How to Install Threaded Countersunk Timber Inserts…

Yessss…. This is pretty easy on the level – but a bit harder on an angle (as in with stairs). And since the drilling posts is repetitive work, you really need a Jig / Template. This can be really nothing more than some scrap material you have around the place. However, we recommend that you use something light, square, and cheap – like Lawn Edging. You can clamp it to your post, mark the holes and then drill through the template. This applies to drilling both your level and angled posts – both end and intermediate.

Once you have the template, there is a method for inserting them at 90 degrees on a level deck or inserting them at an angle (normally 37 degrees to match the stairs) on your stairs.

How do Install Countersunk Threaded Timber inserts into a post on the level?

First, mark out the position of the hole to be drilled on one side of the post (You should do this by using the template).
Drill a 4mm pilot hole .
Measure the diameter of the shaft/tube of the insert and measure the diameter of the threads on the insert.
Select a drill bit that is no more than 1mm bigger than the shaft of the insert – this gives the insert threads plenty of wood in which to bite. (smaller hole for softer wood like pine and larger hole for harder wood like merbau)
Then just free-hand drill with your selected bit (probably about 8.5mm) to a depth of 45mm to allow for clearance at the bottom for the Terminal Swage Stud that gets screwed into the timber insert.
Finally, drive in the countersunk threaded timber inserts with a 6mm hexdrive bit (inserted into your awesome variable speed reversing drill) and snug that ‘puppy’ up. You may need to “pocket” the Insert a bit further into the post so that one side of the lip is not protruding … usually only a few mm. The pocketing process can be done with a 10mm countersunk bit that you have swapped into that drill of yours…

How do Install Countersunk Threaded Timber inserts into a post on an angle?

First, mark out the position of the hole to be drilled on one side of the post (You should do this by using the template).
Drill a 4mm pilot hole – at an angle matching your stairs . If you need a guide, then we recommend that you cut a triangular piece of wood that fits EXACTLY into the angled space/pocket that exists where your post and your top rail meet. This triangle is then used to guide the drill bit to exactly match the angle of the top rail. You put the triangle up against the end post and then ‘lie’ the drill bit along the top of the triangle (thereby matching the top rail angle).
Measure the diameter of the shaft/tube of the insert and measure the diameter of the threads on the insert.
Select a drill bit that is no more than 1mm bigger than the shaft of the insert – this gives the insert threads plenty of wood in which to bite. (smaller hole for softer wood like pine and larger hole for harder wood like merbau)
Then just free-hand – or grab your triangle jig – and drill with your selected bit (probably about 8.5mm) to a depth of 45mm to allow for clearance at the bottom for the Terminal Swage Stud that gets screwed into the timber insert. This expands the pilot hole to the proper size on the proper angle.
Finally, drive in the countersunk thraded timber inserts with a 6mm hexdrive bit (inserted into your awesome variable speed reversing drill) and snug that ‘puppy’ up. You may need to “pocket” the Insert a bit further into the post so that one side of the lip is not protruding … usually only a few mm. The pocketing process can be done with a 10mm countersunk bit that you have swapped into that drill of yours…
Finally, if you don’t like the angled countersunk look of this effect – you can use a 37 degree Beveled Washer to completely finish the installation.

If you use a square bracket piece (as opposed to the Triangle in this example) and make it fairly long , it will act as a guide to indicate if the drill is also drilling square to the timber and not angling across the face of the timber. This approach can also be used to drill intermediate posts straight and level every time – but more on that elsewhere.