Hi

I'm thinking about wether I want a centifugal casting machine, mainly
for zinc and it's alloys.
There are machines available but unfortunately, they all want _my_ money
for _their_ stuff. I think that this machine is simple enough to be home
made.

But before I start, I'd like to know how big the parts are that I could
cast. E.g. size and weight.
Has anybody got experience with that?

Next step are the consumables (silicon, etc.) That ain't a problem, I
found suppliers. They give enough descriptions that I know what I need
and how to use.

Last step is building that little machine. Mechanically no problem, but
as far as I know, the commercial machines use rings (that keep the
silicon in place). And I haven't got that much clue how the ring is
fixed to the spinning disk etc. Has anybody photos/links/descriptions of
that setup?

Well, one thing remains: making the negatives. I know that I need some
special silicon (no problem), but do I really need a vacuum pump to get
the bubbles out? Or does this start yet another project: Build your own
vacuum pump?


Nuff questions for now, any input wellcome.

Oh! What I need it for? I want to cast small/decorative parts for model
engines. Lets say size is maximum 50mm for the biggest elongation. As
soon as my HP is up and running, you'll get an impression. But that will
take another week... (and is again a different project)



Thanks,
Nick
--
"Wissenschafts"-Sendung auf einem der Privat-Kanäle:
"Der Behälter fasst 200.000 Kubik-Liter."
Wie viele Quadrat-Stunden braucht es dann wohl, um ihn voll zu bekommen?

"Nick Müller" wrote in message
...
Hi

I'm thinking about wether I want a centifugal casting machine, mainly
for zinc and it's alloys.
There are machines available but unfortunately, they all want _my_ money
for _their_ stuff. I think that this machine is simple enough to be home
made.

But before I start, I'd like to know how big the parts are that I could
cast. E.g. size and weight.
Has anybody got experience with that?

The spincasting company that used to be in Mount Vernon, NY (maybe it still
is?) told me that their machines were used to cast zinc parts up to around
500g. That was 25 years ago.


Next step are the consumables (silicon, etc.) That ain't a problem, I
found suppliers. They give enough descriptions that I know what I need
and how to use.

Last step is building that little machine. Mechanically no problem, but
as far as I know, the commercial machines use rings (that keep the
silicon in place). And I haven't got that much clue how the ring is
fixed to the spinning disk etc. Has anybody photos/links/descriptions of
that setup?

Well, one thing remains: making the negatives. I know that I need some
special silicon (no problem), but do I really need a vacuum pump to get
the bubbles out? Or does this start yet another project: Build your own
vacuum pump?

'Don't know what you mean about the bubbles. Are you planning to use liquid
silicone? For making high-temperature castings, the silicone I've seen has
been sold in slabs, as a semi-solid, which was pressed around the patterns
and heat-cured. You could get a hundred or more shots in zinc with that,
and, using the very highest-temperature material that was available at the
time, three or four shots with aluminum.

Again, that was 25 years ago. If you have access to really old American
Machinist magazines, you may find the articles I wrote about it. (hmmm...I
see you're in Germany. I guess it's not likely you'll find American
Machinist g)


Nuff questions for now, any input wellcome.

Oh! What I need it for? I want to cast small/decorative parts for model
engines. Lets say size is maximum 50mm for the biggest elongation. As
soon as my HP is up and running, you'll get an impression. But that will
take another week... (and is again a different project)

Unless you're going to make a lot of parts, you may find it easier to model
your operation more like a jeweler's centrifugal-casting setup, with plaster
investment molds rather than silicone. It's one heck of a lot cheaper and
it's slightly more dimensionally accurate.

It's also a lot slower overall, however. It's for onesies/twosies at a time.
The silicone spin-casting is for moderate-run production.

--
Ed Huntress

Ed Huntress wrote:

'Don't know what you mean about the bubbles. Are you planning to use liquid
silicone?

I think it's liquid (but haven't used it).


and, using the very highest-temperature material that was available at the
time, three or four shots with aluminum.

That's not an option. I will use lost form casting (wax) for that
purpose (OK, I get a single shot :-))


see you're in Germany. I guess it's not likely you'll find American
Machinist g)

Maybe yes. In what years? "American Machinist"? I can try at the
Deutsches Museum in Munich. They do have a _huge_ library.


... with plaster investment molds rather than silicone. It's one heck of a
lot cheaper and it's slightly more dimensionally accurate.

The pieces are in the 10th range. How much preciser (in %) are the
plaster molds?


Thanks,
Nick
--
"Wissenschafts"-Sendung auf einem der Privat-Kanäle:
"Der Behälter fasst 200.000 Kubik-Liter."
Wie viele Quadrat-Stunden braucht es dann wohl, um ihn voll zu bekommen?

"Nick Müller" wrote in message
...
Ed Huntress wrote:

'Don't know what you mean about the bubbles. Are you planning to use
liquid
silicone?

I think it's liquid (but haven't used it).


and, using the very highest-temperature material that was available at
the
time, three or four shots with aluminum.

That's not an option. I will use lost form casting (wax) for that
purpose (OK, I get a single shot :-))


see you're in Germany. I guess it's not likely you'll find American
Machinist g)

Maybe yes. In what years? "American Machinist"? I can try at the
Deutsches Museum in Munich. They do have a _huge_ library.

It would have been between January 1978 and January 1980, I'm pretty sure.
There was a news column item and a full feature article in a separate issue.
We had around 1,000 subscriptions in Germany at the time, many of them to
company and other libraries, so you may find it.

There is more up-to-date information on the Web, however. If you can't find
it yourself, let me know and I'll look. At least one of the builders of
spin-casting machines had a very informative website as of two or three
years ago, but I haven't looked since.


... with plaster investment molds rather than silicone. It's one heck of
a
lot cheaper and it's slightly more dimensionally accurate.

The pieces are in the 10th range. How much preciser (in %) are the
plaster molds?

I don't really know. Silicone molds for this work are quite hard after
they're cured, and it isn't a matter of instability of the silicone. The
issue was that the silicone ablates (the surface layer burns off, slowly)
and it also shrinks at the interface with the metal, which results in some
fine cracks that eventually make the mold useless. Again, I'm talking about
silicone formulations that were available 25 years ago. They may have solved
those limitations in the years since.



Thanks,
Nick

You're welcome, Nick. I wish I had more up-to-date information but the last
time I looked things hadn't changed much. I'm sure you can find better
information somewhere on the Web.

Good luck, it's an interesting process. I once investigated it for making
spinning reels (fishing reels) when I was involved in a shop. It didn't look
very good for that product but it has many uses.

--
Ed Huntress

Nick Müller wrote:

Hi

I'm thinking about wether I want a centifugal casting machine, mainly
for zinc and it's alloys.
There are machines available but unfortunately, they all want _my_ money
for _their_ stuff. I think that this machine is simple enough to be home
made.

But before I start, I'd like to know how big the parts are that I could
cast. E.g. size and weight.
Has anybody got experience with that?

Next step are the consumables (silicon, etc.) That ain't a problem, I
found suppliers. They give enough descriptions that I know what I need
and how to use.

Last step is building that little machine. Mechanically no problem, but
as far as I know, the commercial machines use rings (that keep the
silicon in place). And I haven't got that much clue how the ring is
fixed to the spinning disk etc. Has anybody photos/links/descriptions of
that setup?

Well, one thing remains: making the negatives. I know that I need some
special silicon (no problem), but do I really need a vacuum pump to get
the bubbles out? Or does this start yet another project: Build your own
vacuum pump?


Nuff questions for now, any input wellcome.

Oh! What I need it for? I want to cast small/decorative parts for model
engines. Lets say size is maximum 50mm for the biggest elongation. As
soon as my HP is up and running, you'll get an impression. But that will
take another week... (and is again a different project)



Thanks,
Nick

The question tickled my memory, as I used to work at my dad's jewelry
manufacturing plant in the late '40s. We used the traditional spring
wound centrifugal casting machines to make lost wax castings of all
kinds of jewelry pieces in gold and platinum alloys. Our machines were
set in the center of big round galvanized iron washtubs to catch the
splatters if things went wrong.

Molds for those precious metals were made from a plaster like
"investment" material (Inside metal rings, like you mentioned, just
2-1/2" diameter by 3" long pieces of thin wall steel tubing.) and were
transferred with tongs to the machines and "shot" full of molten metal
while still hot from the wax "bake out" furnace, which IIRC brought them
up to a dull red heat. That helped avoid "cold shots" caused by the cast
metal chilling before it fully filled the mold.

Silicone rubber wasn't around then, but we did use rubber molds to
"shoot" the wax patterns in. Those molds were natural rubber vulcanized
in a heated press around a metal "original". They were carefully cut
open with an X-Acto knife to release the original and create the wax mold.

Dad learned his jewelry craft in Germany BTW, circa 1918-1921, before
emigrating to the USA. His half-brother Leo was a Dentist in Dresden and
stayed their until dad helped him and his family get to the USA in the
nick of time in 1939.

Uncle Leo was also skilled in lost wax casting because back then most
dentists had to cast and finish their patients' bridgework themselves,
just like the jewelers did. He worked in dad's jewelry factory through
WWII and also did some unlicensed family dentistry in the apartment he
and his wife lived in. I think he treated almost everyone in the family.
I still remember him drilling away in someone's mouth using his foot
treadle powered drill with it's articulated belt drive system.

Leo once proved before my own eyes how he could make a lost wax cating
without a centrifugal machine by tying a cord onto the mold, melting the
metal in the sprue hole and then snatching that cord and whirling the
mold around his head in a circle. Wowza! That's something I'll never
forget, that and the time I saw a crazy physicist from Cornell
University toss down half a paper cup fill of liquid nitrogen, followed
by his emmiting the longest belch you could imagine.

Back on topic again, there's a quite good thread on the stuff you're
looking for running now on the HSM BBS:

http://bbs.homeshopmachinist.net/For...ML/011810.html

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

Ed Huntress wrote:

[articles]
It would have been between January 1978 and January 1980, I'm pretty sure.

That helps a lot. They won't be in the public part, but they hand it
out, if they have it (not for taking home).


There is more up-to-date information on the Web, however. If you can't find
it yourself, let me know and I'll look.

I would be very glad if you name some links. I'm still on the clueless
side concerning the layout details of the machine.

[precision]
I don't really know.

That sounds good enough. :-)


You're welcome, Nick. I wish I had more up-to-date information but the last
time I looked things hadn't changed much.

That ain't the problem. I prefer having old/outdated information to get
the basic technique and then improve it. I do have an old book about die
(SP?) casting, but only for steel forms and also not for centrifugal.


Thanks so far!
Nick
--
"Wissenschafts"-Sendung auf einem der Privat-Kanäle:
"Der Behälter fasst 200.000 Kubik-Liter."
Wie viele Quadrat-Stunden braucht es dann wohl, um ihn voll zu bekommen?

Jeff Wisnia wrote:

We used the traditional spring
wound centrifugal casting machines to make lost wax castings of all
kinds of jewelry pieces in gold and platinum alloys.

Ah, I see that I had a different setup in my mind. What you mean is some
kind of merry-go-round. :-)
I was thinking about (and have seen*)) a disk where you put the form
(two halves, just looking like a cake) on. In the center of the "form
disks" (the axle) is a hole where you poor the zinc in.
But maybe the merry-go-round-type is simpler. Hmmm... I think its not so
fast to make runs, it's better suited for single pieces.


Molds for those precious metals were made from a plaster like
"investment" material (Inside metal rings, like you mentioned, just
2-1/2" diameter by 3" long pieces of thin wall steel tubing.)

Yes, this is a different proces with the "plaster" and lost wax. I do
have someone here around that I can ask. A very friendly and ingineous
lost-wax-caster. He's casting steel screws with a 0,8mm thread. They
don't have to be re-cut. Incredible!


Back on topic again, there's a quite good thread on the stuff you're
looking for running now on the HSM BBS:

Thanks!

*) Well I have seen it. A year after, when I wanted to look at it
precisely, he didn't show up at the fair. :-(

Nick

--
"Wissenschafts"-Sendung auf einem der Privat-Kanäle:
"Der Behälter fasst 200.000 Kubik-Liter."
Wie viele Quadrat-Stunden braucht es dann wohl, um ihn voll zu bekommen?

Jeff Wisnia wrote:



The question tickled my memory, as I used to work at my dad's jewelry
manufacturing plant in the late '40s. We used the traditional spring
wound centrifugal casting machines to make lost wax castings of all
kinds of jewelry pieces in gold and platinum alloys. Our machines were
set in the center of big round galvanized iron washtubs to catch the
splatters if things went wrong.

Molds for those precious metals were made from a plaster like
"investment" material (Inside metal rings, like you mentioned, just
2-1/2" diameter by 3" long pieces of thin wall steel tubing.) and were
transferred with tongs to the machines and "shot" full of molten metal
while still hot from the wax "bake out" furnace, which IIRC brought them
up to a dull red heat. That helped avoid "cold shots" caused by the cast
metal chilling before it fully filled the mold.

Silicone rubber wasn't around then, but we did use rubber molds to
"shoot" the wax patterns in. Those molds were natural rubber vulcanized
in a heated press around a metal "original". They were carefully cut
open with an X-Acto knife to release the original and create the wax mold.

Dad learned his jewelry craft in Germany BTW, circa 1918-1921, before
emigrating to the USA. His half-brother Leo was a Dentist in Dresden and
stayed their until dad helped him and his family get to the USA in the
nick of time in 1939.

Uncle Leo was also skilled in lost wax casting because back then most
dentists had to cast and finish their patients' bridgework themselves,
just like the jewelers did. He worked in dad's jewelry factory through
WWII and also did some unlicensed family dentistry in the apartment he
and his wife lived in. I think he treated almost everyone in the family.
I still remember him drilling away in someone's mouth using his foot
treadle powered drill with it's articulated belt drive system.

Leo once proved before my own eyes how he could make a lost wax cating
without a centrifugal machine by tying a cord onto the mold, melting the
metal in the sprue hole and then snatching that cord and whirling the
mold around his head in a circle. Wowza! That's something I'll never
forget, that and the time I saw a crazy physicist from Cornell
University toss down half a paper cup fill of liquid nitrogen, followed
by his emmiting the longest belch you could imagine.

Back on topic again, there's a quite good thread on the stuff you're
looking for running now on the HSM BBS:

http://bbs.homeshopmachinist.net/For...ML/011810.html

Jeff


Very cool stuff, Jeff. I like that mold-on-a-rope trick, never heard of
it before.

John

"Nick Müller" wrote in message
...
Ed Huntress wrote:

[articles]
It would have been between January 1978 and January 1980, I'm pretty
sure.

That helps a lot. They won't be in the public part, but they hand it
out, if they have it (not for taking home).


There is more up-to-date information on the Web, however. If you can't
find
it yourself, let me know and I'll look.

I would be very glad if you name some links. I'm still on the clueless
side concerning the layout details of the machine.

OK, here are some photos and a little bit of description from a user:

http://www.geocities.com/eastpac01/spincasting.html

Here's some good info from a builder:

http://www.conquestind.com/spinCasting/FAQ.asp

Here's a photo of a vulcanized silicone mold for spincasting (there also is
a PDF'd article about it at this site). I see they're still using a
semi-solid silicone, rather than a liquid:

http://www.seybertcastings.com/spincasting_page.htm

Another site with written info:

http://www.ravensforgeminiatures.com/faq20413.php

Here's the company I visited and wrote the articles about 25 years ago. They
have instructional videos, etc.:

http://www.tekcast.com/inst.htm

That should get you started. These are the result of a Google search on
"spincast zinc" (without the quotes).



[precision]
I don't really know.

That sounds good enough. :-)


You're welcome, Nick. I wish I had more up-to-date information but the
last
time I looked things hadn't changed much.

That ain't the problem. I prefer having old/outdated information to get
the basic technique and then improve it. I do have an old book about die
(SP?) casting, but only for steel forms and also not for centrifugal.


Thanks so far!

Someone started to describe the dental/jewelry investment/plaster
centrifugal technique. That's good info, too, and I would look into that
method as well, if it were me. They use a more elemental type of centrifugal
machine for that work and you may get some ideas from it.

--
Ed Huntress

"JohnM" wrote in message
m...
Jeff Wisnia wrote:



The question tickled my memory, as I used to work at my dad's jewelry
manufacturing plant in the late '40s. We used the traditional spring
wound centrifugal casting machines to make lost wax castings of all
kinds of jewelry pieces in gold and platinum alloys. Our machines were
set in the center of big round galvanized iron washtubs to catch the
splatters if things went wrong.

Molds for those precious metals were made from a plaster like
"investment" material (Inside metal rings, like you mentioned, just
2-1/2" diameter by 3" long pieces of thin wall steel tubing.) and were
transferred with tongs to the machines and "shot" full of molten metal
while still hot from the wax "bake out" furnace, which IIRC brought them
up to a dull red heat. That helped avoid "cold shots" caused by the cast
metal chilling before it fully filled the mold.

Silicone rubber wasn't around then, but we did use rubber molds to
"shoot" the wax patterns in. Those molds were natural rubber vulcanized
in a heated press around a metal "original". They were carefully cut
open with an X-Acto knife to release the original and create the wax
mold.

Dad learned his jewelry craft in Germany BTW, circa 1918-1921, before
emigrating to the USA. His half-brother Leo was a Dentist in Dresden and
stayed their until dad helped him and his family get to the USA in the
nick of time in 1939.

Uncle Leo was also skilled in lost wax casting because back then most
dentists had to cast and finish their patients' bridgework themselves,
just like the jewelers did. He worked in dad's jewelry factory through
WWII and also did some unlicensed family dentistry in the apartment he
and his wife lived in. I think he treated almost everyone in the family.
I still remember him drilling away in someone's mouth using his foot
treadle powered drill with it's articulated belt drive system.

Leo once proved before my own eyes how he could make a lost wax cating
without a centrifugal machine by tying a cord onto the mold, melting the
metal in the sprue hole and then snatching that cord and whirling the
mold around his head in a circle. Wowza! That's something I'll never
forget, that and the time I saw a crazy physicist from Cornell
University toss down half a paper cup fill of liquid nitrogen, followed
by his emmiting the longest belch you could imagine.

Back on topic again, there's a quite good thread on the stuff you're
looking for running now on the HSM BBS:

http://bbs.homeshopmachinist.net/For...ML/011810.html

Jeff


Very cool stuff, Jeff. I like that mold-on-a-rope trick, never heard of
it before.

John

You'll see it described in some old casting books. It's dangerous but it
works.

Another dangerous trick that works, again from the jewelry business, is
"diecasting" precious metals into a plaster mold, using a wad of wet
newspaper for a diaphragm. You have a pool for the metal cast into the top
of the mold and a short and narrow sprue leading straight down to the mold
itself. You fold up about 1/2" of wet newspaper into an 8-in.-square wad and
soak it. When you pour the metal into the pool, you immediately lay the wad
of newspaper on top of it and slap it with your hand.

This is a good way to splatter molten metal onto yourself and suffer
permanent damage. My uncle was an expert at it. He wore a full-face o/a
welding shield, a leather welding jacket, and leather welding gloves. He
didn't used to, and he had some interesting scars as a result.

--
Ed Huntress

Ed Huntress wrote:
"JohnM" wrote in message
m...

Jeff Wisnia wrote:



The question tickled my memory, as I used to work at my dad's jewelry
manufacturing plant in the late '40s. We used the traditional spring
wound centrifugal casting machines to make lost wax castings of all
kinds of jewelry pieces in gold and platinum alloys. Our machines were
set in the center of big round galvanized iron washtubs to catch the
splatters if things went wrong.

Molds for those precious metals were made from a plaster like
"investment" material (Inside metal rings, like you mentioned, just
2-1/2" diameter by 3" long pieces of thin wall steel tubing.) and were
transferred with tongs to the machines and "shot" full of molten metal
while still hot from the wax "bake out" furnace, which IIRC brought them
up to a dull red heat. That helped avoid "cold shots" caused by the cast
metal chilling before it fully filled the mold.

Silicone rubber wasn't around then, but we did use rubber molds to
"shoot" the wax patterns in. Those molds were natural rubber vulcanized
in a heated press around a metal "original". They were carefully cut
open with an X-Acto knife to release the original and create the wax

mold.

Dad learned his jewelry craft in Germany BTW, circa 1918-1921, before
emigrating to the USA. His half-brother Leo was a Dentist in Dresden and
stayed their until dad helped him and his family get to the USA in the
nick of time in 1939.

Uncle Leo was also skilled in lost wax casting because back then most
dentists had to cast and finish their patients' bridgework themselves,
just like the jewelers did. He worked in dad's jewelry factory through
WWII and also did some unlicensed family dentistry in the apartment he
and his wife lived in. I think he treated almost everyone in the family.
I still remember him drilling away in someone's mouth using his foot
treadle powered drill with it's articulated belt drive system.

Leo once proved before my own eyes how he could make a lost wax cating
without a centrifugal machine by tying a cord onto the mold, melting the
metal in the sprue hole and then snatching that cord and whirling the
mold around his head in a circle. Wowza! That's something I'll never
forget, that and the time I saw a crazy physicist from Cornell
University toss down half a paper cup fill of liquid nitrogen, followed
by his emmiting the longest belch you could imagine.

Back on topic again, there's a quite good thread on the stuff you're
looking for running now on the HSM BBS:

http://bbs.homeshopmachinist.net/For...ML/011810.html

Jeff


Very cool stuff, Jeff. I like that mold-on-a-rope trick, never heard of
it before.

John


You'll see it described in some old casting books. It's dangerous but it
works.

Another dangerous trick that works, again from the jewelry business, is
"diecasting" precious metals into a plaster mold, using a wad of wet
newspaper for a diaphragm. You have a pool for the metal cast into the top
of the mold and a short and narrow sprue leading straight down to the mold
itself. You fold up about 1/2" of wet newspaper into an 8-in.-square wad and
soak it. When you pour the metal into the pool, you immediately lay the wad
of newspaper on top of it and slap it with your hand.

This is a good way to splatter molten metal onto yourself and suffer
permanent damage. My uncle was an expert at it. He wore a full-face o/a
welding shield, a leather welding jacket, and leather welding gloves. He
didn't used to, and he had some interesting scars as a result.

--
Ed Huntress



Yeow.. I'd like to see that done. What's the purpose? To ensure filling
a cold mold?

My favorite is a lost-wax process where the pattern is left in the mold
and the mold and casting material is enclosed in a clay egg.. Put it in
the fire with the mold up and you get the burnout, wait 'till the thing
is hot enough that you know your metal has melted and turn it over and
the metal enters the mold. That always seemed like a cool way to do things.

John

"JohnM" wrote in message
m...

Another dangerous trick that works, again from the jewelry business, is
"diecasting" precious metals into a plaster mold, using a wad of wet
newspaper for a diaphragm. You have a pool for the metal cast into the
top
of the mold and a short and narrow sprue leading straight down to the
mold
itself. You fold up about 1/2" of wet newspaper into an 8-in.-square wad
and
soak it. When you pour the metal into the pool, you immediately lay the
wad
of newspaper on top of it and slap it with your hand.

This is a good way to splatter molten metal onto yourself and suffer
permanent damage. My uncle was an expert at it. He wore a full-face o/a
welding shield, a leather welding jacket, and leather welding gloves. He
didn't used to, and he had some interesting scars as a result.

--
Ed Huntress



Yeow.. I'd like to see that done. What's the purpose? To ensure filling
a cold mold?

Yeah, it's good for items with thin sections and detail. It really puts some
pressure on the metal if it's done correctly.


My favorite is a lost-wax process where the pattern is left in the mold
and the mold and casting material is enclosed in a clay egg.. Put it in
the fire with the mold up and you get the burnout, wait 'till the thing
is hot enough that you know your metal has melted and turn it over and
the metal enters the mold. That always seemed like a cool way to do
things.

That's another interesing one. I wonder how many of these one-off casting
tricks have been lost in time?

--
Ed Huntress

On Sun, 29 May 2005 16:51:12 -0400, JohnM wrote:


Yeow.. I'd like to see that done. What's the purpose? To ensure filling
a cold mold?

My favorite is a lost-wax process where the pattern is left in the mold
and the mold and casting material is enclosed in a clay egg.. Put it in
the fire with the mold up and you get the burnout, wait 'till the thing
is hot enough that you know your metal has melted and turn it over and
the metal enters the mold. That always seemed like a cool way to do things.

John


I have seen it refered to as "Steam Casting" written up in all sorts
of books on jewelery making. There is a pretty in-depth explanation of
the process, and how to do it yourself (along with a bunch of other
interesting stuff) he

http://users.frii.com/dnorris/onlineclasses.html

-AL

""Nick Müller"" wrote in message
...
Hi

I'm thinking about wether I want a centifugal casting machine, mainly
for zinc and it's alloys.
There are machines available but unfortunately, they all want _my_ money
for _their_ stuff. I think that this machine is simple enough to be home
made.

But before I start, I'd like to know how big the parts are that I could
cast. E.g. size and weight.
Has anybody got experience with that?

Next step are the consumables (silicon, etc.) That ain't a problem, I
found suppliers. They give enough descriptions that I know what I need
and how to use.

Last step is building that little machine. Mechanically no problem, but
as far as I know, the commercial machines use rings (that keep the
silicon in place). And I haven't got that much clue how the ring is
fixed to the spinning disk etc. Has anybody photos/links/descriptions of
that setup?

Well, one thing remains: making the negatives. I know that I need some
special silicon (no problem), but do I really need a vacuum pump to get
the bubbles out? Or does this start yet another project: Build your own
vacuum pump?


Nuff questions for now, any input wellcome.

Oh! What I need it for? I want to cast small/decorative parts for model
engines. Lets say size is maximum 50mm for the biggest elongation. As
soon as my HP is up and running, you'll get an impression. But that will
take another week... (and is again a different project)

Thanks,
Nick


We built a spin caster in our shop and it works just fine. You
can get some ideas if you point your browser to
http://www.granthams.com/Spincast/ . There is quite a
difference between a centrifugal caster for lost wax
casting and this spin caster. We cast with vacuum assist,
centrifugal, spin cast and sand, and all have their place.

It's necessary to be able to change the speed for spin
casting. A broken arm centrifugal casting machine is
spring wound and slings the charge into the flask.

Spin casting in a rubber mold requires more attention
to venting. Our spin caster is variable from 0 - 900 rpm,
with most casting at about 250.

For zinc based alloys you may need to use silicone
vulcanized rubber to withstand the 700 - 900 degree F
heat. The RTV silicone we use holds up well for pewter.

And yes, most RTV silicone should be vacuum
degassed to remove the bubbles. However, it is possible
to let it stream into your mold from about 36" to remove
the bubbles.

Our spin caster cost about $100 using material laying
around the shop.

Have fun!

Rod Grantham
www.granthams.com/Projects

Ed Huntress wrote:

[lotsAlinks]

Thanks, very helpful!


Someone started to describe the dental/jewelry investment/plaster

Shure I've seen. But that's investment casting that I'm currently not
interested in.


Thanks again Ed!

Nick

--
"Wissenschafts"-Sendung auf einem der Privat-Kanäle:
"Der Behälter fasst 200.000 Kubik-Liter."
Wie viele Quadrat-Stunden braucht es dann wohl, um ihn voll zu bekommen?

Graphics wrote:

We built a spin caster in our shop and it works just fine. You
can get some ideas if you point your browser to
http://www.granthams.com/Spincast/ .

Great! Exactly what I was looking for!
Have a beer if you should visit the October-Fest in Munic. :-))


Thanks,
Nick
--
"Wissenschafts"-Sendung auf einem der Privat-Kanäle:
"Der Behälter fasst 200.000 Kubik-Liter."
Wie viele Quadrat-Stunden braucht es dann wohl, um ihn voll zu bekommen?