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CNC cutting


#1
Use WD40 as the cutter lubricant. It washes away and leaves a nice
clean surface. I will cut the tool path twice sometimes but mostly
with my plastic. WD40 is the key.  

I would think that WD-40 works, but wouldn’t you have to stand there
over the part and re-spray it several times over the course of cutting
a complete model, as it absorbs into the milled shavings? I guess it
depends on the size of the part. and how much you initially spray.

Lately, I’ve been diluting a concentrate of a water soluable
coolant/lubricant made especially for machining,. I’m not sure it
works much better than regular Windex. I’ve devised a makeshift drip
system out of a covered plastic travel coffee mug, some plastic
tubing and brass valve I purchased at Home Depot. It works
surprisingly well! I can control the flow of the wash from a slow
steady drip to a constant flow, right over the cutting area. I have a
tray to catch the overflow so I can filter the debris out of the used
liquid and recyle it.

Last week one day, I milled 4 two sided models for one client. They
all happened to have tiny lettering, so I had to use a small cutter,
which takes extra time. I also milled a ring that day. With the
windex drip coolant and a light scrub with a toothbrush, they cleaned
up fine. I don’t mean to dispute the efficacy of milling a part twice
to clean out the shavings, but when I have to get work delivered,
milling twice would “gum up” my workflow. :slight_smile:

Model Master’s new CNC mills are accessorized with an automated
coolant system. They also have a product called Hotblock which is
silicone moldable and a composite material called Alumilike which has
the utility of a metal mold but cuts easier, can be plastic injected
and holds a sharp edge.

I  do not cut brass or any metal. It's not necessary. I'll either
cast the wax and mold it, or cut plastic part and mold that. > 

Milling wax and plastic may be good for one-offs and limited
production runs, but over time and repeated use, does a silicone mold
hold the detail and crispness needed for class rings and logo type
jewelry with lettering?

I'm skeptical of those who don't make jewelry yet claim expertise.
I have a new motto about CAD CAM also. "Don't design beyond your
ability to execute." This goes for anyone doing jewelry CAD. Show
me the finished jewelry!! Virtual jewelry is a pretty picture but I
want more 

I agreed with that up until last week, when I found out a CAD
modeler I know, has never worked at the bench, yet he has a pretty
decent (and evolving) sense of jewelry construction from years as a
jewelry salesman. So, I guess it’s hard to make generalizations about
these things.

My experience has been hands-on in custom design retail environments
where if it wasn’t practical or saleable, it didn’t get made. I
worked for someone who has impeccable production-oriented standards.
I used to resent it because I felt it limited my creativity. I
envied jewelers who had art school training, where the emphasis
included stretching the boundaries of conventional jewelry design.

Now, I’m grateful for every silver prototype that ever got kicked
back to me for not being mold-worthy because I apply the same exacting
standards to the CAD work I do for my clients. (Sometimes, I even get
it right, they tell me) :wink: For my own personal satisfaction, I
experiment by modeling the fantasy pieces that I was denied the
opportunity to make at the bench, so, perhaps it all works out in the
end!

Occasionally, I will take a production oriented CAD model and
post-process it strictly to create a nice rendering for my website. In
the CAD program, I’ll shape prongs over a stone or soften the severe
edge of a part that would be polished to a more rounded shape or
even model a bezel down onto a stone, just to make a pretty picture.
It may be superfluous, but I enjoy the creativity of it. I’ve worked
hard to gain the skill to render photo-realistic virtual jewelry
images, and besides, it’s a lot of fun!

Jesse Kaufman
CAD/CAM Technology
Handcrafted Originality
www.jdkjewelry.com


#2
    I would think that WD-40 works, but wouldn't you have to stand
there over the part and re-spray it several times over the course
of cutting a complete model, as it absorbs into the milled
shavings? I guess it depends on the size of the part. and how much
you initially spray. 

We buy WD40 in a gallon can and use a small drip at a time with the
coolant system we added. I suppose it is the same style as the Model
Master system. Again the best I’ve found and the most convent and
economical to use.

    Milling wax and plastic may be good for one-offs and  limited
production runs, but over time and repeated use, does a silicone
mold hold the detail and crispness needed for class rings and logo
type jewelry with lettering? 

I have been using Dow Corning Silastic Silicones since 1977. The
molds do not wear out. I don’t make thousands of a number, but in the
hundreds range you can’t beat them. I compare all silicones to the
Dow Corning Silicones. There are three different harnesses available.
All with excellent working properties. Somewhat had to find though.
Plastic model tooling is my solution for the small to mid range
manufacturer (me). If I need to make 100 of a ring, my cost factor is
down low enough to be profitable. I can have a profitable ring sale
at $40.00 to $100.00 also. With my model and mold costing out below
$25.00.

    I agreed with that up until last week, when I found out a CAD
modeler I know, has never worked at the bench, yet he has a pretty
decent (and evolving)  sense of jewelry construction from years as
a jewelry salesman. So, I guess it's hard to make generalizations
about these things. 

I am learning Matrix this year and hope to add even more options to
my teaching and model making skills. But I do look at things
different than a purely CAD operator.

    Occasionally, I will take a production oriented CAD model and
post-process it strictly to create a nice rendering for my
website. In the CAD program, I'll shape prongs over a stone or
soften the severe edge of  a part that would be polished  to a more
rounded shape or even model a bezel down onto a stone, just to make
a pretty picture. It may be superfluous, but I enjoy the creativity
of it. I've worked hard to gain the skill to render photo-realistic
virtual jewelry images, and besides, it's a lot of fun! 

I’d love to see some finished jewelry photos. Any available?

Best Regards,
Todd Hawkinson
www.ajt-online.com


#3
I  have been using Dow Corning Silastic Silicones since 1977. The
molds do not wear out. I don't make thousands of a number, but in
the hundreds range you can't beat them. I compare all silicones to
the Dow Corning Silicones. There are three different harnesses
available. All with excellent working properties. Somewhat had to
find though. 

Todd, there are some nice rings on your website. Obviously, you have
a lot of experience with mold making.

I’d like to know more about the differences between silicone and
metal molds, as well as the limitations and benefits of.each method.

When you are doing rings in a quantity range of 100’s, with your
system’s reliance on silicone molds, do you find that jewelry with
the small highly raised lettering typical of class rings and logo
jewelry, waxes up and casts with as much accuracy and success as
rings with small recessed lettering? I ask this because I recently
made a medallion with a lot of small raised lettering. It was about
the size of a half-dollar, cut in wax and silicone molded. The
customer also wanted a version 30% smaller… it was determined that
it would be better to cut a metal mold so that the small raised
lettering would be sure to cast up properly.

What’s your take on how metal molds compare with silicone in terms
of fineness of detail and repeatable successful casting of signet,
logo and medallion styles? Accordingly, when designing these styles
intended for silicone molding, does one have to compromise a bit on
small raised features in general? Besides high production runs, in
what other circumstances would it be favorable to use a metal mold?

I am learning Matrix this year and hope to add even more options
to my teaching and model making skills. 

I’m assuming from the work on your website that you now use Rhino
and ArtCAM and/or Cimigrafi, You’ve already got some sophisticated
modeling abilities, so it will be interesting to see how it enhances
your work.

Rhino’s workspace is very customizable. I made a custom rendering
toolbar with an assortment of tools and automated scripts gathered
from some very talented people on the Rhino newsgroup. It makes the
rendering process flow much easier. I can email it, if you’d like to
try it out… Also with the help of the NG, I’ve created jewelry
specific materials and textures, and learned some simple rendering
techniques in Rhino/Flamingo that seem to work reasonably well. I
made a few tutorials of my program settings with step-by-step
screenshots that I’d be happy to share with anyone interested.

I'd love to see some finished jewelry photos. Any available? 

The image of the pendant on a chain with an oval diamond and pave
work around it, is a photo. It was a collaborative project created
with a jeweler during a training session. I think it was his very
first piece designed with CAD.

I also have a photo of a platinum ring, courtesy of Aron Suley of
Jewel Genie Inc., a colleague who also uses the Model Master CNC
system. http://www.jdkjewelry.com/products/fixtures-ring.html

I’m planning to post photos of my work an illustration of the step
by step process from CAD-to wax-to finished piece. So many projects,
so little time!

Best regards,
Jesse Kaufman


#4

Dear Jesse & All, I made metal molds commercially from 1978 through
1985 or so. The price back then started at about $450.00. I can still
make them but the price would have to be over $700.00. They take a
good day to make. With care they will last forever. The material is a
lead like product that has some safety concerns. One style of mold
requires a master pattern to pour the molten metal around. This part
is the blank or model for all production. Another option is to tool
blank metal parts, creating a cavity for the wax or plastic to inject
into. Both methods produce an excellent product that holds a lot of
detail. The ring mold blanks are usually one or two styles that have
the design tooled into the side. Class rings are the example.
Josten’s and ArtCarved make their class rings this way. The master
rings are still hand made in many cases.

The down side of metal molds is the COST! Plenty expensive to set up
between the blank material cost or mold frames (usually custom made).
Tooling machinery is expensive. Holding fixtures also usually have to
be custom made to tool the parts. A metal mold will usually make just
one design. Although I have made hollow ring molds from one outer
master design allowing solid back, hollow back and hollow shoulder
waxes from the same mold. Care must be maintained because if you drop
a part it may not fit back together again. A metal mold is like a
small metal puzzle that actually pulls of the injected wax or
plastic. No undercut off the model will work.

High pressure injection is also required for the best injection and
detail. The Muller Phipps vacuum wax injector is the industry
standard.

    I'd like to know more about the differences between silicone
and metal molds, as well as the limitations and benefits of. each
method. 

With my method the silicone injects a part I feel superior to the
metal for several reasons. First is the cost. A silicone insert in my
mold shell system cost about $4.00. The shell is reusable for any
design the size of the finger hole. I make the finger holes in whole
and half sizes. The blank plastics are also very affordable.

Second for detail, the mold injects everything on the model.
Injection is also done under about 25 psi to deliver the best detail.
I usually clamp the mold onto a Yasui wax injector and leave it on
for about 25 seconds. The part dries with no shrink. In fact if I
were to measure I would bet because of the pressure my parts may even
be one or two percentages larger. Tooling small raised letters may
work better being reversed if possible on some design. But I am happy
with my results.

I usually tool a model for molding with my process so I have blank
plastic parts with surface files that are imported to any surfacing
software and detailed. I use ARTCAM as well as Cimigraphy. I’m hoping
with the Gem Vision folks now selling a CNC mill, my surfacing ideas
will work with 3d design & Matrix.

    What's your take on how metal molds compare with silicone in
terms of fineness of detail and repeatable successful casting of
signet, logo and medallion styles?  Accordingly, when designing
these styles intended for silicone molding, does one have to
compromise a bit on small raised features in general?  Besides high
production runs, in what other circumstances would it be favorable
to use a metal mold? 

The detail tooled in plastic is impressive. The last time I saw
samples cut by the Model Master folks they had a lot of highly
detailed plastic masters as sample models. My molding process would
reproduce these plastics exactly. The manufacturing process that
follows would require experience also. Even Josten’s doesn’t polish
the detailed sides of their rings anymore. They steel shot burnish
them.

I also prefer to inject wax and not plastic. Plastic is harder to
burn out and cast. The shrink on most plastics is unacceptable also.
It all depends on the model and what you are trying to make. Metal
molds are required for many products. Silicone, for me is more
affordable and allows me a quicker turn around time for product.

Again, I would love to see anything finished from a CAD origin.

Best Regards,
Todd Hawkinson
www.ajt-online.com


#5
I'm skeptical of those who don't make jewelry yet claim expertise.
I have a new motto about CAD CAM also. "Don't design beyond your
ability to execute." This goes for anyone doing jewelry CAD. Show
me the finished jewelry!! Virtual jewelry is a pretty picture but
I want more... I'd love to see some finished jewelry photos. Any
available? 
again, I would love to see anything finished from a CAD origin. 

Dear Todd,

Your third request for photos has certainly gotten my attention. I’m
sorry if I wasn’t clear in my previous attempts to answer you.

Because of a carpal tunnel injury, I made a transition three years
ago from working exclusively at the bench, to my current business,
which is CAD modeling and prototyping using a CNC mill.

I’m finding it rewarding, fun and exciting to focus on this
particular aspect of jewelry creation at this time in my career.

I primarily design and mill models for the trade. Most of the time,
I’m call upon to interpret their designs in CAD for manufacturing, so
I usually provide a prototype only. I don’t see a lot of the finished
jewelry, so I can’t take pictures of it, but regardless of that, out
of respect for my customers I don’t publicly display their exclusive
designs.

The images on my website are meant to show a variety of design
possibilities, but unfortunately, I can’t show renderings of some of
my favorite pieces, because of signed non-disclosure agreements with
clients.

I also work with a few casters and bench jewelers to whom I
out-source work for private clients who contact me through my website,
through local contacts, and by word of mouth.

One of my primary goals is to provide a prototype that can be easily
manufactured and finished. I get a good share of repeat business, so
I trust that my customers are satisfied with the work. I’ve become a
little more selective in what I’ll take on, but I’m still open to new
design challenges and I’m constantly learning new techniques.

I’m going to cast and finish some of my own designs to bring to the
upcoming MJSA show in NYC. Then, I can finally take the pictures
you’ve requested.

Your interest in my work is very flattering considering I’ve only
been doing CAD a relatively short time and you have many years of
experience.

If you plan to be at the show, please stop by the Model Master
booth to visit. I love discussing CAD/CAM jewelry and I’m always
interested in learning more.

Best regards,

Jesse Kaufman

JDK Jewelry Design
CAD/CAM Technology
Handcrafted Originality
www.jdkjewelry.com