" a deserter from the Bristol Army, a bell founder by the name of
That's neat, but we can't claim any close relation. At that time, our branch was in Yadkin County, North Carolina, by way of Barbados. No doubt on the run from something else.
Kevin Gallimore
Yes. Either it's a hobby and you enjoy the elegance of the project, or it's a business and you enjoy the economics of making a cool tool yourself.
By the way, it also serves well as a muller, not just a miller.
On Fri, 15 Oct 2004 03:58:36 GMT, Gunner calmly ranted:
Including Gunner's Cat Factory and Rest Home? ;)
------------------------------------------------------------------------- Poverty is easy. *
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That's because they don't know about cousin Elwood....
Kevin Gallimore
Life's too short to spend it ball-milling cat litter.
Exactly! Visit my website:
And on the board of one of the major US zinc smelting companies.
I hear he got another job later on though.
Wow. That's the kind of response that makes this group famous. Thanks to everyone for their tips, especially those of you who have taken the time to put together carefully illustrated guides to help newbies.
First off, I figure I should clarify a mistake, since we've now done some more of our homework.
Paul Revere did not use sand casting to make bells, although we think he did do sand casting. I'll check up on that and report back. The technique was a variation of the lost-wax method. I'll give you the authoritative statement on it: "Bell makers first created an inner 'core' that modeled the inside diameter of the bell. They accomplished this by digging a hole in the ground, building a hollow pile of bricks in the center, covering them in a special mud, and using a pattern to pack the mud into the shape of the interior of the bell. Second they applied a mixture of tallow and wax to the outside of the core, creating a perfect wax model of the bell. Workmen added any lettering or designs to the wax at this point... Third, workers applied numberous thick coatings of 'bell mud' on top of the wax, creating the 'shell,' which was a model of the outer surface of the bell. When the shell hardened, a workman lit a fire inside the hollow brick structure at the center of the core, which melted the wax and allowed it to drain off, hardening the core in the process.... The shell was then hardened with additional fire, and covered in sand or loose soil to prevent it from bursting. Finally, molten metal was poured into the space between the core and the shell."
- from "Paul Revere's Metallurgical Ride: Craft and Proto-Industry in Early America" by Dr. Robert Martello, which happens to be the Ph.D. dissertation of one of our teachers for the course. (Yeah, good thing we found that.)
Also, we took a look at a translation of De Pirotechnia, which was conveniently located in the reserve section of the library. It's pretty interesting, but really long. So, we have one person reading that and reporting back. I think I got the better end of the deal by offering to post to the newsgroup.
As far as the actual casting is concerned, in the interest of time, we've decided to order some Petrobond. Fortunately, we already have some lying around (but not enough to cast the bells), so we're going to try casting white metal on Tuesday. The MatSci professor has some experience with this, so combined with what we've read, we think we can do it without hurting ourselves.
We still have a good deal to work on, and I'll probably be back with more questions about molding shortly.
Thanks again,
Eric Gallimore
Wow. That's the kind of response that makes this group famous. Thanks to everyone for their tips, especially those of you who have taken the time to put together carefully illustrated guides to help newbies.
First off, I figure I should clarify a mistake, since we've now done some more of our homework.
Paul Revere did not use sand casting to make bells, although we think he did do sand casting. I'll check up on that and report back. The technique was a variation of the lost-wax method. I'll give you the authoritative statement on it: "Bell makers first created an inner 'core' that modeled the inside diameter of the bell. They accomplished this by digging a hole in the ground, building a hollow pile of bricks in the center, covering them in a special mud, and using a pattern to pack the mud into the shape of the interior of the bell. Second they applied a mixture of tallow and wax to the outside of the core, creating a perfect wax model of the bell. Workmen added any lettering or designs to the wax at this point... Third, workers applied numberous thick coatings of 'bell mud' on top of the wax, creating the 'shell,' which was a model of the outer surface of the bell. When the shell hardened, a workman lit a fire inside the hollow brick structure at the center of the core, which melted the wax and allowed it to drain off, hardening the core in the process.... The shell was then hardened with additional fire, and covered in sand or loose soil to prevent it from bursting. Finally, molten metal was poured into the space between the core and the shell."
- from "Paul Revere's Metallurgical Ride: Craft and Proto-Industry in Early America" by Dr. Robert Martello, which happens to be the Ph.D. dissertation of one of our teachers for the course. (Yeah, good thing we found that.)
Also, we took a look at a translation of De Pirotechnia, which was conveniently located in the reserve section of the library. It's pretty interesting, but really long. So, we have one person reading that and reporting back. I think I got the better end of the deal by offering to post to the newsgroup.
As far as the actual casting is concerned, in the interest of time, we've decided to order some Petrobond. Fortunately, we already have some lying around (but not enough to cast the bells), so we're going to try casting white metal on Tuesday. The MatSci professor has some experience with this, so combined with what we've read, we think we can do it without hurting ourselves.
We still have a good deal to work on, and I'll probably be back with more questions about molding shortly.
Thanks again,
Eric Gallimore
THe horse dung was almost certainly not used for sand casting but for a ceramic mould casting, for which dung was frequently used throughout history.
Check out "on Divers Arts" which specifically has information on bell casting, and "De Re Metallica". Both are available from Dover.
Also Anders Soderbergs web page may be helpfull,
jk
Once the wax was melted out, what kept the outer mold from shifting relative to the inner core? I'm sure you would have a connection at the bottom (with holes to allow the wax to drain), but would it be strong enough to hold when the molten metal is poured into the mold?
Also, would the metal have to be poured into a hot mold to allow it to flow, or is there wax residue, a carbon layer, or something to facilitate the pour?
Just wondering.
Joe
The assumption is simply the center is held by the central stack up core. The outside is being held out by the outer stack up. Simply, the outer stack up must be strong to hold it's own weight and to be able to span the distance.
Think of a coffee cup over something else. The cup doesn't crush down when their is air space between.
Martin
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