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#1
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Newbie - advice on finishing my first cast
Hello, been posting some at RCM but figured this would be a more appropriate
group. After four attempts I have my first successful cast in sterling and am looking for advice on finishing the piece. It's an eagle shaped pendant, about 1/3 ozt. There's enough detail and shape to it that files and sandpaper would ruin it. I've got it cleaned up well and all investment material is gone. Tried a dremmel with polishing wheel but that didn't get it to where I want it. Was surfing a few suppliers and am thinking a rotary tumbler might work better? Am I on the right track and if so what media(s) would you recommend to finish the job? Been shopping some at Contenti.Com so if you're familiar with their products that'd be cool. Again this is my first successful cast and so if I screw up the piece I won't be heart broken, just trying to teach myself each step. Thanks, - Ben |
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#2
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Newbie - advice on finishing my first cast
On Tue, 27 Feb 2007 05:18:23 +0000, Ben wrote:
Hello, been posting some at RCM but figured this would be a more appropriate group. After four attempts I have my first successful cast in sterling and am looking for advice on finishing the piece. It's an eagle shaped pendant, about 1/3 ozt. There's enough detail and shape to it that files and sandpaper would ruin it. I've got it cleaned up well and all investment material is gone. Tried a dremmel with polishing wheel but that didn't get it to where I want it. Was surfing a few suppliers and am thinking a rotary tumbler might work better? Am I on the right track and if so what media(s) would you recommend to finish the job? Been shopping some at Contenti.Com so if you're familiar with their products that'd be cool. Again this is my first successful cast and so if I screw up the piece I won't be heart broken, just trying to teach myself each step. People have different preferences in regular finishing media. After initial finishing, however, don't neglect the possibility of using chasing tools on the casting, tapping it with a planishing hammer, or hand burnishing it directionally (something a tumbler can't do) in ways that work with the design as you want it. Also consider depletion gilding. |
#3
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Newbie - advice on finishing my first cast
Ben wrote:
Hello, been posting some at RCM but figured this would be a more appropriate group. After four attempts I have my first successful cast in sterling and am looking for advice on finishing the piece. It's an eagle shaped pendant, about 1/3 ozt. There's enough detail and shape to it that files and sandpaper would ruin it. I've got it cleaned up well and all investment material is gone. Tried a dremmel with polishing wheel but that didn't get it to where I want it. Was surfing a few suppliers and am thinking a rotary tumbler might work better? Am I on the right track and if so what media(s) would you recommend to finish the job? Been shopping some at Contenti.Com so if you're familiar with their products that'd be cool. Again this is my first successful cast and so if I screw up the piece I won't be heart broken, just trying to teach myself each step. Thanks, - Rotary tumbler? no It will knock off all the high spots so it looks like its been well worn for many years. the way castings that are rough are cleaned up is by chasing with gravers and chisels. Not too difficult as a technique but your problem will be holding the casting well enough so you can do this without bending it there will be many much more experience3d in casting finishing than me. who may well advise otherwise. Any chance of a picture so we can see what you want to do? |
#4
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Newbie - advice on finishing my first cast
"ted frater" wrote in message ... Ben wrote: Hello, been posting some at RCM but figured this would be a more appropriate group. After four attempts I have my first successful cast in sterling and am looking for advice on finishing the piece. It's an eagle shaped pendant, about 1/3 ozt. There's enough detail and shape to it that files and sandpaper would ruin it. I've got it cleaned up well and all investment material is gone. Tried a dremmel with polishing wheel but that didn't get it to where I want it. Was surfing a few suppliers and am thinking a rotary tumbler might work better? Am I on the right track and if so what media(s) would you recommend to finish the job? Been shopping some at Contenti.Com so if you're familiar with their products that'd be cool. Again this is my first successful cast and so if I screw up the piece I won't be heart broken, just trying to teach myself each step. Thanks, - Rotary tumbler? no It will knock off all the high spots so it looks like its been well worn for many years. the way castings that are rough are cleaned up is by chasing with gravers and chisels. Not too difficult as a technique but your problem will be holding the casting well enough so you can do this without bending it there will be many much more experience3d in casting finishing than me. who may well advise otherwise. Any chance of a picture so we can see what you want to do? Ok but please don't laugh! You had your first cast once too.... http://www.spiderinfo.com/eagle.jpg I know there are issues due to not properly removing bubbles from investment as well as deformed feet from improper sprue mods. But in my defense the wax model wasn't great to start with and again, this is just practice. If you can you describe specific tools and technique in plain English it would be more helpful. Although I appreciate your and the other post I do not know what a graver is, nor do I know what "chasing tools on the casting, tapping it with a planishing hammer, or hand burnishing it directionally". If it's too involved to describe then maybe toss me a link to a good book(?). I have zero experience and don't know anyone who does this locally. Worst of all I'm a visual person who learns best by watching...having to learn this from Internet and books makes it even harder. Thanks again, - Ben |
#5
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Newbie - advice on finishing my first cast
On Tue, 27 Feb 2007 07:47:23 -0800, in rec.crafts.jewelry "Ben"
wrote: Ok but please don't laugh! You had your first cast once too.... http://www.spiderinfo.com/eagle.jpg I know there are issues due to not properly removing bubbles from investment as well as deformed feet from improper sprue mods. But in my defense the wax model wasn't great to start with and again, this is just practice. If you can you describe specific tools and technique in plain English it would be more helpful. Although I appreciate your and the other post I do not know what a graver is, nor do I know what "chasing tools on the casting, tapping it with a planishing hammer, or hand burnishing it directionally". If it's too involved to describe then maybe toss me a link to a good book(?). I have zero experience and don't know anyone who does this locally. Worst of all I'm a visual person who learns best by watching...having to learn this from Internet and books makes it even harder. Thanks again, - Ben Actually, Ben, it's not bad for a first experience. I'm assuming you started with a wax model you purchased, since frankly this is more detailed than most beginners will manage to do when carving their own models the first time. If you carved this yourself in the wax, then feel free to use that beginner term with reservations, 'cause if that's a first ever wax carving, then you've got some talent there... Anyway. You actually are right (Ted's answer notwithstanding) that tumbling is one way to get this to look better. Ted refers to tumbling with abrasives, a process that will actually remove surface metal to clean it up, and is in fact more effective and thorough as a way to really clean up castings fully from start to finish. But doing that is not within the scope of small rotary tumblers, since detailed pieces like this need small tumbling media, which work better in vibratory or other types of tumblers. A rotary tumbler with a bit more muscle than the smallest hobby types, however, could get decent, though not finished, results by tumbling with small sized sttel shot, if the shot shape is chosen right. That process does not remove metal (and does not remove small bubbles, for example), but burnishes metal. The ultimate verson of that, a magnetic tumbler that uses tiny steel needles, would nicely brighten the whole thing down to the tiniest detail. But that still doesn't remove small bubbles, and the machines cost hundreds. Plus, it's better if you start out not by learning automatic finishing methods, but rather, how to do it by hand. That's the real skill in any case. What ted refers to, chisels and gravers, are about the same thing in concept. Gravers are engraving tools, hand held chisels used to trim small amounts of metal at a time. They take some time and effort to learn to use, and frankly, are not really the most commonly used way most people clean up a casting. Most of us start with hand files for the coarse details, like filing off the stump of a sprue, and then move where indicated to tools that fit in a rotary handpiede attached to a flexible shaft motor. On a budget, you can do some of this even with a bench mounted electric drill, though that will be awkward and limited. Dremel type hand motors work well though, for less money, though they too are not as versatile as a proper flex shaft machine.\ For the flex shaft, you can get an enormous variety of small steel cutters (called burs) in all shapes and sizes, and these almost always offer something you could use to get into details to clean up defects, bubbles, and the like. A hand pushed graver can do the same, as Ted suggests. As with burs and cutters, no one shape will do it all. You need a bit of a selection, though with gravers, a smaller selection is needed than with burs. After the gross defects are trimmed off, what remains is simply to smooth and brighten the metal. Here, with silver, I might start with a small wire brush. Use steel or nickel silver, not brass, since brass will leave a yellowish tinge on the metal. That, perhaps with a bit of lubricant (oil, wax, soapy water, etc) will burnish or rub down the metal leaving you with a metallic shine rather than dull matte metal, but it's still mostly a starting point for better polishing. From there, I'd use small rotary bristle brushes, still in the flex shaft, along with various polishing compounds, starting with a tripoli or white diamond "cutting" compound to smooth down surface roughness, then switching to rouge, on a new brush, to polish the metal. After that, I'd switch to a muslin buff, again with rouge compound, to get a higher more uniform polish. The polish will be more on the accessable high spots, but the brushes will reach down into many of the details, leaving only the most recessed areas still unpolished, and hopefully, the initial wire brush at least brightened them up a bit. If this were gold, I might spend more time, with additional small tools, trying to get the best polish down into all the tiny details, but with silver, there's a "gotcha" here. Silver tarnishes in air over time. So the traditional approach, which actually looks pretty good, after putting a pretty good polish on a piece, is to beat nature to the punch, and use a silver oxidizing compound, either a commercial preparation or a solution mixed yourself with a chemical called "liver of sulphur". This will generally turn the whole piece black. Rinse off the solution, dry and go back to the final muslin buff with rouge and again give the piece that final polishing step. You'll be left with a nice dramatic finish with visible details nicely bright and polished, and recessed areas oxidized to a matte black. And back to initial finishing, if in addition to the small bubbles and defects of that sort, the metal itself is rough in texture, more so than a decent casting should be (such as if you got the metal or mold too hot), and you need to remove a bit of the entire surface to smooth it a bit, you might look through the contenti web site at the 3M radial bristle disk brushes. These, like the "hair" brushes used with polishing compound or the wire brush, are used with a dremel or flex shaft motor. You stack up four to six of them at a time on a mandrel (the steel shaft with a screw on the end that holds the things). They have built in abrasive compounds, and are quite effective and refining details like your casting has. Start with the yellow disks, and progress through to finer grits. You can actually, if you use the whole series, do almost all the polishing with these cool little brushes. But the final work with a standard soft bristle (hair, not 3M) brush and rouge will still get down into details better. If you use the 3M brushes, be sure to follow the instructions on mounting them the correct direction on the mandrel (in use, the bristles move in the "drag" direction, pointing away from the direction of rotation), and use them with a light touch, not heavy pressure. And with standard brushes, understand that stiffer bristles and shorter bristles are more aggressive and cut faster than brushes with softer bristles or longer bristles (larger diameter brushes aren't always faster. use them only if you need the depth of pentration of the longer bristles) And just to put this in persepective, It shouldn't be difficult. With practice, you'll be able to fully clean up a casting light that in about a half hour's work or less. Sometimes a lot less... This would be easier if you had someone show you in person. Are you sure there are no local jewelry stores with a workshop that might have someone who, in trade perhaps for you buying them lunch or something, couldn't quickly show you a bit about it? Local community colleges might have art department classes in jewelry/metal working... There's gotta be someone around who can show you. This isn't like some of the more advanced skills in jewelry work where finding someone who knows it well and has the time to teach it can be tricky... And for cost, it shouldn't be hard to find the needed tools pretty easy too. heck, I've seen simple rotary tool kits (chinese cheap versions of dremel type hobby tools) in the hardware and department stores, usually with a kit of basic brushes and cutters, that would probably offer the basics of what you need, for not a lot of money. Putting a good attractive finish on metal offers many variations and options, of course, and can become quite involved. But as a first step, for this casting, I'm thinking you can do well just using the basics, as I've described. Hope that helps. Peter |
#6
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Newbie - advice on finishing my first cast
On Tue, 27 Feb 2007 15:47:24 +0000, Ben wrote:
If you can you describe specific tools and technique in plain English it would be more helpful. Although I appreciate your and the other post I do not know what a graver is, nor do I know what "chasing tools on the casting, tapping it with a planishing hammer, or hand burnishing it directionally". If it's too involved to describe then maybe toss me a link to a good book(?). That's a load of links, but I think that if you go to ganoksin.com and look around you will find articles covering most of it. |
#7
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Newbie - advice on finishing my first cast
Ben wrote:
"ted frater" wrote in message ... Ben wrote: Hello, been posting some at RCM but figured this would be a more appropriate group. After four attempts I have my first successful cast in sterling and am looking for advice on finishing the piece. It's an eagle shaped pendant, about 1/3 ozt. There's enough detail and shape to it that files and sandpaper would ruin it. I've got it cleaned up well and all investment material is gone. Tried a dremmel with polishing wheel but that didn't get it to where I want it. Was surfing a few suppliers and am thinking a rotary tumbler might work better? Am I on the right track and if so what media(s) would you recommend to finish the job? Been shopping some at Contenti.Com so if you're familiar with their products that'd be cool. Again this is my first successful cast and so if I screw up the piece I won't be heart broken, just trying to teach myself each step. Thanks, - Rotary tumbler? no It will knock off all the high spots so it looks like its been well worn for many years. the way castings that are rough are cleaned up is by chasing with gravers and chisels. Not too difficult as a technique but your problem will be holding the casting well enough so you can do this without bending it there will be many much more experience3d in casting finishing than me. who may well advise otherwise. Any chance of a picture so we can see what you want to do? Ok but please don't laugh! You had your first cast once too.... http://www.spiderinfo.com/eagle.jpg I know there are issues due to not properly removing bubbles from investment as well as deformed feet from improper sprue mods. But in my defense the wax model wasn't great to start with and again, this is just practice. If you can you describe specific tools and technique in plain English it would be more helpful. Although I appreciate your and the other post I do not know what a graver is, nor do I know what "chasing tools on the casting, tapping it with a planishing hammer, or hand burnishing it directionally". If it's too involved to describe then maybe toss me a link to a good book(?). I have zero experience and don't know anyone who does this locally. Worst of all I'm a visual person who learns best by watching...having to learn this from Internet and books makes it even harder. Thanks again, - Ben Congratulations Ben!!, An excellent 1st cast, and id say quite saleable when finished Now obviously youve to change a few things to make sure the feet come out as you plan, and as its a pendant, you might consider changing the orientation of the ring at the top. Its also too thin to last any time. you ned to double the thickness and rotate it 90deg. So the chain or cord will lay correctly on some fair maids bosom. As to go ing on and sharpening up some of the detail, it doesnt need it as the design and interpretation thereof are quite sufficient. Youll need to get your own stamps to mark your work with the silver grade ie a 925 mark and say the letter "B" in whatever script you choose. on the back of course Marking your work always puts the price up, and proves youve made it. An essential selling point. Now what you might consider is colouring the casting after youve cleaned it up. IE darken it , then polish off the high spots using a very fine rotary wire brush. Dont use polishing compo as it will fill up the detail. this sharpens up the relief and improves the appearance. When youve done some more casts post another picture alonside your first attempt so we can see the progress. Out of interest, Idont cast anything, all my work is minted now. If I wanted to make this design id invest in the dies and the tooling and be set up to make them by the hundred, This is a cold technique and doesgive the sharp detail you seem to be thinking of.. |
#8
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Newbie - advice on finishing my first cast
On Tue, 27 Feb 2007 16:23:30 GMT in rec.crafts.jewelry "Peter W..
Rowe," , intended to write something intelligible, but instead wrote : On Tue, 27 Feb 2007 07:47:23 -0800, in rec.crafts.jewelry "Ben" wrote: Ok but please don't laugh! You had your first cast once too.... http://www.spiderinfo.com/eagle.jpg I know there are issues due to not properly removing bubbles from investment as well as deformed feet from improper sprue mods. But in my defense the wax model wasn't great to start with and again, this is just practice. If you can you describe specific tools and technique in plain English it would be more helpful. Although I appreciate your and the other post I do not know what a graver is, nor do I know what "chasing tools on the casting, tapping it with a planishing hammer, or hand burnishing it directionally". If it's too involved to describe then maybe toss me a link to a good book(?). I have zero experience and don't know anyone who does this locally. Worst of all I'm a visual person who learns best by watching...having to learn this from Internet and books makes it even harder. Thanks again, - Ben Actually, Ben, it's not bad for a first experience. I'm assuming you started with a wax model you purchased, since frankly this is more detailed than most beginners will manage to do when carving their own models the first time. If you carved this yourself in the wax, then feel free to use that beginner term with reservations, 'cause if that's a first ever wax carving, then you've got some talent there... Anyway. You actually are right (Ted's answer notwithstanding) that tumbling is one way to get this to look better. Ted refers to tumbling with abrasives, a process that will actually remove surface metal to clean it up, and is in fact more effective and thorough as a way to really clean up castings fully from start to finish. But doing that is not within the scope of small rotary tumblers, since detailed pieces like this need small tumbling media, which work better in vibratory or other types of tumblers. A rotary tumbler with a bit more muscle than the smallest hobby types, however, could get decent, though not finished, results by tumbling with small sized sttel shot, if the shot shape is chosen right. That process does not remove metal (and does not remove small bubbles, for example), but burnishes metal. The ultimate verson of that, a magnetic tumbler that uses tiny steel needles, would nicely brighten the whole thing down to the tiniest detail. But that still doesn't remove small bubbles, and the machines cost hundreds. Plus, it's better if you start out not by learning automatic finishing methods, but rather, how to do it by hand. That's the real skill in any case. As a guy who started in jewelry many moons ago as a caster and finisher in mostly sterling, I agree with everything Peter has said thus far... What ted refers to, chisels and gravers, are about the same thing in concept. Gravers are engraving tools, hand held chisels used to trim small amounts of metal at a time. They take some time and effort to learn to use, and frankly, are not really the most commonly used way most people clean up a casting. Most of us start with hand files for the coarse details, like filing off the stump of a sprue, and then move where indicated to tools that fit in a rotary handpiede attached to a flexible shaft motor. On a budget, you can do some of this even with a bench mounted electric drill, though that will be awkward and limited. Dremel type hand motors work well though, for less money, though they too are not as versatile as a proper flex shaft machine.\ eBay is always selling flex-shafts. You can pick 'em up really cheap there. I start despruing with a "Heatless Mizzy Wheel" and a "separating disk" (Be careful with separating disks! They really slice flesh quickly & the shards of broken ones, which means probably every one you use for the first few years, love to lodge in unprotected eyeballs.) From there I go to a blue "Cratex" rubber wheel. For the flex shaft, you can get an enormous variety of small steel cutters (called burs) in all shapes and sizes, and these almost always offer something you could use to get into details to clean up defects, bubbles, and the like. A hand pushed graver can do the same, as Ted suggests. As with burs and cutters, no one shape will do it all. You need a bit of a selection, though with gravers, a smaller selection is needed than with burs. After the gross defects are trimmed off, what remains is simply to smooth and brighten the metal. Here, with silver, I might start with a small wire brush. Use steel or nickel silver, not brass, since brass will leave a yellowish tinge on the metal. That, perhaps with a bit of lubricant (oil, wax, soapy water, etc) will burnish or rub down the metal leaving you with a metallic shine rather than dull matte metal, but it's still mostly a starting point for better polishing. I disagree. Brass will leave a tint, but it polishes off easily. Steel will remove too much metal and he'll lose detail. From there, I'd use small rotary bristle brushes, still in the flex shaft, along with various polishing compounds, starting with a tripoli or white diamond "cutting" compound to smooth down surface roughness, then switching to rouge, on a new brush, to polish the metal. I learned using "tripoli" but accidently discovered a compound called "bobbing coumpound" which I believe is mainly used for polishing steels. It cuts really, really fast and leaves a mat finish. You have to be careful with it that you don't polish off your detail, but on the plus side it cuts really, really fast. I use only one type of bristle brush, a medium with it's own shaft, not those pop-on types. I buy them by the gross from some dental supply house whose name escapes me at the moment (I'm at home now, not work.) After bobbing & washing (ultrasonic with ammonia & detergent, and steaming) I then use a new brush with "Fabu-Lustre" and without cleaning I go to green rouge using the same type brush. After that, I'd switch to a muslin buff, again with rouge compound, to get a higher more uniform polish. I do that standing up at my big wheel. The polish will be more on the accessable high spots, but the brushes will reach down into many of the details, leaving only the most recessed areas still unpolished, and hopefully, the initial wire brush at least brightened them up a bit. The really weird thing about getting those brushes to get down into the low spots is you gotta use LESS pressure rather than more to get deeper. If this were gold, I might spend more time, with additional small tools, trying to get the best polish down into all the tiny details, but with silver, there's a "gotcha" here. Silver tarnishes in air over time. So the traditional approach, which actually looks pretty good, after putting a pretty good polish on a piece, is to beat nature to the punch, and use a silver oxidizing compound, either a commercial preparation or a solution mixed yourself with a chemical called "liver of sulphur". This will generally turn the whole piece black. Rinse off the solution, dry and go back to the final muslin buff with rouge and again give the piece that final polishing step. You'll be left with a nice dramatic finish with visible details nicely bright and polished, and recessed areas oxidized to a matte black. Just be careful with the ultrasonic & steaming after "antiquing." And back to initial finishing, if in addition to the small bubbles and defects of that sort, the metal itself is rough in texture, more so than a decent casting should be (such as if you got the metal or mold too hot), and you need to remove a bit of the entire surface to smooth it a bit, you might look through the contenti web site at the 3M radial bristle disk brushes. These, like the "hair" brushes used with polishing compound or the wire brush, are used with a dremel or flex shaft motor. You stack up four to six of them at a time on a mandrel (the steel shaft with a screw on the end that holds the things). They have built in abrasive compounds, and are quite effective and refining details like your casting has. Start with the yellow disks, and progress through to finer grits. You can actually, if you use the whole series, do almost all the polishing with these cool little brushes. But the final work with a standard soft bristle (hair, not 3M) brush and rouge will still get down into details better. If you use the 3M brushes, be sure to follow the instructions on mounting them the correct direction on the mandrel (in use, the bristles move in the "drag" direction, pointing away from the direction of rotation), and use them with a light touch, not heavy pressure. And with standard brushes, understand that stiffer bristles and shorter bristles are more aggressive and cut faster than brushes with softer bristles or longer bristles (larger diameter brushes aren't always faster. use them only if you need the depth of pentration of the longer bristles) And just to put this in persepective, It shouldn't be difficult. With practice, you'll be able to fully clean up a casting light that in about a half hour's work or less. Sometimes a lot less... This would be easier if you had someone show you in person. Are you sure there are no local jewelry stores with a workshop that might have someone who, in trade perhaps for you buying them lunch or something, couldn't quickly show you a bit about it? Local community colleges might have art department classes in jewelry/metal working... There's gotta be someone around who can show you. This isn't like some of the more advanced skills in jewelry work where finding someone who knows it well and has the time to teach it can be tricky... And for cost, it shouldn't be hard to find the needed tools pretty easy too. heck, I've seen simple rotary tool kits (chinese cheap versions of dremel type hobby tools) in the hardware and department stores, usually with a kit of basic brushes and cutters, that would probably offer the basics of what you need, for not a lot of money. Putting a good attractive finish on metal offers many variations and options, of course, and can become quite involved. But as a first step, for this casting, I'm thinking you can do well just using the basics, as I've described. Hope that helps. Peter |
#9
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Newbie - advice on finishing my first cast
"Peter W.. Rowe," wrote in message ... On Tue, 27 Feb 2007 07:47:23 -0800, in rec.crafts.jewelry "Ben" wrote: Ok but please don't laugh! You had your first cast once too.... http://www.spiderinfo.com/eagle.jpg I know there are issues due to not properly removing bubbles from investment as well as deformed feet from improper sprue mods. But in my defense the wax model wasn't great to start with and again, this is just practice. If you can you describe specific tools and technique in plain English it would be more helpful. Although I appreciate your and the other post I do not know what a graver is, nor do I know what "chasing tools on the casting, tapping it with a planishing hammer, or hand burnishing it directionally". If it's too involved to describe then maybe toss me a link to a good book(?). I have zero experience and don't know anyone who does this locally. Worst of all I'm a visual person who learns best by watching...having to learn this from Internet and books makes it even harder. Thanks again, - Ben Peter, Wow, this is exactly the response I was hoping for, thanks! Really appreciate the thorough and detailed explanation. The model was a purchased from eBay. My first two attempts at casting I didn't want to waste any (had 5) so I used 3/8" sprue wax cut in to 1cm lengths. On the second "spue cast" I got close enough to try the eagle but the chest didn't fill. I was worried more about the wings actually so that was a surprise. Second eagle came out though and I was pleased. Rough but complete cast using steam. On a tip from the book I read I went down to Cabela's today and picked up a vibrating tumbler used for brass bullet casings. Picked one up with "tuffnut" rouge media for less than $50. I was thinking of buying both of these media to use in it as well: http://www.contenti.com/products/cleaners/180-623.html I'm not affiliated with or pushing Contenti, just stumbled on their site and have positive experience ordering there so far. Those products look OK to use? I agree with what you say below as far as doing it manually to acquire skill. I am purposely trying to use the basics due in part to cost but mostly because I want to "earn" any equipment I purchase by learning the manual methods first. But I will be using the dremmel when appropriate. To cast I used a basic oxy/mapp torch, one flask, satin cast, charcoal for burnout and a dill pickle jar lid filled with wet paper towels screwed to a broom handle for steam pressure. Basics. Thanks once again for the post. Helping me learn the language and I'll definately keep this one for future reference. - Ben Actually, Ben, it's not bad for a first experience. I'm assuming you started with a wax model you purchased, since frankly this is more detailed than most beginners will manage to do when carving their own models the first time. If you carved this yourself in the wax, then feel free to use that beginner term with reservations, 'cause if that's a first ever wax carving, then you've got some talent there... Anyway. You actually are right (Ted's answer notwithstanding) that tumbling is one way to get this to look better. Ted refers to tumbling with abrasives, a process that will actually remove surface metal to clean it up, and is in fact more effective and thorough as a way to really clean up castings fully from start to finish. But doing that is not within the scope of small rotary tumblers, since detailed pieces like this need small tumbling media, which work better in vibratory or other types of tumblers. A rotary tumbler with a bit more muscle than the smallest hobby types, however, could get decent, though not finished, results by tumbling with small sized sttel shot, if the shot shape is chosen right. That process does not remove metal (and does not remove small bubbles, for example), but burnishes metal. The ultimate verson of that, a magnetic tumbler that uses tiny steel needles, would nicely brighten the whole thing down to the tiniest detail. But that still doesn't remove small bubbles, and the machines cost hundreds. Plus, it's better if you start out not by learning automatic finishing methods, but rather, how to do it by hand. That's the real skill in any case. What ted refers to, chisels and gravers, are about the same thing in concept. Gravers are engraving tools, hand held chisels used to trim small amounts of metal at a time. They take some time and effort to learn to use, and frankly, are not really the most commonly used way most people clean up a casting. Most of us start with hand files for the coarse details, like filing off the stump of a sprue, and then move where indicated to tools that fit in a rotary handpiede attached to a flexible shaft motor. On a budget, you can do some of this even with a bench mounted electric drill, though that will be awkward and limited. Dremel type hand motors work well though, for less money, though they too are not as versatile as a proper flex shaft machine.\ For the flex shaft, you can get an enormous variety of small steel cutters (called burs) in all shapes and sizes, and these almost always offer something you could use to get into details to clean up defects, bubbles, and the like. A hand pushed graver can do the same, as Ted suggests. As with burs and cutters, no one shape will do it all. You need a bit of a selection, though with gravers, a smaller selection is needed than with burs. After the gross defects are trimmed off, what remains is simply to smooth and brighten the metal. Here, with silver, I might start with a small wire brush. Use steel or nickel silver, not brass, since brass will leave a yellowish tinge on the metal. That, perhaps with a bit of lubricant (oil, wax, soapy water, etc) will burnish or rub down the metal leaving you with a metallic shine rather than dull matte metal, but it's still mostly a starting point for better polishing. From there, I'd use small rotary bristle brushes, still in the flex shaft, along with various polishing compounds, starting with a tripoli or white diamond "cutting" compound to smooth down surface roughness, then switching to rouge, on a new brush, to polish the metal. After that, I'd switch to a muslin buff, again with rouge compound, to get a higher more uniform polish. The polish will be more on the accessable high spots, but the brushes will reach down into many of the details, leaving only the most recessed areas still unpolished, and hopefully, the initial wire brush at least brightened them up a bit. If this were gold, I might spend more time, with additional small tools, trying to get the best polish down into all the tiny details, but with silver, there's a "gotcha" here. Silver tarnishes in air over time. So the traditional approach, which actually looks pretty good, after putting a pretty good polish on a piece, is to beat nature to the punch, and use a silver oxidizing compound, either a commercial preparation or a solution mixed yourself with a chemical called "liver of sulphur". This will generally turn the whole piece black. Rinse off the solution, dry and go back to the final muslin buff with rouge and again give the piece that final polishing step. You'll be left with a nice dramatic finish with visible details nicely bright and polished, and recessed areas oxidized to a matte black. And back to initial finishing, if in addition to the small bubbles and defects of that sort, the metal itself is rough in texture, more so than a decent casting should be (such as if you got the metal or mold too hot), and you need to remove a bit of the entire surface to smooth it a bit, you might look through the contenti web site at the 3M radial bristle disk brushes. These, like the "hair" brushes used with polishing compound or the wire brush, are used with a dremel or flex shaft motor. You stack up four to six of them at a time on a mandrel (the steel shaft with a screw on the end that holds the things). They have built in abrasive compounds, and are quite effective and refining details like your casting has. Start with the yellow disks, and progress through to finer grits. You can actually, if you use the whole series, do almost all the polishing with these cool little brushes. But the final work with a standard soft bristle (hair, not 3M) brush and rouge will still get down into details better. If you use the 3M brushes, be sure to follow the instructions on mounting them the correct direction on the mandrel (in use, the bristles move in the "drag" direction, pointing away from the direction of rotation), and use them with a light touch, not heavy pressure. And with standard brushes, understand that stiffer bristles and shorter bristles are more aggressive and cut faster than brushes with softer bristles or longer bristles (larger diameter brushes aren't always faster. use them only if you need the depth of pentration of the longer bristles) And just to put this in persepective, It shouldn't be difficult. With practice, you'll be able to fully clean up a casting light that in about a half hour's work or less. Sometimes a lot less... This would be easier if you had someone show you in person. Are you sure there are no local jewelry stores with a workshop that might have someone who, in trade perhaps for you buying them lunch or something, couldn't quickly show you a bit about it? Local community colleges might have art department classes in jewelry/metal working... There's gotta be someone around who can show you. This isn't like some of the more advanced skills in jewelry work where finding someone who knows it well and has the time to teach it can be tricky... And for cost, it shouldn't be hard to find the needed tools pretty easy too. heck, I've seen simple rotary tool kits (chinese cheap versions of dremel type hobby tools) in the hardware and department stores, usually with a kit of basic brushes and cutters, that would probably offer the basics of what you need, for not a lot of money. Putting a good attractive finish on metal offers many variations and options, of course, and can become quite involved. But as a first step, for this casting, I'm thinking you can do well just using the basics, as I've described. Hope that helps. Peter |
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Newbie - advice on finishing my first cast
When Ben put fingers to keys it was 2/27/07 10:47 AM...
Ok but please don't laugh! You had your first cast once too.... http://www.spiderinfo.com/eagle.jpg I know there are issues due to not properly removing bubbles from investment as well as deformed feet from improper sprue mods. But in my defense the wax model wasn't great to start with and again, this is just practice. If you can you describe specific tools and technique in plain English it would be more helpful. Although I appreciate your and the other post I do not know what a graver is ... A graver is essentially a _tiny_ chisel/knife/scraper depending on how you hold it and use it. If I were dressing this casting I'd be after it with a couple of gravers, one flat, one rounded, carving off little bits of the bubble-beads at a time. Brace the work well. Take small enough shavings so that you don't have to push very hard, that way you have control and when the cut is done and there's no more metal in front of the tool's edge you don't shoot past and plunge the fool thing into your other hand, or worse, damage some other part of the work. (;D). I'm sure that googling 'graver' and 'how to use a graver' will turn something up. Practice on your sprues and unhappy casting(s). The rotary tools and tumbling stuff are fine for an all over finish, but for addressing the bubbles and specific flaws, the gravers and perhaps some tiny files (for the claws) would be your (well, my) first step. Were I casting this piece, I'd sprue it on the back at both shoulders and vent the backs of the wingtips and maybe the feet. Just a fine wire for a vent and it doesn't even have to come to the surface. Put the sprues and vents in places such that clipping them off, and filing and polishing the stub is easy. When investing, carefully paint the investment into the details with a soft brush popping bubbles as you go. Be quick. _Then_ pour the rest of the investment into the flask. -- Carl West http://prospecthillforge.com : The Blacksmithing Classroom http://carl.west.home.comcast.net "Nothing clears up a case so much as stating it to another person." -- Sherlock Holmes, in "Silver Blaze" |
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