How does a rivet gun work? It pulls a steel mandrel through a rivet body until the back side expands and locks two materials together. That simple pull-and-expand action is why a small tool can make a strong, permanent joint in thin metal, plastic, leather, and other sheet materials.
If you only know rivet guns from quick videos, the process can look confusing. The tool seems to squeeze, the rivet seems to disappear into the hole, and then a stem snaps off. Once you understand what the nosepiece, jaws, mandrel, and rivet body are doing, the whole mechanism makes sense, and it becomes much easier to choose the right rivet, avoid loose joints, and use the tool with confidence.
What a rivet gun actually does
A standard DIY rivet gun, often called a pop rivet gun or blind rivet tool, does not push the rivet into place. It pulls on the mandrel while the nosepiece presses against the rivet head. That pulling force collapses the rivet body on the back side of the material, which creates the clamp.
This matters because many beginners picture the tool like a staple gun or nailer. It is closer to a puller than a pusher. The rivet is already sitting in the hole before the tool does its real work.
The word blind is also important. A blind rivet can be installed when you can only reach one side of the material. That is why rivet guns are common for gutter repairs, sheet metal panels, thin brackets, HVAC covers, and light trailer work.
A lot of people use the term rivet gun for every riveting tool, but that is not always correct. The hand tool in most garages is a blind rivet gun. The air hammer-style tool used for solid aircraft rivets is a different machine, even though both are called rivet guns in casual conversation.
The parts that make the mechanism work
Once you know the main parts, the whole process becomes easy to follow. A hand tool like the Arrow RH200S is a good example because you can actually feel each stage of the mechanism as you squeeze the handles.
The nosepiece supports the rivet head
The nosepiece is the tip that fits over the mandrel. It rests against the flange, which is the visible head of the rivet on the front side of the material. Rivet guns usually come with multiple nosepieces for sizes like 1/8 inch, 5/32 inch, and 3/16 inch.
If the nosepiece is too large, the mandrel may wobble and the pull can feel sloppy. If it is too small, the mandrel will not seat correctly. That tiny mismatch is one reason beginners think the tool is defective when the real problem is setup.
Inside the head, jaws grip the mandrel
Behind the nosepiece are hardened jaws. When you squeeze the handles, those jaws bite into the mandrel and pull it backward through the rivet body. When you release the handles, the jaws reset so they can grab again on the next stroke.
That reset action is a non-obvious part of the mechanism. On larger rivets, the tool may need several pulls, and each pull moves the mandrel a little farther until the rivet sets and the stem breaks at its designed weak point.
The rivet body deforms and creates the joint
The rivet itself has two main working parts: the hollow body and the mandrel. As the mandrel is pulled, the back end of the rivet body mushrooms outward. That mushroomed section clamps the two materials between the back side bulge and the front flange.
Most users focus on the tool, but the rivet is doing just as much work. If the rivet body is the wrong length or wrong material, even a perfectly working gun can leave a weak joint.
Step by step: what happens when you squeeze the tool
The full process is easier to understand in order.
- You drill or prepare the hole. The hole should closely match the rivet size. If you are making clean holes in thin sheet metal, a step drill bit is often the easiest option because it cuts round holes with less grabbing than a twist bit.
- You insert the rivet through both materials. The flange stays on the front side. The longer part of the rivet body and mandrel pass through the hole so the back side can expand.
- You fit the mandrel into the nosepiece. The tool grabs the exposed mandrel, not the rivet body. The nosepiece presses against the flange to hold the rivet head steady.
- You squeeze the handles. The jaws pull the mandrel backward. As that happens, the shaped head on the mandrel pulls against the hollow rivet body and flares it out behind the material.
- The materials get clamped together. Once the backside bulge forms, the joint tightens. A small aluminum rivet may set in one or two strokes, while a larger steel rivet may take several.
- The mandrel snaps off. When the pull force reaches the break point, the mandrel stem breaks with a pop. That sound is normal. The rivet stays in the hole, and the broken mandrel piece comes out of the tool or collects in the stem container on some models.
If you want the full hands-on process after understanding the mechanism, this guide on how to use a rivet gun covers the practical setup and operating steps.
One detail that experienced users notice right away is the change in handle feel. A clean, correct setup feels smooth at first, then firmer as the rivet body expands, and then suddenly lighter when the mandrel breaks. If the handle pressure feels wrong from the very first pull, stop and check the rivet size, nosepiece, and hole before forcing it.
Why rivet size, grip range, and hole prep matter more than most people think
Many guides say to pick a rivet that fits the hole and then squeeze until it snaps. That advice is too loose. A rivet gun works best when the rivet diameter, grip range, and material stack thickness all match each other closely.
Grip range means the total material thickness the rivet is designed to clamp. For example, if your two sheets together measure 0.125 inch, a rivet with a grip range of 0.063 to 0.188 inch is in the right zone. If the rivet is too short, it may not form a proper backside bulge. If it is too long, it can fold badly, spin in the hole, or clamp poorly.
Hole quality matters too. A rough, oversized, or out-of-round hole makes the rivet work harder and hold worse. This is especially true in stainless steel, where drilling cleanly can be harder than the riveting itself. If you are working with tougher sheet stock, this article on how to drill stainless steel will help you avoid work-hardening and sloppy holes.
Material choice also changes how the gun feels. A 3/16-inch steel blind rivet takes much more force than a 1/8-inch aluminum rivet. That is why a light-duty hand tool can feel fine on one job and miserable on the next. The mechanism is the same, but the load on the jaws and handles is not.
Here is the non-obvious part beginners often miss: if a rivet starts spinning before it sets, the tool is not always the problem. The hole may be too large, the stack may be thinner than the grip range, or the materials may not be clamped tightly before setting. Fixing those issues usually solves the problem faster than blaming the gun.
Blind rivet guns and solid rivet guns are not the same tool
Most searchers asking how a rivet gun works really mean a blind rivet gun. That is the common hand, cordless, or pneumatic pull-type tool described above. It uses a mandrel that snaps off after the rivet sets.
A solid rivet gun works differently. It is usually a pneumatic hammering tool that drives a solid rivet while a second tool, called a bucking bar, supports the opposite side. Instead of pulling a mandrel to flare a hollow body, it deforms a solid rivet shank by repeated impact.
The reason this matters is simple: advice for one system can be useless for the other. If you watch aircraft sheet-metal videos and then try to apply those techniques to a pop rivet tool, the steps will not line up. They are related fastening methods, but the mechanics are different.
For most home users, repairs, and light fabrication, a blind rivet tool is the practical choice because you only need access to one side. If you are choosing a tool for regular work, this roundup of the best rivet guns helps compare hand, cordless, and air-powered options.
And if you get stuck without the tool on hand, there are some limited workaround methods in this guide on installing rivets without a rivet gun. They can work in a pinch, but they are not as clean or consistent as using the proper tool.
Common problems and beginner mistakes
Most riveting problems come from setup, not from the tool breaking. Start with the simplest cause first.
The hole is too big
This is the most common problem by far. If the hole is oversized, the rivet body cannot grip the walls properly as it expands. The result is a rivet that spins, sets crooked, or feels loose even after the mandrel breaks.
The grip range is wrong
A rivet that is too short cannot form enough backside bulge. A rivet that is too long may fold over instead of clamping tightly. Many people assume any rivet with the same diameter will work, but diameter alone is only half the decision.
The nosepiece does not match the mandrel
If the mandrel does not sit correctly in the nosepiece, the jaws may slip or the stem may pull at an angle. That can scratch the mandrel, damage the jaws over time, and make the tool feel weak.
The jaws are dirty or worn
Broken mandrel pieces and fine metal dust can build up inside the head. Then the jaws stop biting cleanly, and the tool begins to slip on the next rivet. A lot of people replace the tool too early when a simple cleaning or jaw replacement would bring it back.
The materials were not clamped flat first
If the pieces are separated by a gap, the rivet may pull them together badly or deform in an uneven way. Rivets work best when the materials are already aligned and held snug before you start pulling the mandrel.
Safety matters here too. Drilling and riveting can throw off small metal chips, and broken mandrels can eject unexpectedly. OSHA eye and face protection guidance is a solid baseline if you are working with metal, especially overhead or in tight spaces.
If the tool still slips after you check the hole, rivet, and nosepiece, stop forcing it. Excess force usually damages the mandrel, the jaws, or your hands before it fixes the joint.
Questions people ask before using a rivet gun
Can a rivet gun work on wood or plastic, or only metal?
Yes, it can work on wood, plastic, leather, and thin composites as long as the material is suitable for a through-hole fastener. The key is choosing a rivet with the right diameter and grip range so the backside bulge does not crush soft material. On brittle plastic, use a backup washer if the material around the hole needs more support.
Why does the mandrel snap off?
The mandrel is designed to break at a controlled point once the rivet has been pulled tight enough. That break point makes installation consistent. If it breaks too early, the rivet size, hole size, or tool setup may be wrong.
Do all rivets need the same amount of force?
No. Material and size change the required force a lot. Aluminum rivets are usually much easier to set than steel ones, and larger diameters increase the load quickly, which is why cordless or pneumatic tools make sense for frequent 3/16-inch work.
Can you remove a rivet after it is installed?
Yes, but you do not pull it back out with the gun. You usually drill through the center of the installed rivet head until it releases. Use a bit close to the rivet shank size and go slowly so you do not enlarge the original hole.
How do you know a rivet set correctly?
The flange should sit flat on the front side, the materials should feel tight with no play, and the backside should show a formed bulge instead of a folded or half-set shape. If the rivet spins after installation, it did not clamp correctly even if the mandrel snapped.
A rivet gun is simple once you stop thinking of it as a tool that pushes and start seeing it as a tool that pulls. If you are new, start with 1/8-inch aluminum blind rivets and a solid hand tool like the Arrow RH200S, because that setup lets you feel the mechanism without fighting too much force. Get the hole size and grip range right first, and the rest of the process becomes much easier.
