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John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
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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.
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Regards,
Carl Ijames
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
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