Threaded Inserts

The threaded insert allows you to use machine thread bolts or screws in wood products. These include hard and softwood as well as manufactured products like MDF, particle core, and veneer core plywood. There are two main reasons that I like to use threaded inserts. The first is when I want to increase the pullout strength of a connection I’m making. The second is on projects where thread erosion or stripping will be a potential problem.

I have used threaded inserts over the years in a variety of woodworking projects. They are great when making various types of power and hand tool jigs and fixtures. Oftentimes these projects have a certain level of adjustability, so the threaded inserts allow for tightening and loosening a wood screw without stripping the hole. Threaded inserts are also handy for making furniture that is designed to be disassembled and reassembled a few times. As the father of a daughter who is in university, designing furniture that can be reliably taken apart and moved makes my life much easier.

I’ve used them on display cases where the contents of the case need to be accessible for the user. A common one for me was a display case that held a ceremonial sword for a colonel in the military. The case displayed and protected the sword and scabbard, and it could be accessed when needed for parades or other ceremonial duties. They can also be used for wooden shipping or traveling crates that hold precious cargo, especially if those crates will be used repeatedly, and they are great for installing drawer pulls or handles because of the dependability of the machine threads. These are just some of the uses for threaded inserts, but really, the list could go on and on.

Installing threaded inserts is straight forward. Follow the manufacturers recommendations for the pilot hole size and be sure to drill the hole deep enough to allow the insert to fully seat. In the case of Rampa inserts, the company recommends 10 to 10.5mm depending on the density of the material. 10mm would be suitable for softer woods like pine and 10.5mm would be better for hard maple.

Be extra careful if you are installing the insert close to the edge of a component since there is a chance that the insert can split the substrate. There is a way to secure the insert in place and make sure this doesn’t happen. Frist, drill a slightly larger hole that is equal to the outside diameter of the external thread. In the case of the Rampa insert, the larger hole would be 12mm. Next, mix up some 5-minute epoxy. Then place the insert into the hole and add the epoxy to the sides of the hole. To protect the inner threads from epoxy, cover the bottom of the insert with a small dot of masking tape.

Threaded inserts have been around for quite a while and there are many different types available. Like all hardware, you can get bargain-basement inserts that are poorly made and inexpensive, or you can get well-made versions that will stand the test of time. My vote is always high quality because the cost of good hardware never outweighs the potential failure of a project.

Vic