Guy,
In my experience, there is no point at which you should purge a vat of resin. If there is a ton of crap in the bottom of the vat, I would drain the vat, clean out the vat, then pour the resin back in, filtering it as I put it in. I've used a simple conical paint filter available at paint stores. Then make sure you stir the vat for 12 to 24 hours to get most of the bubbles broken up.
SL5170 has been a very stable resin system, unlike SL5180, which experienced serious viscosity problems 18 months ago or so. So unless you're mixing some of those ceramic powders you guys play with, it should last "forever".
Tim Caffrey
Prototype Express, Inc.
(847) 925-9900
(847) 925-9901 FAX
tcaffrey@proex.com
----------
From: Guy Allen Brady[SMTP:galbrady@engin.umich.edu]
Sent: Friday, September 13, 1996 9:12 AM
To: Rapid Prototyping Mail List
Subject: SL resin perishability
I have a question regarding the perishabilty of stereolithography
resins, particularly SL 5170 epoxy.
As resin is used and replenished with new resin as needed, at what point
do users "purge" the old resin and start with 100% new resin? Does it
ever need to be "refreshed"? If so, what criteria is used to determine
when this needs to be done? Is it too much crap at the bottom of the
vat, viscosity measurements, the "feeling" of the operator, part
quality-strength, rate of resin usage, laser hours, cash on hand to buy
resin....etc.
Is the "old" resin filtered and resued at some point??
Or, are there cases where new resin is added continuously without any
purging process???
I would appreciate any comments on this issue. It would be best to get
both 3D's Resin R&D folks (or equivalent) as well as anecdotal evidence
from typical users.
Thanks, all.
--
G. Allen Brady -- Graduate Research Assistant
Materials Science and Engineering - The University of Michigan
2219 H.H. Dow Bldg. 2300 Hayward Street Ann Arbor, MI 48105
work: 313/936-0177 fax: 313/747-4807 email:
galbrady@umich.edu
http://www-personal.engin.umich.edu/~galbrady
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