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Newbie - advice on finishing my first cast



 
 
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  #1  
Old February 27th 07, 06:18 AM posted to rec.crafts.jewelry
Ben[_2_]
external usenet poster
 
Posts: 9
Default 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



Ads
  #2  
Old February 27th 07, 10:57 AM posted to rec.crafts.jewelry
mbstevens
external usenet poster
 
Posts: 165
Default 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  
Old February 27th 07, 10:57 AM posted to rec.crafts.jewelry
ted frater
external usenet poster
 
Posts: 133
Default 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  
Old February 27th 07, 04:47 PM posted to rec.crafts.jewelry
Ben[_2_]
external usenet poster
 
Posts: 9
Default 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  
Old February 27th 07, 05:23 PM posted to rec.crafts.jewelry
Peter W.. Rowe,
external usenet poster
 
Posts: 355
Default 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  
Old February 28th 07, 03:31 AM posted to rec.crafts.jewelry
mbstevens
external usenet poster
 
Posts: 165
Default 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  
Old February 28th 07, 03:31 AM posted to rec.crafts.jewelry
ted frater
external usenet poster
 
Posts: 133
Default 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  
Old February 28th 07, 03:31 AM posted to rec.crafts.jewelry
Frosty
external usenet poster
 
Posts: 155
Default 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  
Old February 28th 07, 03:32 AM posted to rec.crafts.jewelry
Ben[_2_]
external usenet poster
 
Posts: 9
Default 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






  #10  
Old March 4th 07, 10:05 PM posted to rec.crafts.jewelry
Carl
external usenet poster
 
Posts: 38
Default 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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