SpecialInsert M1 Male B38 Bonding Fastener, 1/4-20 Thread

Description

The SpecialInsert M1 Male B38 is a stud-mount bonding fastener: a 1/4″-20 threaded bolt fixed to a 38mm round, zinc-plated steel baseplate. Instead of drilling and tapping a hole or welding a stud in place, the baseplate is bonded directly to the substrate with a structural adhesive, giving a threaded attachment point on almost any surface without heat, sparks, or mechanical fasteners that could compromise a finish.

Where Bonding Fasteners Fit

Bonding fasteners like this one solve the problem of adding a threaded mounting point to sheet metal, composite, plastic, or painted panels where drilling would compromise a finish or a sealed cavity, or where welding risks warping thin material or damaging a coating. The open-back baseplate design distributes load across the full 38mm footprint rather than concentrating stress at a single drilled hole, which helps the bond carry shear and pull-off loads evenly across the panel instead of at one weak point. Eliminating a mechanical fastener at the joint also removes a path for galvanic corrosion between dissimilar metals, which matters on marine, transportation, and outdoor equipment.

Bonding Fasteners Installation Notes

Surface prep matters more than adhesive selection for these fasteners: clean, degrease, and abrade the bonding surface before applying a compatible structural adhesive to the baseplate, then hold or clamp the fastener in position while the adhesive cures. These fasteners can also be embedded during a molding process for parts made in-house, giving a threaded insert that is part of the part from the first shot rather than a secondary operation. This particular fastener measures about 1.5 x 2 x 1.5 in and weighs roughly 0.3 lb, small enough to stage in volume for production runs. Because the baseplate is zinc plated, it resists corrosion at the joint line, which matters on outdoor or washdown equipment. Browse bonding fasteners for other thread sizes and baseplate styles, and see the SpecialInsert manufacturer site for the full fastener line.

Need Help?

Need help choosing a baseplate size or adhesive for a bonding fastener installation? Call (800) 220-1966 or email [email protected].