3D printing parts using lulzbot mini

[lesthegringo]

Has anyone purchased or used one of these for producing parts? If so, how did you get on and what tips can give?

Cheers

Les

[MoFo]

What kind of parts do you want to produce?

[lesthegringo]

Little detail parts that can't be injection moulded due to their geometry, like airscoops, or stuff like gear doors where ejector pin marks are impossible to avoid. I'd be using it for other non-modeling projects too, like improving my F1 car sim rig, making some 'cockpit' parts for a flight sim, so the detail parts thing would be a nice bonus, if it was possible

Cheers

Les

[MoFo]

Airscoops and gear doors will be pretty much no-go. FDM printers can't handle fine details, and have relatively thick layer heights. And you probably won't be able to print anything thinner than about .5mm. Plus, anything you print will have to be either sanded heavily, slathered in putty (and then sanded heavily), or placed in an acetone vapor bath to smooth the print lines. IMO, an FDM printer has pretty limited uses for the scale modeller - if you view it as a substitute for carving balsa masters, or scratchbuilding shapes with milliput and styrene, it will do that. If you're hoping to make cockpits, or wheels, or anything with detail, not so much.

Sim cockpit stuff would be more doable. The parts will be bigger, details will be bigger, tolerances will probably be looser. You'll still have to fill/sand/acetone the parts, so stock up on automotive filler and/or build a vapor chamber, but that's easier on a 1/1 switch than a 1/48 part.

As an example, here are a few shots of a part I had printed on a comparable FDM printer. These were just a quick test to check overall geometry, since it's a fast, cheap way to print stuff. The actual masters will be run on a much higher-end printer.

Panel lines on the CAD model were .1mm square. They're just blurry shadows on the print. You need features to be at least .3mm - .5mm to print cleanly. Also note the surface rippling.

Comparison with an injected plastic radome. The FDM print will need a ton of sanding to smooth out.

There are also issues with melting. Prints work better when the print head can extrude plastic then move on. When the (heated) print head stays in one place too long, the (melted) plastic can't cool properly, which leads to problems.

If you're scratchbuilding, this would give you the basic shape, but the prints *really* aren't usable straight from the build plate.

[lesthegringo]

Great reply, many thanks. I'd wondered whether all the hype matched the reality, and in fact could see the stria from the printing process on some Eduard F6F engine cowling parts, although to be fair they were finer than those above. I have no way to actually test it myself, so need good feedback like this.

To me it sounds like the technology is not yet ready for home use for modelling. I assume the industry grade items are capable of better but looks like I'll be using this only for non-scale stuff if I do decide to get one

Cheers

Les

[MoFo]

The problem is, 3D printing is a sector, not a single technology. It's a little bit like owning a black and white inkjet printer, and hoping it will match the quality of a high end, archival quality photographic printer.

The Lulzbot (and Makerbot, and Ultimaker, and Prusia) are FDM printers. These are the simplest, cheapest type of 3D printer on the market - they are basically a hot glue gun, mounted on a plotter. Which is why you see so many of them on the market - they're cheap and simple (and some important patents have expired, so they're basically 'open source'). The problem is, their abilities are limited by physics - they extrude molten plastic through a heated nozzle, and the nozzle has to be a certain minimum size or the plastic won't flow. At this point, that means the finest detail it can produce is about .5mm. They also have relatively thick layers - .1mm is *really* good for an FDM printer - and because each layer is made up of a bead of plastic, with rounded sides, those layers are pretty prominent.

Extending the analogy, they're a little bit like a dot matrix printer - simple, crude and somewhat limited in use.

There are many other individual technologies out there. SLA (stereolithography) and DLP (digital light projection) are the next generation that is entering home use, and are far more useful for the modeler. The specifics are different, but they both work by projecting light into/onto a pool of liquid resin. The UV light cures the resin then the part is raised (or lowered) and light projected on the next layer. The main difference - SLA uses a laser to trace the image of each layer; DLP uses a projector to expose the entire image at once. There are a few big benefits for the modeller - first and foremost, SLA and DLP printers typically have much higher resolution than FDM printers - they'll often print details that are .1 or .2mm in diameter. They also have much thinner layers - most start at .1mm, and go down to .03mm or so - and the layers are squarer in cross section. That means finer, less obtrusive print lines. Where an FDM print will need a coat of Bondo before smoothing, an SLA or DLP print might get away with a solid coat of Mr. Surfacer. The two big downsides are, the components are more expensive so the printers cost more, and they get exponentially more expensive as the print area gets bigger. You can put together a LittleRP printer for about the same price as that Lulzbot Mini ($650 for the printer kit, $500 for a 1080p projector), but the Lulzbot has almost 15x the print volume.

Higher end commercial machines will have higher resolution and thinner layers. And/or better software to maximize the equipment. So, even though you can see print layering on some Brassin sets (the MiG-21 wheel wells also show layering, and they rarely smooth out webbing or pour stubs), it's much finer than you would get on home machines. That said, even the best on the market right now aren't perfect, and you will see some print artifacts on your parts. But they are getting pretty close, and I suspect a lot of modellers would be happy using parts right off the build tray.

Finally... if you're interested in seeing what's out there, you absolutely can test stuff out yourself. 3dhubs.com connects people who want to print stuff, with people who have printers, all around the world. There's a pretty good chance you'll find someone that's fairly close by, and while they may not have a Lulzbot, they'll probably have something comparable. And FDM prints are pretty cheap. You can also search by printer model and printer type, so if you wanted to compare that with an SLA printer like a Form2, you can narrow your search to find a source for one of those.

[SoDakZBrusher]

We have been using a SLA 3D printer (Formlabs Form 2) to print aircraft armament models (GBU-31V3 and GBU-54V1/B)/>/>/> since February this year. The Form 2 is excellent for creating very highly detailed, high res prototypes and finished models - were blesed to have sold 125+ Desktop models so far. :)/>/>/> Its not the best printer in the world (there are higher res options if you have $55K+ hanging around) and not cheap at $3,500 but, if you have a good source model it is more than capable of putting out a very nice print. We have prints of JDAMs That you can see the difference between a phillips head and flat head screw on the fuse access door. It would be a bad idea to base an assessment of the utility of a 3D printer based on an FDM printer's output. The best FDM printers resolution is claimed at 25-50 microns however if you look at the output its VERY optimistic. The Form 2 can print a 25 micron output that looks outstanding. I read on here somewhere that you have to print solid prints...not true unless its a very small print - walls would make the outside fragile and the amount of resin saved would be negligible. We print 10" desktop models (made by attaching a 4" tail assembly to a 6" bomb body) and both sections are hollow to save resin. To make them feel more realistic we add fine grain sand into the voids. If your curious check out The Armament Shop page on FaceBook or our website or on eBay. It would be interesting to see what a realistically modelled 1/72 scale -31V3 or -54V1/B would look like.

Edited June 30, 2016 by SoDakZBrusher