ATTN: Chad Buchanan-Post Processing

From: Monica & Glenn Whiteside (
Date: Wed May 13 1998 - 08:37:28 EEST

Dear Chad:

As Yakov said: "Postprocessing is the bane (and major pain!) of our lives."

To do it fast, especially if you're doing a lot of sectioning and bonding,
you'll probably want 2 people doing it. One person to CAREFULLY remove the
parts from the platform with a sharp putty knife and CAREFULLY remove the
larger supports and hand them off to another person to strip the excess
resin off the models (we use 99% isopropyl alcohol but there's also TPM and
propylene carbonate) and remove the small fine supports while the other
person is cleaning off the platform. Cleaning the platform can be a real
chore, especially if some idiot takes it right out of the machine and
sticks it into the postcure apparatus!! You'll need some small needle
files and dental picks to get cured resin out of the platform holes and
clean off the platform well so no debris will contaminate that expensive
vat! Also make sure if you're using compressed air that you have CLEAN air
(use a water/oil trap on your air lines), or else you'll contaminate the
vat by blowing this on the platform. We've found that it's fairly easy to
sand the models in the green state so if you have some areas with bad
stairsteps or support castle residue it's much easier to remove them
carefully in the green state, you could even wet sand with the alcohol but
be careful not to remove too much in this soft gummy state. Then you'll
have to postcure the models for 1-2 hours. Get yourself a good EFOS UV
light gun, some of those Aptek UV adhesive kits and a variety of clamps
(scotch tape also works well - the UV gun will cure the adhesive through
the tape) for bonding - you can use the UV light gun for tacking the parts
together and then use the PCA for a final cure.

I definitely wouldn't get rid of the woodworking equipment - you'll always
find a use for that - you can always use wood inserts (or epoxy
backfilling) to strengthen the SL models e.g. create thin models (to save
resin and build time) in SL (say .050-.200" thick walls with maybe some
built in webs and gussets) for surface definition and then bond in wood
inserts or epoxy resin and filler to add rigidity and strength, if needed.

Good luck and look closely at those supports in Maestro - it isn't all that
"automatic" in generating good supports! Also position parts so that the
Zephyr blade will travel across the thinnest cross-sections and watch the
fill window in the Zephyr blade - it's a real pain if resin is sucked up
into the vacuum lines!


Glenn Whiteside
Cessna Aircraft

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