Introduction: Make a Self Tapping Bolt
Sometimes you may need to add threads to a hole, but you don't want to go buy a thread tapping tool. Making a self tapping bolt is quick and easy. It works great if you need to tap some plastic or wood, but it may not be the best option for thick metal. Either way, Here are the steps for making one.
If you would like to see a video version of this instructable, you can check that out here: https://youtu.be/cg1nVvXhTbA
Step 1: Taper the Tip
Simply grind or file a taper onto the tip of the bolt. The bolt will get hot, so it helps to hold it with some pliers.
Note: You don't have to taper the tip of the bolt, but it does help to get the bolt started when you're using it.
Step 2: Add Some Grooves
Next you'll want to add some vertical grooves into the threads of the bolt. I recommend adding either 3 or 4 grooves, depending on how big the bolt is. These grooves add an opposing sharp edge to the threads of the bolt to help cut the threads into the material when screwing in the bolt.
That's all there is to making a self tapping bolt, but I added a couple more steps to help describe using the bolt.
Step 3: Drill a Hole
When drilling the hole in the material, you want to make the hole a little bit smaller than the diameter of the bolt. If you make the hole too big, there won't be enough material for the threads to hold on to.
Obviously, this isn't the proper way to create a strong, watertight seal for PVC connections. I'm just using this on PVC because it's adequate for demonstration purposes here.
Step 4: Screw in the Bolt
This step is mostly obvious, but there are a couple things to remember. First, try to keep the bolt perpendicular to the surface. Next, you want to push the bolt in as you turn it. This will help it to bit into the material as it's starting to cut the threads. And finally, don't just screw it in all at once. Every now and then, turn the bolt backwards about half a turn. This helps it to cut better threads into the material.
Step 5: And That's It!
And that's all there is to it! This works good if you need to make threads in soft material, or thin metal. If you need to thread a hole in thick metal, you may be better off getting a thread tapping tool. Thanks for checking out my Instructable!