DeWalt DWMT70778 - User Manual

Questions and Answers

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christine30Aug 17, 2025
What to do if my DeWalt Paint Sprayer is spitting, spraying irregularly, or fluttering?
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  Nicole MillerAug 17, 2025
  If your DeWalt Paint Sprayer is spitting, spraying irregularly, or fluttering, it could be due to several reasons. The fluid nozzle might be cracked or worn, or there could be a leak at the fluid nozzle's thread or the fluid needle. The needle packing might be worn out, or there might not be enough fluid in the cup. Alternatively, the vent hole in the container cover could be clogged. To resolve this, try the following: tighten or replace the fluid nozzle, tighten the fluid nozzle, tighten the compression nut assembly or replace the needle packing, fill the cup with more fluid, or clean out the vent hole.
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Whitney BrownAug 20, 2025
Why is my DeWalt DWMT70778 Paint Sprayer producing an unatomized or spattered spray?
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  vincenthernandezAug 20, 2025
  An unatomized or spattered spray from your DeWalt Paint Sprayer can occur if the material is too heavy, the air pressure is insufficient, the fluid pressure is too high, or there's dried material on the tip of the fluid nozzle or air jets of the air cap. You can try thinning the material or using a larger orifice fluid nozzle set, increasing the pressure to within limit, reducing the pressure, or cleaning the nozzle and air cap.
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anthonyrodriguezAug 22, 2025
What to do if my DeWalt Paint Sprayer material is leaking from the nozzle when the trigger is released?
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  Ashley TaylorAug 23, 2025
  If material is leaking from the nozzle of your DeWalt Paint Sprayer when the trigger is released, it could be due to a worn fluid needle, dried material in the tip of the nozzle, or a loose packing nut. Try replacing the fluid needle, cleaning the nozzle, or tightening the needle packing nut by turning it counterclockwise.
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Christopher JohnsonAug 25, 2025
Why is my DeWalt DWMT70778 gun splitting?
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  Amy CochranAug 26, 2025
  Gun splitting in your DeWalt Paint Sprayer is often due to air getting into the paint stream, similar to when the cup is running out of paint. To resolve this, check and tighten the fluid needle packing nut, tighten the fluid tip, check the fluid tip seat for damage, ensure proper gun-to-cup seating, and verify that the cup is correctly fastened to the gun.
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Erika PetersenAug 27, 2025
What to do if material is leaking from the fluid inlet of the cup on my DeWalt Paint Sprayer?
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  alexander22Aug 27, 2025
  If material is leaking from the fluid inlet of the cup on your DeWalt Paint Sprayer, it's likely due to a loose cup or foreign substances on or between the cup thread and fluid inlet. Try tightening and cleaning the cup, or replace it if necessary.
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Henry DavidAug 30, 2025
Why is my DeWalt DWMT70778 Paint Sprayer producing excessive fog?
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  Dana WilliamsAug 30, 2025
  Excessive fog from your DeWalt Paint Sprayer is often caused by air pressure that's too high for the viscosity of the fluid. To fix this, reduce the air pressure and/or open the fluid control knob.
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Nicholas LeeSep 1, 2025
What causes a split pattern in my DeWalt Paint Sprayer and how to fix it?
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  Dale DavisSep 2, 2025
  A split pattern in your DeWalt Paint Sprayer can be caused by air pressure that's too high for the material viscosity or by dirty or distorted air horn holes, or one of the air horn holes being completely obstructed. To address this, try the following: 1. Reduce the air pressure. 2. Turn the pattern control knob clockwise to decrease the fan width and turn the fluid needle adjusting nut counterclockwise to increase fluid flow. 3. Rotate the air cap 180 degrees to see if the pattern follows the air cap, indicating an issue with the air cap. 4. Clean and inspect the horn holes. If the horn holes are distorted, replacement is necessary.
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karen33Sep 4, 2025
What to do if my DeWalt DWMT70778 has a heavy top or bottom pattern?
- B
  Brittany SmithSep 4, 2025
  If your DeWalt Paint Sprayer is producing a heavy top or bottom pattern, it's likely due to a dirty or damaged air cap or fluid tip. Rotate the air cap 180 degrees. If the pattern follows the air cap, clean and inspect it; replacement may be necessary. If the pattern doesn’t follow the air cap, clean and inspect the fluid tip for dried paint, dirt, or damage; replacement may also be necessary.
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Jonathan BurgessSep 6, 2025
What causes inadequate air delivery in my DeWalt DWMT70778 Paint Sprayer and how can I fix it?
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  Jeffrey DurhamSep 6, 2025
  Inadequate air delivery in your DeWalt Paint Sprayer can be caused by a partially closed air needle, dried material in the air jets or air cap, or an obstruction in the air line. To fix this, open the control knob, clean the air jets and air cap, and remove any obstruction in the air line.
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fodomSep 9, 2025
How to fix air back pressuring into the cup of my DeWalt DWMT70778 Paint Sprayer?
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  David HaynesSep 9, 2025
  If air is back pressuring into the cup of your DeWalt Paint Sprayer, it's likely due to excessive air blowing back into the cup. Try tightening the fluid tip, checking the fluid tip seat, and inspecting for any damage to the fluid seat on the tip or the seat on the gun head.

Summary

Save These Instructions

Improper Operation Warning

Improper operation or maintenance could result in serious injury and property damage.

Read Manual Warning

Read and understand all warnings and operating instructions before using this equipment.

Eye Protection Requirement

Operators and others must wear ANSI Z87.1 CAN/CSA Z94.3 approved safety glasses.

Hearing Protection Requirement

Operators and others in work area must wear ear protection.

Risk to Breathing (Asphyxiation)

Features

Spray Gun Body

Describes the spray gun body's design for balance, light weight, and precision.

Spray Gun Cup

Details the spray gun cup capacity, lid design, and ease of removal.

Material Filter

Explains the function of the material filter in protecting against contaminants and small particles.

Air Cap Horns

Describes how air cap horns allow for two different spray patterns.

Air Volume Control Knob

Explains how the air volume control knob regulates airflow and reduces overspray.

Air Inlet

Details the air inlet size and connection for the air supply.

Fluid Control Knob

Explains how the fluid control knob adjusts the amount of material released.

Pattern Control Knob

Describes how the pattern control knob adjusts the width of the fan spray.

Fixed Hook

Notes the presence of a fixed hook for convenient hanging of the spray gun.

Installation

Air Supply

Details the recommended air supply hook-up, pressure limits, and hose requirements for optimal performance.

Maintenance Continued

Cleaning

Provides step-by-step instructions for cleaning the spray gun after each use.

Lubrication

Outlines lubrication procedures to ensure effective and high-quality performance of the spray gun.

The DEWALT DWMT70778 Gravity Feed Touch-Up Spray Gun is an instruction manual for a spray gun designed for precision jobs, offering a well-balanced and lightweight body. It is a compact tool with a fine spray capability.

Function Description

The spray gun's primary function is to apply paints, lacquers, thinners, and base coats through a gravity feed system. It features various controls for precise application:

Air Volume Control Knob (F): This knob regulates the air flow, allowing for a maximum of 30 PSI to reduce overspray and ensure efficient air consumption.
Fluid Control Knob (I): This control adjusts the amount of material released, influencing the density of the "fan spray." Turning it counterclockwise increases material release, while clockwise decreases it.
Pattern Control Knob (H): This knob adjusts the width of the "fan spray." Counterclockwise rotation increases the width, and clockwise decreases it.
Trigger (E): Depressing the trigger fully sprays material. Partially depressing it releases only air.

The spray gun cup (A) holds the material to be sprayed. The air cap (C) with its horns (D) allows for two distinct spray patterns: horizontal and vertical, which can be achieved by rotating the air cap 180 degrees. A material filter (B) is integrated between the spray gun cup and the air cap to prevent contaminants and small particles from entering the spray.

Important Technical Specifications

Model: DWMT70778
Feed Type: Gravity
Nozzle Size: 0.8MM
Cup Capacity: 8.8 Oz. (250ML)
Pattern Length: >3.5" (90MM)
Min. Working Pressure: 30PSI
Max. Working Pressure: 60PSI
Average Air Consumption @50PSI: 4.1 SCFM (2.0 L/s) / 1.4 CFM (0.67 L/s)
Net Weight: 0.75 LBS (0.34Kg.)
Air Inlet Size: 1/4" NPS(M)
Recommended Hose Size: 3/8" (10MM)

Usage Features

The spray gun is designed for ease of use and precision.

Gravity Feed System: The gravity feed design ensures a consistent flow of material to the nozzle.
Adjustable Spray Patterns: The air cap horns (D) can be rotated to switch between horizontal and vertical spray patterns, providing versatility for different applications.
Material Filter (B): An optional material filter protects against contaminants, ensuring a smooth and clean spray.
Air Inlet (G): Located at the bottom of the handle, the 1/4" NPT air inlet connects to a standard air supply.
Fixed Hook (J): A hook on the body allows for convenient hanging and storage.
Pre-shipment Treatment: The gun is treated with an anticorrosive agent before shipment, requiring thorough flushing with thinner before first use.

Maintenance Features

Regular cleaning and lubrication are crucial for optimal performance and longevity.

Cleaning:
- After each use, empty the material cup and replace it with a suitable solvent or thinner.
- Operate the trigger until all material traces disappear and the gun is thoroughly clean.
- Clean the air cap with a brush.
- Wipe the exterior of the gun with a solvent-soaked cloth or use cleaning brushes to remove accumulated material.
- The air cap and fluid nozzle must be kept clean. If necessary, remove and soak them in solvent. Avoid using hard objects to clean clogged holes, as this can cause irregular spray patterns.
- When removing the fluid nozzle for cleaning, squeeze the trigger to prevent damage to the fluid needle tip.
- Caution: Do not soak the entire spray gun in solvent or thinner for extended periods, as this can damage lubricants and impair operation. Avoid lye or caustic alkaline solutions, which can attack aluminum alloy parts.
Lubrication:
- After cleaning, lubricate working points with straight mineral oil or castor oil.
- Periodically apply a few drops of oil to the tapered sections of the fluid nozzle to ensure easy air cap operation.
- When spraying water-based materials, coat the fluid nozzle inside and outside with straight mineral oil after each use.
- The outer diameter of the needle sleeve in the fluid needle assembly should be lubricated occasionally with straight mineral oil.

Safety Guidelines

The manual emphasizes several safety precautions:

Always wear approved eye and hearing protection, and respiratory protection.
Never aim the spray gun at anyone or spray near sparks, open flames, or pilot lights.
Ensure the work area is well-ventilated.
Disconnect the spray gun from the air source before disassembly or service.
Do not use latex or other heavy paints with this spray gun.
Never exceed the maximum working pressure of 60 PSI.
Be cautious when handling solvents and thinners, and dispose of used cleaning materials properly.
Avoid using solvents like 1,1,1-Trichloroethane and Methylene Chloride, as they can react with aluminum and create an explosion hazard.
In case of injection injury, seek immediate medical attention.
Oil daily for optimal performance.