Re: Bell cap how to

[Magnus]

It's neither here nor there with you, yet you felt it necessary to bring it up last post. I think I can safely say you have some issues....most of which is the inability to prove your point. Not to mention the obvious fear you have of me contacting Carol...I think once again you've really gone out on a limb with no evidence to back of your claims, and have no wish to look any less credible than you've made yourself out to be.

Unless anyone has any serious objection, I'm going to lock this thread, since Brian is clearly unable to provide any more evidence for his claims.

EDIT - This thread will be divided into the how-to and other.

[Magnus]

Thanks for splitting that Christian...now if anyone wishes to post here and add to the futility, please do so lol.

[jvrjenivs]

I reread some of the posts on here and have to admit I misread one post. Has to do more with my dyslexia, as I simply substitute a word and thus have read another reasoning as was told. Haven't anything to do with my English. Now I see you don't argue the clothing protection function, as I thought you did. I try to do this in simply language. Also my last course on mathematics was about 1.5 years ago, so forgive me as something isn't totally scientifically noted.

Now, we should go further with the mechanical explanation of riveting, as that's what you're after, aren't you. I mean, how all forces work on the pieces and where they differ from a regular washer. First, we have to start with the simple law action = - reaction. This simply tells you that when you add force on something, the same force will be replied to it. So, if you have your rivet on your support and use your hammer to bounce onto it, it will give the same force back to the hammer. Okay, that's the first force that is working on the system.

Next, we have a rivet made of soft metal, which, under the above mentioned force seems to change his shape. The force added will try to compress the rivet, but that doesn't gonna work, so the rivet will be bounced to the sides and lock into the washer. Not, this is all the same by any kind of washer. But now we gonna look closer at what a regular washer will do and what the washer we discussed here will do.

First, the regular washer, is flat and thus can hardly move in horizontal direction (that is in the direction of the sheet). Also, only a small piece (relative) of the rivet is in contact with the washer. Now, this result in a change of shape of the part of the rivet 'above' the washer. Most force will thus be used to reshape the washer. Now we look at the Bell-cap.
First we have to see we here have a piece that has a slightly bigger contact surface with the rivet. We also have a form that can a bit easier change his shape. If we now add force to the rivet and want it to devide to the sides it will both reshape the rivet but also reshape the washer to the shaft, more as the 'normal washer'. Also, as the shape of the washer is a dome, when adding force to the rivet, you also add some force to the washer, as it is at the same surface as the rivet. This means that there is even less force needed to peen all together.

Here is where Brian estimates that he only need 10% of the force needed by a normal washer. of course we can set up a system to measure this, but do we really need to do so? I also feel it need much less force to rivet this way. So that is always better for all materials involved.

Hope this all is clear.

[jvrjenivs]

Ok, since you're unable to address any of the points in my posts we'll play it your way. PM me the "lady's" email addy and I'll ask her.

Why should we bother here with this stupid discussion. She has enough to do. And for her email, I don't like putting other ones email addresses online (because of spam bots), but just go to the website of the Archeological department of the university of Amsterdam. The email of mw. dr. C. van Driel-Murray is on there.

[Magnus]

I wasn't going to do that Jurjen, that is why I asked Brian to pm regarding it. I found Carol's email anyway with a bit of searching.

[PhilusEstilius]

Jurjen.

That is an interesting link that you have given for there are many things I do want to look into in it.

[PhilusEstilius]

Jurjen.
Having read your mechanical explanation on riveting I find it very well explained and where one now considers the comparisons between a regular flat washer and the bell-cap, it does indeed show just how much less force, and peening that is required.
Therefore with much less peening of a rivet there is a marked reduction in damage to what ever is being fitted to leather, such as beltplate, decorative plates and studs to chamfrons, or indeed as you have shown at the start of your "How To" a Horse bronze to harness.
It does clearly show that even thousands of years ago there were people who had technological expertise, we may never know just who first invented these things but I'm very sure it may have been a craftsman or engineer.

[Magnus]

Jurjen.
Having read your mechanical explanation on riveting I find it very well explained and where one now considers the comparisons between a regular flat washer and the bell-cap, it does indeed show just how much less force, and peening that is required.
Therefore with much less peening of a rivet there is a marked reduction in damage to what ever is being fitted to leather, such as beltplate, decorative plates and studs to chamfrons, or indeed as you have shown at the start of your "How To" a Horse bronze to harness.
It does clearly show that even thousands of years ago there were people who had technological expertise, we may never know just who first invented these things but I'm very sure it may have been a craftsman or engineer.

No it doesn't Brian. Still going on and on about it are you? You will be required to provide evidence, not opinion of this.

[PhilusEstilius]

Matt.

Where you have made the statement ""No it doesn't Brian." would you please clarify, then where you continue with the other statement "Still going on and on about it are you." would you also again please clarify that statement

[Magnus]

Brian, there is no clarification required. You are fully aware of the issues I've presented previously regarding your posts. I'm not going to reiterate it because you're acting ignorant of them now. Bottom line is that in keeping with the forum decor you are strongly advised to back up your theories with more than opinion and unsubstantiated testing. There is a good chance this un-written rule will be put into effect, so you may as well start now.

[Matthew Amt]

Avete!

I probably shouldn't jump into this, but I'm seeing some odd interpretation of some of the evidence. These so-called "bell caps" (stupid name but I don't give a darn about that!) are apparently found in large numbers on some horse chamfrons--okay, I've never studied such things so I'll just have to accept that. They are also said to be found on 3 belts, including 2 from the UK and one from Holland. Going back through this thread, I saw the photo of the broken plate with the buckle that Brian posted (and I remember seeing a lovely reconstruction he did of the whole belt a few years back!), but I must have missed the reference to the second UK belt part find. Presumably it was a single plate, or maybe a couple plates found together?

The third find is the Velsen belt, of course. But I've just been looking through the report on that find, and I'm sorry to say that those really just look like washers to me! Reference: J.-M. A. W. Morel & A. V. A. J. Bosman: "An Early Roman Burial in Velsen", in Roman Military Equipment: The Sources of Evidence, Proceedings of the Fifth Roman Military Equipment Conference 1989.

I re-read the section describing the belt parts, and the term "bell cap" is not mentioned, nor anything like it. The washers are called "washers". On one plate they are rough rectangles, while the other 7 plates each have one or more round washers. All the round washers are slightly dished or domed, but none are shown or described as being countersunk, in fact the side view clearly shows the peened rivet ends projecting beyond the surfaces of the washers. Moreover, some of the washers are mounted hollow side in (like the so-called "bell caps"), some are hollow side OUT, which would seem to be in exact opposition to the purpose described for the "bell caps". Two of the washers have "bites" out of the edge, showing that no great care was taken in punching these out from their sheet, since the punch overlapped the hole left by the previous washers. One washer even has a stub of sheet still hanging off the edge, which to me looks like it was MADE to snag on a tunic! Bottom line: these are simple discs punched from sheet brass, their slight dishing due most likely to the hole being punched in the center.

Now, did I miss a reference to "bell caps" in this article? If so, can anyone tell me what page it's on? The Vindonissa catalog might be showing *one* example, on a piece of horse harness fitting (#1317 on Tafel 48), but none identifiable on any belt plates, etc., though there are a dozen or so washers and a number of sloppily clenched rivet shanks.

So my conclusion, based on the evidence presented, is that these gizmos were NOT in any way commonly used on military belts. But like I always say, show me the evidence to the contrary, and I will cheerfully eat my words!

Unfortunately, I have to rely on the words of experts in this field, because I have no artifacts of my own to study, and neither the funding nor the time to travel overseas to handle artifacts in museums or private collections. So I'm stuck with drawings and photos, and word of mouth. My own experience is not nearly so great, since in 20 years I've only made or helped with a good dozen reproduction Roman belts, and 6 or 8 segmented loricae. I consider myself pretty good at riveting, and with no training and pretty inadequate tools very rarely cause damage to belt plates and other items while peening rivets, using regular flat washers. The belt I usually wear has rectangular washers, and I've never noticed it snagging or tearing my tunic. Nor have I seen such damage on other tunics belonging to people in my legion, though I confess I don't inspect them THAT closely!

Like Matt Lanteigne, I'm very puzzled by the claim that it takes significantly less effort to peen a rivet shank with a so-called bell cap than over a regular washer. As he says, the shank must be peened enough to make it larger than the hole. The shape of the washer should not matter. Moreover, it is repeatedly claimed that with care, the rivet shank is countersunk into the "bell cap", and it is even mentioned that with some *filing* the finished shank will be made smooth enough not to snag on clothing or skin. But with a regular washer, no care is needed at all! Bang bang bang, and it's done. However, I have not tried these gizmos, so my observations cannot be taken as conclusive.

At some point I'll have to see if I can find pictures of the insides of those horse chamfrons. It seems odd (though very Roman!) to use such a complicated way of protecting the horse's skin from rivet shanks, when a simple lining would have done the trick. But I can hardly dispute the use of "bell caps" in that context without knowing more. I can only say that as a feature of belt construction, they must have been very much the exception--which makes sense to me since they seem to be unnecessary.

Valete,

Matthew

PS: Jurjen, please put the photos back on your tutorial! I COMPLETELY understand your disgust with the arguments, and have often felt like you, but it was good information and well-presented.

[PhilusEstilius]

Matthew.

Where you point out that Morel and Bosman do not metion bellcap that is right and I must stand corrected.
I must therefore make my apology to all for this was a mistake on my part, however I must point out that it was not intentional nor indeed was it to mislead.

Where I did mention that C.-van-Driel Murray did refer to these things as bellcaps it comes from the same publication that you have used to explain the Velsen beltplates. It has to be said that where none of us are perfect in our postings or complete statements, I have to point out that without trying to be rude in any way at all there is a bit of inaccuracy in some of your own explanation about these Velsen plates.
Then where you refer to the washers being simple discs punched out of sheet brass, their slight dishing due most likely to the hole being punched in the centre one must consider as being conjecture or opinion on your part.
Also you say that like Matt Lanteigne you are puzzled by the claim that it takes less effort to peen a rivet with a bellcap than a regular washer, then the only way this could be clearly defined other than making and useing them to gain such experience of them would be under laboratory conditions with specialistic equipment.
Then where you say from not having tried these things that your observations cannot be conclusive, would it be coorrect to say that they should be discounted.

[Magnus]

Um, no Brian, because simply put (and the issue that you can't seem to get your head around) is that the force required to peen something isn't dependent on the washer shape, but the amount of force used on the rivet shank end. You're touting this like it's some kind of discipline...it's peening.

If anything, your heavy bias towards these washers should be warning to anyone reading this thread, that what you are posting should be taken with a giant grain of salt to say the last.

And what is this:

Then where you refer to the washers being simple discs punched out of sheet brass, their slight dishing due most likely to the hole being punched in the centre one must consider as being conjecture or opinion on your part.

For real? How else did they warp? Geez, talk about conjecture...coming from the guy who makes up evidence :lol: Hello pot, I'm the kettle.

[Matt Lukes]

Okay, on the request of the original thread writer and because things are just going round and round instead of moving forward really anywhere, we've decided to end this thread here.