RE: [rp-ml] FW: Geometric Accuracy of RP parts

From: Good, Jim <Jim.Good_at_tbe.com>
Date: Tue Dec 28 2004 - 20:22:30 EET

Yes, cost of ownership will be an important variable, but for my purpose
reliability and repeatability will be very important. When we are on the
Moon or Mars, it is critical that we can validate the acceptability of the
part prior to installation. Obviously, we want it to be economically
viable, we MUST have an efficient and reliable system, as Marshall stated.
We'll work on the cost later! I do wish I had more of those "big bucks" to
make a large number of test parts and also have an extensive scanner
research budget! Luckily, vendors have been very good to me and have been
very helpful.

Jim

-----Original Message-----
From: Marshall Burns [mailto:MB-ListMail2@Ennex.com]
Sent: Tuesday, December 28, 2004 10:55 AM
To: rp-ml@rapid.lpt.fi
Subject: Re: [rp-ml] FW: Geometric Accuracy of RP parts

Ernst,

        I certainly agree that cost of ownership is an important
parameter for design of a fabber, but ...

        The original application proposed by Jim was in space, where
efficiency and ease of use are much more important than cost of
ownership.

        And even here on Earth, there are two considerations:

                -- There are applications where it's worth the extra
cost to have a system that generates the right geometry the first time,
without the operator needing to check it and either modify it or submit
a bad build for refabbing. Example from not that far in the future:
Surgeon in the operating room making a plate to be installed in a
patient's body.

                -- The cost of such a scanning feedback system will come
down in time and eventually will be part of every mainstream fabber.
(When we have mainstream fabbers!) It's part of the purpose of the space
program to spend the big bucks to develop this kind of stuff so the rest
of us can have it for cheap later on.

Best regards,
Marshall Burns
www.fabbers.com

> -----Original Message-----
> From: owner-rp-ml@rapid.lpt.fi
> [mailto:owner-rp-ml@rapid.lpt.fi] On Behalf Of E.Mueller@gom.com
> Sent: Tuesday, December 28, 2004 04:00
> To: Anshuman Razdan
> Cc: Good, Jim; Marshall Burns; owner-rp-ml@rapid.lpt.fi;
> rp-ml@rapid.lpt.fi
> Subject: RE: [rp-ml] FW: Geometric Accuracy of RP parts
>
>
> Hello RP's,
>
> The RP system has to have a reasonable cost of ownership to
> be successful. If the build process of a RP system has to be
> based on a built in scanner to receive accurate, reliable and
> consistent parts, this RP system has no chance on the market.
>
> The problem comes if the part is removed from the RP system,
> has to fit into the existing assembly and perform the needed
> functionality. Then a measuring system can define the
> deviations between the build versus the designed form or
> define the modifications needed to perform the needed
> functionality. For simple parts, a CMM is a good solution. If
> the part is complex, with free forms, warped or bended, a
> scanner is usually preferred to understand the problem (3D
> color plot with selected deviation flags) and get it fixed.
>
> Then depending on the selected measuring technique, the
> specific preparations have to be done to get data fast and in
> good quality (e.g. built a fixturing for the part on a CMM or
> dull shiny or transparent parts for scanning).
>
> I do not fully agree with the statement: "it depends on the
> tolerance", it depends much more on the part, the available
> time and the application.
>
> We wish you a happy new year, with best regards
>
> Ernst Müller www.gom.com
> GOM International AG e.mueller@gom.com
> Bremgarterstr. 89b Tel. ++41 56 631 04 04
> CH - 8967 Widen, Switzerland Fax:++41 56 631 04 07
>
>
>
>
>
> Anshuman Razdan
>
> <Razdan@asu.edu>
>
> Sent by:
> To
> owner-rp-ml@rapid Marshall Burns
>
> .lpt.fi
> <MB-ListMail2@Ennex.com>, "Good,
> Jim"
> <Jim.Good@tbe.com>,
> rp-ml@rapid.lpt.fi
>
> 28.12.2004 05:48
> cc
>
>
>
> Subject
> RE: [rp-ml] FW:
> Geometric Accuracy
> of RP parts
>
>
>
>
>
>
> It depends on the tolerance. Laser is good, but requires dull
> surfaces for best results. Any sharp angles or shiny metal
> will throw it off. There are other metrology techniques but
> they are not fast. Speed vs accuracy is the age old problem.
>
> AR
>
> -----Original Message-----
> From: owner-rp-ml@rapid.lpt.fi
> [mailto:owner-rp-ml@rapid.lpt.fi] On
> Behalf Of Marshall Burns
> Sent: Monday, December 27, 2004 7:57 PM
> To: 'Good, Jim'; rp-ml@rapid.lpt.fi
> Subject: RE: [rp-ml] FW: Geometric Accuracy of RP parts
>
>
> Jim,
>
> This is a very important idea you're looking into.
> I don't have
> specific recommendations of scanners for you, but just
> thought I'd
> chime in about the concept. Even in a terrestrial
> application, it's
> this kind of thing that will provide the feedback to
> ensure that a
> fabber is on track, and let it make mid-course corrections. It's
> obviously that much more critical in a remote application, like
> space.
>
> I'd be interested to learn more about your project as it
> progresses.
>
> Best regards,
> Marshall Burns
> www.fabbers.com
>
>
>
>
> -----Original Message-----
> From: owner-rp-ml@rapid.lpt.fi
> [mailto:owner-rp-ml@rapid.lpt.fi] On
> Behalf Of Good,
> Jim
> Sent: Monday, December 20, 2004 13:45
> To: rp-ml@rapid.lpt.fi
> Subject: [rp-ml] FW: Geometric Accuracy of RP parts
> I thought I would throw this out. I am looking into inspection
> equipment that will verify the geometric accuracy of my RP part,
> after fabrication, and actually during fabrication.
> I've looked at
> laser scanning and got some good input already. I'd
> like everyone's
> opinion on what system they are using and what they
> believe to be the
> best system to verify geometric accuracy. The ultimate
> goal is to
> build a fabricator that contains an integral inspection station.
> This system would be used in space for repair and
> fabrication of new
> parts. Any thoughts?
>
> Thanks,
>
> Jim Good
>
> Muniz Engineering Inc.
> In Situ Fabrication and Repair (ISFR)
> 256-726-1199
>
> jim.good@tbe.com
>
Received on Tue Dec 28 19:04:24 2004

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