Monthly Archives: September 2020

How to Install Brass Threaded Inserts

I’m currently working on building a crib for my firstborn son. There are two elements of this design that make it unique among the furniture that I’ve created in the past:

  1. The mattress should have two distinct heights: an upper height for when he is an infant, and a lower height for when he is a toddler
  2. I need to be able to disassemble the piece; both to move it into the nursery, and for storage once my son has outgrown it

I opted to solve both of these problems by building the crib out of five flat pieces that are affixed to one another using 3/8” brass screws and threaded inserts. I chose brass here for its aesthetics, thinking that the brightness of the brass would play nicely against the warmth of the wood.

The product that I chose for this purpose was E-Z Lok 3/8”-16 threaded brass inserts:

The kit comes with some the threaded inserts, and appropriately sized drill bit, and a slot head driver that is supposed to allow you to drive the threaded inserts home using a drill. Separately, I purchased some slot head brass screws that thread into these inserts from McMaster Carr.

When choosing these fasteners, I made the mistake of assuming that both the screws and threaded inserts needed to be made out of brass brass.

In practice, the threaded inserts are never visible when the crib is assembled, so I could easily have used a threaded insert that was made out of steel, which would have handily avoided all of the problems that I encountered when trying to drive the relatively soft brass inserts into the hard oak of the crib body.

On the right, a virgin threaded insert. To the left, a threaded insert that was destroyed when I tried to drive it into the end grain of a piece of oak using the tool included in the kit

After a few of the brass inserts tore themselves to pieces during my early testing (which I thankfully conducted on scrap, and not on my finished piece), I turned to Reddit to ask the community of r/woodworking for help installing these fasteners.

The solution came from user u/okacookie who suggested that I thread a nut most of the way onto a 3/8”-16 hex head bolt, and then thread the bolt into the threaded insert, jamming the threaded insert up against the nut. This way, a hex driver or ratchet can be used to drive the threaded insert into the oak workpiece without having to rely on the flimsy slot head that has a tendency to rip to if you so much as look at it the wrong way. Once the threaded insert has been driven home, the bolt can be backed out, leaving the insert behind.

In practice, I found that starting the threaded insert with the slot driver that was included in the E-Z Lok kit before switching out to the jam nut and ratchet combination worked best for me.

In closing, if you find yourself using these brass threaded inserts, first ask yourself if they absolutely have to be made from brass. If not, use a stronger metal. If so, ditch the silly slot head driver and use a bolt with a jam nut to get the job done.

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Filed under Product Review, Wood Working