Roman Bellows

[Hibernicus]

Seeking input.

I built a double chamber bellows, works great.. 42x28.. yeah, its medieval but I was familiar with it

Here's a pic on its first day of use...
http://legio-ix-hispana.org/gal_muzeo/img_sangandbellows.jpg

and it's forge.... It comes apart for transport..
http://legio-ix-hispana.org/gal_muzeo/img_pilaintraining.jpg
The fuel is mesquite charcoal.. real charcoal, not briquettes.. 40lb sack from a restaurant supply store. Neighbors prefer the aroma of mesquite over that of coal!

Am almost finished building a double bladder bellows - Iron Age .. each bellows is 24" across.. something more appropriate for 1st C AD

However, the next bellows project is a piston pump, much like a Roman water pump...

Anyone have any experience with this sort of set up?

The cylinders will be wood, much like staves in a barrel, except straight.

[solvarr]

The things we found when we were playing with that design.

I say playing because we were using Innertube rubber instead of leather because it was free an let us mock up bellows easily without spending hundreds on leather.

The ribs really helped our performance since it made the bladder behave more like a piston and less like dizzy Gillespie's cheeks.


we setup a two valve system in the ones we made.

A standard intake valve under the handle which was a peice of rubber tacked in four places under the intake hole (leather worked better here than the rubber)

In the base we made what we called a tongue valve.
we made a rectangular piece of rubber and made it so it would naturally rest on the square output channel in the base of the bellows.
if you do it right it closes off most of the air from the forge on the filling stroke and gets out of the way when you are pumping the air out to the forge

I have evidence for the top valve.
The bottom valve was just us saying romans weren't dumb.

Have you seen the portable roman foundry on the viking bronze website?

[Hibernicus]

I have seen these pages. Good stuff!

[matt87]

Hi there Hibernicus and welcome to IFI! Some very interesting stuff there, especially since I'm a second-year archaeology student at Exeter University, taking modules in archaeometallurgy and the Roman Army! My dissertation will probably be on some aspect of ancient iron smelting. I visited a Roman-period ironsmelting/smithing site and an iron-ore extraction site on a field-trip yesterday. (I also have a great interest in experimental archaeology, especially with regards to metallurgy.)

[Hibernicus]

Matt,
Wonderful!

You familiar with Dave Sims? His publications have been very useful.

Smelting is the next step for me. Not this year, though! I live smack dab in the middle of the city. A forge and bread oven in the back yard are enough smoke. Only had the fire department out once in 15 odd years. :D

[Frosty]

Welcome aboard Hibernicus.

You bring interesting questions, thank you.

Matt87. Pictures please.

Frosty

[dablacksmith]

ive seen a cylinder blower in use ..I used to do a heritage festival and there was a Koreian or vietnamese village setup that had a forge with one .. was interesting had great supply of air.. i dont know if it is the same as what your talking about but It was interesting... good luck!

[matt87]

Pictures of the two sites aren't all that exciting, mainly due to the weather. (We spent much of the day inside a cloud.) Here are a couple of pics I nicked from some friends.

The first picture gives an overview of the smelting site, which is located in a small river valley. The horizontal platform in the centre of the picture is where the smelting actually occured. The two vertical dark blobs are people. Much of the platform is made up of slag and other smelting debris, as well as earth dragged down form further up the slope. As you can imagine, this is a considerable amount of material. The site is completely littered with tap slag, as well as furnace lining and charcoal. There are several large pieces of slag (over 12 inches in diameter) which have been broken up from even larger pieces. They have a shape indicating that slag was tapped into a bowl-shaped depression. These large pieces show perhaps eight layers, each one representing a different smelt. The slag is quite dense, containing much 'wasted' iron, in the form of iron carbonite. (Roman-period smelting was not as efficient as that of later periods.) We took samples of these slags and will be analysing them later.

This smelting site is knonw to have been operated during the Roman 'occupation' (i.e. between AD43 and AD410). It is not obvious however exactly who ran it (the roman army, locals supervised by the Romans or local entrepruneurs). It is known though that the Romans were the main consumers of the iron smelted here and the qualitities of iron produced were far in excess of local demand. Charcoal was produced on site, and iron ore (haematite mainly) was transported to here, as charcoal was the more difficult to transport (it crumbles too easily).

The extraction site is locally known as Roman Lode, though this is a modern name and does not indicate a neccesarily Roman exploitation. It is known that this area has been exploited and mined for approximately 4,000 years, though not neccesarily continuously. There is evidence all over the local landscape showing mine work from throughout this time. The picture shows a typical open-area excavation thought to be from the Roman period. They range from just a few feet deep to perhaps 15 feet. (I suspect that many of them have been partially refilled due to soil falling in.) The area is rich in various iron-bearing rocks, and the ores have been exploited until the early to mid 20th century.

These sites were excavated a few years ago, run by my metallurgy tutor and two other archaeologists at the uni, who accompanied us on the visit. (There is another dig being planned at the moment.) If you're expecially keen, PM me and I'll point you the direction of excavation reports etc.

Hibernicus, I'm afraid I'm not familiar with him, and a cursory Google search returned nothing relevant. What is his area of expertise?

[Hibernicus]

David Sims, Iron for the Eagles for one
Oxbow Books

Another title: Beyond the Bloom


Articles in JRMES.
Journal of Roman Military Equipment Studies

[Ted T]

Hibernicus,
First off, Welcome to I Forge Iron.
I am always amazed by people such as your self. I applaud your willingness to bring to our attention and share a different aspect of time and place of how the craft was employed. It is not only interesting to me, but most enlightening.

[Hibernicus]

Thank you Old Rusty Ted,

Happy to share, but I see loads to learn here as well!

The first pic is an example of a pump found and partly restored. Note the valves!


The next pic is of a simpler design using flap valves.. the stump contains a different pump.

[matt87]

Sean, may I ask what role you represent at reenactments? I'm a little confused between your BS gear and the Legionaries in your avatar.

[Dave Leppo]

The “piston pump” you describe reminds me of the air pumping system used at the Hopewell iron Works in eastern PA – national historic site. A water wheel turns pitman cranks on each side of itself, which drive pistons in huge wooden cylinders via rods. The pistons push air into a central valve assembly built into a big wooden box.
Hopewell Furnace National Historic Site
check out the second picture.

[ThomasPowers]

Check valves on bellows: Theophilus in 1120 A.D. gave descriptions of building both organ bellows and metalworking bellows. The organ bellows included a check valve on the outlet. The metalworking ones did not.

Strange as we would think that since they knew about them they would have used them; but this does not seem to be the case.

Well building a set like they are described and using them I found out that in paired single action bellows you do not need a check valve if they are run correctly.

Two things help: one leaving a small air gap between the bellows nozzle and the tuyere intake---for my system the distance that worked best was about the diameter of the tuyere pipe. When I was reading "The Mastery and Uses of Fire in Antiquity" I noted that they mentioned this was known in the archeological record and he speculated that it was for aspirating more air into the system---but that it wouldn't do that very well. (I corresponded with the author and told him of my experiments and how in my case the gap was not for aspirating more air; but for protecting the bellows from pulling hot gasses and small bits of burning charcoal into the bellows)

Two, pumping the belows in opposition so that one is pushing air into the tuyere while the other is inflating so the airblast form one prevents the other from sucking in the hot gasses or coals. The funniest part is starting the bellows up as you start in increasing partial pumps---stair stepping them until you are at full inflation---if you have an airgap you can see the hot gasses oscilate in the tuyere---the goal is to not let it reach the bellows end before they other bellows blasts it back into the forge.

If you are trying to be accurate in your portrayal you must always be careful of what we would do vs what they did. Some times what they did seems very odd to us; other times it turns out that their ways actually work better than what we would try if doing it ourselves.

The biggest problem with using early paired bellows is that they require a full time bellows thrall as it's not very efficient switching back and forth from working the fire and smithing to pumping the bellows located on the side or back of the forge. We got around this by having paired smiths---one would forge while the other would pump and then they would trade off at intervals---or getting a young lad who was interested in the process and sentancing him to pump them for the smiths.

[Hibernicus]

to Matt87
"Sean, may I ask what role you represent at reenactments? "

The club's persona is that of a company of soldiers stationed some miles from the legionary fortress on extended duties in a temporary camp. In 2007 we decided to expand our portrayal to include Engineering. This gives us the opportunity as a group and as individuals to portray other aspects of Roman military life as part of our public presentations. We recently built a 16' crane... don't know it full load capabilities.. yet! We recently experimented with a portable forge set up at a 3 month long museum display we did in Anaheim Calif. For fun we've dug entrenchments with hand made tools (Roman pick axes, shovels..) and are trying to coordinate a project in 2009 to include several dozen soldiers digging/constructing a camp entrenchment.

My role.. I am President of Legio IX Hispana. But as a Roman soldier I usually portray a Centurio (centurion). Since I know a bit more about swinging a hammer at hot iron I also do some smithing.

[Hibernicus]

Goatman, thanks very much.

And Thomas.. thank you!
You wrote: "If you are trying to be accurate in your portrayal you must always be careful of what we would do vs what they did."

That is a serious problem for 1stC AD Roman reenactment. We do not know many things. In order to fill gaps in the knowledge we often draw from earlier or later decades/centuries. For example: there is no archaeological evidence for padding worn under armor in our time period. We know it was worn a few centuries later and we know the armor works exceptionally well with padding. So, we wear padding.

.. and again: "Some times what they did seems very odd to us; other times it turns out that their ways actually work better than what we would try if doing it ourselves."

Exactly! We used to make a hinge for the body armor with powertools... angle grinder with a narrow cutting wheel, dremel, and such.. took about an hour (if you had experience) to complete one hinge and the armor has 8 of them! Then after reading about using chisels to cut brass sheet and after a bit of experimentation we found we could make a hinge in 20 minutes. And now we have a way to demonstrate hinge manufacture at public presentations!

[Hibernicus]

Thanks again Thomas.. your post inspired an internet search that eventualy led me to an archaeological report about a possible air pump associated with metal work in a Roman context in Britain! I've written for a copy of the report!

[ThomasPowers]

Great! tell us about it when you get it? Is it a BAR? I've been trying to get one of those for "The Metallography of Early Ferrous Edge Tools and Edged Weapons" for several years; out of print and not common sigh. (IIRC it includes an analysis of a roman edged weapon in it).

[Duco de Klonia]

Hi,

Nice discussion here.

I'm new to this forum and like to join in on this bellows subject.

I ran into this problem,- how to make a "Roman" belows - , when last year (2008) I had to set up a field forge for the Archeon in the Netherlands.

I realized it would not be a simple kite-shaped bellows as we know nowadays.

I asked virtually any known forum & blacksmith I knew, and also on the armourarchive.org forum, but nothing.

Even no pictures, reliefs etc.

I found a part of the possible answer in the picture shown here on this forum of the metal waterpump.
It had 2 chambers, valves and a horizontal lever, and it was ROMAN.

I had seen pictures of ancient north African bellows, and the were made of wood an just looked like it.

I figured the Romans occupied north Africa for quiet a long time and perhaps left this pump-technique there.

I made a very, very simple double chambered portable bellows and it worked like a charm. Without any problems it worked for more then a year.

It was build with PVC-pipe for the chambers (I just could not build wooden chambers, no time etc.) and covered them with wood.
I made wooden discs of 2cm plywood with holes in them to be covered with a leather flap ( piston up- leather uncovering holes leaving air in, piston down-leatherflap closes pushing air down)

Those discs connected to a simple wooden rod, loosely attached with a screw, around those discs a smple layer of felt was nailed for a seme airtight seal.

Two of those chambers were mounted on a plank with wooden column in between. this collum was to pivot the lever, and this lever rod was connected to the rods coming from the pistons.

And yes, two copper pipes coming from the cambers, joining together in a small camber with leather "flap" valves and so the 2 airflows coming together as 1.



it works so well, and it looks very Roman, but no, I can not be sure they had bellows like that.
I hope they did have them.

Let me know wat you think.

[thecelticforge]

I have seen bellows like these work well, also Roman.
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[matt87]

Welcome to the forum Duco. A very interesting and useful first post!

[ThomasPowers]

I haven't seen any original evidence this type was used. IIRC I have seen bag bellow in a stone carving; perhaps at the museum at Bath?

Always hard when there isn't much in the way of documentation, makes you wish the red vase painter had been roman instead of greek!

[Duco de Klonia]

I'm aware of the risks of inventing historical stuff.

The resemblence of the African bellows and the Roman waterpump construction hit me in a "flash" ....it felt a kind of logical.

They must have known the technique.

But they also could have invented the paperclip too. They knew the techniques to make one also, but they still didn't make one.

We will never know.

Using this forge & bellows I made last year:

A lot of iron arrowheads,
a iron spoon/fork combination
some spearheads
an Umbo shieldboss
a lot of nails
casted bronze buckles
made a oil lamp ("8" shaped flat barge with a hanging loop)
fibulea
knifes

Me - left & Ben, right in the Archeon '2008