seeking thoughts on Somos 8120

From: Gabe Clark (
Date: Tue Feb 02 1999 - 21:27:42 EET

Hello list,
        This is the summary from the responses I got back. I appologize for
taking so long to post it. From what I gather, just about everyone likes the
Dupont resin more. If anyone disagrees with this statement please respond.
 Thanks to everyone.



I was a former Plynetics Express employee and was involved in beta
testing Somos8120 on an SLA350. Here are my observations.

1. Parts built in 8120 are milky white in color and look stunningly
beautiful (as you can see I am clearly biased here.) In general our
customers were very satisfied with the sheer aesthetics of these parts.

2. With an Ec of 5.2mJ/cm^2, Dp of 5.3mils, as far as my resin knowledge
goes, 8120 has the highest photospeed compared to any other DuPont/Ciba
epoxy resins currently available.

3. Downfacing surfaces are smooth, so are vertical walls. Support
removal is a breeze.

4. At least two gentlemen (both considered SLA experts) felt 8120 is
superior to its Ciba counterpart SL-5520(??). I cannot comment on this
as I haven't used the Ciba resin.

Now, the other side of the story:

1. Thin, long walled geomteries tend to deform heavily. (BTW, Don't ask
me to define my highly technical phrase "thin, long walled geomteries."
-:) Seriously, I don't have data to give any numbers here. Take it for
what it's worth.

2. It's tremendous photospeed cannot be exploited fully to our advantage
since 3D machines cannot keep up. For instance, recommended maximum
draw speed for high accuracy on an SLA350 is only 100in/sec. Assuming
150mW power at vat and ACES build style, hatch velocities shoot upto
250in/sec or even more depending on beam dia. (We can overcome this
problem to some extent by using wideweave styles with high hatch

3. Flexibility is gradually lost over a few months. Exposure to direct
sunlight accelerates the rate at which parts loose flexibility.



Dear Clark,

here is the same text, I sent to Mike; just some information from our
point of view.

Alphaform is a german service bureau running 8 SLA machines and 3
sintering stations. We are also a european distributor of DuPont Somos
resins. We are running the 8120 and the 8110 with solid-state laser
and with HeCd-laser, we also did the installation on a
Ar-Ion-laser-based machine at BMW here in munich. All installations
are on STEREOS machines, but I think the results we see are
representative for this resin-family.
 Our experiences with the 8100-family are great:
 it is the fastest resin, we have ever had on our machines
 support removal is real easy
 down-facing surfaces are pretty nice
accuracy is real good (we build details smaller than 0.5mm), even with
high scanning speeds we are using it on the big machine
(600x600x400mm^n) with a doctor blade and the results are good,
tolerance of closed volumes is excellent, flat areas can be covered
 Cleaning up is easy withTPM or polypropylencarbonat and isopropanol
you can handle the material real hard, we tried to break some by
dropping them and as long as you do not excedd the 20%-30% elongation
it is not possible to break the part
 humidity resistance is excellent, the material is stable against
break fluid and a lot of solvents
 machining is like machining POM or PP (drilling, cutting, tapping) it
is possible to glue the materail with special glue components

I know, this all sounds very positve , may be too positve, but it
really is like that. For experiences on 3D Systems machines you
probably should contact Kamesh Tata (formerly Plynetics Express). He
is available at: "Kamesh Tata" <>

If you need more information or want some testparts to be build, just
contact me. I do not put this message to the rpml, because as a
distributor it looks to much like advertising.

Best regards
Ralf Deuke
Internal service and material distribution
Alphaform GmbH
Kapellenstr. 10
85622 Feldkirchen, Germany
Tel: 0049 89 90 50 02 51
Fax: 0049 89 90 50 02 90



We switched to the DuPont 8120 in one of our SLA-5000s and love it! Faster
build times, the parts clean easier and are much more durable than the 5195.
DuPont has been great to work with and helped us get up and running in a

We don't have experience with the new Ciba resin so I can't give you
feedback there.

Jay Jacobs
Brookfield Rapid Solutions
(603) 577-9970



I as well as Kamesh am a former Plynetics Express employee and beta
tested Somos8120 in another SLA350 out in Beaverton,OR. I agree with
Kamesh's observations on 8120. This resin has some wonderful
characteristics namely: fast photospeed, easy support removal and
clean-up (usually you can just scrape the part off with a puddy knife
without removing the tray), sands quickly, and that milky white color.

Although this is the best resin I have used in a SLA350, these are some
limitations I have observed. So take these into account when making your

1.) . Quickcast parts are possible but you will need to increase the
number of borders to make it work. Always use thickskins and avoid using
hexagon buildstyle. Its too weak in the green state for 8120

2.) Large thin parts out of 8120 may not be suitable for silicone rubber
tooling. The weight of the rubber may deform the part. Thicker walled
parts were fine.

3.) If assembling a segment do not use native 8120 to bond together.
User Aptek SL-Lo or Loctite. They are much stronger. Hybrid parts,(hard
epoxy and flexible epoxy) were easily bonded together using Aptek or

James Neville
RP Engineer


> Ron Clemons and Mike Miller needed info on bureaus using 8100 resin. I
>have beta tested this resin for DuPont and I am currently using it in my SLA
>500 machine. My customers are very pleased with this resins flexibility. It
>lets them do snap fits over and over many more times than with the other more
>brittle resins. Side wall quality at .004 and .006 is excellent. This is also
>a very fast resin, my Ec is 7.3 and Dp is 5.9. Even though this resin is
>flexible it still has rigidity at the thicker wall thicknesses, so customers
>that do not need flexible materials can still have their parts made from 8100
>resin and be satisfied. If you do need to swap out vats between 7100 and 8100
>it only takes about a half an hour because the two resins are very
compatable. This resin also machines well and sands very smooth. Clean
up using TPM and ISP alcohol is very easy. Support removal is really
easy, a putty knife wilI slide right under the base and lift off the
>part with out any chipping. If any one has any other questions feel free to
>ask. I will do my best to answer your questions. If you need parts built call
>(724) 337-3836 or e-mail we do build for customers
>outside of Alcoa.
> Robert Speer (724) 337-3836
> Alcoa Tech Center
> 100 Technical Dr.
> Alcoa Center, Pa. 15069

Gabe Clark                         
Rapid Prototype Manager                           (801)-328-8220
Solid Design & Analysis                   

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