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CAD/CAM and CNC milling


#1

Hello,

I have worked quite a bit on a manual lathe and milling machine
(although I am definitely not a machinist or very computer savvy)
and relate to the method and design possibilities. Soon I will be
developing a production line and I have been considering CAD/CAM and
CNC milling to produce components.

I have a number of questions - many that have been partially
answered by following various threads on this topic. On two
occasions, to ascertain quality of production, I sent a machined
master to two different casters requesting that a rubber model be
made and 10 pieces be cast (in silver). Both batches came back with
different problems - wax distortion, excessive clean-up, air
bubbles, etc. that resulted in excessive clean-up. These
experiences have made me question the ability to job out work and
receive the quality that I require.

I don’t really want to set up my own casting facility at this time.
My thinking is that I could produce individual waxes using a CNC
mill and then send them away to be cast - presuming that a completed
wax sent to a caster would fare better in regards to quality
control.

What are others experiences or thoughts?

As well, I have heard varying thoughts on Model Master - the steep
price tag as well as ease of use. Any thoughts? Keep in mind that I
am unlikely to be very adept at configuring a system from scratch.

Thanks so much and I apologize for this log-winded missive.

Donna Hiebert


#2
I sent a machined master to two different casters requesting that
a rubber model be made and 10 pieces be cast (in silver).  Both
batches came back with different problems - wax distortion,
excessive clean-up, air bubbles, etc. that resulted in excessive
clean-up.  These experiences have made me question the ability to
job out work and receive the quality that I require. 

It’s possible that some of the problems may be due to the design of
your prototypes themselves. some designs are very difficult to inject
without air bubbles in some areas of the piece. If you are not
familiar with the principles of casting, the design of your pieces
may be contributing to porosity in some areas of the castings.

I don't really want to set up my own casting facility at this
time. My thinking is that I could produce individual waxes using a
CNC mill and then send them away to be cast - presuming that a
completed wax sent to a caster would fare better in regards to
quality control. 

I am using a Taig mill. Most of my designs take several hours or
more to mill. It wouldn’t be economically practical to do production
volume waxes with a milling machine uunless the retail prices of the
pieces were many hundreds of dollars apiece. I do quite a few one-off
pieces on my mill but add $100 or more to the price of the work for
milling the wax. I think others may charge more than this for milling
but my studio is in a fish processing plant… Another problem with
doing production waxes on a milling machine is that you would have
to use a high resolution in the milling in order to reduce the
finishing time. This would make the milling of each piece slower
again.

As well, I have heard varying thoughts on Model Master - the steep
price tag as well as ease of use. Any thoughts?  Keep in mind that
I am unlikely to be very adept at configuring a system from
scratch. 

I use Rhino for CAD, Desk Proto for my CAM and a CNC Taig machine
for milling. The Taig machine isn’t pretty but it’s accurate, rugged
, dependable and inexpensive. The system worked beautifully right out
of the crate. The snag is the software, not the milling machine. I
probably spent a hundred hours doing tutorials in Rhino before I was
happy with the models I was producing. ArtCam and some of the other
expensive software are probably a lot easier to learn but cost maybe
ten times as much.

cheers, Robert Hood


#3

Donna; If all ten pieces were made from the RTV mold, which should
be the first step then any imperfections, Tool lines or artifacts
will show up in the resulting castings, as far as entrapped air
bubbles, that’s a bad casting pure and simple, same with the
distorted waxes. I have been getting waxes done from two sources, one
source CAN do a decent job when they feel like it, The other source
is sending me wax patterns that are almost perfection, First let me
say that I don’t like to use RTV molds for production runs.

I would rather cast one or two pieces from the RTV mold then Finish
them Remold them into Vulcanized Silicone and get a wax pattern that
when cast requires Very little clean-up.

My main concern is that RTV molds do not last near as long as
Vulcanized Rubber or Silicone, then there is the trade off of the wax
looking as though it had been polished and buffed (silicone) or the
mold lasting For many many years. I’ve been using Castaldo High
strength Silicone for the past 7 or 8 years, and the molds are still
good.

I have a few made from Castaldo Econo-sil that are a bit older than
that, and they are still serviceable, But they haven’t had the use
that the High strength molds have. I have used the No Shrink Pink,
and it’s OK I’m not exceptionally crazy about it, the molds that I’ve
done with it are at least 12 to 15 years old But they don’t have the
finish quality that the silicone molds do.

And I have several hundred Natural Rubber molds , most are Castaldo
White label since I don’t do a lot of rings, some of these molds
have had over a thousand pieces run through them.

Yes there will be a SLIGHT shrinkage to deal with I guesstimate
about 4 to 8 percent, a lot of this is dependant on the quality of
the CAM wax, which gets back to your other question about Jewelsmith
and it’s horrifying cost.

I think if you can afford it, the software is one of if not the
best. As far as the cost of their mill, I think it’s a bit too steep,
It’s very good equipment, but WOW I don’t think that it will do much
that any other good mill will.

And for around 3,000 dollars you can get a very good closed loop
milling machine with Servo motors instead of stepper motors, that
will run Jewelsmith quite well.

You still need a Cam program AND THERE AGAIN Delcam has one of the
best with Mill Wizard.

There is a relatively new program I’ve been trying to find out about
from a French Company Vision Numeric, called 3Design>jewel. I’ve
been trying to get a price from them for the past week but I guess
they don’t want any American Currency, either that or they are on one
of those Long holidays I keep hearing about.

From what I’ve been able to find out it is Very much like ArtCam
Jewelsmith, and I think (ok insert funny joke here) it’s about half
the price.

This puts it in the same price rage as Jewelcad and JewelSpace 3D.
But Neither of these are as easy to operate as ArtCam Jewelsmith.
I’ve heard that it is by far the best and most intuitive program on
the market.

Kenneth Ferrell
www.shadras.com


#4

You are in the same position of many people who are getting started
in the CAD CAM side of our industry. As a service bureau, we run
several different software and use a few different output machines
because one software or one output does not always meet the needs of
different designs. One of the main questions here is what is your
budget? If you have unlimited capital, then the answer is easy, get a
few different programs and a mill and a printer. Like most of us
though, budget is a concern. Here is how I would recommend that you
proceed.

Learn a software first, I will get the agent for gemvision/ matrix
for you in your country and I will help you find a service bureau in
your country. Then you can try various output methods such as milling
and printing before you commit to a large investment.

Matrix is a library for Rhino, its very good and I believe it is
worth the money at about $8000 The Matrix rep is Bill letwin
www.letswinconsulting.com He can answer questions on Matrix. But
there is a much cheaper alternative that will get you started and do
just about everything that Matrix does. Also there should be some
local classes in rhino at community colleges in your area. Check out
Rhino at http://www.rhino3d.com/jewelry.htm The least expensive way
to get started is by getting Rhino and Flamingo with techjewel check
out http://www.techjewel.com/Ingles/techjewel.htm

Please be aware that milling cannot do everything, sometimes you can
cut a part in half to hollow it, but in general undercuts are not
easily done unless you do a flip that is two sides and then a rotary
cut. Milling is great, we run artcam and a modelmaster mill it is not
as quick nor as easily done as printing.

email us again with any questions

Thomas Cavagnaro, GG
Cadsmithing, LLC
480 688 4136
cadsmith@cox.net
www.cadsmithing.com


#5
On two occasions, to ascertain quality of production, I sent a
machined master to two different casters requesting that a rubber
model be made and 10 pieces be cast (in silver).  Both batches came
back with different problems - wax distortion, excessive clean-up,
air bubbles, etc. that resulted in excessive clean-up.  These
experiences have made me question the ability to job out work and
receive the quality that I require. 

Could it be that these masters were extremely difficult to cast?
Usually professional casters will do a better job than one can hope
to achieve by doing it oneself. But a thorough knowledge of the
molding and casting process will enable one to design pieces that are
more suitable, and come out better. Extremely thin planar pieces, for
example, tend to distort on unmolding. Some configurations with deep
pockets will catch air no matter how they are placed in a mold. Big
differences in thickness will lead to shrinkage porosity. Maybe you
could, in a non-confrontational way, ask the casters what you could
have done differently to make things work better.

    I don't really want to set up my own casting facility at this
time. My thinking is that I could produce individual waxes using a
CNC mill and then send them away to be cast - presuming that a
completed wax sent to a caster would fare better in regards to
quality control. 

You would avoid the distortions and cleanup associated with the
rubber molding and wax injection process. But making each wax pattern
individually would be more work, even if you have a CNC machine.
Also, the carving wax used for CNC work casts differently than
injection wax - make sure the casting service you use is willing to
use a different burnout cycle for your pieces. However, once you got
good casts from your parts, you could have rubber molds made from
them - remember to calculate the shrinkage factor, if they have to
accept standard stones.

    As well, I have heard varying thoughts on Model Master - the
steep price tag as well as ease of use. Any thoughts?  Keep in mind
that I am unlikely to be very adept at configuring a system from
scratch. 

It’s an excellent system if you can afford it, but it’s not the only
way to go. Roland, for instance, makes some versatile machines that
are capable of highly detailed 3d scanning as well as CNC carving,
which make it easy to model a sculptural part at a comfortable scale
in wax or clay, scan it, and carve a part reduced to the size
required, or to generate a left-facing part from a right-facing one.
They come with all the software required for scanning, milling, or
toolpath generation, although you still might want a CAD program for
design purposes. Taig mills are another alternative you might look at

  • they are very robust machines for their size, capable of cutting
    molds directly into steel, or of cutting positive models in wax.

Andrew Werby
www.computersculpture.com


#6

Kenneth, I am glad to see that your enthusiasm is growing for the
technological arena of CAD/CAM. Keep it up.

    There is a relatively new program I've been trying to find out
about from a French Company Vision Numeric, called 3Design>jewel.
I've been trying to get a price from them for the past week but I
guess they don't want any American Currency, either that or they
are on one of those Long holidays I keep hearing about. 

If you were calling France, then your would have been
forwarded to the USA Corporate offices. Here are the details.

	Cathy Mendelsohn
	Sales & Marketing Coordinator
	Vision Numeric USA, Inc.
	3379 Peachtree Rd. NE, Suite 260
	Atlanta, GA  30326
	Tel:  678-904-2909
	Fax:  678-904-2908
    From what I've been able to find out it is Very much like
ArtCam Jewelsmith, and I think (ok insert funny joke here) it's
about half the price. This puts it in the same price rage as
Jewelcad and JewelSpace 3D. But Neither of these are as easy to
operate as ArtCam Jewelsmith 

I don’t see where there might be a joke to insert regarding price.
Solidworks was the first program to break the price barrier, where
programs such as ProE and Catia where 5-12 times the price with
annual maintenance running more than the cost of Solidworks as a
package. Rhino is another example of where price was a major
consideration, and for the money and putting aside the learning
curve, it is very hard to beat for what it was designed to do.
Therefore, if the price grabbed your attention, then seriously look
at the power that 3Design offers, because you will be laughing all
the way to the bank. When you see it in action, there is a very high
probability that you may ammend your thoughts on that note.

    I've heard that it is by far the best and most intuitive
program on the market. 

That debate is wide open. Every single one of us have our fav
programs, and everyone has an opinion on which is the best and why.
All I will say about this, is that individuals need to see things in
action before coming to a conclusion based on what they hear :slight_smile:

I would never say that ArtCam and JewelSmith are not solid
solutions, because that would be untrue, but there’s more to this
than meets the eye, in that familiarity of name recognition is a big
plus. Take a good look at 3Design, and then see how they stack.

3Design is an extremely well priced tool with a tremendous amount of
power. It is a parametric driven solution, which means that you can
draw free form, or have the geometries dimensionally driven. The
whole platform was designed from the bottom up specifically for the
Jewellery Industry, utilizing Kernel, Parametrics and full
associativety of its geometries and surfaces, which is very important
for things to update automatically and to update in the correct
proportions.

Artcam has the edge on Type3, not as a solution, but name
recognition. This is because, Model Master did a great job on
marketing the solution here in the US and Type3 is just beginning its
focus on marketing the US. Name recognition is half the battle, and
is, in all essence, why more people know about Artcam than Type3.
Having said that, Type3 is huge in Europe and in Asia and the US will
see more of its power as time goes by.

Best Regards.
Neil George
954-572-5829


#7

Neil Thank you for the I had found it myself this
afternoon. I plan to call them Monday. My reference of “insert funny
joke here” was not toward any software, it was in reference to the
fact that ‘I think’! I found out about 60 years ago I shouldn’t take
my self too seriously. (I’ll email you the story off line, and I
think you’ll see what I mean),

I do think they should do as most of the computer peripheral and
hardware companies have done, and put links to their
regional/international offices or representatives! I was about to
give up on finding any thing about their software, and as I said from
the small bits that I have heard, it’s very good, and if the price is
better, that’s even better.

Thank you though for the I appreciate the help (do I do
another insert joke here line or just leave well enough alone) Oh
what the heck "So his wife stands up and says if you’re a trained
therapist then you can help him "

Thanks, I genuinely do need and appreciate all the help I can get.

Kenneth Ferrell
www.shadras.com


#8
    I do think they should do as most of the computer peripheral
and hardware companies have done, and put links to their
regional/international offices or representatives! I was about to
give up on finding any thing about their software, and as I said
from the small bits that I have heard, it's very good, and if the
price is better, that's even better. 

Kenneth,

They do have that It is under contact us, which calls up
a location option which then allows you to select your location from
a world map. I enjoyed our brief discussion this morning, and on that
note, feel free to get in touch any time you need any assistance.

Best Regards.
Neil George
954-572-5829