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Overview

Mechanical 1/4 Turn Quick Set Clamps

Mechanical Quick Set Clamps

quick-set-clamp-photo

When to Use 1/4 Turn Quick Set Clamps:

Use mechanical quick set clamps with dies having slotted die plates and enough over slot clearance for the set clamp body.  U-Slot brackets or ears may also be added to the dies or a heel block added to the back of the clamp for some applications.

How they work:

To use, move clamp into position and manually hand tighten nut using the large diameter knurled surface.  Use a wrench to torque to the desired preload.  The large bronze alloy nut acts as an easy turning, anti-galling, large surface thrust bearing arrangement for superior performance.

Model 255 clamps require approximately 125 ft.-lbs. of torque to preload the clamp to 10,000 lbs. clamping force.  Model 259 clamps require approximately 350 ft.-lbs. to preload clamp to 20,000 lbs. clamping force (unlubricated threads).  Clamp preload should be limited to 20,000 lbs. and 40,000 lbs. respectively.

Options and features:

ARA vs. FRA.  Free Rotation (FRA) clamps use standard threaded bolts, while Anti-Rotation (ARA) models use modified threads to prevent the clamping plate from spinning about the bolt.

STN or TSB. Stud with attached T-Nut (STN) is standard for a wide range of clamping heights. Forged T-Slot Bolts are also in use for some sizes.

HB Option.  In cases where customers desire to use the clamp in applications without slotted die plates, a heel block may be added to the clamp to support the back of the clamp.  (Clamping force is 50% of rating.)  For this option specify HBX.XX at the end of the part number.  (X.XX = clamping plate height in inches.)

Nut Retention Option. In cases where customer desires to prevent the nut from coming off the bolt. A stop mechanism is added to the top of the bolt. Use STL in place of STN (or TSL in place of TSB) in the part number for this option.

Applications / Sizing

Applications/Sizing

Standard Configurations

Model 255 clamps are designed for 3/4” T-Slots and Model 259 for 1” T-Slots. The part number references the “bolt length”, which is not the clamping height, but rather the complete length of the bolt. The charts show nominal clamping height for standard T-Slots. The bolt length can be selected for the part number below.

Model 255
TSB Nominal Clamp Height**		 Clamp Range B*
(Standard 3/4” Slot)
Min.     Max.		 A+B*
Min.     Max.		 C D E
0 – 1 0” 1.125” .75” 2.0” 2.0” 2.5” 4.0”
1 – 2 .875” 2.125” 1.75” 3.0” 2.5” 5.0”
2 – 3 1.875” 3.125” 2.75” 4.0” 2.5” 6.0”
2½ – 4 2.375” 4.125” 3.25” 5.0” 3.0” 7.0”
3 – 5 2.875” 5.125” 3.75” 6.0” 3.5” 8.0”
3½ – 6 3.375” 6.125” 4.25” 7.0” 4.0” 9.0”
Model 259
TSB Nominal Clamp Height**		 Clamp Range B*
(Standard 1” Slot)
Min.     Max.		 A+B*
Min.     Max.		 C D E
0 – ½ 0” .6” .75” 1.6” 2.4” 2.5” 4.0”
¾ – 1½ .75” 1.6” 1.75” 2.6” 2.5” 5.0”
1¾ – 2½ 1.75” 2.6” 2.75” 3.6” 2.5” 6.0”
2¼ – 3½ 2.25” 3.6” 3.25” 4.6” 3.0” 7.0”
2¾ – 4½ 2.75” 4.6” 3.75” 5.6” 3.5” 8.0”
3¼ – 5½ 3.25” 5.6” 4.25” 6.6” 4.0” 9.0”

* T-Slot neck height (dimension A) is assumed to be .875” for 3/4” slots and 1” for 1” slot.
**STL/TSL Stype with retaining ring incure a ¼” reduction in maximum clamp height.
Suffix (– TSB) may replace ( – STN) if TSB is available and substituted. STN has no minimum on clamping height range as it has threads to the T-Nut. Maximum clamping height is calcuatied as follows:
Model 255 BMAX = E – 3.25
Model 259 BMAX = E – 4.00
*** TSB and TSL are available in some sizes and may be substituted for STN/TSL styles depending on available stock.

Quick Die Change QDC Quick Set turn Clamp Lightning fast Time Saver when installing dies
PFA QDC forged T bolt vs. Stud and T nut layout

Clamps are provided with T-Slot Bolt “TSB” (Item A) or Fully Threaded Stud and T-Nut “STN” (Item B) depending on clamp size, clamping height, and availability. The new standard will become all Stud and T-Nut arrangements over time.

Quick Die Change QDC Quick Set turn Clamp Lightning fast Time Saver when installing dies - part number specification
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