Steel
side draft coal forge in my old shop. Des Moines, Iowa
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UPDATED September 16th, 2019.
Steel
side draft coal forge in my old shop.
Built of brick and steel plate as an experiment to see if a hoodless design would make the task of heating the iron more comfortable and convenient. This forge outperformed any other type of forge I have ever used in such dramatic fashion, that I will continue to build this style of forge in the future in preference over any other. This was my third forge and was designed for making wrought ironwork (gates and railings), tools, machine parts, and horseshoes. The chimney drew smoke in all types of weather including heavy snow, heavy rain, and very windy days. And the chimney drew smoke so strongly that the smell of coal smoke had been completely and permanently banished from the shop. And by this I mean that ALL smoke went up the chimney - not just some of it.
Page updated September 17, 2019. Under construction, re-write in progress.
The forge shown here at right, was inspired by the large shop forges that were featured in the book The Blacksmith ~ Ironworker and Farrier by Aldren A. Watson. The large hearth size offered plenty of space for placing tools and coal and hot iron, near the fire. The chimney flue is 12" square. A large chimney cap kept rain and snow out. The hearth plate measuring 72" long by 40" wide, was made of 5/16ths steel plate reinforced with 1/4 x 2 inch angle iron. The hearth plate was supported by the corbelled sides of the lower chimney at one end, and by two brick pedestals built over the front of the forge foundation at the other end. A tool rack was cast into the brick structure to hold hardies and hardie tools. Detachable tongs racks were made to hang from the edges of the hearth plate. The internal chimney dimensions were taken from an article in an old issue of the Anvils Ring. I had discovered entirely by accident, after witnessing the action of a smoke shelf that I had inadvertently created while stacking brick up between the fire and the rear wall of another forge - that smoke shelves have a tremendous influence on reestablishing smoke draft in a chimney that has experienced a downdraft due to wind turbulence. That forge was my old fabricated steel forge that is featured further down this page. Anyone that claims that smoke shelves don't work, obviously hasn't ever worked with a properly designed smoke shelf. My steel and brick forge (shown here) was a great success and I plan to build another like it again in the future. And now let's look at where the chimney design came from.
Chimney
design based on article by Dimitri Gerakaris in the Anvil's Ring. Internal
dimensions of the chimney were based roughly on those found in the Anvil's
Ring Vol. 7 #1 from March 1979 (also known as the Hoodless Forge issue). These
designs were chosen because they did not smoke like other chimneys of the previous
era. Anyone that has seen an old brick chimney built during the 1900s is aware
that the chimneys during that era were all smoky. The internal designs of these
chimneys solved the smoky chimney problem and featured a smoke shelf to help
chimney draft during weather turbulence.
Forge construction took about 2 weeks. The weight of masonry requires the builder to add no more than about 2 to 3 feet per day. The temperature dropped during the second week as I was building the chimney and work slowed to 2 feet per day.
Materials used in this forge & chimney construction. Materials were good quality brick and mortar. 1/2 inch rebar was also used throughout the lower part of the foundation and up through the level of the upper smoke chamber (near the top of the wooden knock-down forms seen in the picture at right. No flue tiles were used in this forge due to problems trying to obtain them. The hearth was made from 5/16 inch steel plate.
Knock-down
forms used during construction. In the photo near right is the chimney under
construction, this time showing the forms used to support the uncured masonry
while constructing the smoke shelf and the upper smoke chamber. The forms were
designed to be broken apart and removed after construction. The lintel bar was
also supported by wood blocks to prevent its weight from damaging the mortar while
the mortar was curing. The sloped wall of the smoke shelf was created by ramming
mortar against the knock-down forms and packing the inner part of the shelf with
mortar broken bricks and rubble as fill material. This method of creating the
smoke shelf resulted in all exposed inner surfaces inside the chimney being smooth
and clean. Rebar was cast through the walls of the chimney and horizontally
through the smoke shelf - strengthening the mortar and rubble construction of the
shelf.
At far right is a photo of the chimney a little later in construction after the brick has been built up over the wooden forms. The corbelled shelves built low on the sides (level with the bottom of the smoke entrance) will support the chimney end of the steel hearth. The hearth is made of 5/16 inch steel plate and is very heavy and will remain stationary, so the only place where it will be bolted down is to the masonry legs at the front of the forge. The hearth simply rests under its own weight along the corbeled sides of the chimney since it isn't likely to move if it is bumped or struck. A hardie rack was cast in place in the mortar near the base of the chimney. The space between the rails of the hardie rack fits my anvil tools, or about 1-1/8" between rails.
Positioning
of the firepot in front of the chimney. Because room inside the shop was at a
premium I was forced to locate the chimney as near to the wall as possible and so
the smoke hole in the chimney was offset to compensate for firepot placement. The
photo (right) shows the position of the firepot near the chimney. The rear edge of
the firepot is about 3 inches from entrance to the smoke hole of the chimney. This
was one of my experiments to find out if it was beneficial to place the firepot on
a rotating separate plate to allow the firepot to change position for different
jobs. I recommend that others don't do this because the firepot is never rotated.
I now build coal forges with the firepot inset into the hearth, so the edges of
the firepot are placed level with the surrounding hearth plate surface.
Refractory material protects brick nearest firepot. Fireplace cement was molded onto the front surface of the chimney nearest the fire to help protect the masonry. The intense heat of the fire would quickly deteriorate the masonry otherwise.
Lintel bar. A lintel bar of angle iron supports the brick structure above the smoke entrance in the bottom of the chimney. The lintel bar is offset outward, so that a small sheet metal hood can be hung from the protruding edge of the lintel bar.
Hearth. The raised sides of the hearth are made of 1/4 x 2 inch flat steel, and are welded around the perimeter of the hearth to help keep fuel from falling off.
The
photo (far right) is a view of the side of the hearth nearest the smith. At center
of this photo the cutout area of the rim around the forge hearth, is clearly
visible. The small hearth extension is visible (an extension of the hearth
projecting out towards the smith) at the cutout area. And of great importance in
this view is the reinforcement of the edge of the hearth in this area. It can be
clearly seen that edge of the hearth is reinforced around its perimeter by the rim
welded to it, but to remove a portion of the sides or rim anywhere along the
hearth would leave it weak and prone to bending or collapse in that area. To
strengthen this area the rim or side of the hearth is continued from underneath
with a piece of 1/4 x 2 flat material welded to the underside of the hearth edge.
The reinforcement overlaps the ends of the sides from underneath and gives maximum
reinforcement to support this area as though no cutout existed. Also visible in
the photo (near right) is the plumbing of the air blast pipe from the blower.
The
blast air delivery piping is placed around the front of the forge and then
down and backward into the hollow of the chimney where it then bends up and
forward again to enter the tuyere pipe of the firepot. This was a mistake. Each
bend of the air pipe restricts the flow of blast air. Had a hole been built into
the lower-rear of the brick chimney structure, a single bend, or possibly a bend
and a half would have directed air into back of the tuyere. There are a total of 5
bends between the blower and the tuyere pipe in this picture. Each bend makes it
more difficult to get air into the fire.
Simple
hanging tongs racks were fashioned from 1/4 x 1" flat stock which were made to
hang from the sides of the hearth rim. The racks hung down well below the top
edges of the hearth rim so that the ends of the jaws of the tongs were made lower
than the hearth rim so that they didn't foul tooling or iron while working in the
fire. At lower left is the smaller tongs rack near the anvil which kept the group
of tongs most used or needed immediately.
Firing
the forge for the first time. In the photo at left (Click on the thumbnail) a
fire has been lit for the first time in this forge and a small bar is being
heated. This was in the middle of December and the cold weather slowed the curing
of the mortar so I didn't want to chance a large full size fire. Even with a small
fire like this one, notice that the draught of the chimney is so strong that it
actually bends the flame backwards towards the smoke hole. The edge of the rim
which runs around the hearth, cutout to allow for level placement of the iron
through the fire. In the picture at left the iron and tongs can be seen hanging
over the edge of the forge nearest the smith. A small extension plate was welded
to the edge of the hearth plate here at an angle slightly above horizontal, to
give added work area to help support long pieces in the fire and to help keep fuel
from falling off the edge. Also notice the group of fire bricks laid along the
fire both in front of the fire and behind it inside the chimney. These bricks
create a trough to help build up the height of the fuel in the fire and to help
maintain the fire. Some of the older all-brick and mortar forges were built with a
trough cast into the surface of the hearth to create this same effect permanently.
To see what this effect is based on, look at the pictures on the
Dows Blacksmith forge.
These
pictures show the forge as it looked after more than a year of use. At right is a
photo showing the forge and most of the shop area. Coal was simply dumped in a
pile on the hearth with as much as 100 lbs. of coal on the hearth when a new bag
of coal was added. The hearth was large enough to support all of the coal with
plenty of room left over for placing tooling in easy reach, and for small bars or
objects to cool safely before quenching. Fire bricks are placed around the
perimeter of the firepot to help raise the height of the fire. Free hanging tongs
racks were hung on the side of the forge hearth for tongs used most often, and
another hung at the front of the hearth for tongs that were used less frequently.
Tongs racks were hung low enough to allow the jaws of the tongs to remain below
the hearth and out of the way to avoid snagging tooling and work being moved back
and forth around the fire. The building was very small but with convenient and
efficient placement, the shop was uncluttered and everything was in comfortable
reach - anvil, blower, hearth, water barrel, vise, and drill.
A
piece of pipe or other object placed across the opening of the hearth rim near the
fire kept fuels from falling off the hearth during use. Seen here in the working
photos at left are some large scrolls being heated. The weight of the scrolls
rests on the pipe placed across the opening in the hearth edge, but if it caused
any obstruction to placement of objects in the fire, the pipe could be removed
quickly. The small shelf near this opening in the hearth edge, was slightly
inclined to help fuels stay on the hearth when the opening here was not blocked up
with pipe. As can be seen in these photos, smoke entering the side draft chimney
literally lays over sideways to enter the bottom half of the entrance in the
chimney. This demonstrates the strength of the draw acting on the smoke and
forcing it into the chimney.
After months of continuous work, cinders accumulate in a sloped pile in the bottom opening of the chimney. This poses no problem and is actually desirable. The cinders or fines protect the bottom surface of the chimney from direct flames of the fire. Periodically some of the excess cinder pile will need to be removed (about once a year) and discarded.
There are about 6 firebricks in front of the fire to raise the height of the fire - making the fire deeper and easier to maintain. More firebricks are hidden beneath the cinders between the firepot and the chimney entrance.
At
left are two photos of the view the blacksmith sees while standing at the anvil.
At
right is the view of the shop and forge when looking into the building. Because of
the tiny size of this shop ( 11' x 16) space was at a premium. Behind the
photographer and to his left and right were a drill press and a Little Giant
25-pound power hammer.
Hardie racks were cast into the brick work on the side of the lower section of the chimney during construction. Hammer racks were cast into the rear of the brick structure to hold lesser used hammer tools. Again the pipe laying across the cutout area of the rim of the forge hearth is visible here in place to help hold fuels on the hearth. The pipe is not necessary, but is a simple and quick convenience.
Not visible here also, was a wood-burning stove for heat. The stove was located to the left of the forge in this photo and about 6 feet away from the smith.
At
left and below left, are photos of my first successful forge built of angle iron
and sheet metal. A Centaur Vulcan firepot and a British Alcosa F-70 hand-cranked
blower, both bought new, from Centaur Forge are installed on this forge. Firebrick
lines the rear wall of the hood right up to the bottom of the chimney flue. This
steel forge (photo at left) worked well enough that I used it for 6 years. It was
a of a conventional style of fabricated forge with a half hood. Similar in design
to modern fabricated forges which can still be purchased from Centaur Forge today.
A tong rack was welded to the front to support some of the tongs I used for
blacksmith work. Firebrick lined the rear wall of the hood up to just below the
chimney pipe. Smoke actually is attracted to brick structures and will hug this
wall until entering the chimney. The top of the fire brick acted as a smoke shelf
- helping to control the back drafts that would otherwise push smoke back down the
chimney during wind gusts on windy days. It should be noted here that, the
original hood configuration allowed smoke to blow back down the chimney during
wind gusts on windy days. After adding the brick wall under the hood (as shown in
the photo at right), these back drafts stopped, and the rolling action that the
smoke shelf caused on the smoke was quite visible during wind gusts by simply
looking under the hood. There was one more row of brick stacked up under the hood
- but due to the dark photo, this is not visible. The top of the brick was 4
inches above the bottom edge of the hood. Only after building up the back wall on
this forge to its final height, did I finally discover the effects of a smoke
shelf. It was this forge shown at right, that caused me to seriously consider the
contributions that the smoke shelf offers in chimney construction. The open
construction of this style of hood allows the smith to look up under the hood to
see how well smoke flows over a smoke shelf under every condition. And just for
the record, I never intended to build a smoke shelf on this forge. The smoke shelf
is an incidental part of stacking up a brick wall behind the fire to help guide
the smoke. My discovery of the action of smoke shelves was entirely accidental.
The chimney is a custom made sheet metal pipe, made at a local fabrication shop. A new Alcosa F-70 hand cranked blower was fastened to an arm extending from the back of the forge. The firepot was a Centaur Vulcan which at that time cost about $85. (They are about double that in price now I think.) Firebrick was then built up around the fire pot to help create a deeper fire and make use of gravity when tending the fire. The forge hearth measured about 40 inches side to side, and about 60 inches from front of tongs rack to rear of chimney. Hearth height (from floor to hearth level) was approximately 32 inches. I used this forge to make everything from wrought iron gates to draft horse shoes. All of the tongs seen in these photos are made by me as well.
The
firebrick in the back of the hood wasn't in my original plan. But over time as I
learned to use the forge for more complex forgings and repairs, the brick wall in
the rear of the chimney and the bricks around the fire were added. It basically
evolved over a year until the forge looked as it does in the first photo shown
above right.
Note the convenient position of the blower which is mounted so that the crank does not come in line with the path that long bars take when placed in the fire. Long bars could thus be heated with this forge without fouling them with the hand crank of the blower.
One problem encountered with this forge is height of the tongs racks. I found
through experience that tongs should always be hung so that the jaws are below the
level of the forge hearth so that they don't interfere with or foul the bars or
objects that are placed in the fire. This is especially a problem when working on
large scrolls and parts for gates and when making repairs to large awkward machine
parts.
My
newest semi-portable steel forge
Here is my latest all steel semi-portable side draft shop forge. The side draft
hood is fabricated of sheet metal and angle iron welded together. The dimensions
for the inside of the hood follow the internal dimensions of the sidedraft forge
designed by Dimitri Gerakaris in the Anvil's Ring issue March 1979 and are similar
to the dimensions used in the brick chimney seen above. To see more on this forge
go to the Steel Sidedraft Forge
page here:
http://www.beautifuliron.com/cf_MySteel.htm
The hearth plate was cut out of the remains of the hearth plate of the brick and steel forge (photos at top of this page) when I moved to my new shop. While I plan to build a large forge again in the future for my ornamental ironwork, a good sidedraft forge was needed in the interim which could be transported to use in the field as well as setup permanently in a shop setting. The hearth measures 32" wide by 36 inches long, and stands 31-1/2" tall or about 1" below the knuckles of the hand when standing beside it. The firepot is a Centaur Vulcan saved out of the brick forge above and the blower is the same Alcosa seen in the photos of the brick forge above on this page. The firepot measures roughly 13-1/2" wide by 12-1/2" long (the longer dimension being across the width of the forge or in line with the steel bar seen placed across the forge in the photo at left). The distance between side edges of hearth and edges of firepot is 9". The rear edge of the firepot is 7-3/4" from the rear of the hearth and the front edge is 15-3/4" from the front of the hearth.
Latest update 17 September 2019.
The author can be emailed at address in picture below:
Page created around November 1999.