About Turnbuckles ,Stainless Steel Turnbuckles

Turnbuckles are used in rigging to join wire-ropeor cable to an anchor point or other length of wire. They have a screw thread for precise length and tension adjustment. Most turnbuckles are forged or cast from stainless steel or low carbon steel. They are machined to product specifications and then quenched, tempered, plated with zinc, or hot-galvanized. Products with self-colored finishes and yellow chromate coatings are also available. Stainless steel turnbuckles are designed for applications which require high strength-to-weight ratios and minimum turnbuckle diameters. They combine very high tensile strengths with ductility and corrosion resistance. Some cable turnbuckles are made of 304 or 316 stainless steel. Others use 1030 carbon steel. For all types of turnbuckles, there are several basic configurations: stub end, eye and eye, hook and hook, jaw and jaw, and jaw and eye.Stub end turnbuckles feature a steel rod that protrudes at both ends. Eye and eye turnbuckles have two circular or oval-shaped eyes. Hook and hook turnbuckles and jaw and jaw turnbuckles have either two hooks or two jaws, respectively. Jaw and eye turnbuckles are designed for specialized applications.

Selecting turnbuckles requires an analysis of product and performance specifications. Basic measurements include diameter, take up, length, and estimated weight. To determine the extended length, turnbuckle suppliers usually add the amount of the take up to the length in the closed position. For turnbuckle eyes, specifications include: outer diameter (ID), inner diameter (ID), total diameter, eye thickness, and maximum load. Turnbuckle hooks carry specifications such as jaw type, throat opening, jaw thickness, maximum load, jaw ID, and total diameter. Measurements such as hole-center to jaw-end and hole-center to shank are also important considerations. Dimensions for turnbuckles are measured in English units such as inches and fractions of inches (in), or metric units such as millimeters (mm). Both types of turnbuckles can use either left hand threads or right hand threads. For inch-based turnbuckles, thread choices include: 10-32, 1/4-20, 1/4-28, 5/16-18, 5/16-24, 3/8-16, 3/8-24, 1/2 13, and 1/2-20. Metric turnbuckles carry thread designations such as M5 x 0.50, M6 x 1.00, M8 x 1.25, M10 x 1.50, and M12 x 1.75.

Using screw threads to tighten the standing rigging

A turnbuckle (sometimes known as a bottlescrew) is an ingenious mechanical device used to apply tension to a sailboat’s standing rigging wires, lifelines, and so forth. It consists of an elongated metal link, or a tube, with a left-hand thread in one end and a right-hand thread in the other. Thus, when the matching turn-buckle is turned, it will take up slack in an attached wire and maintain tension.Closed-body turnbuckles are sleek and streamlined, but they are prone to corrosion from water that can enter the center adjustment holes and remain inside. The corrosion will, of course, be invisible until the turnbuckle is taken apart or falls apart at sea. Open-body turnbuckles are much safer because they do not hold water and any corrosion will be immediately apparent.

 

A standard open-body turnbuckle(left) is less prone to corrosion than one with a closed barrel (right).

 

Proper turnbuckle proportions.

For standard, open-body bronze or stainless steel turnbuckles, the screw diameter should be twice the diameter of the rigging wire. That goes for the opening between the turnbuckle jaws as well, and the clevis pin through the jaws should also be twice the diameter of the rigging wire.Shroud turnbuckles are normally fastened at their lower ends to chainplates. There is always the possibility of vibration and metal fatigue at that spot, so there should be a toggle, or universal joint, between every toggle and its chainplate. Similarly, there should be a toggle between every mast tang and shroud eye.