A 6mm screw requires a 4.8mm drill bit for a suitable pilot hole. How Much Smaller Should A Pilot Hole Be For A Screw? In our metric screw size chart, you’ll find all the information you need to buy the right size of screws for your project. Our chart includes: You may have noticed in the table above, I have listed sizes for a pilot hole and a clearance hole, but what is the difference? The purpose of a pilot hole is to clear the diameter of the shank or body of the screw so that only the threads engage with the wood fibers. Failure to do this will result in wood splitting, especially in hardwoods or MDF-type products.

Most softer woods may not need a countersink but hardwoods nearly always need one. Some wood screws come with small raised parts under the screw head. These are what chew the wood and allow the screw head to bury itself flush with the timber surface.

Terms You Must Know to Read Metric Screw Size Charts

The correct size pilot hole for a screw should be 75-80% of the screw diameter. I usually go slightly smaller in softwoods and slightly larger in hardwoods. What Size Drill Bit For A 6mm Screw?

If your wood screws are smooth under the head, you may require the use of a countersink bit. Just try one first in a scrap piece.Red wall plugs require a 6mm drill bit for installation and are suitable for use with screws with a diameter of 3.5mm to 5.00mm. They can support weights of up to 15kg, making them suitable for medium-weight items such as small cabinets or bookshelves. When installing a red wall plug, make sure the plug is the same length as or longer than the screw you’ll be using. It is also important to avoid overloading the wall plug with too much weight, as this can cause it to fail and the item to fall. Brown Wall Plug Calculate Pilot Hole Size: The general rule of thumb is to use a pilot hole that is about 75-80% of the screw diameter. So, for a 5mm screw, you’d calculate it as follows: What about the thread per inch number? In this case, it means that the screw has the standard number of threads. The Only Metric Screw Size Chart You’ll Need In our metric screw size chart, we provide the pitch for both coarse and fine threads. 3. Screw Length A coarse screw is a screw with a low number of threads along the screw. While a fine screw has a high number of threads.

Yes, you can screw timber together without a pilot hole although there are some details to consider. When we screw into timber without a pilot hole, the screw will always take the path of least resistance. Metric screws are listed by the diameter of the screw thread in millimetres by the length of the screw (in millimetres). The diagram below shows the diameter and length of a screw. For example, 4.5 x 40mm means the screw has a thread diameter (including teeth) of 4.5mm and the length from the head (assuming the head is flat) to the tip of 40mm (see diagram below). If the head is round or will protrude from the surface then the length of the screw is measured from under the head. The length represents the amount of screw screwed into the material. Dimensions of a screw Imperial Screw Sizes To choose the right size wall plug, you need to know the diameter of the screw you’ll be using. Once you know the screw size, you can select the appropriate wall plug colour. It’s important to use a wall plug that is the same length as or longer than the screw you’ll be using. If the wall plug is too short, it won’t be able to provide enough support for the screw. How Much Weight Your Wall Plug Can Hold?

Whether you’re buying screws online or in-store, if you don’t know how to read screw callouts, you’ll probably end up getting the wrong size. This will mean your screw could go in on an angle and sometimes the screw could poke through the side of the material. This nearly always happens when you are screwing into end grain or screwing a box together.

With a round headed screw the length is measured from below the head because the length is classed as the amount of the screw that will be in the material it is screwed into. In the example of the wood screw with a round head shown below, the diameter of the head (B) is approximately equal to twice the diameter of the shank of the screw (D). The depth of the head (H) is approximately equal to 3/4 of the diameter of the shank (D). Wood screw with a round head Imperial to metric screw conversion chart Screw GaugeAlthough it might seem hard to understand screw sizes, it’s actually a lot simpler than what you think. If you need to hang items that are heavier than what a standard plastic wall plug can support, there are other options available. On the other hand, non-countersinking threads are designed so that their heads remain above the surface. Once you figure out the meaning of each number found in screw callouts, you’ll find that reading callouts and screw size charts is a piece of cake. As you can see metric callouts and metric screw size charts are much easier to read and understand than imperial.