Installing The T-nuts - Corner Gussets

There's nothing worse than being in the middle of a job and realizing a tool, material, or supply wasn't at hand. Had that experience the other afternoon while I was slathering some sloppy epoxy onto some T-nuts.  No Varsol-soaked rag at hand.  Talk about frustration with gooey epoxy all over my fingers!  We don't want to be in that kind of situation when we're installing T-nuts with the epoxy glue.

Let's review the parts of a T-nut so that we all understand what I'm talking about below.
The Tools, Supplies & Materials For Installing T-Nuts
Here's the list of tools, materials, and supplies we'll need to have close at hand when we install the T-nuts. We'll be using this same method a couple of more times when we install the T-nuts for the carry-plates and the alignment pins/ connector bolts.

In the photo above, left to right, top to bottom, we have
  1. Varsol (turps, paint thinner, etc) for cleaning the epoxy off our fingers between installs.  Also for cleaning excess epoxy off of the wood.  (Canadian Tire sells an "odourless" varsol in a quart/ litre can. It may also be available at your local building supply store.)
  2. Shop rag to be used in conjunction with the varsol.
  3. Four (count em!) corner gussets with the holes drilled and marked "Top" (the underside is marked "Bottom").
  4. 1/2" wrench (or socket & ratchet, etc) that fits over the bolt head next to it. Make sure it fits!
  5. 5/16"x 1" bolt with 5/16" fender washer (or similar kind of washer) used to torque the T-nuts into the holes in the gussets.
  6. Four 5/16" T-nuts. Make sure the 5/16" bolt screws easily into each T-nut!
  7. Wooden shishkebab skewer (nail, rod, or other suitable item) used to apply epoxy glue to the barrel of the T-nut.
  8. Epoxy glue (resin & hardener). Use the "5-Minute" kind.
  9. Plastic lid to mix the epoxy resin and hardener on. (I rescued it from the recycle bin.)
  10. Underneath it all is some wax paper so that the mess is easy to clean up.
Take a look at that 5/16" bolt and the "fender washer". You might be tempted to whack the T-nut into the gusset with a hammer (I did that the first time round). All that's going to do is crack the wood. An easier way is to thread the bolt from the bottom side into the T-nut and tighten the bolt so that it pulls the T-nut into the wood. It results in a very snug and secure fit.

Make sure the wrench fits over the head of the bolt and the bolt threads easily into the T-nut. I've had to scramble for my tool box when I discovered I had a 9/16" wrench instead of the 1/2" one with a T-nut loaded with epoxy. Talk about a mess.

Before we use the bolt, we're going to give it a wipe with varsol and clean it with varsol after each use. We don't want the bolt stuck halfway in the T-nut because some epoxy decided to harden before we were able to unscrew the bolt. I had to grind off the head of a bolt last month because of that. Talk about smoke and burnt wood! Almost set off the smoke alarms.

As we torque the bolt into the T-nut, epoxy will squeeze out from underneath the head of the T-nut.  We'll have to spread this around (a varsolled finger works best) and wipe off any excess.  So, make sure you soak the shop rag in varsol right after you mix the epoxy.  

I've gathered all of these items together in one place within easy reach cause once we start to mix and apply the epoxy, things will move real fast.

Mixing The Epoxy & Installing The T-nuts
Now that we've gathered all the supplies in one spot, we're ready to start installing the T-nuts into the corner gussets.

Step 1) Squeeze equal gobs of resin and hardener onto the plastic lid.  Mix it well with the skewer. 

Step 2) After you've mixed the epoxy, soak the shop rage in varsol.  You'll need it to clean off the excess epoxy from the wood and to clean your fingers.

Step 3) Next, load the barrel of the T-nut with epoxy, taking care not to get any inside the threaded part.  Make sure to put on lots of epoxy as we want the glue to squeeze out from underneath the washer part of the T-nut so as to securely hold the T-nut in place.


Step 4) Insert the T-nut into the drilled hole on the "Top" (I like to use 5-minute epoxy cause it mixes nice and thick and doesn't drip all over the place). 

Step 5) While you hold the T-nut in place with one hand, insert the bolt and fender washer into the hole on the bottom.

Step 6) Screw the bolt in all the way until it's finger tight.

Step 7) Torque the bolt down with the 1/2" wrench.  As you torque the bolt down, it will draw the spurs of the T-nut into the wood.  Tighten the bolt until it's really snug and tight.

Step 8) Unscrew and remove the bolt and the fender washer.

Step 9) As you tighten the bolt, excess epoxy will ooze out from under the top of the T-nut. Spread this around (a "varsolled" finger works best) so that you fill the gaps between the edges of the T-nut and the 1" recessed hole.

Step 10) Wipe off any epoxy that spills over the edge of the hole with the shop rag soaked in varsol.

Step 11) Repeat Steps 1) to 9) for the other gussets and T-nuts.  

Step 12) Let the epoxy dry for 24 hours.

Long Gussets - Drilling Holes & Installing T-nuts
So far, we've been discussing installing T-nuts for triangular gussets.  We almost forgot the "long gussets" - the ones that are made from the 1"x 4"s (3/4"x 3 1/2") cut to 22 1/2".  You may want to use these long gussets for added stability and where clamping space isn't at a premium.  If you're building a modular home layout, you definitely want to use long gussets, particularly if the width is going to exceed 24" and the length longer than 6'. 

Step 1) - Measure and mark the location of the holes for the T-nuts at 1 3/4" from each end and side (ie half of 3 1/2").  Drill a 1/8" pilot hole at each end of the two gussets so that subsequent drilling operations line up.

Step 2) - Counter-sink the hole by 1/8" so that the head of the T-nut will be below the surface of the gusset (and our Styrofoam flush with the top of the module) using either a 1" Forstner bit or a 1" spade bit. As you finish each hole, lay the head of the T-nut into the cut and make sure you can't see any of the head when you scan across the surface.

Step 3) - Clamp the gusset on top of a scrap piece of wood to reduce splintering when the drill bit breaks through the other side. Drill a 3/8" hole right through the wood so that the barrel of the T-nut fits into the hole.

Step 4) - Test fit each hole by pressing the barrel of the T-nut into the hole. You should have a nice tight fit.

Step 5) - Mark each piece as "Top" as shown below and "Bottom" on the other side. It will save you headaches later on.

Step 6) - If store labels are stuck to the wood, lift them off and rub the glue off with varsol and a shop rag.  If we don't wipe off the glue, the outline of the label will be obvious when  we paint the modules. 

Step 7) Install the T-nuts using the same procedure as in our previous blog.

We've condensed some of these steps in the photo below.  

Next up - End Plates & Side Pieces - "In" and "Out", "Top" and "Bottom"

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