----Original Message-----
From: Dave Pinkston <dpinkston@masco-rd.com>
To: 'rp-ml@ltk.hut.fi' <rp-ml@ltk.hut.fi>
Date: Wednesday, July 08, 1998 9:50 AM
Subject: SLA build problem.
I have just installed a SLA5000 and I am starting to run parts through
it. (Boy that is pretty obvious). The last two nights the sweep stalled
on the fill layer a top surface. It seems that the surface did not
adhere to the bottom layers which allowed for separation of layers. It
also does not happen to all the parts being built. Is this a setup
adjustment or do I have to be aware of some condition and compensate for it?
Thanks
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Dave:
Have you checked the resin level in the Zephyr recoater blade? When we
recently set up our SLA-5000 we had several problems with the vacuum system.
Call 3D's field service and they can adjust the level for you, or if you
can't wait for them, the vacuum adjustment knobs (there's 2 of them, one for
fine and one for coarse adjustment, I believe the one on the left is the
fine one) are located directly behind the vat, just remove the lower sheet
metal panel (without the laser running for safety purposes) and look for 2
black knobs about 2 feet high, you'll also see the vacuum pump which looks
real similar to an aquarium pump. Be careful (do it slowly, make an
adjustment, then let it stabilize for approx. 15 seconds before you make
another adjustment) when adjusting because it is real easy to go too high
and you'll have to clean the line out again.
Several vacuum adjustments had to be made so that the resin remained at the
right level in the blade (1/2 - 1/3 full in the sight glass on the back of
the blade). The reason we lost vacuum was that resin had been sucked up
into the line which blocked the lines and we had to remove them (both the
metal line on top of the blade and the plastic line running back to the
adjustment knobs) and clean them out with isopropyl alcohol. If the resin l
evel is too low, which can be caused by the line blockage, you'll have
problems with inadequate resin deposition, especially if you're building
parts with a lot of surface area.
Another item we found was that the default blade speed set up by field
service was too fast (2 in/sec, which is listed in the resin parameters for
SL5195) and we had to reduce this to 1 - 1.5 in/sec (in Maestro) otherwise
the build would crash. This also caused inadequate resin deposition.
Hope this helps,
Glenn Whiteside
Cessna Aircraft Co.
e-mail: siderwhite@worldnet.att.net
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