Hello all,
Yes I'm back on the list and in need of help!
With out describing the parts in full this may be difficult but I'm hopeful
that someone will have an answer because its completely baffled me!
I have been building a part that looks like a turbine and the orientation is
such that the build lines are in the direction of air flow. This provides
us with the best possible looking blade and the least amount of cleanup both
with regard to supports and general part cleaning. The parts are small and
we are building them on an SLA-500 using SL5180 and QuickCast 2.0. The room
that the equipment is in is climate controlled such that the temperature has
not deviated from 72 degrees F and the humidity has not deviated from 32%
in the fours years that the lab has been in operation. Resin temperature is
at 31 degrees C. When the first set of these patterns were built in April
and May of this year they were within .002" of tolerance and we satisfied
the customer (engineering) with the required number of castings. Knowing
that the part would be required again in several months I placed the build
files ( .bff) on a separate hard drive for later use. Two weeks ago I was
asked to rebuild several patters and now they are .020" to .030" out of
tolerance. In one case the part is .020" out on one dimension and right on
another dimension. One part comes in large while another comes in small.
Literally the only thing that has changes is a new laser and all other parts
seem to come in. These parts by the way are segments and when enough are
complete they are assembled to a fixture. At this point I am thinking it's
the human variable and not the machine that is causing things to go crazy.
Any all comments would help.
Sincerely,
Karl Denton
Lead Engineer
Williams International
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