3D Printing

[Carl Ijames]

"John Larkin" wrote in message
news:dlq1v9tes4qqgga70jgj5g968hefjevbm1@4ax.com...

On Sun, 17 Aug 2014 12:34:17 -0400, Phil Hobbs <hobbs@electrooptical.net>
wrote:

On 8/15/2014 8:40 PM, Jasen Betts wrote:
On 2014-08-14, Dave M <dgminala4444@mediacombb.net> wrote:
I'm starting to get interested in 3D printing. My primary purpose would
be
to make parts for obsolete equipment, and other parts that are no longer
available. These parts often have imbedded metal parts, such as a metal
ferrule inside a knob, or an imbedded nut or mounting tab.
Can 3D printers make such parts?

No, but you can make two parts that interlock to capture the metal, or
design for the metal being a press-fit.


Another approach is to make a plaster mould and cast it. You have to
make some jig to hold the metal part where you want it while the
material cures, but that isn't a fundamental problem in most cases.

Devcon polyurethane is a good material for this.

Cheers

Phil Hobbs

Hobby stores have cool plastic casting supplies.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
========================================================================

I've bought a few different polyurethane rubbers and hard plastic from
www.smooth-on.com, and am a very satisfied customer. They also have lots of
very good how-to articles, picture stories, and now more and more videos.
Even if you never buy from them -)) it's worth it to go read their stuff
on pulling molds from originals and casting.

-----
Regards,
Carl Ijames

 

[Rich Webb]

On Thu, 14 Aug 2014 13:51:01 -0500, "Dave M"
<dgminala4444@mediacombb.net> wrote:

I'm starting to get interested in 3D printing. My primary purpose would be
to make parts for obsolete equipment, and other parts that are no longer
available. These parts often have imbedded metal parts, such as a metal
ferrule inside a knob, or an imbedded nut or mounting tab.
Can 3D printers make such parts? If so, is any additional equipment or
unique model of 3D printers required?

Monoprice has a model that appears to be a clone of a Makerbot printer at
about half the price. Reviews seem to indicate that it is an excellent
printer, although not perfect. I guess that 3D printers are relatively new
on the scene, and will improve in time.

Thanks for any insight,

Coming in late to the discussion -- got hit by the Win7(64) BSOD from
the latest Black Patch Tuesday. &^$^%&# Microsoft

Embedding nuts and such like is quite possible. The print needs to
stay in place on the build platform and the print paused just as it's
starting the layer that covers the nut, which has to rest flush with
or just below the last printed surface. But it's basically pause, pop
it/them in, and hit continue.

For strength, parts are certainly weakest in the layer plane and thin
walls or toothpick-sized risers normal to the layer plane can be
fragile. On the other hand, I did some custom length hex standoffs in
ABS, 1/4" on the flats and not quite 1.25 inches long, F-to-F for #4
machine screws that were too tough to break by hand. Also, no nuts
needed, just size the holes right.

Cosmetically, they're always recognizable as printed parts. Any good
consumer grade machine should be able to do 0.1 mm layers ("normal"
layer thickness nowadays is 0.2 mm) but 0.1mm ups the build time and
it's still recognizably "printed." ABS, but not PLA, can be vapor
smoothed with acetone.

PLA prints at a lower temperature (about 200C), doesn't require a
headed build plate (although it helps for sticking the all important
first layer), and shrinks about 0.2% as it cools. It has a harder
surface than ABS but it tends to break rather than yield. Glass
transition temperature is about 65C, so leaving PLA parts in a hot car
is a bad idea. Smells like waffles when printing.

ABS prints at around 230C but does need a hot build plate (I use 110C
for the first layer, 85C for subsequent) and an enclosed, draft-free
chamber. Shrinks about 0.7% and can delaminate or curl during printing
if conditions aren't right. Tougher than PLA and bends rather than
snap. Higher glass transition temp (abt 105C). Smells like burning
plastic when printing, though, so a filtered exhaust is suggested.

There are some "exotic" filaments (nylon, PVA, etc.) but PLA and ABS
are the bulk of the raw materials used in consumer machines.

It's not (yet?) a point'n'click technology. Leveling (tramming) the
build plate and preparing the build surface (AquaNet hair spray is
actually a favorite for this ;-), tweaking filament feed rates and
melt pool ooze compensation, extra cooling fans or not, etc. are all
part of the fun.

The Monoprice printer looks like a rebadged FlashForge Creator X,
which is indeed one of the MakerBot Replicator 1 clones. It will do
PLA just fine as-is (hint: cover the build platform with 3M blue
painter's tape that has been wiped with isopropyl alcohol for a good
surface for PLA) and ABS if the top and front are covered to exclude
drafts. Hairspray (AquaNet unscented extra hold) on either Kapton or
glass as a surface for ABS. Should be a good, decent machine. Do give
it a once over for loose screws. Also flip it over to expose the main
PCB and check that the connectors there are all tight. There's also a
bad habit on some of these of tinning leads going to screw compression
connections, which IMHO is A Bad Thing, especially for the main 24V
power connections. I'd clip off the tinning and either go commando or,
better, crimp on ferrules if you've got some.

Do not dive in and try printing giant skulls (or whatever) right off.
Start with the 20x20x10mm calibration boxes until you've got leveling
and surface prep down and your extrusion multipliers are tweaked in.

Your main board will be similar to the MightyBoard Rev E. Schematics
over at http://www.thingiverse.com/thing:16058

There's a FlashForge group over at
https://groups.google.com/forum/#!forum/flashforge