CBOXTEC RoboticsRobotics guides

Does the gripper stroke cover your part sizes?

Compare jaw travel with the actual fingertip opening range, including the smallest part, the largest part and clearance for approach.

Three schematic views of a parallel gripper: closed jaws, open jaws and offset fingertips with a different contact gap.
Original schematic, not to scale. A and B: with equal opposed linear travel s, the gap changes by 2s. C: fingertip shape changes the contact gap. No product capacity is shown.

Check what the stroke number measures

SCHUNK lists 6 mm per jaw for the PGN-plus-P 64-1-P. In a symmetric parallel gripper, two opposed jaws each moving 6 mm change their separation by 12 mm. That is a change in gap, not the maximum part width.

The 2s relationship assumes equal, opposed linear jaw travel and unchanged fingers. Do not apply it to angular or adaptive fingers without the manufacturer's motion drawing.

Write down both ends of the opening range

Robotiq documents 0–85 mm for the 2F-85's default opening and 40–125 mm with reversed fingers. Both spans are 85 mm; their endpoints differ.

Record the minimum and maximum gap at the actual contact surfaces. A stroke number alone does not tell you either endpoint. These Robotiq ranges describe that product configuration, not CBOXTEC grippers.

Compare the installed fingers with the part drawing

For an outside grasp, check that the open fingers can approach the largest part with suitable clearance, then reach the smallest part's intended grip surfaces when closing. Include part tolerances and positioning variation; there is no single clearance value for every application.

Use the installed fingertips, pads and grip height in the drawing. For an inside grasp, compare the insertion envelope and expanded contact position with the bore instead. An outside-width calculation does not cover that case.

A dimensional fit does not prove the part will stay held

Robotiq's custom-fingertip guidance calls for checking mounting, finger dimensions and full-stroke clearance. Review the selected gripper's own drawings and limits before changing fingers.

After checking fit, assess finger mass and overhang, available gripping force, part surface, motion and stopping conditions. A wider opening does not by itself establish retention or allowed part mass. Mechanical changes and operating validation require the applicable instructions and a qualified assessment.

Ask for the opening range in your proposed configuration

Send the supplier the smallest and largest part dimensions with tolerances, intended grip faces, part mass and surface condition. Include a sketch of the approach direction and nearby tray or fixture walls.

Ask for a dimensioned drawing of the installed fingers, usable opening endpoints, applicable force and finger limits, and the supported mechanical, power and control interfaces. CBOXTEC Robotics supplies robot arms and grippers; model selection needs these details, not just a stroke number.

Manufacturer references

Discuss arm and gripper requirements