Zephyr on SLA500

From: William G. Noack (Bill.Noack@morristech.com)
Date: Tue Oct 15 1996 - 19:54:32 EEST


Hello all,

We have been using the factory installed Zephyr on our SLA500 since the
machine was delivered in July 1996. Our previous SLA experiences are
with a SLA250/30 with a cantilevered doctor blade and SL5170. Compared
to our 250, the Zephyr has eliminated bubbles, allows easy building of
trapped volumes of any size, and reduced z waits for all geometries to
10 to 15 seconds. So overall, we are happy.

A couple of minuses with zephyr is with large width flats or large width
trapped volumes (in our experience 6 inches or larger), you will need to
use 3 sweeps in order to "dispense" enough resin on the parts. Also the
Zephyr seems to work better when using slow sweeps of 1" per second or
less. This really seems to eat up a lot of the other time savings that
Zephry gives you.

Aside from these problems, we are still fighting some part building
problems that may be related to Zephyr or may be related to SL5180
and/or SLA500. Early on we were experiencing ballooning/waffling on
medium and large (3 by 3 or larger) flat down facing surfaces. We then
ran window panes and christmas trees to dial in the parameters of the
machine. We still experienced the same problem. Since then we have
increased FDF from 0.008 (default) to 0.014, reduced support spacing
from 0.4 to 0.35 inches, increased predip from 15 to 40 seconds (on the
first 10 layers), and used 3 sweeps (on the first 10 layers). Now we
are getting a nearly flat bottom surface but the 2nd, 3rd, 4th, and 5th
layers (large flat only!) of the part are delaminated with a lot of
uncured resin trapped there. After this point, the problem is self
correcting (luckily) and the rest of the part is hard and solid.

Does anyone have a similar experience and a solution? I would greatly
appreciate the input.

So, the jury on Zephyr is still out for us. We've never had (the
luxury) of using a docotor blade on a SLA500 to draw any comparisions so
we'll keep plugging till we get everything to work the way it should.

Thanks,

Bill



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