Tensile Strength (106 Pa) Material Type 4.6 M5 - M36 225 400 Low or medium . A bolt head size chart is a tool that provides a visual representation of the different sizes of bolt heads, typically showing the size of the bolt head in both imperial and metric units. See Our Other FREE Downloadable Resources Use this chart to determine the mm size of the M value stamped on a bolt. The cement board type is fully threaded, securing the backer board to subfloors or wall studs. We use the TPI to determine the threads fineness. It evolved through a series of amendments in the said act. An M4 screw is slightly larger than an M2. When the thread pitch is dropped from the specification, it means that the bolt is coarse-threaded. There are two different methods of sizing wrenches - the standard method (SAE) and the metric sizing. Sheet metal screws secure sheet metal. Use the below bolt hole clearance chart for Metric size bolts and screws. These screw threads are selected from ISO 261. The M5s dimensions are significantly thicker than an M4 but can be used in several applications. If you are using the metric system, use the cm or mm side of the ruler to measure the diameter. The popular use of flange bolts including car exhaust, Plumbing, electronic devices, and hard-to-reach applications. The maximum tensile strength is 500MPa and the maximum yield strength is 210 MPa. Anchor bolts come in different types based on the installation method. For metric bolts, head size is measured in millimeters. Width of nut across flats Using a bolt with the right sizes is vital for jobs in various machinery and equipment. For example, an M3 bolt with a medium fit would have a 3.4 mm clearance hole. Just make sure youve got a high bolt grade or class. Also, you need to show them which standard . Take the diameter of the bolt, and multiply by 1.5. For standard bolts, the head size is measured in inches or fractions of an inch. On the other hand, it still uses millimeters to measure length. However, metric bolt head size is measured in millimeters. Determine the maximum torque according to bolt (nut) size and grade. ANSI B18.8.2 If the bolt body is the same for all bolt types, then the head is the complete opposite. If you want to convert millimeters to inches, you can either divide the figure by 25.4 or multiply it by 0.0394. Thread pitch refers to how tightly the thread of a bolt goes around the bolt shaft. Handbook of Bolts and Bolted Joints - John Bickford 1998-04-28 Presenting time-tested standard as well as reliable emerging knowledge on threaded fasteners and joints, this book covers how to select parts and materials, predict behavior, control assembly processes, and solve on-the-job problems. J-bolts are usually used in structural applications, for example, when you erecting a new building or garage, you need to secure walls to concrete foundations with J bolts. Then, when you unscrew the bolt, you wont be able to use another bolt in place. Check the Head Height/Thickness column to ensure that a bolt lays flat to where its screwed. A bolt gauge is divided into standard and metric sections. Youll notice that they all start with an M followed by a number. Carriage bolts are usually used to fasten metal to metal or metal to wood. To calculate the gauge and head sizes, you can use the formula below. In the second column, you have the bolt diameter in decimals or whole numbers. For example, in M6-1.0*20, the "M" means the Metric thread designation, the digit 8 refers to the Nominal diameter (in millimeters), 1.0 refers to the pitch, and 20 refers to the length. The bolt body has three dimensions that are essential to any bolt size chart: bolt diameter and thread pitch. For example, a bolt and nut may be described as being diameter. Bolts are a kind of externally threaded fastener used with a nut. In this article, well go through a complete guide of bolts, which involves bolts definition, types, dimensions explain, and the standard bolt sizes chart in metric and imperial. Metric fasteners are measured by length and pitch, or the distance between threads. Remember that the standard bolt size equivalent is an approximation, not a direct equivalence. THREADS PER INCH The decimal equivalent of the number of threads in an inch. 9/16. Our Gujarat Division provide total Fasteners Solutions for various projects in India & overseas so far we have supplied Square Drive Pan Head Machine Screws, SS Machine Screw to more than 30 countries like UK, Ireland, Vietnam, Philippines, South Africa, Australia, Kenya, Nigeria, Iran, Russia, Japan, Canada and many more European & African Countries , We have wide range of manufacturing capabilities and due to our proven track record & only 1% rejection rate became Raaj Sagar Steels an ideal choice for major EPC Contractors across the globe for their Steel Fasteners requirements. Other types are used for drywall and concrete. It specifies the dimensions and tolerances for both metric and imperial bolt head sizes, as well as the corresponding wrench sizes and other details. They are represented in an alphanumeric code, which is difficult to understand if you are not familiar with it. For example, a number 3 is smaller than a number 11. Brass, nylon, stainless steel, steel, aluminum, and titanium are a few of the materials used in fabricating this type. Dont choose rain chains before reading this + DIY options. 24 mm. One part has coarse threads, while the other is an unthreaded shank. (Nominal diameter is more of a label than a size. " Drive. Otherwise, there will be a bump. If the packaging has measurements indicated in the metric system, the first digit represent the diameter. If there are four thread gaps in a one-inch length, the thread pitch would be 0.250 inches (one inch / 4 thread gaps = 0.250 inches). The measurement refers to the size of the square used to attach the to socket to a wrench or a ratchet. Use a ruler: If you dont have a bolt gauge or caliper, you can use a ruler to measure the bolt head size. Any bolt can be divided into two main parts: the body and the head. Do keep in mind that in reality, the actual diameter would vary between 1.9mm to 2mm because of manufacturing tolerances. Fraction . " Drive. Raaj Sagar Steels manufacture and supply a comprehensive range of Slotted Machine Screws, Spanner (Snake Eye) Machine Screws. Once you have these values, you can now divide the length by the number of thread gaps. Thats half a mm between the crest of each thread. Which size bolt will you need to replace it? In general, the first thing that you should do is consider whether youre using a bolt thats shorter or longer than 6 inches. Based on their threading, eyebolts can be divided into machine screw threading and wood screw threading. Physically, they look similar. Try Fastener Dimension Guide now. When we say bolt size, we mean the diameter of the bolt shank. This tells you its a metric bolt.Although Metric bolts are measured in millimeters (mm) the M value is a measurement size, not the actual size of the bolt in millimeters. They are significantly larger than most other screws. ANSI B1.13M, also identified as ASME B1.13M, defines the standard for metric screw threads in American units with metric units in parenthesis. Mating fasteners are known by many other different names. However, here's a quick overview from the chart: The M2 screw size has a diameter of 1/16 inch. One millimeter is the equivalent of 3/64 of an inch, so you can get pretty exact! It has three vital dimensions: size across its flats, size across, its corners, and the head's height. Now the wider applications of U bolts including clamp any kind of tubing/round bar. There is an exception thoughif pitch isn't specified, the fastener is coarse threaded. Every metric bolt is assigned a class number in terms of megapascals (MPa). | CNCLATHING, Compare Different Fasteners: Difference Between Bolt, Screw, Rivet and Nut | CNCLATHING, What are UNF Threads and UNC Threads? Metric thread pitch is distance per thread: 10x12x1.25 would be dia x length of thread from head x mm between threads. (1), Nut & Bolt Thread Checker (Complete SAE/Inch and Metric Set) - 26 Male/Female Gauges - 14 Inch & 12 Metric - Quickly Checking Nuts and Bolts Inch or Metric and Verifying The Size and Thread Pitch, Stainlesstown Nut Bolt Thread Gauge (Blue). Make sure you get the right screw length, thread diameter, and screw threads for your project. How do you convert Metric and Standard? TPI is used only with American fasteners. 4 ways to earn from home by fixing and flipping small engines. It will not waste your time. For example, an 3/8 bolt with a close fit would have a W (0.3860) clearance hole. The bolt chart provides both US and metric stud sizes. Bolts are a type of essential fastener that often assembled with nuts. [1] On the other hand, bolt torque size charts have many variables and different measurements for each bolt grade/class. To determine the correct size u-bolt for your application is important. THREAD (BOLT THREADS) A raised, helical rib or ridge around the interior or exterior of a cylindrically shaped object. Download the Imperial Clearance Hole Chart to save the chart as a PDF - useful to print out to have next to your tools.. Want to determine what size clearance hole for Metric, for example, a 10.5 mm clearance hole is required for an M10 close fit, then check out our chart here. In both charts, theres a minimum and maximum diameter for each bolt. These selected sizes are recommended also for general engineering use. US Hex Bolts. These parts are standard across all bolt types and consist of the head and body. Body Diameter - There may be a reasonable swell or fin under the head or die seam on the body not to exceed the basic bolt diameter by the following: 0.030" for sizes up to 1/2" 0.050" for sizes 5/8" and 3/4" 0.060" for sizes over 3/4" to 1-1/4" 0.090" for sizes over 1-1/4" to 2" 0.120" for sizes over 2" to 3" 0.190" for sizes over 3" Generally, the metric system is easier to understand. Their threads make them easy to install and remove, making them incredibly convenient. All units in inches. The gauge indicates the diameter. My best advice to avoid buying a bolt with the wrong thread pitch is to bring a good bolt from the engine that fits in the bolt hole to your local hardware store for direct comparison. It has a hex head, so you need a socket and ratchet or a wrench to secure it in place. Proof Strength (106 Pa) Mini. The second column has the tensile strength of each grade measured in PSI, followed by the yield strength in the third column. The good news is that you can now confidently say that you know all about bolts and bolt size charts. The M5 screw size has a diameter of 5mm. Thread Dimensions - Imperial Thread Sizes Chart Here are two imperial thread sizes table defines thread dimensions of coarse threads (UNC/UNRC) and fine threads (UNF/UNRF). For nuts, size will appear as diameter and pitch. Metric Fasteners; Socket Screws; Hex Bolts; Nuts; . Composite deck ones have fine threads and a small head. RAAJ SAGAR STEELS Address: 163, Dr.M. 1. US Hex Bolts - Metric - ANSI/ASME B18.2.3M Dimensions of Hex Bolts - Metric units. Sometimes, they do not know much about it. Finding the right type and specifications will hold materials together nicely. Now that weve covered all the technical aspects of a bolt size chart, lets look at an example to cement this information. G. Mahimtura Marg, 3rd Kumbharwada, Mumbai-400 004 (India) City: Mumbai-400 004, India Phone: +91-22-6659 5285 , 6639 4214 Email: info@raajsagarsteels.com Website: www.raajsagarsteels.com key personnel Contact Person: Mr. Milap Mehta Cell: +91-9869 532 584, Uae , vietnam, qatar, Saudi Arabia, italy, thailand , bangladesh, philippines, Pakistan, Trinidad Tobago, Sri Lanka, Bahrain , sri lanka, kuwait, chennai, bangladesh, Sri Lanka , Saudi Arabia, Bangladesh, singapore, india, philippines , oman, Copyright 2017 Raaj Sagar Steels| All Rights Reserved | Website designed & SEO by, Metric Bolt Conversion | Fastener Conversion Chart, Coarse thread pitch partially threaded (specify grade), Coarse thread pitch fully threaded (specify grade), Fine thread pitch partially threaded (specify grade), Fine thread pitch fully threaded (specify grade), Nylon insert locknuts (specify pitch and class), All metal locknuts (specify pitch and class), Socket head capscrews (normally GR 12.9 and coarse thread), Flat head socket capscrews (normally GR 12.9 and coarse thread), Socket setscrews (normally GR 12.9 and coarse thread), All threaded rod (normally 1 meter lengths, specify grade and pitch), Fastener Chart | Metric Bolt Conversion | Common DIN Numbers for Metric Fasteners | Diameter/Decimal/Metric Chart for Small Diameter Fasteners. Start at the first thread, which gets the number zero. [in] Normal Fit [in] Close Fit [in] Loose Fit [in] #0: 0.0600: 0.076: 0.067: 0.094 #2: 0.0860: 0.102: 0.094: 0.116 #4: 0.1120: 0.128: 0.120: 0.144 . Download the Metric Clearance Hole Chart to save the chart as a PDF - useful to print out to have next to your tools. For any other types that are not countersunk, measure from the flat underside to the tip. Because this is approximately the same as the Major or Thread diameter the thread diameter measurement can be used for fully threaded bolts. (Standard) / Metric Calculators; Pitch Conversion: TPI Metric, Metric TPI; Spanner Sizes; Allen Key Sizes; Metric to Imperial Chart. To take advantage of the convenience these fasteners offer, you need to match them accordingly based on their sizes. This is because the threads are not the same size and will strip or cross thread. In the metric system, its the distance between two threads in millimeters. Heres an example of a metric bolt specification: M5-1.0 x 20. US to Metric Conversion Table Print this page . If you work with small engines long enough, you will eventually encounter a broken or missing bolt. Discover more about the small businesses partnering with Amazon and Amazons commitment to empowering them. Understanding Inch & Metric Thread Callouts. 1 to 5/16) 1/8 Inch Heavy Gauge Steel Screw Checker, Made in USA, Nut and Bolt Thread Checker (Inch & Metric) -26 Male/Female Thread Identifier Gauges - 14 Inch & 12 Metric, Male/Female Gauges for Quickly Checking Nuts and Bolts Inch or Metric and Verifying The Size, 1035 Piece Grade 5 Nut Bolt and Washer Assortment Hex Head Bolts, Hex Nuts, Lock and Flat Washers Standard Coarse Thread with 30 Plastic Bins, 28 Bolt and Nut Identifier Gauge Nut and Bolt Thread Checker 14 Metric & 14 Standard Ruler with Inches and Centimeters On Both Sides, 32 Pcs Upgrade Original Thread Checker (Inch & Metric) - Size Gauge Measuring Tool for Imperial and Metric Nuts 32 Male/Female Gauges - 17 Inch & 15 Metric, VIGRUE 467PCS Heavy Duty Bolts and Nuts Assortment Kit, Grade 8 1/4-20 5/16-18 3/8-16 Hex Bolts Nuts Washers Set, Includes 15 Most Common SAE Sizes, Length 1/2" to 2", Growth Chart for Kids - Gift for Children's Height. Nearest . For projects that require high holding power, you can use fine threaded bolts, which have more threads and can withstand pressure. A wood screw has a pointed tip that aids in wood-to-wood fastening. If you live in the U.S., chances are you have more SAE wrenches in your tool box. The boltchart provides both US and metric stud sizes. A common type is the pan head with a round head. Again, the greater the number, the greater the stress the bolt can handle. You can use a multi-material one in several materials, such as drywall or sheet metal. These thread sizes and classes represent bolts and screws, as well, as other standard external threads. These standards dictate things like thickness and screw thread. The coating prevents corrosion from happening as a result of mortar and moisture. The challenge often comes when purchasing online. There are actually up to four pitch . The gauge sizes do not have a direct connection with the actual head size. Bolt head size charts are used as a reference guide to help users select the appropriate size of bolt head for a given application. For the most part, however, the metric charts have columns that list the equivalent or approximate sizes to the standard bolt sizes. The first column contains bolt grades (standard) or classes (metric). Is it hard to breathe in Colorado? If you are working with steel construction fasteners you can select either EN 14399-3 for HR fasteners or EN 14399-4 for HV fasteners. 7/8. The most important bolt body dimensions to know include: The bolt diameter is the main size considered and it is measured across the bolt shank or its threaded area. If there are 6 thread gaps, divide 1 inch by 6, resulting in thread gaps of .1667 inches. The outermost part is where you will want to measure from. The greater the pitch on metric fasteners, the more distance between threads. 8mm falls in between and converts to a 5/16 or 11/32 standard. Lag bolt size charts, however, have one extra column for Shoulder Length. Elevator bolt size charts and carriage bolt charts also have two extra columns: Square Width and Square Depth. There is also the Allen drive, which has a six-sided socket. This column is to help you quickly find the equivalent or approximation of metric bolts. Several kinds of bolts exist, which include Hex bolts, J bolts, T bolts, Anchor bolts, and Flange bolts. Not to scale. No need to worry, though, because these are clues that you can work with. Keep in mind that when purchasing ones with measurements that are listed in the metric system, the initial number is the diameter. The metric socket size is as follows-. Where we also manufacture Square Drive Pan Head Machine Screws, SS Machine Screw and Stainless Steel Metric Machine Screw for industries like Oil & Gas, Petrochemicals, Refineries, Thermal, Nuclear sector, Solar Power Plants, Atomic Energy, Defense and Aerospace etc. The threads provide a sturdy grip, allowing them to meet the requirements of any project. The M10 screw size has a diameter of 3/16 inches. You can screw bolts on anything from drywall, metal, wood, to steel. The measurement of an inch nut or bolt will be listed as the thread size a number between one and 12 or an inch increment followed by the threads per inch (TPI). Thread pitch can be further described as coarse or standard, fine, or super fine. Individual sizes should be checked before specifying any . Flange boltThe flange bolt has a circular flange under the head that acts like a washer to distribute the load. Clevis Pin Size Chart ANSI Clevis Pin Size Chart Table; Cone Head Rivet Size Chart ASME B18.1.1 Cone Head Rivet ; Cotter Pin ANSI B18.8.1 Cotter Pins Size Chart per ANSI B18.8.1; Dowel Pins, Machined Size Chart ANSI ASME Machine Dowel Pins Chart per. The thread pitch can be further classified as coarse, fine, and superfine. Why is this math lesson necessary, you say. But the size of a metric fastener is more accurately specified using diameter, pitch and length dimensions, in millimeters. How do you tell if a bolt or nut is standard or metric, and what size wrench or socket to use? Hex bolts are designed with a hexagonal head that to be driven by a wrench and external machine threads, maybe partially threaded or fully threaded. Hex bolts can be used for infrastructure that requires a strong fastener with high tensile strength properties, they can also be used in tight spaces with limited access because tools can access them from all angles, or fastening wood, steel, or other materials in bridges, buildings, and more construction projects. Regardless of which method you use, its important to be precise and take multiple measurements to ensure that you get an accurate reading of the bolt head size. Sponsored . 3/8 Drive. Metric Bolt Size Chart Thread Pitch Conclusion Introduction to Bolts, Nuts and Washers A Bolt is a cylindrical object with a hexagonal (sometimes square) head on one end and threads (fully or partially) on the other end. Diameter/Decimal/Metric Chart for Small Diameter Fasteners Fastener Conversion Chart Use millimeters to measure from one side of a thread to the other. Thread Pitch A larger number means a bigger diameter, whereas a smaller number means a smaller diameter. Bolts Types and Sizes: Metric & Imperial Bolt Dimensions Chart | CNCLATHING, Thread Types, Terms, Designation, and How to Identify & Measure Threads | CNCLATHING, Different Types of Screws and Their Uses Understanding Wood Screws, Machine Screws and More | CNCLATHING, What is Thread Milling & How Does a Thread Mill Work | How to Thread Mill | CNCLATHING, Thread Sizes (Dimensions) Explained Imperial & Metric Thread Sizes Chart | CNCLATHING, Machine Screw Diameters Chart and Unified National Thread Sizes What is a Machine Screw | CNCLATHING, Guide to Design and Machining Thread: How to Cut an Internal & External Thread? Hanger boltHanger bolts are headless bolts with threads on both ends, used to suspend objects from or attach items to wood, it will add an external thread or create a hidden fastening joint. For standard-size bolts, the thread pitch is either fine or coarse. When taking the length of a screw, we use meters. Screws are very versatile, making them a popular choice among people. It specifies the dimensions and tolerances for both metric and imperial bolt head sizes, as well as the corresponding wrench sizes and other details. The has a cylindrical, raised, hex-socket head, while the latter is headless. The thread pitch is the distance between each thread in mm. Use the dimensions of your bolt to determine the appropriate size nut. The gauge (imperial) is approximately the heads size in millimeters (metric). To get this final measurement, use a ruler or measuring tape. For some time, the imperial system had been the standard measurement system. You may get false or inaccurate information. For flat-headed ones that are countersunk, measure from the tip to the top of the head. Kindly say, the Metric Bolt Size Chart Pdf is universally compatible with any devices to read bolts types and sizes metric imperial bolt dimensions web aug 18 2020 the size of a metric bolt is specified using pitch diameter and length in millimeters for example in m8 1 0 20 the m means the metric thread designation the digit 8 Lag boltLag bolts, also known as lag screws, one of the toughest fasteners are extremely sturdy. Let's Fix! A U-bolt would be described by the size of the pipe it is clamping. The M corresponds to the outer diameter in the metric system, so an M2 has a diameter of 2mm. In the standard chart, a bolts tensile strength is represented as grade radial marks on top of the bolts head. I'm Leon, and this is where I share 25+ years' experience servicing outdoor power equipment. Sex boltThe sex bolt, also known as a barrel bolt, connector bolt, or binding barrel, is a type of mating fastener combining a nut and a screw, it consists of a barrel with internal threads and a screw with external threads, both the barrel and screw have heads designed to clamp material between the head of the barrel and the head of the screw. Thread pitch. Shoulder bolts usually used to attach pulleys, moving engine parts, gears, rolling wheels, and stripper plates. Coarse-threaded ones have a wider space between threads. 3. It helps in fastening wood pieces together. The length of a metric bolt is measured and defined in exactly the same way as imperial bolts (fasteners). The diameter in the imperial system is represented in either fraction of an inch or a gauge number. No inquiry is too large or too small, we specialize in locating hard to find items. They can be helpful in determining the size of a bolt head when only the bolt is available. Check out thestandard bolts size chart in metric or imperial below. It consists of a series of holes of different sizes, and you simply place the bolt head in the hole that fits it best. A bolt heads diameter depends on its shanks diameter. put up with me, the e-book will unconditionally song you new event to read. But it is easier to specify the components by a single size designation since the bolt and nut are mating components.). Hex head ones are an exception to this rule, which means you need to measure from the bottom of the head. However, there is no correlation or scientific explanation here. When choosing bolts, you will encounter different sizes and types, and this article will help you select the right size for your construction project. If the diameter is less than 1/4 inch, the diameter will be listed as a number between zero and 12; the larger the number, the closer it is to 1/4 inch. In stock and ready to ship. Thread pitch and thread spacing mean the same thing, so dont get those two confused. Take, for example, eye bolt size charts. A sample application of an M6 is attaching the equipment to the vertical uprights of a rack. Here are some points to keep in mind when getting the length: Once you have the length, it is time to get the diameter. It was introduced in the British Weights and Measures Act of 1824. First, look at the chart and find bolts that have a half-inch diameter. First, you need to convert the fraction to decimals. They are fully threaded and are available for use with self-drilling points and pre-drilled holes. M3 bolt = 5.5 mm M4 bolt = 7 mm M5 bolt = 8 mm M6 bolt = 10 mm (most common small engine bolt size) M7 bolt = 11 mm M8 bolt = 13 mm (very common bolt size) M9 bolt = 17 mm (very common bolt size) M10 bolt = 19 mm M12 bolt = 22 mm 1. You will want the entire thing to lay flat, which means the head will need to lie off of the edge of a table or other surface. Bolt Size Bolt Dia. According to their construction, eyebolts can be classified as the forged and bent eye. Different Types of Roof Sheathing and Their Benefits. It may take additional time to adjust if you are already comfortable with the imperial system. The M4 screw size in inches is the equivalent of 0.15748. Our metric stud bolt to nut table is meant to help determine the correct size bolt or nut for your purpose. The size of a metric bolt is specified using pitch, diameter, and length in millimeters. 22 mm. When measuring the length of a flathead screw, start on top of the head down to the stem. Flange bolts feature a nozzle, thereby speeding the assembly while eliminating the washer. The bolt body consists of its shaft with the threaded area. Still, there are some oddly shaped bolts out there. We typically use the threads mentioned above in rack applications. How to Tighten Your Door Handle Quick & Easy! hbspt.cta._relativeUrls=true;hbspt.cta.load(755974, '39b18361-88bb-44bf-ab1f-a16e8df62b5f', {"useNewLoader":"true","region":"na1"}); NOMINAL DIAMETER (NOMINAL BOLT DIAMETER) The diameter equal to the external diameter of the threads or the overall diameter of the part. You can find it in security fixings, such as locks and hinges. CNC milling services and machining techniques at Junying are capable of production and finishing for vast types of fasteners including bolts, screws, nuts, and other threaded parts. Bolt size is measured across the head of hex and square bolts, from flat side to flat side, just like Standard bolts. Sometimes, the pitch is omitted in the abbreviated format, such as M8-20, this means the bolt has a coarse thread. The bolt body is the main shank with full or partial threads. These standards are very strict. Thread sizes for coarse and fine pitch thread were created using the standard sizes from ASME B1.13M. SAE and metric nuts and bolts will need to be used with the corresponding wrench sizes. bolt thats 6 inches or shorter has a 1.25-inch thread length. They can ensure a reliable, long-lasting connection between two sections of a large and enclosed area. Then, measure the distance from the center of the bolt head to the farthest point on the bolt head. Unified Thread Standard (UTS): The Unified Thread Standard is a standard for screw threads that is used in the United States and Canada. When it comes to things as intricate as sizes, knowing the bare minimum helps. The head has the largest diameter, the shoulder is described by its diameter and length, and the diameter of the threaded part is slightly smaller than that of the shoulder. IMPORTANT SCREWS LINKS :Pdf:Dimensions:Faq. Now that you know how to take the measurement, the next step is to place the ruler down the axis to get the thread count.