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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Casting practice
It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . Anyway , the pour came out well too other than the H2 microbubbles , and that piece is in the lathe now for machining . -- Snag As soon as I get the rest of my sand up here I'll be ready to start casting shaper parts ... |
#2
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Casting practice
"Terry Coombs" wrote in message
... It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . Anyway , the pour came out well too other than the H2 microbubbles , and that piece is in the lathe now for machining . -- Snag As soon as I get the rest of my sand up here I'll be ready to start casting shaper parts ... The clerk at MG Stevens told me the porosity meant my sand was too damp, though he gave me a small bag of broken degassing pellets. http://www.mgstevens.com/ I might take my patterns to a local art foundry: http://www.granitestatefoundry.com/ So far I've built up machine parts that could be candidates for casting by welding, annealing and forging/jacking out the shrinkage distortions. Unlike casting all the metal doesn't have to be heated red-hot at the same time, and it gives the tensile strength of steel rather than aluminum. -jsw |
#3
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Casting practice
Jim Wilkins wrote:
"Terry Coombs" wrote in message ... It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . Anyway , the pour came out well too other than the H2 microbubbles , and that piece is in the lathe now for machining . -- Snag As soon as I get the rest of my sand up here I'll be ready to start casting shaper parts ... The clerk at MG Stevens told me the porosity meant my sand was too damp, though he gave me a small bag of broken degassing pellets. http://www.mgstevens.com/ I might take my patterns to a local art foundry: http://www.granitestatefoundry.com/ So far I've built up machine parts that could be candidates for casting by welding, annealing and forging/jacking out the shrinkage distortions. Unlike casting all the metal doesn't have to be heated red-hot at the same time, and it gives the tensile strength of steel rather than aluminum. -jsw My understanding of hydrogen gassing in aluminum is that it's from the propane flame and dirty feed stock - and those degassing pellets are basically the same thing as pool chlorine IIRC . What you're talking about is probably surface porosity , which can be caused by excess moisture in the sand . Too hot a melt can contribute to that too . What I'm talking about is throughout the entire casting . After looking at where I've already machined this blank , all I've got this time is surface defects most likely caused by being too hot and the rough sand I used for my first batches of greensand . The rest of my crushed olivine and bentonite is coming home the day after Christmas . Then I'll have the materials to make finer-grained molding sand .. -- Snag And as much else of my stuff as will fit in the SUV- The Wife has some items I'm supposed to find room for too . |
#4
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Casting practice
"Terry Coombs" wrote in message
... Jim Wilkins wrote: "Terry Coombs" wrote in message ... It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . Anyway , the pour came out well too other than the H2 microbubbles , and that piece is in the lathe now for machining . -- Snag As soon as I get the rest of my sand up here I'll be ready to start casting shaper parts ... The clerk at MG Stevens told me the porosity meant my sand was too damp, though he gave me a small bag of broken degassing pellets. http://www.mgstevens.com/ I might take my patterns to a local art foundry: http://www.granitestatefoundry.com/ So far I've built up machine parts that could be candidates for casting by welding, annealing and forging/jacking out the shrinkage distortions. Unlike casting all the metal doesn't have to be heated red-hot at the same time, and it gives the tensile strength of steel rather than aluminum. -jsw My understanding of hydrogen gassing in aluminum is that it's from the propane flame and dirty feed stock - and those degassing pellets are basically the same thing as pool chlorine IIRC . What you're talking about is probably surface porosity , which can be caused by excess moisture in the sand . Too hot a melt can contribute to that too . What I'm talking about is throughout the entire casting . After looking at where I've already machined this blank , all I've got this time is surface defects most likely caused by being too hot and the rough sand I used for my first batches of greensand . The rest of my crushed olivine and bentonite is coming home the day after Christmas . Then I'll have the materials to make finer-grained molding sand . -- Snag My sand came from the heap at an iron foundry. I used a plastic tub of Rutland stove gasket cement for the ingot mold pattern and some of the fine lettering from the bottom is legible. That gasket cement works well to secure the cut end of silica braid on thermocouples to 2000F. -jsw |
#5
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Casting practice
On Mon, 22 Dec 2014 11:01:19 -0700, "Bob La Londe"
wrote: I can help with casting: First tie on what you will be casting. Then turn on all the brakes, and set the spool tension until so that from shoulder height it drops to the ground with only about one loose wrap as when it stops with no thumb pressure. Now practice at that setting with light side arm flicks. Once you have your hand trained for that you can let off some of the brakes or lighten the spool tension to cast better. Use your thumb to lightly feel the spool as it spins out while casting, and if it feels like its bunching up clamp down with your thumb to stop a bad cast. If you continue to have an issue with backlash stretch out as far as you think you will cast on average, and put a wrap of tape around the spool. Then reel up over the layer of tape. Practice until you can make good casts anywhere in that range 99% of the time. LOL. I'm glad you did it. I was going to suggest some tips for timing the backcast, and to stay away from shooting heads until he got that right with a double-taper, but I restrained myself. -- Ed Huntress |
#6
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Casting practice
On 12/22/2014 12:01 PM, Bob La Londe wrote:
I can help with casting: First tie on what you will be casting. Then turn on all the brakes, and set the spool tension until so that from shoulder height it drops to the ground with only about one loose wrap as when it stops with no thumb pressure. Now practice at that setting with light side arm flicks. Once you have your hand trained for that you can let off some of the brakes or lighten the spool tension to cast better. Use your thumb to lightly feel the spool as it spins out while casting, and if it feels like its bunching up clamp down with your thumb to stop a bad cast. If you continue to have an issue with backlash stretch out as far as you think you will cast on average, and put a wrap of tape around the spool. Then reel up over the layer of tape. Practice until you can make good casts anywhere in that range 99% of the time. LOL. Whats a good ratio of trout to pound of molten aluminum? Does it matter if they are brown or rainbow? David |
#7
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Casting practice
"David R. Birch" fired this volley in news:m79oel011g1
@news7.newsguy.com: Whats a good ratio of trout to pound of molten aluminum? Does it matter if they are brown or rainbow? I find roughly about ten or twelve pounds of brookies to a half-ounce of casting alloy -- just roughly. Usually, the metal is "lost" after too many re-castings, and must be replenished. That ratio can be increased significantly with the right surface finish in the mold. With the addition of sodium chloride, one can get the ratio up to a couple-hundred pounds of blues per ounce of casting alloy. Lloyd |
#8
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Casting practice
On Mon, 22 Dec 2014 13:16:30 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote: "David R. Birch" fired this volley in news:m79oel011g1 : Whats a good ratio of trout to pound of molten aluminum? Does it matter if they are brown or rainbow? I find roughly about ten or twelve pounds of brookies to a half-ounce of casting alloy -- just roughly. Usually, the metal is "lost" after too many re-castings, and must be replenished. That ratio can be increased significantly with the right surface finish in the mold. With the addition of sodium chloride, one can get the ratio up to a couple-hundred pounds of blues per ounce of casting alloy. Lloyd But brookies and rainbows are suckers for metal. Browns tend to be more demanding. For them, the question is how many pounds of brownies do you get per wood duck? We won't lower ourselves to think about how many pounds of minnows it might take. -- Ed Huntress |
#9
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Casting practice
On Sun, 21 Dec 2014 17:43:29 -0600, "Terry Coombs"
wrote: It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . In my testing, any (relatively) inert gas will work about as well, which is not very. The ultimate solution is to prevent hydrogen pickup in the first place. Induction heating with a tight fitting crucible cap pretty much accomplishes this objective. So does purging a closed crucible in a combustion furnace with inert gas. If you do have hydrogen in solution, this stuff is the best I've found http://www.budgetcastingsupply.com/p...p/2011-010.htm It looks like charcoal and stinks badly in the can. It must be held at the bottom of the crucible until the reaction is complete. They sell pellet holders for large batches but for the small batches I do (20 pounds or less), I made a plunger out of a large stainless sewing thimble, perforated by many tiny holes and a SS rod welded to the tip. John John DeArmond http://www.neon-john.com http://www.fluxeon.com Tellico Plains, Occupied TN See website for email address |
#10
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Casting practice
Neon John wrote:
On Sun, 21 Dec 2014 17:43:29 -0600, "Terry Coombs" wrote: It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . In my testing, any (relatively) inert gas will work about as well, which is not very. The ultimate solution is to prevent hydrogen pickup in the first place. Induction heating with a tight fitting crucible cap pretty much accomplishes this objective. So does purging a closed crucible in a combustion furnace with inert gas. If you do have hydrogen in solution, this stuff is the best I've found http://www.budgetcastingsupply.com/p...p/2011-010.htm It looks like charcoal and stinks badly in the can. It must be held at the bottom of the crucible until the reaction is complete. They sell pellet holders for large batches but for the small batches I do (20 pounds or less), I made a plunger out of a large stainless sewing thimble, perforated by many tiny holes and a SS rod welded to the tip. John I'm doing the same thing using pool chlorine granules . My cup needs to be larger I think . How do you load your cup ? I wrap the stuff sometimes flux in foil and push it in . Plunge and stir and stay upwind of the fumes .. I'm not real likely to go induction or resistance , I like the setup I'm using . Covering the crucible is an option , though that would make it difficult to add stock as it melts down . I think part of my problem is that this stuff came from stuff like truck rims and other dirty scrap . I also have some once-melted in an electric furnace stock that doesn't have the porosity problems . -- Snag |
#11
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Casting practice
On Tue, 23 Dec 2014 13:13:44 -0600, "Terry Coombs"
wrote: Neon John wrote: On Sun, 21 Dec 2014 17:43:29 -0600, "Terry Coombs" wrote: It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . In my testing, any (relatively) inert gas will work about as well, which is not very. The ultimate solution is to prevent hydrogen pickup in the first place. Induction heating with a tight fitting crucible cap pretty much accomplishes this objective. So does purging a closed crucible in a combustion furnace with inert gas. If you do have hydrogen in solution, this stuff is the best I've found http://www.budgetcastingsupply.com/p...p/2011-010.htm It looks like charcoal and stinks badly in the can. It must be held at the bottom of the crucible until the reaction is complete. They sell pellet holders for large batches but for the small batches I do (20 pounds or less), I made a plunger out of a large stainless sewing thimble, perforated by many tiny holes and a SS rod welded to the tip. John I'm doing the same thing using pool chlorine granules . My cup needs to be larger I think . How do you load your cup ? I wrap the stuff sometimes flux in foil and push it in . Plunge and stir and stay upwind of the fumes . I'm not real likely to go induction or resistance , I like the setup I'm using . Covering the crucible is an option , though that would make it difficult to add stock as it melts down . I think part of my problem is that this stuff came from stuff like truck rims and other dirty scrap . I also have some once-melted in an electric furnace stock that doesn't have the porosity problems . I'm not a caster, but I've read that motor oil on dirty aluminum is a major source of porosity problems. That source recommended soaking your scrap in a warm lye solution to get rid of the oil. But don't leave it in for long, because lye will also get rid of your aluminum. d8-) -- Ed Huntress |
#12
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Casting practice
On Tue, 23 Dec 2014 13:13:44 -0600, "Terry Coombs"
wrote: snip I'm doing the same thing using pool chlorine granules . My cup needs to be larger I think . snip short piece of black iron [no zinc] pipe. Hold in tongs or weld to rod. Use aluminium foil on each end. Fill with generic chlorine pool shock treatement. Plunge below surface and agitate, being careful not to breath the fumes. In using "dirty"/salvage aluminium I have had some success in using a good amount of kosher salt as a flux. Dump in enough to form a skin when the charge melts and skim the large amount of dross that usually forms. -- Unka' George "Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants, but debt is the money of slaves" -Norm Franz, "Money and Wealth in the New Millenium" |
#13
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Casting practice
On Tue, 23 Dec 2014 15:05:12 -0500, Ed Huntress wrote:
On Tue, 23 Dec 2014 13:13:44 -0600, "Terry Coombs" wrote: Neon John wrote: On Sun, 21 Dec 2014 17:43:29 -0600, "Terry Coombs" wrote: It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . In my testing, any (relatively) inert gas will work about as well, which is not very. The ultimate solution is to prevent hydrogen pickup in the first place. Induction heating with a tight fitting crucible cap pretty much accomplishes this objective. So does purging a closed crucible in a combustion furnace with inert gas. If you do have hydrogen in solution, this stuff is the best I've found http://www.budgetcastingsupply.com/p...p/2011-010.htm It looks like charcoal and stinks badly in the can. It must be held at the bottom of the crucible until the reaction is complete. They sell pellet holders for large batches but for the small batches I do (20 pounds or less), I made a plunger out of a large stainless sewing thimble, perforated by many tiny holes and a SS rod welded to the tip. John I'm doing the same thing using pool chlorine granules . My cup needs to be larger I think . How do you load your cup ? I wrap the stuff sometimes flux in foil and push it in . Plunge and stir and stay upwind of the fumes . I'm not real likely to go induction or resistance , I like the setup I'm using . Covering the crucible is an option , though that would make it difficult to add stock as it melts down . I think part of my problem is that this stuff came from stuff like truck rims and other dirty scrap . I also have some once-melted in an electric furnace stock that doesn't have the porosity problems . I'm not a caster, but I've read that motor oil on dirty aluminum is a major source of porosity problems. That source recommended soaking your scrap in a warm lye solution to get rid of the oil. But don't leave it in for long, because lye will also get rid of your aluminum. d8-) Perhaps it works because it etches off the oily layer of metal. Dunno, just a guess... -- Tim Wescott Wescott Design Services http://www.wescottdesign.com |
#14
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Casting practice
On Tue, 23 Dec 2014 16:49:35 -0600, Tim Wescott
wrote: On Tue, 23 Dec 2014 15:05:12 -0500, Ed Huntress wrote: On Tue, 23 Dec 2014 13:13:44 -0600, "Terry Coombs" wrote: Neon John wrote: On Sun, 21 Dec 2014 17:43:29 -0600, "Terry Coombs" wrote: It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . In my testing, any (relatively) inert gas will work about as well, which is not very. The ultimate solution is to prevent hydrogen pickup in the first place. Induction heating with a tight fitting crucible cap pretty much accomplishes this objective. So does purging a closed crucible in a combustion furnace with inert gas. If you do have hydrogen in solution, this stuff is the best I've found http://www.budgetcastingsupply.com/p...p/2011-010.htm It looks like charcoal and stinks badly in the can. It must be held at the bottom of the crucible until the reaction is complete. They sell pellet holders for large batches but for the small batches I do (20 pounds or less), I made a plunger out of a large stainless sewing thimble, perforated by many tiny holes and a SS rod welded to the tip. John I'm doing the same thing using pool chlorine granules . My cup needs to be larger I think . How do you load your cup ? I wrap the stuff sometimes flux in foil and push it in . Plunge and stir and stay upwind of the fumes . I'm not real likely to go induction or resistance , I like the setup I'm using . Covering the crucible is an option , though that would make it difficult to add stock as it melts down . I think part of my problem is that this stuff came from stuff like truck rims and other dirty scrap . I also have some once-melted in an electric furnace stock that doesn't have the porosity problems . I'm not a caster, but I've read that motor oil on dirty aluminum is a major source of porosity problems. That source recommended soaking your scrap in a warm lye solution to get rid of the oil. But don't leave it in for long, because lye will also get rid of your aluminum. d8-) Perhaps it works because it etches off the oily layer of metal. Dunno, just a guess... I certtainly cleans it. But lye works on oil by saponifying it, which makes it soluble in water. That's how they make traditional soaps, by saponifying fatty oils with lye. If you've ever had gun parts, especially barrels, professionaly hot-blued, the last step before dunking it in the bluing solution is to boil it in lye. Unlike aluminum, lye doesn't attack steel, but it saponifies any remaining traces of oil, which will wreck a hot-bluing job. -- Ed Huntress |
#15
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Casting practice
F. George McDuffee wrote:
On Tue, 23 Dec 2014 13:13:44 -0600, "Terry Coombs" wrote: snip I'm doing the same thing using pool chlorine granules . My cup needs to be larger I think . snip short piece of black iron [no zinc] pipe. Hold in tongs or weld to rod. Use aluminium foil on each end. Fill with generic chlorine pool shock treatement. Plunge below surface and agitate, being careful not to breath the fumes. In using "dirty"/salvage aluminium I have had some success in using a good amount of kosher salt as a flux. Dump in enough to form a skin when the charge melts and skim the large amount of dross that usually forms. I've used borax in brass melts as a cover to help slow oxidation and zinc fuming , never considered it for a cover flux with aluminum . I've also used crushed glass with brass , what a mess that made . The set of rims these ingots came from were cheap wheels , spun/stamped/welded assemblies and they were pretty nasty , road grime and such. The ones I have left to process are cast and fairly clean . Maybe a combo of cover flux and chlorine degassing will clean this stuff up . -- Snag |
#16
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Casting practice
On 12/21/2014 6:43 PM, Terry Coombs wrote:
It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . Anyway , the pour came out well too other than the H2 microbubbles , and that piece is in the lathe now for machining . I saw the header and my mind immediately went to fishing. I thought you were about to reveal one of your secrets. |
#17
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Casting practice
Tom Gardner wrote:
On 12/21/2014 6:43 PM, Terry Coombs wrote: It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . Anyway , the pour came out well too other than the H2 microbubbles , and that piece is in the lathe now for machining . I saw the header and my mind immediately went to fishing. I thought you were about to reveal one of your secrets. My fishing secret is that I don't ... I think the last time I wet a hook was probably 25 years ago . -- Snag |
#18
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Casting practice
On Wed, 24 Dec 2014 07:27:14 -0600, "Terry Coombs"
wrote: Tom Gardner wrote: On 12/21/2014 6:43 PM, Terry Coombs wrote: It's been a while since I molded and cast anything , so I decided to get a little practice today . First melt was an old cast aluminum decorative skeleton key . Wall hanging doodad , about 2 feet long and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be an end cap on a ball mill cylinder . That went well so I cut up a couple of ingots snd fired the furnace back up . I'm going to have to address the hydrogen porosity I'm seeing with some of my stock . I've tried chlorine pool granules and that works well enough , but the fumes are dangerous so I'm thinking about bubbling some CO2 in the melt to degas . Anyway , the pour came out well too other than the H2 microbubbles , and that piece is in the lathe now for machining . I saw the header and my mind immediately went to fishing. I'm surprised that your li'l lesbian mind didn't think of knitting, Tawm. Y'know, cast on, cast off. I thought you were about to reveal one of your secrets. My fishing secret is that I don't ... I think the last time I wet a hook was probably 25 years ago . +1, but I recently bought a collapsible pole and reel, JIC. -- With every experience, you alone are painting your own canvas, thought by thought, choice by choice. -- Oprah Winfrey |
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