Blacksmiths were primarily tool makers. There weren't places like the Home Depot to pick up a hammer, or shears, or an ax. Most other trades at the time would require SOMETHING from the smith, be it tools, or shoes for their horses, or the iron pieces for harnesses. They would often repair broken tools and sharpen blades as part of their daily routine. And they were constantly making nails.

By the late 14th-early 15th century, blacksmithing had become highly specialized when it comes to manufacturing weaponry and armor. Most weaponry was piecemeal work and required input from multiple craftsmen across a wide variety of trades during the manufacturing process. A smith would forge blanks and other iron pieces for swords, a leatherworker would make the sheath and belt, a woodworker would make the handle, and they would be assembled and finished by a cutler. Likewise with armor. So, no, the "average" blacksmith in London would likely never make armor.

Because of the time it took to learn the trade, and the skill and strength necessary to perform the job, blacksmiths have been greatly respected throughout history, and were relatively well-educated. They typically had an understanding of weights & measures, and were highly skilled technical artisans. Their function to society can be measured by how much of the English language still references the trade.

The Worshipful Company of Blacksmiths was first mentioned in 1299 and was established to set the standards of the trade in London. Since it was considered such a good living, many families bought apprenticeships for their sons to give them an opportunity at a fairly lucrative career. Blacksmiths were part of the burgeoning middle class during this time period as well.

The techniques used by a blacksmith varied between jobs, and include drawing out (reducing width and increasing length), upsetting (increasing dimension by reducing length), bending, punching, forge welding, and swaging (using specialized tooling to shape the iron).

Also, how many competitors do I have? Is there any regulation for quality, are there guilds I am a part of?

How reliable are the sources of iron and coal? What happens if there's a shortage for a while?

How long would my apprenticeship have lasted? How did one transition from being an apprentice to mastery, and how old would I be at the time?

I'm very interested in the money question. What sort of compensation would have been made for an average/well-respected/insanely famous blacksmith of ~1400 in London (or other places if you know about them)?

How do I get into the business; is it a family business or are there apprenticeships?

Are there rules and regulations from the crown about who I can and can't smith for, and perhaps any regulations on what I can smith? (ie. In most modern day countries, not every citizen can own every type of gun etc)

Edit: Spelling.

This link is a great little snapshot to the relative wealth of various professions and what that income means in real terms in c.1380

http://www.luminarium.org/medlit/medprice.htm

I know it's not quite what you asked, but it's very relevant and useful nonetheless.

I'm a hobbyist blacksmith, and a history buff. Most of my knowledge of middle age blacksmithing is from De Rey Metallica by Agricola, published in 1550. It's a little late, but blacksmithing didn't really change very rapidly...honestly much ever. You can compare this to another major work on the subject, Joseph Moxon's Mechanick Exercises from 1678, and you'll see that very little changes.

In 1400, it looks like London blacksmiths might be making horeshoes. But as time continued, in densely populated areas, horse-shoe makers began to specialize, and came to be called "Farriers". I'm having trouble finding a really good source on this though.

Blacksmithing was fairly well evolved by 1400. The traditional type of anvil you're used to seeing, known as the "London pattern" did not exist yet. An anvil would look more like a rectangle of iron with slightly rounded edges. No horn, no pritchell hole. I see movies and illustrations get that wrong all the time.

As mentioned, a London blacksmith would use a charcoal forge. Never coal. For the time being, England still has plenty of trees. But the growth of blacksmithing and ironmaking is what causes them to run out in the centuries to come.

The average London blacksmith would never make new armor, no. Armor smithing involves a very different set of skills that are rarely needed in regular blacksmithing.

While sword smithing is pretty much the same techniques as blacksmithing, a regular blacksmith would not be making swords. A sword smith would be a specialized trade by then. That said, a blacksmith, or rather, apprentice, might certainly make arrowheads.

As mentioned, a blacksmith is mostly going to focus on tools. Axes, hatchets, picks, knives, pokers, chisels. They'd also make hardware. Hinges and handles for doors, fences, and window-shutters. Hooks, trivets, spits. Nails and spikes (large nails) were beginning to become popular, though they are simple enough and needed in enough volume that boys, possibly not even considered apprentices would be employed for that task.

You might aid other tradesmen, making tires for wheelwrights, or barrel hoops for coopers (though metal hoops on barrels was less common, and only used for certain specific applications).

Here's an interesting tidbit I just confirmed: in 1400, we are not quite certain whether or not the ability to turn wrought iron into steel was known. The process is known as "cementation". It basically involves covering iron in charcoal powder, heating it slowly, hammering it, and repeating. The first confirmed source that discusses it isn't until the 16th century. If it was known, it was kept secret. (source).

Once steel was discovered, it would have only been used sparingly. Basically, you'd only weld a small piece of steel right at the cutting edge of a tool. The rest would be wrought iron. This was done purely for cost reasons, and continued as a practice until the Bessemer process of steel making was perfected to the point that steel cost the same to make as wrought iron.