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Graphite pencil Leads


#1

I used to inject wax around graphite pencil leads in order to cast
long cheniers. About 15 years ago the makers of pencil leads switched
to a clay-like substance that unfortunately disintegrated in the burn
out. I have looked in vain for a replacement since and was wondering
if anyone knows where to buy pure graphite leads. 1 mm would be the
best size. Thanks

Dennis Smith - thejewelmaker


#2

The local engineering supply house here carries them in a wide array
of size and hardiness so I would check with your local supply house
if you can do fine them I will be more then happy to send you the
contact for our local supply houses we use them for
temporary hinge pins while soldering the tubing

Rodney Abel


#3

I Googled pencil lead and found loooots of info on the subject. One
of the most complete was Wikipedia which gave the complete history of
pencil lead. Following as a quote from that entry:

“Even though the natural deposits of pure graphite are tapped out,
it is still possible to write the way Englishmen did centuries ago,
without clay or wax additives leaving oily stains on paper. Chemical
supply companies commonly sell 99.995% pure graphite rods in 3 mm and
6 mm diameters”

I would expect you will also find on smaller dia of pure
graphite rods. I didn’t have the time to check.

Cheers from Don at the Charles Belle Studio in SOFL where simple
elegance IS fine jewelry!


#4

Dennis - I too, used to use graphite pencil leads, until they changed
the recipe. Now, I use a surgical stainless steel from
smallparts.com. I don’t have the stock number handy, but let me
know, and I can get it for you. One important tip if you use it,
though, is to give the wire a twist before investing. If you don’t,
you will have a heck of a time removing it from the casting.

Kindest regards,

Stuart J. Adelman, Designer
www.ArtelleDesigns.com
763-559-0044


#5

I have had great success in buying drafting leads ove rthe years as
companies sold out try auctions for vintage pencil leads $10 can get
you a nice asst :))

teri
Silver & Cameo Heritage Jewelry
www.corneliusspick.com


#6

Hi Dennis,

I used to inject wax around graphite pencil leads in order to cast
long cheniers. About 15 years ago the makers of pencil leads
switched to a clay-like substance that unfortunately disintegrated
in the burn out. I have looked in vain for a replacement since and
was wondering if anyone knows where to buy pure graphite leads. 1
mm would be the best size. 

20+ years ago, I worked in a gold jewelry factory for a few years as
modelmaker/moldmaker/supervisor, and we used old drill bits for the
inside of tubing for hinges. We had little silver knobs that we
attached as handles, in fact.

Thanks for the trip down memory lane.

Cynthia Eid
http://www.cynthiaeid.com


#7
I wanted to get something cast that had tubes through which a
chain would pass.  Since I wanted a mold made so I could have lots
of them I thought sticking something in place before molding and
before casting would solve my problem.  The caster said they used
to use graphite to do that (so I knew the idea I had "invented"
was nutso) but that the graphite had lost quality and was sticking
inmetal.Well, I got an idea to ask about ceramic rods.  I wrote to
a few manufacturers and I am enclosing an excert from a reply that
I got.  I'd like ya'll to chew on this, toss it around and let
everybody else know what you think. 

I have a few options for you. Precious metals will not adhere to
the majority of ceramic materials. The problems you will encounter
are thermal shock and the low thermal expansion coefficient of the
ceramics relative to the metals. That said, I can offer three
materials that I believe will survive the application. Aluminum
oxide, mullite and boron nitride. Aluminum oxide and mullite must be
cut with an abrasive diamond wheel. The boron nitride can be cut
with a knife. Of the three, boron nitride will be the most thermal
shock resistant, followed closely by the mullite and the alumina a
distant third. Fortunately for you, the geometry is small so I think
all three would survive the application. If you are concerned about
reuse and mechanical strength, the alumina is strongest with mullite
a close second. Boron nitride is significantly weaker. Thermal
expansion may be a problem even with the small diameters. Once the
metal reaches solidus, it will shrink faster than the ceramic thus
becoming locked into the metal ring. Geometries may be small enough
that this is not a problem or you can pull out the ceramic shortly
after solidus is reached.

As an alternative, have you considered the use of coatings on a
steel pin? If you have an acetylene torch about, try making a rich
flame and depositing carbon onto a metal pin and use it. Carbon and
graphite are remarkably good release agents. Acheson colloids sells
graphite laden liquids that can be painted on also. You might try
your local weld shop and see if they sell a braze stop-off. The
stop-offs are ceramic powders in a vehicle designed to stop the
adherence or flow of braze alloys. They are readily available in a
number of forms from multiple sources. You can also obtain a boron
nitride spray from us with outstanding release characteristics.

I like the fact that several options seem reasonable.

Even with ideas to solve the chain channel problem, the two
commercial casters I talked to did not want to get involved with the
project (piece too large) in fine silver.

Enjoy - Justine