[ELECTRON] Proposed new club + Arduino meet up

[Blair Thompson]

I have seen other reprap experimenters talking about using enclosures.  I
for the life of me cant remember whom.  What I do seem to recall was that
they were using the heated bed as the main heating source for the enclosure
and then using a temperature controlled fan to maintain the ambient
temperature inside the case.  I seem to remember a temperature of around 40c
as being in the ballpark as to what was useful.  

If I remember quickly, what the experimenters were trying to achieve was
reduction of distortion in taller models.  Warping occurs sometimes when
parts of the model at the base cool while those at the top i.e. the most
recently printed are stil hot.  An enclosure serves to reduce the difference
in temperature from the most recently printed parts of the model to the
least recently printed.  

I have been trying to perfect my machine and have found that fan cooling of
the filament as it is laid down makes a difference to the quality of the
prints in either ABS and PLA.  For ABS however I also have to lay a skirt
which reduces the cooling at the bottom of the model from either my cooling
fan or from the movement of the Y axis.  I was getting lifts from the build
plate before I started using the skirt.  I don't know if this will improve
PLA prints as I have not tried it yet, Imanaged to get good prints without
it.

The layer thickness you reference for the Reprap of 0.3mm depends on the
extrusion nozzle aperture width.  With a 0.5mm width and 3mm filament the
layer thickness works out at about 0.4mm using the sfact software as a
slicer.  You can get lower by using different filament thickness and
different nozzle aperture widths.  What you gain in fidelity you lose in
build speeds though.  

One idea I had was to not build the reprap using triangular vertexes, but
rather to build an MDF cube but use the Prusa dimensions and mechanical
parts.  This would certainly allow experimentation in terms of retaining
some ambient heat around the models being created.

Regards

Blair.

Ps  I just got a delivery of various screws and bolts that I needed.  I of
course ordered a few extras.  All but the M8 washers arrived today.  



-----Original Message-----
From: members-bounces at electronclub.org
[mailto:members-bounces at electronclub.org] On Behalf Of Brian Loudon
Sent: 08 November 2011 21:29
To: Discussion list for the Electron Club
Subject: Re: [ELECTRON] Proposed new club + Arduino meet up

Hi to those interested in RepRaps, I came across this patent relating to
temperature and flow control for professional Fused Deposition Modelling
systems ;

http://www.google.co.uk/patents?hl=en&lr=&vid=USPAT5866058&id=OgUXAAAAEBAJ&o
i=fnd&dq=stratasys+patent+fused+deposition+modelling&printsec=abstract#v=one
page&q&f=false

The stratasys Dimension printers achieve .178 mm, .254 mm or .33 mm layer
thicknesses,
http://www.dimensionprinting.com/3d-printers/3d-printing-comparison_chart.as
px

the reprap is quoted as a layer thickness of 0.3
http://reprap.org/wiki/Mendel

The patent above emphasises the importance of temperature and the
professional machines all have enclosures, makes me wonder if the reprap
performance can be optimized?

cheers

Brian



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