"Stupendous Man" <sp...@trap.com> wrote in message
news:6e5f5nF...@mid.individual.net...
> I am considering making some parts from 4130 streamline tubing, (the
> smallest, .030 wall) and would like to bend it into gentle curves. It looks
> like sand bending may be the way to go.
> Has anyone done this? What method did you use?
> I'm not using it for aircraft, so it doesn't have to retain all of it's
> strength, but I don't want any crushes.
Cerrobend is a low temp bismuth alloy used for bending thin wall tube.
It melts in boiling water.
Dang you are the man. Although I found the reference to Field's metal even
more interesting.
"Field's metal, or Field's alloy (named after Simon Quellen Field), is a
fusible alloy that becomes liquid at approximately 62 蚓 (144 蚌). It is a
eutectic alloy of bismuth, indium, and tin, with the following percentages
by weight: 32.5% Bi, 51% In, 16.5% Sn.
As it contains no lead nor cadmium, it is a non-toxic alternative to Wood's
metal.
It is used for die casting and easy prototyping."
Melting temp of 144F. Dang. I think we could just set out in the sun
(maybe in a black pan) here in the desert and it would just run right out.
If not, I'm sure I could put it in the attic of one or two of the house I've
had the misfortune of pulling wire in during the summer.
http://www.kindt-collins.com/catalog_pdfs/88-89.PDF
http://www.freemansupply.com/DuplicatingWhiteMe.htm
Now that is some cool stuff. The immediate thing that comes to mind is
making two (or more) piece molds. Use two different melting point alloys.
Pour the hotter one first. Drill in alignment pins, spray with a non stick
agent, and then pour the lower temp over the blank and first piece. If you
have any issue with pouring you can just machine in some vent grooves in
either piece afterwards. Because both are relatively low temp alloys you
could hand carve your blank out of wood, or even piece it together and just
glue the pieces to make your blank. Need a smooth surface? Just over pour
the first piece and mill flat before pouring the second piece.
"Bob La Londe" <nos...@nospam.no> wrote in message
news:g5o903$3a2$1...@registered.motzarella.org...
Geez, and the obvious... If a mold becomes outdated you just melt it down
and use the material again.
The melt temps are so low, you can mold off wooden parts, or use mass
casting plastic tooling resins.
A good release agent for pouring the low temp metals, is acetylene soot.
Turn on the acetylene only, adjust until blowing some good black smoke, and
flash the area to be molded.
Yep used to use smoke on bullet and jig molds a long time ago. If I was in
a hurry between runs I used PAM unflavored cooking spray too.
http://www.gizmology.net/fusiblemetals.htm has a good list of
compositions and melting points of several dozen low-temp
alloys.
This might not be relevant to your idea, but note that Styrofoam is
easier to cut than most wood and is commonly used as a mold for
Lipowitz Metal (Cerrobend).
Eg http://www.jrtassoc.com/rad_oncology/mold_room/index.html sells
melters, alloy, automated mold cutters, etc. into a high-priced
medical market. A typical radiation therapy block uses around 5
pounds of Cerrobend.
-jiw
Depending on thickness and complexity, yes.
But if you can live with a higher melting point, kirksite is more popular
for short run aluminum forming tools.