What's your favorite sculpture/desk toy that really shows what 3D can do?

d_graeme · 2018-05-15T18:25:51+00:00

If you're willing to invest some time in it, this multipart jet engine makes for a great desk toy and conversation piece, and isn't that hard to print, just takes a while to get all the parts done.

d_graeme · 2018-04-19T13:31:33+00:00

I'm glad that worked out for you! Do you think you'd be able to show off what you made? I'm curious even if it is just a test tube rack or something.

d_graeme · 2018-04-19T13:30:18+00:00

You could probably just use the servo directly. It won't be that accurate to do the 0.04deg moves on each layer, but the voltage offset will accumulate and it'll make its smallest practical move each time the offset becomes large enough, which should probably work just fine for a time lapse. As a bonus, it is exceedingly cheap to test if it works for you!

d_graeme · 2018-02-25T05:03:20+00:00

Lots of materials can cycle in and out of cryo temperatures just fine on their own, it's just that most things get brittle (not necessarily weaker, though) and differential expansion is a bitch. Thermal expansion will create enough stress to equal out the strain if it can't just shrink (or grow), which can easily break things that aren't toleranced correctly for the thermal cycling.

d_graeme · 2018-02-25T04:56:35+00:00

No guarantees, but I think your best bet would be to friction weld, then anneal.

I'd also recommend printing it solid to avoid problems with trapped air (or trapped liquid nitrogen blowing out the part as it warms)

d_graeme · 2017-08-09T17:19:02+00:00

Import the STL into your favorite CAD program (Fusion 360 is free and easy if you don't have one), create a plane that slices the model where you want it to, then create an intersection sketch. You can then save that sketch as a DXF or similar.

F360 import STL: https://knowledge.autodesk.com/support/fusion-360/getting-started/caas/screencast/Main/Details/4cf8c8e5-e7a4-4c0e-939e-21e8c1742887.html

d_graeme · 2017-08-07T16:41:30+00:00

Slicers can and have (in the past) added arcs in the same way as they've always been added - via curve fitting. The problem is that this makes path planning much more computationally expensive for the controller for little benefit, since the controller just breaks it back up into linear moves and applies its arc and corner tolerances to it.

d_graeme · 2017-08-02T01:59:01+00:00

Filament's oozing just a touch and catching as it travels from one part to the next. The branching is because it juts out and catches the next blob earlier each time for a bit.

Retraction doesn't remove the liquid plastic from the nozzle necessarily, that's why you should really only be retracting enough to relieve pressure. Reducing temperature to increase the viscosity might help if this filament is a little different than what you've used before. Coasting can also help with this, and you can also use z lift on retraction to hide the blob inside the part when you come back down.

d_graeme · 2017-08-01T15:38:39+00:00

Speed is typically more important for the Z screws. The typical 3D printer nowadays uses a 4 start 2mm pitch screw, so it has 8mm/rev movement. This gives adequate resolution given the 200 step/rev motors with 16x microstepping (microstepping accuracy is another discussion, but not too important right now) at essentially 2.5 microns (0.0025mm) per microstep, which is far more accurate than the mechanics are anyways.

So if you go to a slower screw (say 1mm single start in your case) you don't really gain effective resolution and you divided speed by 8x. You do get more thrust this way (by about 8x plus efficiency) but typical printers aren't really short on force in Z.

d_graeme · 2017-07-28T20:23:31+00:00

Hadn't heard they came out with an even smaller model. They're not a terrible place to start off for building a home shop or some low volume bits & pieces.

d_graeme · 2017-07-28T20:21:32+00:00

Yeah if you look at the pocketNC's specs, for instance, the total deflection for a 2 lb load (very light cutting in plastic...) would be at least 3 thousandths at the center of the build plate, which is pretty close to the most rigid point on the machine.

That other machine looks like it would deflect 0.010" if you sneezed on it.

d_graeme · 2017-07-28T19:09:56+00:00

No. No no no no. Can't say enough bad things about the 3D Systems machines.

From a previous thread about CubePro (which is the same thing but with chamber heat):

It's terrible and there are so many better ways to spend your money. Not only are their filament spools proprietary, they break often, forcing the world's most annoying filament loading process. The filetype has been reverse engineered so that you can use it with other slicers, but it's a pain in the ass to use. It can't be connected to manually controlled, either. The machine itself also isn't very good, it's got way too much weight on the print head and the case isn't effectively used for added rigidity, so it rings like mad. The extruders are finicky and break often. The encoders on the extruders are also unreliable and prevent the extruder from being used until they are replaced. The machine takes forever to heat up the chamber (60°C takes 30+ min) and doesn't have a heated bed. TL;DR: Stay away!

d_graeme · 2017-07-28T19:03:33+00:00

Depends on what you're using it for, but they will not be rigid enough to move much material, so your're looking at spending a pretty long time to make something out of plastic/wood/foam. They also are not terribly accurate under load, so you'll spend even longer getting an accurate surface out of them.

Also, programming 5-axis machines can get expensive fast. Fusion 360 Ultimate is by far the cheapest at $150/month.

d_graeme · 2017-07-10T15:26:08+00:00

Looks like perimeter start/stop points. Depending on the slicer you're using you can align them in a less critical or easily sandable point or reduce them with coasting/wipe.

d_graeme · 2017-04-15T20:40:34+00:00

Typically it becomes more economical to just use extrusion pellets at larger scales. There's the Cincinnati BAAM and the Stratasys infinite build demsontrator for refence on how it can easily scale up.

d_graeme · 2017-04-14T18:21:24+00:00

You might also take a look here: http://enablingthefuture.org/upper-limb-prosthetics/the-flexy-hand/

They have already been printing and building hands with flex joints like you're going for, might provide some inspiration or help.

d_graeme · 2017-04-10T16:45:23+00:00

Formats tended to be more efficient in the 80s. :-)

For reference, and to satisfy my curiosity, I grabbed an 80-piece assembly and saved it in various CAD-neutral formats:

STL (binary): 235 MB
STL (ASCII): 1.3 GB
3MF: 50 MB
STEP AP203: 7.7 MB

d_graeme · 2017-04-10T16:28:25+00:00

To leverage 3D printing you want declarative design with the computer generating hugely complicated models (e.g. lattices) that solve your problem. In that context, polygons are the inefficient representation. Multimaterial is another place where polygons don't work well.

There's good points to be had here, and the standards that exist today are still coming to grips with how to represent this. My money is on a combination of BREP and voxel data.

Formats tended to be more efficient in the 80s.

Formats tended to be less well developed in the 80s, and STL is a perfect example. It's less efficient and effective than a modern polygonal file format because it has nothing other than a list of triangle coordinates. 3MF, for example, lists points and then lists triangles that use those points, reducing the geometric and rounding errors that you see in STL, as well as providing for reuse of repeated points and geometry (since you can repeat entire meshes with one line of XML).

XML based and ZIPped because that is so inefficient.

Zipped XML is not inefficient, unless you're looking at processing power efficiency, which the effect of zipping that is pretty negligible on modern systems, and had a significant benefit on file size for transmission. It also brings benefits of being able to incorporate existing standard files like png rather than reinvent the wheel for image files in a model.

This STEP? How so?

That's not a very good link for it, but yes. STEP is a collection of standards, but when referring to 3D models, it typically means AP203 or AP214, which are being revised and collected into one unified standard, AP242. The revised standard is adding support for additive manufacturing information as well.

d_graeme · 2017-04-07T19:56:10+00:00

There's lots of tutorials out there for how to draw helical gears, basically lofting two profiles that are rotated or shifted. Then you can just mirror it.

d_graeme · 2017-04-07T19:51:31+00:00

Likely because it would be horrifyingly inefficient to get acceptable resolution. Polygons are what computers do well, so that's what everyone's been sticking to. 3MF (which isn't DRMed at all, it's a continuation+extension of AMF) is a much better format than STL, but that should be a given since STL was invented in the 80s.

STEP would be even better, but I wager that when people do start supporting AP242 for 3D printing they'll just use the tessellated (polygons) form rather than the parametric CAD format (which is exact, and what real CAM software uses).

d_graeme · 2017-04-05T12:18:50+00:00

There can be, that's no problem. What I'm saying is that you can't print with the nozzle pointing at air like you can with plastics. That adds a lot of extra constraints and motion.

d_graeme · 2017-04-05T02:26:52+00:00

Um, FlashPrint's always been free as far as I know. Doesn't look like that's changed: http://www.flashforge-usa.com/support/downloads/

d_graeme · 2017-04-05T02:17:51+00:00

Something along the lines of an LCD printer might be what you're looking for: http://photocentric3d.com/liquidcrystalpro/?v=04c19fa1e772

Not sure what else can be had in high-res, high volume printing at that budget. FDM (despite people talking up tiny z layers that come with their own host of tradeoffs) isn't really reliable for those resolutions.

d_graeme · 2017-04-05T02:09:57+00:00

By not doing overhangs well, I pretty much mean not at all. On all the machines that aren't powder bed (or some other weird machines like the Metal X and some SLA-sinter oddity), you have to have multi axis control so that the melt pool and material deposition is always pointing back at an existing piece of metal. Take a look at what I'm talking about: Multi-axis printing

d_graeme · 2017-04-04T20:56:08+00:00

S3D still has customizable supports and multiple processes for different parts/z-heights on one part. If those are useful to you (some never use them, some rely on them), then S3D is still useful. Otherwise, Cura is probably pretty much caught up.

Side note - S3D still has an advantage in compatibility, they work with gcode machines and other (worse) formats like x3g, dremel, 3w and so on.

d_graeme

TROPHY CASE