7 x 1-1/2 in. Kreg Fine-Thread Pocket-Hole, Zinc, Square - Qty:100

Kreg Zinc Screws are a good choice for a wide variety of indoor projects with limited exposure to the elements.

Zinc screws provide adequate rust protection, and serve as an affordable alternative to our more protective Blue-Kote and stainless screw varieties.

The silver appearance of Clear Zinc has been around for many years and remains very popular. It also provides a moderate level of rust protection. Since this is a true electroplating, the zinc coating is part of the surface of the steel and very durable.

Deep Thread: Characterized by a reduced diameter shank resulting in a deep thread profile. A single lead thread, meaning that one revolution advances the screw one pitch. (Pitch is equal to 1 divided by the number of threads per inch. For a screw with 10 threads per in., one revolution will advance the screw 1/1O in. into the wood.)

The deep thread form provides superior resistance to pull-out. This design feature is commonly called a Lo-Root® or Production Screw.

In 1908, P. L. Robertson began to manufacture a square recess impression in the head of a screw in Milton, Ontario, Canada. He was a brilliant toolmaker that injured his hand while driving a slotted screw and started developing a better recess. At that time, it was a revolutionary change in the fastener industry. It has a more positive fit that reduces "cam out" and requires only 4 foot pounds of pressure to keep the bit engaged. An early attempt to introduce these Square Recess Screws into the United States failed so they were confined to the Canadian Market until the 1970s. The Phillips Head was introduced in the 1930s and would ‚¬Å“cam out‚¬ instead of being over torqued by the new power drivers of the time. Henry Ford tried out Square Drive and found them to save time in the production of the Model T. Ford wanted to License the Square Drive and when Robertson refused, Ford went with the Phillips and allowed the Square Drive to be used in Ford's Canadian Production. For the auto industry that was fine where woodworkers work concerned about the finished look of their product. Eventually, the Robertson Recess screws migrated across the border making their place in the furniture and woodworking trades, especially with the growing popularity of pocket hole joinery. A new hybrid is the combination of the Square-Phillips, Combo or Recex Recess that you can use either or Square/Philips bits. The first patent was issued in 1909 and the last patent expired 55 years later in 1964. For his invention, P.L. Robertson screws and screwdrivers carry his name to this day.

1.The Evolution of the Screw and Screwdriver

FEATURES:

• Clear Zinc Plated Steel
• Washer Head for slightly more areas which can be better suited for soft wood vs. the traditional pan-head screws.
• Square Drive recess for positive bit engagement.
• Thread length = 7/8 in.