Yes, the Romans made very precise threads, as has been shown in the construction of the three pronged speculum (medical instrument). However, it would indeed be a cumbersome mechanisme.
Thomas, you are right in questioning the existance of a lip. It is one of the weak points of the slider theory, as this would not really be needed other that as a stop to the trigger bar, but that would have been limited by the handle anyway. However, the lip is indeed not very sturdy. It could have been worn, presuming the crossbow placed in the grave had seen some use. Given the forces applied, wear on the inside of the nut would be expected from repeated firing, certainly if the trigger was made of iron. Too bad not all pieces have been drawn, for the iron bar with the two projections described may have been the triggerbar, revolving on those two projections. However, with out a picture, that is impossible to judge, as the position of said projection on the bar is not described.
Quote:I do believe it will work fine, actually :-)
That very well might work, but in the absence of any evidence from the sources or analogies it still would not have any scientific value, since it would remain only a modern construction.
Quote:Although what I suggest is a bar underpinning the nut, so it does not rotate as it is held in place like Thomas describes.
With this construction, your handle will simply get stuck due to significant friction and you will not be able to pull it.
Quote:I realise the handle found is thought to be of a dagger, but it is found in context with the crossbow pieces and no remnants of an iron blade are present, linking it to a dagger.
Robert, you missed the fact that the article mentions 2 knife blades in the grave.
Quote:for which there is really no obvious function
This handle was to hold the crossbow — it was convenient and stylish. Carved knobs of stonebows were pressed against the stomach or hip when bending.
I mentioned the knife finds to him already, although there are no images. Its still possible they could have decorated the handle with bones.
Furthermore, it would not generate so much friction as you would be unable to pull it the handle back. Reconstructions have already been made of this style, Comitatus did one back in the 90's (although it used a screw) and there a few others out there with a sliding handle.
You are certainly right about the analogies. But that does not mean there was not something different used before the well tried method of later era. The rotating nuts seem to have a square deep slot, which is best held in place with a sliding mechanisme as opposed to a tilting one as in the Z style trigger. As Evan remarks, there have been others going for the sliding mechanisme (although that does not make it right (or wrong)), it just shows the line of thinking in trying to figure out how the early crossbows worked given the very limited data. The upper lip of a slot is however subject to much wear, so that could be a reason for the introduction of the Z shaped trigger and a nut with a lip at the underside. Look at where the slot is on this picture, it is at the back of the nut, not underneath:
The friction would not be all that much, actually, certainly not something one cannot overcome by a steady pull. Do not forget these bows were not the 125 # medival bows. I hope to reach a poundage of half that. They also found a strip of bone that had been in contact with iron, so perhaps there was a bone strip on top of the bar to provide a slick surface. But that is indeed pure speculation.
I did not miss the reference to the knifeblades, but the presumed handle parts were found separated from the blades, even though the bone knob still showed a portion of an iron "tang". I have a LOT of pictures and drawing of knives, when knives are found with handleparts preserved, these are always in a relation to the blade. Furthermore, the handle shape is uncommon for late Roman knives. That is what got me thinking about a different kind of use. Now, even if the parts are indeed the handle for the crossbow, that still does not mean they were part of a triggermechanisme, I realise that.
The knobs in the drawings do not look like something made to be pressed into the stomach :-) .
Given the limited archological and iconographic evidence, how would you think the early crossbow worked, Idar?
Looks good, totaly believable (although I think I would have added a simple spring, we know they used those in locks and things), Thomas, but what about the (more abbundant) nuts with the hole/slot cut in the back of the nut? Any dating on those for the Roman period? And how would that work?
Quote:[...] Thomas, but what about the (more abbundant) nuts with the hole/slot cut in the back of the nut? Any dating on those for the Roman period?
The only slotted nut that could be from the Roman period is the one from Carnuntum. The dating of the Austrian nut, however, is difficult: http://ads.ahds.ac.uk/catalogue/adsdata/...17_321.pdf (p. 319). Its design (indistinguishable from medieval ones, see Ildar's picture) is another factor that makes a later origin plausible.
Quote:And how would that work?
It would work like a conventional nut-lock crossbow.
Quote:Are all nuts found made of bone, by the way?
The prefered material was antler. According to Egon Harmut, the nut and handle from Burbage are also made out of antler (that's why I suggested an antler handle, BTW).
Quote:There is another thing puzzling me. Neither of the two pictures show the bow being fastened with lashings.
Stone carvings often omit details.
Quote:What are your thoughts on the way the bow was fastened to the stock.
If I would build an arcuballista, I would use the generic medieval binding for the following reasons: quite obvios method of attachement, almost self-explanatory, easy, cheap, ubiquitous, used for centuries, arcuballista possibly antecessor of medieval crossbows.
Quote:Is there an ancient text that descrides such a lashing and does it indeed apply to this type of crossbow.
I'm not aware of such a text.
Quote:Also 36 cm drawlength does not seem a lot for a bow 90 cm wide.
As the bow would belong to a crossbow, the draw length wouldn't be to short (just take a look at medieval examples).
Quote: Do not forget these bows were not the 125 # medival bows. I hope to reach a poundage of half that.
What makes you think that the draw weight was that low? If using a bow not (much) stronger than a hand-held bow, wouldn't it be quite useless to make a rather complicated device like a crossbow?
The trigger mechanism of the crossbow enables you to use a draw weight that high that couldn't be (comfortably) managed by the human body alone. So why waste this advantage?
Quote:Why is the recess to hold the bow in the stock that deep?
I had three reasons for opting for a deep socket:
[li]According to Holger Richter and Egon Harmuth, the crossbows of the early Middle Ages are the successors of the roman arcuballista; the crossbows of the early Middle Ages often are depicted with a deep socket.
[li]The arcuballista shown by the carving from Solignac also seems to have a deep socket.
[li]If you combine a "short" draw length with little space behind the nut, you need to elongate the front of the stock in order to make the stock that long that it matches the relief from Puy (forearm-stock ratio).
