Ha! I'm glad someone besides me is racking their brain on this!Indianer wrote: ↑Fri Mar 08, 2024 2:55 pm
Brother, it just Struck me... you can't just turn it outwards like that. You have to stretch it with a straight peen. Did u do that? You nick the line where the roll starts, bend out just a few degrees, then you stretch. It'll roll itself out a good bit like that. That's how Dubé does it.
This thread is long and I'm on my phone. Sry if I missed sth.
I considered a cross or straight peen, but opted against it to avoid hammer marks. Per advice I picked up from some of Mac's threads and videos, I went with a round faced hammer. This seems to work nicely and I got one to 90 degrees this way, albeit with substantial flaring out of the curl. I suppose I really could use a cross or straight peen, since the hammer marks are going to all end up on the inside of the roll and it might be faster, but playing around with things, I suspect the over flaring would still be an issue, since I am stretching the (temporarily and to be rolled back the other way) upper most edge out to a larger radius.
Since this area is top most area is destined to roll back on itself, my current thinking is, "Why bother pulling it all the way out to begin with?" I just need to stretch out the middle of the incipient roll, not necessarily the top. I played around with this on some scrap, as detailed above, and the results were encouraging, apart from the mess I made by doing it in a chewed up vise.
I think the trick to this is that there is no trick. I've just been over thinking it. The simpler method, at least in my current theory, is to think about it as mostly a synclastic curve. Initially, I was thinking about it as an anticlastic curve, which is also is; however, as several people have pointed out, once the roll is formed, dealing with the bottom half of the ring is not really a big deal.
I won't be able to get into my friend shop until probably next weekend. In the mean time, I am thinking over the advice given above and trying to figure out the best way to knock volume in the roll with what I have available to work with. Kristoffer's suggestion of a hinge block is very appealing to me. I might give that a shot in the interest of getting past this frustrating stall and feel like I am making some progress in the greater project. On the other hand, I really do need to learn to do this with just a hammer and anvil since I need to do a whole lot more of these types of edges later on. It seems worthwhile to invest some time in scrap and the "Thick Forehead" method Kristoffer mentioned until this is relatively easy, and spare myself this frustration with other parts.
Edit: Hmmm... When I read your suggestion, I was thinking only about a straight peen perpendicular to the edge. I was just considering it more and, perhaps, rounded straight or cross peen parallel to the edge might be helpful.
Ah! The fun of making armor! So many ways to do similar things! The challenge is choosing the best one for what you're working on at the moment.