How Does a Screwgun Work?

General Construction Screw Gun

• A general construction screw gun is useful for all types of construction jobs except when working with drywall. According to ProRemodelingTips.com, a general purpose screw gun -- also known as an impact driver -- spins at 2,500 revolutions per minute, or RPM, and has a high amperage motor. This combination of slow revolutions and power are necessary to effectively drive screws with larger heads into surfaces. The nose piece of an impact driver is adjustable to accommodate different screw sizes and changes in desired screw depths. This tool has a built-in clutch to allow the device to run without the driver bit actively rotating.

Drywall Screw Gun

• A drywall screw gun operates at 4,000 RPM, much higher than an impact driver. The increased speed is necessary to power a screw through drywall and have the screw actually sink into a wood stud beneath the surface. A drywall screw gun doesn't have sufficient amperage to work with surfaces other than drywall. Using the tool on a harder surface or with a larger screw could easily overwork the motor. Like an impact driver, the nose piece of a drywall screw gun is adjustable. A drywall screw gun also has a built-in clutch.

Electric or Pneumatic Power

• A screw gun's power supply may come from one of two sources: electricity or air/gas pressure. An electric screw gun can either plug into a wall outlet or use a chargeable battery pack in much the same way as a portable electric screwdriver. A pneumatic screw gun uses pressurized air or gas to provide the power necessary to properly sink screws into surfaces. A portable electric screw gun makes the most sense for home use because a pneumatic screw gun requires an air/gas compressor as a power source. A pneumatic screw gun also generates more power than an electric screw gun. This makes the device dangerous in inexperienced hands.

Auto-Feed or Manual Guns

• An auto-feed screw gun has screws loaded into the tool through a small belt system on the front. The tool eliminates the need to manually reload screws after each application. This provides an advantage for a large scale job where hundreds of screws are necessary to complete the task. A manual screw gun works with one screw at a time. This type of tool is ideal for a home repair job where only a few screws are necessary to complete an installation or fix a problem.