8 x 5/8 in. Pan-Head Wood, 18-8 SS, Square - Qty:100

Stainless Steel Square Drive Pan Head screws have a flat surface under the head to ensure that they won't pull through softer materials the way a flat head screw will.

These are ideal for attaching metal hardware that does not have a countersunk hole. Like the Stainless Steel Flat Head screws, use a slightly oversize pilot hole to avoid breakage. Note that these have a tapping type thread which increases the strength of the screw, but reduces holding power compared to the deep thread.

Stainless Steel: No discussion of corrosion resistance would be complete without mention of stainless steel screws. Although all products corrode sooner or later, stainless steel continues to provide excellent protection. Stainless steel is a general term for a large group of alloy steel that contains at least 10.5% chromium. Since the carbon content of stainless is quite low, oxidation (rusting) is also quite low. However, since the carbon content is low, the steel cannot be hear treated to adequate levels. As a result the screws are soft and break easily when used in wood applications where high levels of torque strength are required. Pre-drilling all screw holes and using larger gauges of screws can compensate for this problem.

The Nickel used in manufacturing Stainless Steel make them non-magnetic and will not hold to a magnetic bit.

18/8 grade stainless steel is one of two of the most common grades used in food preparation, dining and cookware. 18/8 stainless steel is comprised of 18% chromium and 8% nickel. 304 grade stainless steel is made up of no more than 0.8% carbon and has at least 50% iron. The chromium is what binds oxygen to the surface of the product to protect the iron from rust (oxidation). Nickel also enhances the corrosion resistance of stainless steel. The higher the nickel content, the more resistant the stainless steel is to corrosion.

The second most popular type of stainless is Type 316. 316 stainless lowers the chromium content from 18% to 16%, and the nickel content is increased to 10% and 2% molybdenum is added to the mixture. The change in the chromium/nickel ratio along with the addition of the molybdenum increases the resistance to chlorides. This is why Type 316 stainless is recommended in more corrosive environments, such as oceanside and pools where the material will be exposed to chemical, solvent, or salt water corrosion. This makes it the preferred material for marine construction.

Tapping Style Thread: Also known as "Type A" or "Wood Tapping," this is 'basically a sheet metal type thread. It is a single lead, fine thread design (meaning more threads per inch). Also, the thread form is basically an "equilateral" triangle, instead of 'the special "flattened" triangular thread which is used for "Deep" threads. Generally, the entire screw shank is threaded, which makes sense for a sheet metal screw, of course.

Square Drive Recess: This recess was invented by P.L. Robertson (founder of Robertson, Inc.) in 1908 and was the first production fastener with an internal recess.

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 "cam out" instead of being over torqued by the new power drivers of the time. Henry Ford tried out Square Drive an