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No Undercut
Fixed

ST-1200 Line - Size 4 Studs

Material
Stud: hardened steel
D-Ring: hard music wire
Wing: carbon steel

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

Optional Stainless Steel: Change the finish suffix from Z3CT to SS (e.g., 121J-450-SS)
Stud: 303 Stainless Steel
D-Ring: 400 series Stainless Steel
Wing: 300 series Stainless Steel

Optional Finishes: Change the standard finish (-Z3CT) to the desired finish. See finishes page.

Note: The size 4 stud is also available in a self ejecting configuration (type SE). See this link for additional information.

Stud Dimensions

SLOTTED: 121J-4*-Z3CT   FLUSH: 126J-4*-Z3CT
Slotted Oval Head Stud Picture
Click here for the Engineering Drawing		 Slotted Oval Head Stud Dimension Drawing   Flush Head Stud Picture
Click here for the Engineering Drawing		 Flush Head Stud Dimension Drawing
WING: 121J-W4*-Z3CT   PHILLIPS: 121J-P4*-Z3CT
Wing Head Stud Picture
Click here for the Engineering Drawing		 Wing Head Stud Dimension Drawing   Phillips Recess Head Stud Picture
Click here for the Engineering Drawing		 Phillips Recess Head Stud Dimension Drawing
HEX: 121J-H4*-Z3CT   KNURLED: 1211-4*-Z3CT
Hex Recess Head Stud Picture
Click here for the Engineering Drawing		 Hex Recess Head Stud Dimension Drawing   Knurled Head Stud Picture
Click here for the Engineering Drawing		 Knurled Head Stud Dimension Drawing
RING: 122J-R4*-Z3CT   TAMPER RESIST: 1230-4*-Z3CT
Ring Head Stud Picture Ring Head Stud Dimension Drawing   Tamper Resist Head Stud Picture\ Tamper Resist Head Stud Dimension Drawing

* is the "Stud Grip" from the table.  For example, 121J-440-Z3CT is an oval head stud with a "Stud Grip" of 40.

The undercut is a part of the stud which is smaller in diameter than the stud shank. The undercut is located directly under the head. This decreased diameter is where the retainer fits to prevent the stud from coming out of the mounting hole.

The "J" designation in the 121J- part number indicates a Variable undercut. That is, the length of the undercut varies with the length of the stud. The Variable undercut is shown on this page.

The "N" designation in the 121N- part number indicates that the stud has no undercut. These were formerly referred to with a designation of "O" (i.e., AO and FO). The no undercut is shown on this link.

The absence of either the "J" or "N" designation indicates a Fixed size undercut. That is, the length of the undercut is the same for all stud lengths. The Fixed undercut is shown on this link.

Note: For all raised head styles, the "G" (Grip) and "U" (Undercut) dimensions are measured to the underside of the head. For the flush head style, the "G" (Grip) and "U" (Undercut) dimensions are measured to the top of the head.

Stud Grip Undercut Dimension (U) Grip Length (G) Weight
All Except Flush Flush Head Only Slotted,
Phillips,
Hex Recess		 Flush
(inch) (mm) (inch) (mm) (inch) (mm) (lb) (g) (lb) (g)
25 .100 2.54 N/A N/A .250 6.35 --- ---
30 .100 2.54 .175 4.45 .300 7.62 .0038 1.72
35 .150 3.81 .175 4.45 .350 8.89 .0043 1.95 .0040 1.81
40 .200 5.08 .200 5.08 .400 10.16 .0048 2.18 .0045 2.04
45 .225 5.72 .225 5.72 .450 11.43 .0053 2.40 .0050 2.27
50 .250 6.35 .250 6.35 .500 12.70 .0058 2.63 .0055 2.49
55 .275 6.99 .275 6.99 .550 13.97
60 .300 7.62 .300 7.62 .600 15.24 .0069 3.13 .0064 2.90
65 .350 8.89 .350 8.89 .650 16.51
70 .350 8.89 .350 8.89 .700 17.78 .0078 3.54 .0075 3.40
75 .400 10.16 .400 10.16 .750 19.05
80 .400 10.16 .400 10.16 .800 20.32 .0088 3.99 .0086 3.90
85 .500 12.70 .500 12.70 .850 21.59
90 .500 12.70 .500 12.70 .900 22.86 .0096 4.35 .0094 4.26
95 .600 15.24 .600 15.24 .950 24.13
100 .600 15.24 .600 15.24 1.000 25.40 .0110 4.99 .0105 4.76
105 .600 15.24 .600 15.24 1.050 26.67
110 .600 15.24 .600 15.24 1.100 27.94
115 .600 15.24 .600 15.24 1.150 29.21
120 .600 15.24 .600 15.24 1.200 30.48

N/A = Not Available

Self Ejecting Assembly Picture
 Type SE

ST-1200 Line studs may be ordered as SE (Self Ejecting) assemblies. A stainless steel ejecting spring and a black plastic cup are sold attached to the stud. The SE ejection is partial, being limited by the length of the stud undercut not occupied by the cup, panel, and stud retainer. Ejection will normally be sufficient to give a visual cue of an unlocked stud. Also, ejecting spring tension holds an opened stud firmly, easing removal and replacement of vertical panels and panels with multiple fasteners.

Self Ejecting Assembly Drawing

Stud ejection = Dimension "U" (length of undercut) - total height of the cup (.090" [2.29 mm]), panel, and retainer. See stud selection tables for Dimension "U".

DFCI does not recommend using the SE option on any studs where Dimension "U" (length of undercut) is less than .300" (7.62mm). That is, on any stud less than -60 length.

Type SE ejecting stud assemblies are compatible with all receptacles in their size.

Sizing: When calculating the pileup for sizing an SE configuration, .090" (2.29 mm) must be added for the SE Cup.

Callout: Insert "SE" in front of the finish suffix. For example: Part Number 121J-460-SE-Z3CT.

For additional Self-Ejecting options, click this link.

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.