When working with or designing metal parts, being able to have threaded holes for bolts is something that is great, and often taken for granted. It allows pieces to be attached together and detached easily. This is more of a challenge and often not considered for woodworking projects because wood isn't as strong as metal.
Luckily, tapping wood is actually pretty easy, and can be strong with some minor additions, giving your wood projects more flexibility.
What You'll Need
- Drill bits
- Thin CA glue
Step 1: Drill
For making a threaded hole, you first need to make a main hole that removes most of the material, except for the threaded area. To know what size you need for your pilot hole, here is a link to a convenient chart. If possible, use a drill-press so your hole doesn't wobble around. It should be as straight and consistent as possible so your threads have lots to grab onto. Using a hand drill is more likely to make a little bit sloppier hole, but would work if you are careful.
Step 2: Tap
If you have a proper tap, you can tap the pilot hole the same way you would any other material, but you won't need any oil. Since wood is really soft, you can likely "tap" the hole using just the bolt you want to put in it. Getting it threaded at the start can be a little tricky. Make sure you push the bolt into the hole while turning it so the threads catch.
As you are turning the bolt into the hole, watch out as the bolt can get hot with all the friction. Take your time. Also, don't tighten the bolt all the way down as this can strip the new threads you made.
Step 3: Reinforce the Threads
This really is the trick to the whole thing. Thin CA glue flows really well and will soak into the pores of the wood and around the threads, reinforcing the entire thread. Once it dries, you have the strength of the wood, and the glue, which will hold your bolts tight.
Put a few drops in the hole so it runs down the side. Make sure to cover as much of the thread as possible. For a small hole, 2-3 should be enough, but a bigger/deeper/wider hole may need more drops.
When you put the glue in, you may see a little puff of smoke come out of the hole, Not to worry, this is common.
Step 4: Done
Leave the glue to dry for a few hours. Once it's dry, take your bolt and re-screw it into the now completed hole. It may be a little tight at the beginning as the bolt needs to push/cut the glue away, but once it's been put in once, it should be smoother from then on.
Now that the hole is threaded and sealed, you can disassemble and reassemble your projects really easily, and attach parts together in ways that you usually can't with woodworking.