May 22, 2015 Coupling nuts are used to join two externally threaded objects. They are also referred to asextension nuts. They are threaded fasteners and are mainly used to join two male threadsoften threaded rods. The exterior of your fastener is typically a hex hence. A wrench may be used to hold it in position. These nuts are of various designs and varieties. Reducing Coupling Nuts You may use these nuts to fasten and join two different sizes of thread. They are usedwhen you want to join two rods of different width. Sight Hole Coupling Nuts These types of coupling nuts have a sight hole to observe the amount of engagementbetween your two rods as you join them to determine how deep the rods are fastened intothe nuts. The threads on these nuts are left-handed. These are perfect when you want tomake assemblies of long rods from several short rods joined. With the help of the sighthole, you join the rods to a certain distance to make firm joints, ensuring that your resultantlong rod will not affect at any joints made. Coupling Nuts Dimensions The dimensions of your coupling nuts are all described by the standard industrial fastenerInstitute in standard IFI-128. It is advisable to give your joint a plain finish toensure maximum strength. Finishes for Coupling Nuts Depending on the bar stock used, different types of finishes are used. These finishesinclude hot rolled finishes and cold drawn finishes. When you require your formed longmetal rod straight, you should use cold drawing. That does not involve any temperature.You just pass your rod through a die at room temperature. When passing the rod throughthe die, its diameter is reduced by up to 20 percent, making it uniform all through….