Wood screws have an aggressive thread profile designed to maximize the holding power needed to form strong joints in wood. Recommended for use with ACQ, CA and CCA treated lumber, plus cedar and redwood where they won’t stain the wood. Most deck screws have a type-17 (auger type) thread cutting tip for installation into decking materials. Sharp Threads and Proper Head Angle cuts cleanly without crumbling or crushing, reducing splitting and cracking. Pencom offers a chart with recommended torques for various grades and sizes of screws.
Three things; if you are going to use a lock washer but do not want the material to be damaged put a flat washer between the lock washer and the material being secured. For hobbyists designing things that aren’t mission critical, it’s probably not unreasonable to assume that about 1/3 of the external load is felt by the bolt, but in stiff joints with very flat surfaces (bumpy surfaces add to joint-spongyness), less than 1/7 of the load could be placed on the bolt (ref 1, p. 431). Made from harder steel that can penetrate wallboard and studs, drywall screws drive in quickly and without the need for predrilled pilot holes.
We have both Machine Screws and Cap Screws as well as Thread Forming Screws, Thread Cutting Screws and Self-Tapping Screws on this website. Screws with larger heads offer more contact area with the work surface and a greater resistance to penetration and pull-through. On the Fuller bits, the problem, as I see it, is that wood screws are NOT tapered except at the very tip. To help speed up automobile production, the cam out helped prevent workers from over-tightening Phillips head screws with early power drivers, which lacked torque-limiting adjustability. Stripping screws starts to sound pretty attactive if that is what is involved with silicon-bronze!!
To keep the head of a finishing nail from showing, try this: After it has been nailed into the wood, use another nail as a nail set, then fill the indentation with wood putty. There can be enough metal transfer from a file to your stainless piece to cause rust to star. Hot-Dipped Galvanized: For outdoor use, this provides the best (common) protection next to stainless steel. In addition to greatly reducing the number of stripped and broken screws, it also reduces the chances of spliting the wood. Zinc plating: Because of steel’s tendency to rust, you’ll never get bare steel fasteners.
The holding power of a nail with a smooth shaft depends on friction between the shaft and the surrounding wood fibers. This offers a reasonable amount of hold in hardwoods, but in softer species, the smaller heads tend to crush the wood at the surface. I have now bought some silicon bronze plus tapered bits from Jamestown Distributors and plan to also buy a few stainless steel from one of the other places indicated above just in case the silicon bronze don’t work out.
Countersunk Self Tappers are available in slot , pozi , phillips and square drives , the countersunk head allows for the user to achieve a flush finish with the surface of the material. BUT the new ones are Forged and not machined so the top of the screw is rounded over w/ the crisp sharp edge around the head. Anzor Deck Driver – 6 Lobe Drive Stainless Steel Decking Screw our new 316 stainless ‘Deck Drivers’ self-drill into soft and hardwood timber. Machine screws are generally stronger than wood screws, have finer threads and are made more precisely.
Wood screws also taper along the threaded portion optimizing the screws holding power in wood. Hi-Lo thread (Rockler Hi-lo screws; Kreg® Hi-lo pocket-hole screws): A dualthread screw with a coarser, sharper outer thread and a finer inner thread. QuickCutter thread (Quickscrews production screws): Deep threads and an extra-long flute above the point. The force / tension in a spring depends only on its stretch (F=kx), and if the bolt head isn’t moving, the tension isn’t changing.
Square-X Drive screws and Highpoint screws have specially formulated dry coatings that make them easier to drive while preventing surface corrosion (they’re recommended for interior applications only). Inexpensive and quick to install, FastCap plastic screw cap covers have small tabs that snap into the head recesses of square drive, flat head screws. A hanger bolt has wood screw threads on one end and machine threads on the other.
Security Heads (tamper proof): These screws have heads that are either impossible to reverse or require a special driver to operate. Undercut self tappers also known as Truncated self tappers are similar to countersunk only the head is undercut to around 70% of its normal side height. Torx bolts and screws are very popular in the automobile industry, sheet metal industry and plastics industry.
As a hull twists in a seaway, the full shank screw is superior to those with rolled threads and undersize shanks both in strength and by the fact that the shank is in full contact with the sorrounding wood. Flat and Oval Head: The most common type of head for wood, these heads end up flush or below the surface of the wood when installed. In some screws, the head can be removed by breaking it after installing the screw.