Rune Allnor wrote:> Jerry Avins wrote:...>>As an amateur silversmith, I make square wire from round with hammer and >>anvil block. One of the most impressive bit of blacksmithing I ever saw >>was the transformation of a 1" square, 8" long rod into a 2" cube by >>hammering it only on its ends. Much depends on how it is heated in the >>forge and with a torch. > > > I never assigned that sort of "torture" to others, but at one point I > did try to implement an Singular Value Decomposition from scratch. While > I never quite got there, I did find out how much I am willing to pay for > a good numerical library...There are some things one can't buy. The presents I made for my sisters' twelfth birthday were twisted copper and silver #8 wires (about 1/8" diameter). They were square for the middle inch only, the rest being round. The middle parts were set side by side to make a rectangular cross section 1/8 by 1/4, and the round parts twisted together. (The two ends have opposite-handed twists.) Then I hammered the twists to the same cross section as the middle, and shaped the bracelet to fit their wrists. To have part round and part square wire, you have to make it. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Convolution
Started by ●February 6, 2006
Reply by ●February 7, 20062006-02-07
Reply by ●February 7, 20062006-02-07
Jerry Avins wrote:> Rune Allnor wrote: > >> Jerry Avins wrote: > > > ... > >>> As an amateur silversmith, I make square wire from round with hammer and >>> anvil block. One of the most impressive bit of blacksmithing I ever saw >>> was the transformation of a 1" square, 8" long rod into a 2" cube by >>> hammering it only on its ends. Much depends on how it is heated in the >>> forge and with a torch. >> >> >> >> I never assigned that sort of "torture" to others, but at one point I >> did try to implement an Singular Value Decomposition from scratch. >> While I never quite got there, I did find out how much I am willing to >> pay for >> a good numerical library... > > > There are some things one can't buy. The presents I made for my sisters' > twelfth birthday were twisted copper and silver #8 wires (about 1/8" > diameter). They were square for the middle inch only, the rest being > round. The middle parts were set side by side to make a rectangular > cross section 1/8 by 1/4, and the round parts twisted together. (The two > ends have opposite-handed twists.) Then I hammered the twists to the > same cross section as the middle, and shaped the bracelet to fit their > wrists. To have part round and part square wire, you have to make it. > > JerryAt least you didn't have to mine and smelt the metal.
Reply by ●February 7, 20062006-02-07
Stan Pawlukiewicz wrote: ...> At least you didn't have to mine and smelt the metal.Wise guy! To win a bet, I actually smelted lead once and extracted its rather high (2%) content of silver. The bet was to prove I could do it with stuff in my basement. (I did it outdoors; it made a lot of SO2.) Galen (lead sulfide) is particularly easy to smelt and there's a neat trick for extracting silver from metallic lead.) Details only on request. I don't want to be boring. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●February 8, 20062006-02-08
Jerry Avins wrote:> Stan Pawlukiewicz wrote: > > ... > > > At least you didn't have to mine and smelt the metal. > > Wise guy! To win a bet, I actually smelted lead once and extracted its > rather high (2%) content of silver. The bet was to prove I could do it > with stuff in my basement. (I did it outdoors; it made a lot of SO2.) > Galen (lead sulfide) is particularly easy to smelt and there's a neat > trick for extracting silver from metallic lead.) Details only on > request. I don't want to be boring.OK, I'll bite. I have fiddled around with metallurgy just enough to be interested... Rune
Reply by ●February 8, 20062006-02-08
Rune Allnor wrote:> Jerry Avins wrote: > >>Stan Pawlukiewicz wrote: >> >> ... >> >> >>>At least you didn't have to mine and smelt the metal. >> >>Wise guy! To win a bet, I actually smelted lead once and extracted its >>rather high (2%) content of silver. The bet was to prove I could do it >>with stuff in my basement. (I did it outdoors; it made a lot of SO2.) >>Galen (lead sulfide) is particularly easy to smelt and there's a neat >>trick for extracting silver from metallic lead.) Details only on >>request. I don't want to be boring. > > > OK, I'll bite. I have fiddled around with metallurgy just enough to > be interested...Crush the galena. Divide it 1/3, 2/3. Heat ("roast") the 2/3 in air, stirring occasionally. 2PbS + 3O2 -> 2PbO + 2SO2. PbO is yellow. Pb2O3 is red. When the yellow starts to darken, stop. Crush the PbO and mix with the PbS. Cover loosely to exclude air but allow gas to escape and heat again. 2PbO + PbS -> 3Pb + SO2 Zinc and lead are immiscible, but silver dissolves in both. Zinc is "hungrier" for silver than lead is, so when molten zinc and lead are stirred together, most of the silver ends up in the zinc. Take "up" literally; the zinc floats on the lead where it can be skimmed off as the mix cools. (Zinc solidifies first.) Zinc sublimates readily. Heating the zinc in an open crucible leaves the silver behind, partly oxidized. The best way is heating the zinc in the closed bottom of a long tube. There is practically no oxidation of the silver and the zinc resublimates as dust in the upper end of the tube, where it can be collected and reused. WARNING! Breathing zinc vapor causes "welders disease". Not a cumulative poison. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●February 9, 20062006-02-09
Check the following link: http://www.songho.ca/dsp/convolution/convolution.html Hopr it helps. ==song==
