Are you looking to make a PVC prop armature that has movable joints? Wouldn’t it be great if the prop had hinges and ball joints so the arms and legs could move just like an action figure? Well, luckily you don’t have to pay for expensive tools or buy special parts – now you can make all these things with ease using common store-bought materials. In this tutorial, I’ll show you how to create a variety of joint types to convert your static, single pose PVC body frames into versatile articulating joint armatures that you can either lock into different poses or motorize to perform life-like movements!
Hinge Joints
Hinge joints like you find in fingers, knees, elbows and toes allow only bending and straightening movements primarily in one plane. Adding movable hinge joints to an otherwise static prop or PVC armature instantly allows you to create more dynamic poses or even motorize motions like arms reaching out, legs moving up and down, sitting, standing or even kicking. On top of that, they’re among the easiest articulated joints to implement into a PVC body frame or armature.
How to Make Movable PVC Hinge Joints
There’s no shortage of clever hinge joint creations in maker and Halloween forums. From the simple and inexpensive to the complex and over-engineered, hinge joints are the most popular type of articulation to start with and like most homemade props, there’s no one way to go about it. Sometimes having too many design options can be overwhelming so here are three popular methods I use myself that are inexpensive and can be made by modifying store-bought materials.
Hinge Joint 1: Heat & Pinch PVC Ends
This is by far the least expensive and easiest method for creating quick hinge joints. If you have to create more than one posable figure and are crunched for time, this method is the way to go. First heat the last 2″ of an end of PVC pipe with a heat gun. The PVC will start becoming pliable and you can test how flexible it is by gently pressing it on a workbench or floor. Once it’s easy to deform, clamp the end and squeeze it together as tightly as you can. Let it cool to the touch and release the clamp. I recommend rounding off the corners by trimming them with a dremel tool, metal file or sander.
Repeat this process with another piece of PVC pipe and drill a hole through both flattened ends with a power drill. Then connect both pieces of PVC pipe with a bolt and nut. A 1-1/4′ – 1-1/2″ bolt length should be sufficient. For smoother articulation add a washer or two between the PVC connection to reduce friction. You can adjust the tightness of the bolt depending on how much free movement you want. The more you tighten the bolt, the more the joint will be “locked” into position. This allows you to create different static poses or leave some joints movable to motorize them. I like to cut my PVC pipe 1″ from the hinge so that I can put a 1″ coupling on it and connect any length of limb in the future. In the picture below, one of the parts is already cut at 1″ but the other was left longer to fit another project.
An alternative to using a heat gun to mold the PVC pipe is to dip the end in boiling water. This also does a good job in softening it and then you can proceed with the rest of the steps. Dipping the piece you molded in cold water helps “set” it faster.
Hinge Joint 2: Chain Link Fence Rail Ends
Chain link fences have a variety of fittings and accessories that you can integrate as is or with small modifications into your articulated or motorized prop projects. One very useful fitting is the chain link fence rail end. Just bolt two of them together and you have an instant hinge joint!
I normally use 1″ PVC to build my armature frames so the diameter of the rail ends will be slightly too big and won’t hold the PVC pipe without some help. I either use two small screws or a through-bolt with a nut to secure the PVC pipe into the chain link rail end. Like with the hinge type above, it’s best to include one washer or more between both chain link fence rail end connectors for smoother movement.
Hinge Joint 3: Aluminum, Brass or Steel Flat Bar
This is the first hinge method I came up with but decided to mention it last because I tend to use the other two methods a lot more. This method requires three nut-and-bolt combos per joint instead of just one for the other two methods so it’s slightly more expensive. You’ll also need flat bar stock in your choice of aluminum, brass or steel which is also more expensive than the other materials mentioned above. Finally, it requires a few more steps than the other methods. All this being said, it still makes a great hinge joint and many people do it this way so I decided to include it in the list.
Aluminum flat stock is the easiest to cut and work with so I recommend trying that out first over brass or steel. A good width is about 3/4″ and you want to stay at about 1/8″ for thickness. Buy enough length to cover all your hinge joints. Each joint will require two pieces of flat bar at 4″ each in length. The first step is to cut as many 4″ pieces as you need. You’ll need to drill three holes through each flat bar piece for the bolts. Two holes are for bolting through one end of a PVC pipe to lock the flat stock in place and the remaining hole is for the bolt that goes through the articulating piece of PVC. Drill a hole 1/2″ from each end of your flat bar then pick an end and drill the final hole 1-1/2″ from the end. Repeat this for all the flat bar pieces you cut for your armature.
Use your drilled flat bar pieces as a template to mark drill holes on your PVC pipe ends and drill straight through both sides. Place a flat bar piece on each side and sandwich the assembly together with bolts and nuts. If you over-tighten you’ll notice that the PVC pipe begins to compress. Using a spacer, bushing or wooden dowel with a through hole inside the PVC helps prevent it from compressing. Leave enough space between the two hinged ends of the PVC pipe so they don’t knock into each other when articulating. If have clearance issues, you can notch away the part that’s making contact.
Pivot Joints
In addition to bending limbs with hinge joints, you can add another layer of interest by being able to turn or rotate them as well. Pivot joints like you find in the neck and to some degree in the elbow allow limited rotating movements. For instance, a head that can only hinge forward to look down at the ground or up to look at the sky, will now be able to turn side to side to look left and right. Another great use for a pivot joint is in the elbow to rotate the forearm to make the palm of the hand face up or down. Pivot joints can be combined with hinge joints to get the benefits of both – bending and extending along with rotation.
How to Make a Movable PVC Pivot Joint
When it comes to the world of PVC armatures you’ll commonly see pivot joints called pin-and-slot joints. The name pretty much describes how they’re built. Since I normally use 1″ PVC coupling for my joints, my pin-and-slot joints are made with 1″ and 1/2″ PVC pipe. The goal is to cut a 1/4″ wide slot on the PVC coupling. The length of the slot will determine how much rotation you get. The longer the slot, the more the rotation. You can cut the slot either using a miter saw or dremel tool. I normally try to cut two slits side-by-side using a miter saw and roughly the same depth. Then slip in the 1/2″ piece of PVC pipe you want to articulate into the 1″ PVC pipe on the slot side until you see it through the slot. Drill a hole through the inner pipe just on the side you see and insert a short bolt to secure it. You can now rotate the inner piece of PVC pipe along the length of the slot.
Another modification is to drill a large hole on the opposite side of the 1″ PVC pipe and use a longer bolt that goes from the slot in the front through the inner pipe and out the large hole in the back with a nut for more stability.
Ball Joints
While combining pivot joints with hinge joints will solve most of your movement goals, ball-and-socket joints adds yet another level of posing and articulating options. This type of joint like you find in shoulders and hips allow backward, forward, sideways and rotating movements. Incorporating ball joints into the shoulders and hips of your PVC armature now gives you the ability to move arms and legs in virtually any circular direction.
How to Make a Movable PVC Ball-and-Socket Joint
Our goal is to push the open end of a PVC pipe around a ball that’s slightly larger than the opening of the pipe. Sticking with our 1″ PVC armature, I find that golf balls or wooden balls about the size of golf balls work really well and are easy to drill into. The first step is to prep the ball. Drill a hole through the center of the ball and out the other side. Countersink the hole on one side of the ball with a larger drill bit so the head of a bolt will sit inside and the top of the head will be flush with the outer surface of the golf ball. I assume many of you reading this don’t have a drill press to drill straight through the ball. At this time, I don’t either so I used a bench vise to clamp the ball still, making it easier to drill through. Thread the bolt through the ball and screw on a nut or two on the opposite side. Tighten the nut to help pull the bolt head down into the countersink but not so tight that you crack the wooden ball or deform the golf ball. The nut not only prevents the bolt from backing out, it also will provide clearance over the socket when articulating. If your nut is thin, you may have to add another nut like I did. With the ball portion of our ball-and-socket joint complete it’s time to move on to the socket part.
Cut a relief notch at one end of a 1″ PVC coupling and try to stay 1/4″ from the stopper ring on the inside. We’re going to be heating the end of the PVC coupling with the notch to try and expand it over the golf ball. Place the ball back in the vise and grip it by the nuts. In the photos, you’ll see I worked ahead and gripped the assembly by a 1″ cap but this can rock back and forth as you hammer down on the PVC coupling. Heat the notched end of the PVC coupling with a heat gun until it becomes pliable and then insert it over the ball and hammer down. Keep reheating until you can push the coupling over about 3/4 of the ball. Don’t heat the PVC coupling while it’s on the ball! Golf balls are rubber and it could deform with continuous heat. Always remove the PVC coupling to heat it. Use a hammer to hit the PVC coupling downwards to help push it over the ball. Let it cool or use a wet cold rag to “set” the socket.
The last thing to do is drill a hole through the top of a 1″ PVC end cap and then slide the cap through the bolt coming out of the ball until the top of the cap hits the nut. Secure the cap on the inside with a washer and nut.
Now you have a ball-and-socket joint assembly that’s ready to receive 1″ PVC pipe on both ends. Whether you decide to permanently glue your 1″ pipe into the ball joint assembly or make a temporary connection with a bolt to secure the pipe is up to you. These joints are inexpensive to make so you can always whip up more. I usually prefer a temporary connection because I often upgrade my projects and it’s convenient to swap in a different length PVC pipe down the road if I want to change the size of my armature.
Build Your Own Articulating Joints
I’ve shared with you some of the methods I use to create a variety of movable joints and every time I build a new character, I come up with new ways to articulate them. The methods I’ve described are a fantastic way to bring your props to life without putting in too much effort or spending a ton of money. With DIY movable ball and hinge joints for PVC prop armatures, you can customize your props to perform whatever action you want. Additionally, you can use these steps to fine-tune the articulation and durability of your prop so that it will last as long as possible. Whether you’re an expert prop maker or still new to the craft, you’ll never stop coming up with better ways to do things so start experimenting!
If you get stuck or need more direction, I invite you to join our Engineering Artists community where you can master vital animatronics and robotics skills to accelerate your growth in less time with real-time interactive courses focused on doing along with a motivating community to keep you on track.
Some links in this post are to affiliate sites. If you purchase something through them, I may earn a small commission — which costs you nothing! I am very grateful for your support when you use my links to make a purchase.