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Quarter Turn - ST-1200 Line

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Manufactured in
the United States of America!

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DFCI Fasteners
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ST-1200 Line Studs Picture

ST-1200 Line offers the largest quarter-turn fastener selection in the industry.

Every fastener in the line is based on the rugged spiral cam stud and spring-wire receptacle design. The advantages of this design are readily apparent when a ST-1200 Line Fastener is operated in comparison with other quarter-turn types, especially after prolonged use. The fastener provides a firm locking tension with a crisp and positive lock. The end of the stud cam presents a solid over-rotation stop. Wear is minimal and performance is maintained over thousands of use cycles. Stud shanks are smooth, with no pins or lugs to hang up in support holes.

Designers evaluating quarter-turn fastener performance over the full service life of their product will find an outstanding choice in ST-1200 Line.

ST-1200 Line fastener components consist of:

  • a spiral-cam stud,
  • a stud retainer, and
  • a receptacle consisting of, or containing a wire form spring.

As the stud is rotated, the quarter-turn spiral cam engages the spring-wire receptacle and pulls it up and over the cam peak. The spring snaps into the detent at the end of the cam, holding the fastener in a firm locked tension. The cam peak resists opening rotation of a locked stud under vibration.

The selection and installation planning of fasteners can influence the security of the fastened parts. Product information and support service is intended for use only by persons with mechanical engineering qualifications sufficient to manage the responsibilities of:

  1. Analyzing fastener performance in relation to the service to be met, and
  2. Planning appropriate fastening locations and installations.

The following is a partial list of design criteria which should be used in selecting the correct fastener for your application.

  • Tensile Load (average)
  • Shear Load (average)
  • Maximum Load
  • Vibration
  • Number of Cycles
  • Environmental Concerns
  • Appearance
  • Mounting Location and Clearance
  • Weight

The above considerations, along with the performance chart parameters should be utilized in choosing the appropriate fastener type, head style, receptacle, finish, and materials.

Selection Procedure

1. Select a fastener size, using the performance table shown below. The size selected applies to the stud, retainer, and receptacle.
2. Select an appropriate stud head style.
  • Slotted (oval) (121J)
  • Wing (121J-W)
  • Flush (126J)
  • Ring (122J-R)
  • Phillips (121J-P)
  • Hex (121J-H)
  • Knurled (1211)
  • Tamper Resist (1230)
3. Select a stud retainer. Some criteria for retainer selection are:
  • Desirability of radial and axial stud play in the unlocked position.
  • Degree of protection needed for panel hole and outer surface.
  • Whether retainer may be allowed to cause a gap between stud panel and receptacle support.
  • Installation cost.
  • Plastic Half Grommet
  • Stainless Steel Snap Ring
  • Aluminum Half Grommet
  • Aluminum Full Grommet
  • Retaining Spring

[ST-1200 Line Stud]

4. Select a receptacle type.

All of the ST-1200 Line receptacles, except the Press-In type, provide the same optimum performance standards as listed in the Performance Table.

  • S-Spring
    (All Sizes)
  • Weld Plate
    (All Sizes)
  • Slip-On
    (Size 4 and 5 only)
  • Clip-In
    (Size 4 only)
  • Rear Press-In
    (Size 3 and 4 only)
  • Front Press-In
    (Size 4 only)
  • Right Angle Spring Plate
    (Size 3, 4, and 5 only)
  • Side Spring
    (Size 3, 4, and 5 only)
  • Corner Spring
    (Size 3, 4, and 5 only)

[ST-1200 Line Receptacle]

5. Now determine the thickness of:

  • the material in which the stud is retained (panel),
  • any air gaps and any part of the stud retainer thickness not buried in either the panel or support (gap), and
  • the material to which the receptacle is attached (support).
Assembly Drawing showing components of Total Material Thickness

Then determine the total pileup between the level of stud head contact with the panel (top of Panel) and the level of receptacle contact with the underside of the support (bottom of Support), in the closed position. Refer to the examples on each receptacle page, which will guide you to the Grip Length selection table.

6. Self-ejecting stud assemblies prevent stud play in the open position and provide a visual cue of an open fastener.

Note: When our existing supply of Cadmium plated parts is exhausted, DFCI Solutions, Inc will no longer offer Cadmium plating as an option.

In place of the Cadmium plating, we recommend:

Clear: Zinc Trivalent Clear .0003 thick. Trivalent Chromate Clear with Sealer (RoHS Compliant)
Specification(s): ASTM-B-633, Type III, SC 2, Clear
Suffix: -Z3CT

Black: Zinc Trivalent Black .0003 thick. Trivalent Chromate Black Dye with Sealer (RoHS Compliant)
Specification(s): ASTM-B-633, Type II, SC 2, Black
Suffix: -Z3BT

Yellow: Zinc Trivalent Yellow .0003 thick, Trivalent Chromate Yellow Dye with Sealer

We recommend the Z3CT finish instead of the Z3YT finish. The Z3CT finish is much more cost effective and provides the same salt spray benefits as the Z3YT finish. (RoHS Compliant)
Specification(s): ASTM-B-633, Type II, SC 2, Yellow
Suffix: -Z3YT

The colored finishes offer no advantage over the clear other than the color, and they are more expensive.

Stud Part Numbers
The stud part number is divided into 5 parts.

  For example: 121J-340-Z3CT 121J-325-SS
1. Head style: 121J- = Slotted (oval) 121J- = Slotted (oval)
2. Shank diameter: 3 = 3/16" 3 = 3/16"
3. Grip Length: 40 25
4. Stainless Steel Identifier: Omitted -SS
5. Finish suffix: Zinc Trivalent Clear .0003 thick. Trivalent Chromate Clear with Sealer (RoHS Compliant)
Specification(s): ASTM-B-633, Type III, SC 2, Clear
Suffix: -Z3CT


Fastener size: 3 4 5 65
Stud End Diameter: 3/16
(4.78 mm)
(6.35 mm)
(7.95 mm)
(10.31 mm)
Stud Head Diameter: 5/16
(7.95 mm)
(18.75 mm)
(14.30 mm)
(17.48 mm)
Locked Service Tension (lb): 20 30 45 55
Max. Tension w/o Distortion (lb): 45 60 85 110
Rated Shear (lb): 100 150 200 300
Wear Life (Thousands of uses): 5 5 25 40

Maximum Sheet Separation at 150% of Locked Service Tension: .05" (1.27 mm)