How to Use Self-Tapping Screws

Posted by Bob Bawden on 10/22/2018 to Technical
We have explained different methods already of securing your furniture grade PVC structure, but we haven't gone into detail on self-tapping screws. If you are making a larger, more complex structure and you don't want a permanent solution like glue for securing your structure, then read this blog post!

For projects using 1 1/4" and 1 1/2" furniture grade pipe and fittings, you need something more substantial than our plastic rivets to secure your joints - something like self-tapping screws. These are great for when you're making projects such as goal posts, which are likely to be facing more impact than smaller projects like shoe racks. To fit the screws to your larger project, you will need a drill, a 3mm drill bit, and some number 8 self-tapping screws. We recommend using pan-head screws, rather than countersunk screws, because countersunk screws eat into the plastic and weaken the joints. An additional piece you can have is a screw-cap, which covers the obvious screw-head coming out of your pipe with a white dome.

To start, you need to mark your pipe with the depth of insertion into the fitting. This is because you otherwise won't know if your pipe is fully into the fitting or not, which could alter your measurements. What you need to do is line the bottom of your pipe up with the outside of the fitting, where the next joint starts, and this way you can mark the pipe at the point where the end of the fitting should come to. To mark your pipe, the best thing to use is a pencil - using a permanent marker might risk the look of your structure. 

Next, you need to insert your pipe into the fitting and hammer it in to make sure the pipe goes all the way down to the ridge inside the fitting. A wooden or plastic mallet is the best thing to use here, so that the outside of the fitting isn't damaged. If you don't have either of these and you can only use a metal hammer, you must put a piece of wood in between the fitting and the hammer and hit that so that you don't mark your fitting.

Now you need to drill your pipe and fitting. If you want your structure to look as slick and smooth as possible, we recommend choosing to drill around the back of your fitting, where it won't be visible. Take your pencil again, not a permanent marker, and mark in the middle of the joint where you want the screw to go. Then, take your drill and drill through the wall of the fitting and the wall of the pipe - don't go through to the other side!

Once you have drilled your hole, you can put your self-tapping screw in. If you don't want the screw-head to be visible, we recommend using a screw-cap. Simply insert the screw through the screw-cap and then put the screw into the hole, clipping the cap over the top of the screw-head when it's in nice and firm. If you try to put your screw into your joint without drilling a hole first, you will make a mess of the hole, because the plastic will melt slightly as the friction of the screw tries to rip into the plastic. This will make an ugly hole which might not let your screw the whole way in, and also might mean you won't be able to put another screw in after taking out the first, which means you won't be able to dismantle and reassemble your structure properly.

If you would like to see a video demonstration of using self-tapping screws with a furniture grade structure, you can watch our YouTube video here!