RE: clear aorta model

From: Blasch, Larry (
Date: Tue Mar 11 2003 - 19:06:13 EET


Is this a one time project or do you expect to be making these as regular

If you expect to be doing this repeatedly, the latex lay up process may
provide inconsistent results.

>From your description of the item it sounds like you may want to contact
someone who can produce an extrusion using a variable orifice to create the
part(s) directly.

We use blow molding vendors that extrude variable profiles which are then
blown out into a mold. the end result is a part with substantial
shape/angle/thickness variation over the length of the part. They can
control the extrusion process very precisely. None of the molders that I
work with do prototyping, they use the process for volume production, but
there may be someone out there doing prototypes.

Another idea, since it sounds like you need the hold the interior dimensions
of these items, you may be able to create the core as an RP part, and slip a
heat shrink tube (electrical insulation supply) onto the core and shrink it
on with a hot air gun. This is readily available at most electrical supply
houses and is commonly made of Teflon. It may not be flexible enough, but it
will assume the shape of the core quite nicely. It comes in various sizes
and each size only shrinks so much, but you may be able to piece the part
together with overlapping sections. Depending on the RP core material, you
could dissolve or break the core out of the post shrunk shape.

Larry Blasch
Design Engineer
CAE Systems Administrator
OPW Fueling Components
P.O. Box 405003
Cincinnati, OH 45240-5003 USA
Voice: (513) 870-3356
Fax: (513) 870-3338


-----Original Message-----
From: []
Sent: Tuesday, March 11, 2003 9:08 AM
To: Doug Groh;
Subject: Re: clear aorta model


Thank you for the reply. I had thought of making a mold with an investment
core to make the part in a flexible silicone or urethane.
Two problems I foresee are,
     1. registering the core in the mold. Buttons about .1" dia. could be
used for this,
     and filled later while the silicone is still fresh.
     2. Filling the mold. With a wall thickness of about .05" and a 22"
     the odds of getting an air void seem too good.
I am now leaning towards brushing on a clear latex over a thin wall
investment. My wall will not be perfectly uniform, but I definitely will
not have voids. My unknowns are; tear strength, and clarity of the latex.

Don A. Smith
Technology Resources
Baxter Healthcare Corp.
Rt 120 & Wilson Rd. - RLP-30
Round Lake, IL. 60073
(847)270-3972 ph.
(847)270-3926 fax


                    "Doug Groh"

                    <dgroh11@comca To:,

                    Sent by: cc:

                    owner-rp-ml@ra Subject: Re: clear aorta model




                    03/10/03 09:26




I am not sure what this physical model looks like, but did you look at
reversing the model to a negative and casting silicon into the void.
To be simply put. It would be like taking a macaroni shaped sla model and
doing a boolean to remove the model shape from a block . You can then cast
into the void and create the macaroni noodle with silicon rubber, or
soft (shore "A" )urethane.
Materialize also allows you take the outer shape, and by doing some
separations you can take the outer and add thickness to it to create a
shell. Then do the same with the inner. place them together and cast into
It is a little more complicated than that, but it is possible.
Doug Groh
3G Services Inc.

----- Original Message -----
From: "James P. Harrison" <>
To: <>; <>
Sent: Monday, March 10, 2003 10:36 AM
Subject: RE: clear aorta model

> We have had a lot of success with this type of work. Give me a call.
> Jim
> James P. Harrison
> Vice President Of Product Development
> 3Dimensional Engineering, Inc.
> 2991 N. Powerline Road
> Pompano Beach, FL 33069
> P: (954) 972-9906
> F: (954) 972-8903
> -----Original Message-----
> From: []On
> Behalf Of Don Smith
> Sent: Sunday, March 09, 2003 11:26 AM
> To:
> Subject: clear aorta model
> List:
> I am making a model of the Aortic Arch, from the top of the heart
> down to and including the bifurcation of the iliacs. The total
> length of the part is about 22".
> Requirements are:
> 1.)ability to see through; (not clear)
> 2.)pliable (like silicone tubing)
> 3.)Tear Strength (pumping during lab tests)
> I plan on using a thin wall z-corp pattern of the bloodflow scan.
> Polishing the pattern, and brushing on clear latex. After curing
> break out the z-corp pattern.
> I have thought through molding the part using a wax core and RTV
> mold; and I think the core would be too difficult to register; and
> the mold too difficult to fill without getting voids.
> I have produced a similar part by successive dipping in alphatic
> urethane, but this produces a part with varying wall thickness.
> Any suggestions will be helpful.
> Don

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