How to Determine Screw Size Thread Count Step 1. Lay the screw down on a flat surface. Step 2. Place a steel rule down the axis of the screw . Step 3. Count the number of thread gaps within 1 inch of the screw . Step 4. Divide the count of thread gaps into the length. Step 5. There are thread gauges you can use to determine the diameter and threads per inch. For instance the 10 in 10-32 is the diameter, the 32 means it has 32 threads in a length of 1''. The larger the diameter number, the thicker the bolt. To determine if the screw size you have is appropriate for fastening certain objects, a sizing chart is available for this purpose. Manufacturers of these items supply the market with various types and sizes to suit the buyer’s needs. The word “penny” is used as an identifier for screw length.

Steps to Choosing the Correct Screw: Select a style. heree in a variety of styles — flat head, Phillips, square and torque. Square and torque heads make it easier to keep your drill bits in place and prevent slipping and stripping. Select a screw size. M2.5 Screws . For instance if you are measuring an M2x5 pan head screw the overall length will be 6.60mm but it will be listed under the M2x5 because a pan head is measured from underneath the head where as a standard flat head screw takes its size from the measurement taken from top to bottom. When screwing into the end grain, aim for at least two inches of thread in the board. As a general guideline, you can use #8 diameter deck-type screws for most utility tasks. Use 1-1/4 inch screws for basic tasks where strength is less of an issue or when attaching two …

If you have some stray screws and bolts (a.k.a. fasteners ) lying around and aren’t quite sure what size they are, or if you need to replace a missing bolt on a piece of machinery and need to know what size to get, here are some methods to easily figure that out. How to Size Machine Screws . Getting the right size machine screw for your project can be a frustrating experience. Not only do you need to know the diameter and length of the screw , you also need to know the thread pitch, or number of threads per inch. Screws of the same diameter with a different thread pitch are not interchangeable, Length . As a general rule, the length of fasteners is measured from the surface of the material, to the end of the fastener. For fasteners where the head usually sits above the surface such as hex bolts and pan head screws , the measurement is from directly under the head to the end of the fastener.