Copyright(C)2018 Fasco Boeki Co.,Ltd. All Rights Reserved.

Product category

BobTail Large

□ There is no pintail!

・ There is no breaking noise of the pin and the fastening          is quiet.
  ・ There is no breakage, so no waste is generated.
          ・ No need for surface treatment on the fractured    surface.

□ Visual inspection is possible

・ Correct strength is secured if at least one round indicator is crushed. Consolidation of inspection processes increases production efficiency

□ High seismic resistance!

・ The collar crimped to the bolt thread forms a permanent, shock-resistant connection.

Next-generation large diameter hack bolt

It becomes removable compared with the past and board thickness is wide.

□ Reduced amount of swaging

・ By improving the special tool, it is possible to swage with less force. In addition, fastening speed is faster than conventional products, and durable products can be made quickly and cheaply.

[Junker's vibration test]
  Bobtail 14 mm diameter, 10.9 class

The chart on the left shows that the nut and bolt axial force (clamping force) dispersion is considerably wider than Bobtail. In conventional bolt and nut, the tightening load is rapidly damped when vibration starts, while Bobtail keeps it constant.
Every second

[Gap comparison at installation]
                 The hack Bobtail lock bolt has a low thread shape, has no gap compared to the standard bolt and nut, and has a shape that is difficult to loosen in vibration. In addition, because of the smooth thread, it has a structure with less stress concentration.

Bobtail      Standard bolt nut

[Visual inspection to see at a glance]
      ・ The installation indicator of the color flange which is Huck's exclusive design, you can see the completion of swaging of the bobtail collar.


Before conclusion       After conclusion

[Conclusion process]

1. Insert a bolt into the hole and screw the collar to the pin.
* The screws are not for tightening. For temporary fixing.

2. Start by putting the tool on the parallel threaded pin tail. As the puller pulls the bolt into the tool, it simultaneously pushes the collar and eliminates the part gap.


3. The anvil starts swaging by starting to pull at the specified strength.
While the collar bites into the thread, it extends the collar forward to obtain the required axial force.

4. When the swage is complete, release the switch and the anvil will return to the rear, releasing the pintail from the puller.

Round head      Truss head      Flange head      90 ° Counter head      3OSS cap

Grade 5 = Standard (inch) Upon request 8.8 grade = Available (meters)
Grade 8 = Standard (Inch) 5/8 ", 16mm Class 10.9 = Standard (Meter) on request

Large Bobtail Bolt Head Dimensions (Inches & Meters) Units = mm

Note) Truss head and 90 ° countersunk head upon request.

[Standard head style and strength level]

Inch Size Large Bobtail Dimensions and Data

[Inch Size Large Bobtail Color Dimension] Unit = mm

[Inch size Large Bobtail bolt dimensions] Unit = mm

Meter Large Bobtail Dimensions & Data

[Meter Size Large Bobtail Color Dimension] Unit = mm

[Meter Size Large Bobtail Bolt Dimension] Unit = mm

Inch Size Large Bobtail Bolt Part Number Selection Chart

BT → flange head
DT → Carbon steel Grade 8
16 → 1/2 "diameter
8 → Tightenable thickness 12.7-22.69 mm
GA → Galvanized 10μm Trivalent clear chromate finish


Meter size Large Bobtail bolt part number selection chart


MBT → flange head
DT → Carbon steel Grade 8
20 → M20 diameter
70 → Tightenable thickness 65-75 mm
NP → Geomet 1 layer type


Surface treatment: NP JIS Z2371 salt spray
After 48 hours

Inch & Metric color part number selection chart

MBTC → 10.9 grade
R → carbon steel
20 → M20 diameter
BL → trivalent zinc plating clear chromate finish

* For the combination of special tools, please see the separate tool table.