02-27-2012, 08:30 PM
Thanks for your prompt response. So what I gather is that you would prefer 10/90 tin bronze also for your commercially available helmets if it was more affordable? Your effort is truly laudable and inspiring, I just want to ask a couple of more questions to better understand where you are heading with this.
I saw this statement on your website: "The original museum helmets are largely epoxy bandages holding them together as they have lost much of their density and are more like foil than bronze, weighing between 3-5lbs. on average. However a new or 'live' helmet would have all of the bronze's original density. There is no difference between an ancient bronze alloy and a modern one, being exactly the same elements involved. The estimated weight of these helmets as new and finished should fall between 6-8lbs. most likely but it will be hard to estimate at this time." (http://www.dioskouri.com/Helmets.php)
The weight you are aiming for -- together with you previous comment that: "A Silicon bronze helmet is going to price out around $1000 USD and that is not including my labor! That's simply the cost of metal and forming. The clean up and polishing ends up [..]" -- suggests to me that you intend to cast helmet blanks with the lost wax method only aided by the force of gravitation. And that you will end up with blanks that are basically the finished net shape that requires little hammer work. Is this the direction you are taking?
If so, my main concern is that you, like you say, will have to put down such copious amounts that you won't break even, and that the helmets will be too heavy and, as you also indicate, too soft.
I have been thinking about these problems and done quite a few experiments, clay originals, and moulds, for quite a few days each year over the past six years. My conclusion so far is that for me it would be best to cast a blank that looks almost like an Apulo Corinthian, without any undercuts, and then hammer raise the last part of it to harden and make the metal more dense. Or to cast a thick, flat helmet blank and use assisted hammering on the inside and then raise it from the outside. In either case its possible to use more cost-efficient casting methods like sand casting. And it would be possible to get a lighter helmet without wasting too much bronze to grinding.
But maybe this discussion is more suitable in a thread of its own as it might not be too interesting for others in this thread.
I saw this statement on your website: "The original museum helmets are largely epoxy bandages holding them together as they have lost much of their density and are more like foil than bronze, weighing between 3-5lbs. on average. However a new or 'live' helmet would have all of the bronze's original density. There is no difference between an ancient bronze alloy and a modern one, being exactly the same elements involved. The estimated weight of these helmets as new and finished should fall between 6-8lbs. most likely but it will be hard to estimate at this time." (http://www.dioskouri.com/Helmets.php)
The weight you are aiming for -- together with you previous comment that: "A Silicon bronze helmet is going to price out around $1000 USD and that is not including my labor! That's simply the cost of metal and forming. The clean up and polishing ends up [..]" -- suggests to me that you intend to cast helmet blanks with the lost wax method only aided by the force of gravitation. And that you will end up with blanks that are basically the finished net shape that requires little hammer work. Is this the direction you are taking?
If so, my main concern is that you, like you say, will have to put down such copious amounts that you won't break even, and that the helmets will be too heavy and, as you also indicate, too soft.
I have been thinking about these problems and done quite a few experiments, clay originals, and moulds, for quite a few days each year over the past six years. My conclusion so far is that for me it would be best to cast a blank that looks almost like an Apulo Corinthian, without any undercuts, and then hammer raise the last part of it to harden and make the metal more dense. Or to cast a thick, flat helmet blank and use assisted hammering on the inside and then raise it from the outside. In either case its possible to use more cost-efficient casting methods like sand casting. And it would be possible to get a lighter helmet without wasting too much bronze to grinding.
But maybe this discussion is more suitable in a thread of its own as it might not be too interesting for others in this thread.
