FA1: How to unscrew and screw screws correctly

Many people use a screwdriver without giving it much thought. However, science can be applied to this process to avoid stripping screws. Luckily, Nerf uses descent quality screws on their blasters. The most important thing to do when unscrewing or screwing a screw is to apply as much pressing force as rotational force, if not more! Pressing force is important because the contact between the screwdriver to screw is angled upward for easy insertion of the screwdriver. However, this means that if insignificant pressing force is applied with strong rotational force, the screwdriver will slip against the screw and pop out, damaging the screw.

The size and type of the screwdriver used is also important. Both attributes contribute to how flush the screwdriver fits with the screw. In terms of size, never ever use an undersized screwdriver; if anything, use an oversized one. When screwing, an undersized screwdriver contact the screw where it is the weakest and most vulnerable to stripping. In addition, low profile, flat tip screwdrivers are preferred as they dig into the screw, maximizing the contact area between the screwdriver and screw. Jeweler's screwdrivers usually have flatter tips than normal ones. A figure is shown below to demonstrate flatter screwdriver tips.

Fig. FA1.1 – screwdriver comparison: normal on the left, flatter tip on the right

It is possible to grind down the tips of normal screwdrivers so they dig deeper into screws and create the same effect as flatter tip screwdrivers. However, purchasing the right screwdrivers (high quality and/or flatter) is recommended over this. How well a screwdriver is paired with the screw can be determine by measuring the screwdriver's fit to the screw. To do this, insert the screwdriver into a fixed screw (screwed-in screw or a screw held tightly with fingers), then lightly press the screwdriver down into the screw and gently turn the screwdriver clockwise and counter-clockwise in a back and forth motion. If the fit is good, there should be very little rotational movement that the screwdriver exhibits during this motion. If the screwdriver rotates significantly, then it is not a good match to use with the screw. The largest Philips screwdriver in the Stanley jeweler's precision screwdriver set is a good screwdriver for Nerf applications: amazon link. Wiha precision screwdrivers work amazingly if quality is desired: amazon link. The Wiha precision screwdrivers exhibit the tip profile of a normal screwdriver as opposed to that of the flatter tip screwdriver. However, they are engineered so precisely that the screwdriver dig deep into the screw to allow the sidewalls of the screwdriver and screw to be perfectly flush with each other.

Another good idea is to layout the unscrewed screws in positions that correlates to their actual screw positions on the blaster. This takes up a bit of space, but with the organization, every screw can be screwed back into the same screw hole they were unscrewed from. Keeping the screw and screw holes matched allows for better fitting of the screws. If there is plastic in between the threads of the screw after removal, clean it off by squeezing the screw with fingers and rotating the screw counter-clockwise with a screwdriver. Furthermore, there is also science behind the order at which the screws are screwed back into the blaster. The order that the screws should be screwed back in should start at the center of the body surface and radiate outward. This means that screws that are nearest to the center of the blaster shell should be screwed in first while the screws on the edge of the shell should be screwed in last. If multiple screws are the same distance away from the center, then randomly select a screw to start and screw in the remaining screws in an order such that the next screw is furthest away from the current screw. Examples of correct screw orders are shown below.

Fig. FA1.2 – equal distance screw order example

Fig. FA1.3 – radiating and equal distance screw order example

Screwing screws in the correct order reliefs stress on the material body, keeps the joint surfaces flush and allows for more of the screw's retaining force to be used as bonding force.

In standard applications, turn the screwdriver counter-clockwise to unscrew a screw and clockwise to screw a screw (lefty loosy righty tighty). If a screw does not loosen with a good amount of force, double check to make sure that the screwdriver is being turned counter-clockwise to unscrew the screw. If screwing in a unique position and/or with the non-dominate hand, mentally double check the rotation of the applied force for correctness. In certain situations, it may be necessary to verify the rotation direction with two or more different thought processes, as a single method alone may be deceiving. When screwing in a screw, it is wise to first place the screw in the screw hole, then rotate it in the loosening direction (yes, loosening!) while holding the screw perpendicular to the screw hole (either with the other hand or by tilting the screw with the screwdriver) until a small tick or jolt is heard/felt. Once this happens, reverse the direction of rotation and start screwing in the screw normally while maintaining the screw perpendicular to the screw hole. This process assures that the screw is aligned to the opening groove of the screw hole from the start and also prevents misalignment between the screw thread and screw hole groove. For the first few turns of screwing in a screw, apply gentle force and turn the screwdriver slowly. If strong resistance is felt while doing this, it means that the screw thread and screw hole groove is misaligned. When this occurs, stop screwing immediately, unscrew the screw and restart the screwing process to correct the error.

The position where the screwdriver is gripped to turn it is also a key component of screwing screws. Screwdrivers have multiple positions to grip for screwing. The widest gripping area provides the most torque, but is the slowest screwing speed. The narrowest region provides the fastest screwing speed, but applies the least torque. The diagram below shows a cross-section view of a typical screwdriver.

Fig. FA1.4 – screwdriver grip positions

Use the high torque area to break the initial friction when unscrewing a screw or apply sufficient force to finish screwing in a screw. Once the initial friction is broken when unscrewing or initially screwing in the screw, use the high speed area to quickly unscrew or screw a screw. It is also possible to use the stem of the screwdriver to screw even faster! Using the high speed area of the screwdriver's grip or the screwdriver's stem to initially screw in a screw will also make it easier to detect misalignment and potentially cause less damage from this error.

Although most of these tips may seem pointless, following them will prevent hardware damage and prolong its life. Once these techniques become familiar, they hardly require any additional time to carryout. If a screwing job is necessary, put on some music and do it right from the start!