Rolling Roman Iron for Segmentata Plates

[Matt Lukes]

You mean that would require a person to apply the pressure? No way that'd work dude...

[richsc]

I have no idea what sort of rollers we're talking. How large, and probably made of stone? If so, they would be hard to destroy and some evidence for them ought to be somewhere. Mistaken for columns?

[Matt Lukes]

No, they'd have to be iron or steel- but the thing is that there would have only had to have been a fairly small number relatively and thus it's not odd that we have never found any as they could simply have decayed. Given that we've never found a muscled cuirass, and have only a rather small number of helmets, swords, mail and plate armors- all of which had to exist in the hundreds of thousands overall, it doesn't really surprise me.

As I said, they need only have been small since the widest plate of any segmentata found is only about 9.5cm (3 3/4")- that means a roller just a bit longer and maybe 5cm (2") in diameter? It'd have projections at either end to fit into a frame and maybe some sort of attachment points for a crank arm- one of the two rollers would anyay.

Here are a selection of rollers for a modern desktop mill:



And here's a mill itself- the mechanism at the top is for adjusting the separation of the rollers so isn't a necessary part of the machine- it really only needs the frame to hold the rollers, a couple of gears and the crank arm.

[M. Demetrius]

Had the Romans invented metal gears?

I've seen some stuff made from interlocking wooden pegs mounted on offset wheels, which really amounts to the same thing.

Just asking, not quarrelling. It seems like some kind of grain grinding mill variant could work....

[Matt Lukes]

Well ballistae and catapultae are all reconstructed with ratcheted gears- and I believe those are based on Greek finds, so metal toothed gears seem to be quite old. I believe grain was always ground in horizontal rotary mill stones- but it has been mentioned that some form(s) of rolling mill were used for making olive oil at the time

[kazeryu]

(Ressurrecting ancient thread)

I was also wondering about a grain grinding mill being used to roll iron - as a finishing pass, not complete shaping.

What sort of mills did the Romans have? Water powered?

[richsc]

Water powered: think of that find in southern France with cascading mills and multiple wheels.

[kazeryu]

I'm not quite up to par on my historical finds... :oops: does that place have a name I could google?

Thanks,
-R

[Titus Marius Secundus]

I don't know if this can help, but make sure to read or skip right down to the bottom part of the page.

http://en.wikipedia.org/wiki/Roman_engineering

Sam.

[Cerco 21]

There are a few wrong notions floating around.

First Steel vs Iron, while steel does indeed contain Carbon it must contain between 0.2 and 2.1% anything above that and were talking about cast iron which is brittle. The main problem dealing with "steel" is having the right conditions. Heating iron on top of coals will add to the carbon content making cast iron... That's why you'd need a smelting and pouring structure.

Steel has a crystaline structure that changes with temperature and there are structures which are more resilient than others so after heating the metal to the desired structure you need to "lock it" that is called tempering the metal, which can be done by dipping it into water, heated oil or a salt bath. Volumes are written about the multiple variations possible, I'm in no way an expert in archeometallurgy but from all I gather there were regions where you produced better steel, due to local factor such as alloy elements in the mineral itself, alloy elements in the temper water/salts/oils or "blessing" the plates by buring them in the ground (which allowed the lower carbon metal to become corroded and then joining several resulting plate together).

I fear that I'm already boring you...

So cold rolling steel was possible, but like the steel manufacture itself it would probably be a local thing.

Regaring ratched gear on Balistas an Onagers, SOME had ratched gears (including reducing gears), but most tension groups (modioli) did not have ratchets at all.

[kazeryu]

I fear that I'm already boring you...

Not one bit! I enjoy learning such tidbits.

[Cerco 21]

I fear that I'm already boring you...

Not one bit! I enjoy learning such tidbits.

Another helpfull thing to know, one I imagine a series of smiths learned the hard way, is that after cold bending metal you'll get a stress acumulation over the "bent" part, this stress can be relieved by re-heating the metal, however re-heating will cause the crystaline structure to change again, so you'll need to do a new heat treatment, new tempering etc. If you don't relieve thoses stresses the part will be very fragile were it was worked.

There are 2 very interesting books called "Engineering in the Ancient World" by J.G. Landel and another called "Engineering the Ancient World" by Dick Parry (notice the almost same title). In them you can find several photos, diagrams and interesting and usefull information.

[Crispianus]

Greetings, An interesting discussion but I think there is a slight flaw to do with the machinery and nature of the iron plates to be rolled, a blacksmith keeps his work straight by adjusting blows accordingly(either by hand or powered hammer) no matter how irregular the original bar of metal may be.. a machine cant do this so any irregularity in the thickness of the hammer forged bar or plate being rolled would result in the plate snaking... the same can be said to be true of the rollers themselves, a wide set of rollars would be more effective in keeping the plate even, as any tilt in a narrow rollar would result in a banana shaped piece of metal of uneven thickness... in any case some hand work would be necesary to correct the problem and straighten the plate strip.. personally I believe a simple set of calipers would ensure a consistant thickness in a piece of sheet metal within reason...
What material would you use for the bearing considering the high loading?
has anyone considered a drop hammer with a smooth flat face....

[Crispianus]

Greetings, An interesting discussion but I think there is a slight flaw to do with the machinery and nature of the iron plates to be rolled, a blacksmith keeps his work straight by adjusting blows accordingly(either by hand or powered hammer) no matter how irregular the original bar of metal may be.. a machine cant do this so any irregularity in the thickness of the hammer forged bar or plate being rolled would result in a narrow plate snaking sideways... the same can be said to be true of the rollers themselves, a wide set of rollars would be more effective in keeping the plate even, as any tilt in a narrow rollar would result in a banana shaped piece of metal of uneven thickness... in any case some hand work would be necesary to correct the problems and straighten the plate strip.. personally I believe a simple set of calipers would ensure a consistant thickness in a piece of sheet metal within reason...
What material would you use for the bearing considering the high loading and potential wear?
has anyone considered a drop hammer with a smooth flat face....
Additionally as has already been said the plate strips are not very wide so a flatting hammer hit with either a sledge or perhaps a powered hammer would likely produce the required result..