Screws and bolts again

They all are used for different applications. They are not, mostly not, interchangeable. For example you can't use a machine screw where a lag bolt is needed. just won't work.

Try Googling it.

Googling will get me a thousand sites that want to sell me these items but nobody who can teach me exactly what they are and what are the differences between them. I came here for that. I found your previous thread on the difference between a screw and a bolt helpful and thought someone here could also explain the differences between the various types of screws and bolts.

Googling machine screws and machine bolts has led me to the conclusion that in the industry they are identical? Yet if I declare what a customs officer considers a screw as a bolt it can lead to major trouble for the importer. And no customs does not provide definitions of the terms they insist we should know.

The tariff contains all kinds of dilemas like this, another example is pipe fittings, broken down into "pressure type" or "drainage type". OK I get the difference but nowhere are we told just how much pressure a pipe fitting has to be able to withstand to switch categories.

I was hoping cr4 would be a place I could get the opinions of experts in the fields.

You can find most of the definitions at www.boltscience.com and the Industrial Fasteners Institute publishes Fastener Standards and other publications that contain fastener standards, illustrations and definitions. Just Google "Industrial Fasteners Institute" to find their website.

There are differences in the threaded fasteners you asked about (although it's hard to imagine how those differences matter from a tariff standpoint; at least with the tariff numbers and classifications listed). Some of the differences are subtle. Hex head and machine, for example, since machine bolts can also be hex head (the primary difference is standard thread length). Hex cap screws are simply finished hex head bolts and carriage bolts can be round head with a long or short square neck or with a ribbed or fin neck. There are several types of plow bolts; primarily based on head variations and number. Lag bolts (or maybe they mean lag screws)?

Thanks for those links, some of my questions are answered there and I will pursue the others with them.

Thanks again