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October 05, 2026 3 min read
You took your spray gun apart to clean it. Now you’ve got the gun body and a handful of parts sitting on the bench.
So what goes where?
Putting a spray gun back together isn’t complicated once you understand the basic parts and the order they go back in. And knowing how your gun comes apart and goes back together is an important part of learning how to properly set it up, clean it, and troubleshoot it.
In the video below, I walk through the basic components and reassemble the gun step by step.
The exact design will vary depending on the spray gun you’re using, but most automotive spray guns have the same basic components:
Fluid nozzle
Air cap
Needle
Needle spring
Fluid adjustment knob
Paint cup or disposable paint cup adapter
Air inlet
Optional at-the-gun air regulator
Before you start putting everything back together, make sure the parts are clean and free of dried paint or other material.
I start by installing the fluid nozzle into the gun body.
The fluid nozzle is where the paint or other material exits the gun before being atomized by the air cap.
Thread it into the gun carefully. You want it properly seated, but there’s no reason to get carried away tightening small spray-gun components.
Next, slide the needle into the back of the gun.
Be careful with the needle. The tip needs to remain straight and undamaged so it can properly seat against the fluid nozzle.
This is also one of the areas where proper spray-gun lubrication matters. You want the moving components operating smoothly without introducing lubricant into places where it can contaminate your paint.
I’ll cover spray-gun lubrication separately.
Want to know where and why I lubricate a spray gun during assembly?
Check out my [Needle Juice article here].
With the needle in place, install the needle spring followed by the fluid adjustment knob.
The fluid adjustment knob controls how far the needle is allowed to move when you pull the trigger. That affects how much material the gun can deliver.
For now, we’re simply putting the gun together. Proper fluid adjustment is a separate subject—and an important one.
Next comes the air cap.
Thread the air cap assembly onto the front of the gun.
The orientation of the air cap determines the direction of the spray pattern, and its relationship with the fluid nozzle is a major part of how the gun atomizes material.
Again, we’ll get into those adjustments separately. The goal here is simply to get the gun properly assembled.
On this gun, I’m using a disposable paint cup system, so an adapter threads into the top of the gun.
Different guns and cup systems use different adapters, so make sure you’re using the correct adapter for your particular gun and disposable cup system.
Once it’s installed and secure, the disposable paint cup can be attached.
The last thing I like to add is an air regulator at the gun.
Having a regulator right at the gun allows me to see and adjust the air pressure where it matters rather than relying only on the regulator back at the compressor.
Air pressure is one of the most important spray-gun adjustments, but the correct pressure depends on the gun, material, setup, and manufacturer’s recommendations.
That deserves its own discussion.
Learning to paint isn't just about pulling the trigger.
You need to understand the equipment.
Know what the parts are. Know how the gun comes apart. Know how it goes back together. Then learn what each adjustment actually changes.
Once you understand the gun, setting it up for different primers, paints, clears, and other materials becomes a lot less mysterious.
Next, I’ll get intohow to set up and adjust a spray gun, including fluid control, fan adjustment, air-cap orientation, and air pressure.
Because the better you understand your equipment, the easier it is to figure out what’s happening when the spray pattern isn't doing what you want.
More real-world automotive paint, body, restoration, and garage tips at V-Twins to V-8s.
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This site documents real builds, tools, and shop work from my own projects. Some pages are showcases. Some are how-tos and tool reviews. If you’re working on a project and want experienced guidance, I offer one-on-one coaching.