Drill And Tap Size Guide For M5 X 17 Screws

When working with screws, it's important to know the correct drill and tap sizes to ensure a secure fit. The tap size chart provides standard tap sizes, specifying the diameter and thread spacing for fractional, metric, and screw sizes. For an M5 screw, the recommended drill size is 4.2mm, although some people have used 4.5mm without any issues. It's worth noting that the tap size chart also provides the recommended tap drill size for each standard tap size, which should be used for drilling the initial hole.

Tapping sizes and recommended drill sizes

For an M5 screw, the recommended tap drill size is 4.2mm. This measurement is crucial for drilling the initial hole that will be tapped. While some sources suggest that a 4.5mm drill bit can be used and may be more readily available, especially in the UK, the ideal size is 4.2mm for a proper fit.

It is worth noting that the tap size chart serves as a reference for standard taps, and the recommended drill sizes are not absolute requirements. In practice, it is common to use slightly larger drill bits, such as 4.3mm or even 4.5mm, for an M5 screw, depending on the material being drilled and the specific application.

When selecting the appropriate drill size, it is essential to consider the desired thread engagement percentage. A higher thread engagement, typically around 75%, results in a stronger joint and prolongs the life of the tap. However, it is also important to assess the loading of the joint and the actual loads the screw or bolt will experience.

In summary, while the recommended tap drill size for an M5 screw is 4.2mm, there is some flexibility in drill bit selection, and sizes up to 4.5mm can be used depending on the specific requirements and considerations of the application.

Metric units and conversions

The International System of Units (SI) is the standard metric system used in most countries today. It consists of seven SI base units: length, mass, time, temperature, electric current, luminous intensity, and amount of substance. The metric system is used almost universally in science, including in the US, but some countries like the United States still use their own system of units.

The basic metric units include meters (m), kilograms (kg), seconds (s), kelvin (K), and ampere (A). These units are distinct from the imperial system, which includes units such as feet, yards, inches, and pounds.

Metric conversions are straightforward due to the system's decimal nature. For example, in the metric system, length follows a simple pattern of increasing and decreasing by a factor of ten:

1 kilometer = 1000 meters

1 meter = 100 centimeters

1 centimeter = 10 millimeters

Other metric units follow similar patterns:

1 liter = 1000 milliliters

1 liter = 10 deciliters

1 kilogram = 1000 grams

Converting between metric and non-metric units, such as between the metric system and the imperial system, is also possible using conversion factors. For instance, 1 inch is equal to 2.54 centimeters, and 1 pound is equal to 0.456 kilograms.

When it comes to the specific case of an M5 x 17 screw, the "M" denotes that it is a metric screw, and the number after the "M" indicates its diameter in millimetres. So, an M5 screw has a diameter of 5 millimetres. The "x 17" part of the designation indicates that the screw is 17 millimetres long.

Coarse vs fine thread spacing

When it comes to choosing between coarse and fine thread spacing for screws such as the M5 x 17, there are several factors to consider as each type of threading has its own advantages and disadvantages.

Coarse thread fasteners, with their wide and deep ridges, are the more common choice for construction and general applications. Their key advantage is their tolerance; they can be lightly damaged and still work effectively. This is because coarse threads have more material between the threads, making them less likely to strip or cross-thread. They are also less susceptible to galling than fine threads, as fine threads have more turns per inch, generating more friction and increasing the chances of galling. Coarse threads are also better at handling obstructions, such as dirt, and can be fastened even when not fully clean.

On the other hand, fine thread fasteners have their own benefits that make them ideal when specific requirements are needed. Fine threads have a higher tensile strength and can be measured more accurately, making them suitable for applications where specific strength is crucial. The shallow peaks and valleys of fine threads make tapping a hole significantly easier, as there is less material to cut. Fine threads also have a shallow pitch, making them less prone to loosening over time due to vibrations. Additionally, fine threads require less torque to develop equivalent bolt preloads and have a smaller tendency to loosen due to their smaller thread incline.

In summary, coarse thread fasteners are generally more versatile and suitable for most applications, especially in construction. Fine thread fasteners, while more challenging to obtain, offer specific advantages in terms of strength, accuracy, and vibration resistance, making them ideal for applications where these factors are critical.

When it comes to the M5 x 17 screw, the specific choice between coarse and fine thread spacing would depend on the particular requirements of the application. Coarse threads would be suitable for general-purpose use, while fine threads would be advantageous in applications requiring specific strength, accuracy, or resistance to vibrations.

Screw size numbers and their relation to diameter

The numbers on a screw, such as #6 or #8, refer to the diameter of the screw. This means that a higher number indicates a larger diameter. For example, a #4 screw is designed for small crafts, jewellery boxes and attaching hinges, and is very light-duty. A #6 screw is used for small crafts, hinges, drawer slides, children's furniture and toys, and is light-duty. A #10 screw is used for general construction and heavy-duty furniture, and a #12 screw is for heavy-duty construction and hanging solid-core doors.

The same principle applies to metric screw sizes. An M5 screw has a diameter of 5mm, and an M24 screw has a diameter of 24mm.

In the US, fractional sizes are listed in inches, while metric sizes are listed in millimetres. For example, a #6 screw has a diameter of 0.136 inches, and an M5 screw has a diameter of 5mm or 0.197 inches.

When selecting a screw, it is important to consider the specific application and any special requirements. For instance, when drilling a hole to match a screw size, it is crucial to use the correct diameter to prevent splitting or damage to the material being fastened.

Tap drill size for initial holes

When tapping threads, it is important to start with a pilot hole. This initial hole will guide the tap and help ensure the accuracy of the final thread size. The size of the drill bit used for this initial hole is critical and should match the recommended tap drill size for the specific tap being used.

Tap drill size charts provide the recommended drill bit size for each standard tap size. These charts specify the diameter and thread spacing of taps in fractional, metric, and screw sizes. The recommended tap drill size is based on the diameter and thread count or pitch of the tap.

For an M5 x 17 screw, the recommended tap drill size is typically between 3.5 and 4.0 mm. This size drill bit should be used to create the initial hole before tapping to ensure the tap can be started accurately and the desired thread size is achieved.

It is important to note that the tap drill size is different from the final thread size. The tap drill size is slightly smaller than the major diameter of the screw thread. This allows for some material deformation and a tight fit when the screw is inserted into the tapped hole.

Frequently asked questions