These expanding fixturing pins install into your own fixtures to provide a solid, repeatable, and low-profile workholding solution.

Pins are machined from 17-4 stainless steel. The bottom of each pin is machined to +0.0000" -0.0005" [-0.013 mm] from the nominal diameter for accurate location in your fixtures, while the top portion is slightly tapered for easy installation and setup of the workpiece. Each pin includes one expanding pin body and one torx-socket parabolic bolt.

What are the benefits of using expanding fixturing pins?

• All-access machining: expanding pins remain nestled inside of existing holes in the part, giving full access to the external features of the workpiece.
• Lower material cost and cycle time: with full access to the workpiece periphery, there's no more buying oversized stock for Op 1 just to machine away its “hat top” in Op 2.
• Minimized part stresses/deformation: pins deliver high clamping force while constraining the part in a relatively free state; ideal for large, thin components that would otherwise bow under external clamps or vises.
• Easy changeover: pins provide secure workholding and accurate, repeatable location of the parts, making changeover between components a breeze.

How do your expanding fixturing pins work?

Like an expanding mandrel, these pins use the tightening of a screw to drive expansion and apply clamping force to an inner diameter. A custom parabolic-head bolt engages an internal taper on the pin, and radial grooves machined into the pin allow it to expand outward and increase in diameter as the screw is tightened (see animation in product photos).

This parabolic bolt reduces internal friction and, combined with machined lubrication-retention grooves, directs more force to your part’s sidewalls than a full-contact tapered bolt.

Pins are designed to expand elastically up to 0.01" [0.25mm]. Most pins will expand significantly beyond this but may not 'spring back' to their nominal diameter. For example: our 0.500" pin will clamp a 0.530" bore, but will not spring back to its original 0.500" diameter afterwards. It will spring back enough to continue being used in a 0.530" bore.