That looks great Lin. I really like that hand crank blower but that coal forge with that brick chimney is really beautiful.

That's awesome.

I watched the construction of this and the shop build progress on FB. It's been quite the journey and accomplishment Lin.

As I contemplate building something very similar in my next shop, what are some of the things you think could be easily missed in the design and construction?

Anything that your experience with the forging medium that you would recommend that might be forgotten by someone relatively new to the use and care of a masonry forge?

There are a couple of things to prepare for and allow for.

One is the allowance for wear or protection from "wear" immediately around the draft opening. In other words, use fire brick right around the opening or else you would need to have a layer of potter's clay that would be changed every year or two to bear the brunt of the extreme heat. Either one is fine as long as you take steps to protect and buffer the main brick from the sudden temperature changes. Historically, potter's clay is used. The opening is laid up large enough to allow for the inclusion of the potter's clay. This is usually no more than a brick width. I used fire brick and a hood to keep the extreme heat at some distance.

Another thing is to get the ratio of chimney area to throat area about 10 to 7. My chimney inside area is about 100 square inches (12 OD inch tile) so my throat would need to be closed to about .7 times 100 or 70 inches. I made it 8.8 x 8.5 = 72.5

This close enough to draft fine. I asked a lot of folks and checked online and settled on this ratio. I honestly think a lot of the ratios and technical reasons why these old flues work has been forgotten and you may have to find one that works and mimic it.

Also, the back of the flue is sloped to direct rain water out the front. Yes, this is into and onto the forge table but it's better than water sitting in the chimney and freezing. I fine that the amount of water this generates is very small compared to the trouble you will have with busted brick. Of course, you can simply put a chimney cap on but I chose to not do that since historically there was none.

One observation about the top of chimneys. Nearly all of the chimneys in Arkansas in the 1800's (including fireplaces) had the brick stepped out and back in at the top. I had mine done this was as well. It not only looks like a neat termination but I also believe this may help with the draft in some way.

In my forge, I included a brick from the Bill Moran School of Bladesmithing in Old Washington, Arkansas, a brick from my high school (now demolished), and a brick from the extras here at the museum.

Thank you Lin. All good advice to save for later. I have built more than a few masonry wood burning fireplaces and the ratio of chimney/flue area to hearth opening (I think that's what you mean by "throat") is quite different. I imagined that this was the case, because many of the coal forges I have seen look like the areas are closer to each other than on a typical wood burner. So, you have a larger chimney flue than the heath opening, which is opposite from a wood burning fireplace.

It's sort of a choke point that is smaller with a particular ratio of reduced area.

|quoted:

It's sort of a choke point that is smaller with a particular ratio of reduced area.

I'm sorry, but now I'm confused. In the first post you said "get the ratio of chimney area to throat area about 10 to 7." So. if the chimney is 10 size units, the throat is 7 size units. Or did you mean that to be the other way around? In the second post you describe it as a choke point, which makes me think the chimney flue is smaller than the heath opening. This makes much more sense from my experience building wood burners.

No, by choke point I simply mean a tight place in the throat.

In a forge flue like mine, there Is a distance the smoke travels horizontally to reach the vertical flue. It's within that travel that mine has a smaller area (7x10). The main flue is bigger in size (10x10).

The actual opening that is near the fire can be flared bigger to cover a broader x higher area. But can lose it's effectiveness if too big.

I would imagine that there are factors that would affect this ratio the would call for adjustment or even eliminate it (choke point) all together for a better drawing flue. But these factors can only be known by building a lot of these things.