FW: SLS Somos problem

From: Miller, Michael W (Mike.Miller3@PSS.Boeing.com)
Date: Fri May 15 1998 - 04:17:01 EEST

Excuse my ignorance but for these somos builds are people using the old
metal scraper or the new (rubber) scraper?
What does DTM recommend?
Michael W Miller (Mike.Miller3@PSS.Boeing.com)
The Boeing Company MS 17-PE B-XT62
Propulsion Experimental Hardware 206-655-3289
Rapid Prototyping 655-4366 Lab 655-4365

> ----------
> From: lphan@or1.plynex.com[SMTP:lphan@or1.plynex.com]
> Sent: Thursday, May 14, 1998 12:08 PM
> To: RPML
> Subject: RE: SLS Somos problem
> I have to agree with David Leigh. The problem is mainly due to the
> roller bumping into the part. Changing the layer thickness somewhat
> reduces the problem, but decreases part resolution. Currently, at
> Plynetics Express we are building SLS Somos parts between .005"-.007"
> layer thickness with a fairly good success rate. I believe the key to
> prevent the roller diameter from increasing in size during the build
> is to start out with a super clean roller and scrapper. Therefore,
> during the machine preparation make sure to dress the roller and have
> the scrapper sit "water-tight" (hint: you should not be able to see
> between the scrapper and the roller) against the roller. This will
> help cut down the powder from accumulating on the trailing side of
> roller during build.
> The bottom line, this is a roller issue and until the problem is
> fixed, don't count on the build to come out every time.
> Long Phan
> Plynetics Express Corporation
> Tel 503-531-2701
> Direct 503-531-2707
> Fax 503-629-6208
> email: lphan@or1.plynex.com
> www.plynex.com
> ----------
> From: harvest@ns.vvm.com[SMTP:harvest@ns.vvm.com]
> Sent: Thursday, May 14, 1998 3:36 AM
> To: RPML; dsbrown@conceptual-reality.com
> Subject: Re: SLS Somos problem
> Somos Problem . . .
> The issue is that the roller is bumping the part . . . This is why
> DTM recommends .008" layers. This doesn't do much for part
> definition in a material that is not real good for definition to
> begin with.
> So, why is it bumping??
> I have not noticed any curl in the parts, so the parts are not
> "jumping" up in front of the roller. So, what could it be?? The
> roller is hitting the part, not vice versa. The roller has not
> changed and the powder is not sticking up out of the bed, so . . .
> the powder is sticking to the roller. If you notice, the part starts
> fine, but as static or adhesion starts, the build will crap out
> because the effective roller diameter has increased and is now
> interfering with your part.
> Building a base won't work because the part is not curling. Lower
> laser power won't work, because the roller is the issue. So, fix
> your roller issue, and you've fixed the problem. That's about all
> the free advice you'll get from this here yocal.
> David Leigh
> ****************************
> Harvest Technologies
> Rapid Prototyping Services
> (254) 742-1822
> harvest@harvest-tech.com
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