A SLEC-M6-A-EL 4.650~+0.3 M6 -0.15/0.85 5.5
SLEC-M8-A SLEC-M8-A-EL 6.050~+0.5 M8 -0.35/1.25 7
SLEC-M10-A SLEC-M10-A-EL 7.50~+0.5 M10 -0.5/1.5 9.5
SLEC-M12-A SLEC-M12-A-EL 8.50~+0.5 M12 -0.5/1.5 10.9

SLEC-AClamping Screws with Eccentric Head

Recommended size of linear guideway rail

Unit : mm

Nominal of Rail Rail Width
Applicable Clamping Screws with Eccentric Head
#9 9 SLEC-M3-A SLEC-M4-A
#12 12 SLEC-M3-A SLEC-M4-A
#15 15 SLEC-M3-A SLEC-M4-A
#20 20 SLEC-M4-A SLEC-M5-A
#25 23 SLEC-M5-A SLEC-M6-A
#30 28 SLEC-M6-A SLEC-M8-A
#35 34 SLEC-M8-A SLEC-M10-A
#45 45 SLEC-M10-A SLEC-M12-A
#55 53 SLEC-M12-A

Related Products

Also, Clamping Screw with Eccentric Head, which has a guide section below the head, is available.
SLEC-B Ferrosoferric oxide film.
SLEC-A-EL Electroless nickel plating.

SLEC-AClamping Screws with Eccentric Head

SKX Hexalobular Wrench

SLEC-AClamping Screws with Eccentric Head

SKX-N Hexalobular Wrench for Extremely Limited Access Spaces

SLEC-AClamping Screws with Eccentric Head

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