4 ms·
Fasteners are categorized using a higher-level system because there are multiple, independent dimensions--thread pitch, thread width, shank width, unthread shan
by wahern 6y ago
Fasteners are categorized using a higher-level system because there are multiple, independent dimensions--thread pitch, thread width, shank width, unthread shank length, threaded shank length, head type, tip type, etc--at play, and the relationships are relatively arbitrary (AFAIU--maybe there's some sophisticated, deliberate geometry at play I'm not aware of). There's no such thing as a 3 1/2" screw--there are many different types of screws that are 3 1/2" long, and they each have a particular label. So you can't really directly compare the qualities of metric or American standard fastener sizing systems.
- stormdennis 6y agoI must put you on to my carpenter friend then, seems he's wrong. Not in America btw.
- wahern 6y agoIf you do a particular type of work, such as building decks, then 3 1/2" will mean a very specific type of screw. But if you go into a good hardware store (Ace, a smaller, neighborhood chain, is often better than big-box Home Depot or Lowes in terms of variety) and tell the clerk you want a 3 1/2" long screw, things can get frustrating rather quickly unless you can provide some context. When you're working with wood, it's easier to fudge things, but when you're working with machine screws, details like pitch and shank profile often cannot be ignored.
- jabl 6y ago> AFAIU--maybe there's some sophisticated, deliberate geometry at play I'm not aware of Some earlier fastener standards were somewhat arbitrary, but mechanical engineers have calculated "optimal" values for these parameters, and e.g. the ISO metric screw thread parameters are based on such calculations.