Questions on designing for the ultimaker.

[gibbons 0]

Not an ultimaker owner just yet.

I have some basic questions on designing objects for the ultimaker to print, (without using NetFabb to design break away supports.)

Keep in mind I’m more interested in printing objects with the best quality so time isn’t much of a factor. So if it takes forever to print at 0.02 layer height so be it.

• Overhang Angle – What can you get away with? (Repraps list approximately 45 degrees.) How do tiny layer heights influence this?

• Bridging – metric distance for bridging a horizontal gap without incident? Influenced by tiny layer height?

• Wall thickness – or rather how thick should the thinnest parts be as a rule of thumb, lets just say the whole thing is solid and not honeycombed. (Any differences between PLA and ABS)

• Printing with PLA vs ABS – From what I gather the Ultimaker is geared towards PLA Printing. Can it also print ABS out of the box without modifying the machine? Again layer height, do things get strange with ABS for thinner layers?

So very close to hitting the order button.

When I’ve had my work milled with a tiny CNC machine it takes a lot of time to prep my designs specifically for the limitations of the machine. At this stage just trying to ease any concerns. And get a better idea of what I can print.

Thanks for any feedback!

[Daid 298]

Overhangs up to 60deg can be achieved. 45deg is a safe bet always, but more can be achieved.

Bridging is troublesome at 0.1mm layers, it still works, but comes out less pretty. For high quality prints I recommend avoiding bridging large gaps.

With thin parts you run into the "thin wall" problem. Which means it no longer puts in an infill while it should. Depending on what you are making, walls thinner then 1.6mm can be troublesome. However, if you use different settings this sometimes can work. For example, for these small gears:

http://daid.eu/~daid/IMG_20120520_230452.jpg

I used only 1 perimeter line of 0.4mm, instead of the normal 2 lines. Which made the infill better. However, this setting would not have worked in combination with overhangs.

I have no experience with ABS, but I've read that it's harder to print ABS at thin layers.

[gibbons 0]

Thank you so much for the quick reply Daid.

Now as far as PLA goes is there anything I should be aware of as far as the material goes? (IE, how it behaves at different thicknesses, or the usual do not drop, do not leave out in the car on a hot summer day)

I’d like to eventually do some items that have ball and socket armatures but unsure if I could pull it off without having a thick clumsy design.

[Daid 298]

Now as far as PLA goes is there anything I should be aware of as far as the material goes? (IE, how it behaves at different thicknesses, or the usual do not drop, do not leave out in the car on a hot summer day)

Do not get it over 70C, or it will go soft. It can get this hot in a car, behind a window, in the sun. But that's rare.

Do NOT dishwash it!

As for strength. *bonk* I usually throw my rotating cube gears:

http://daid.eu/~daid/IMG_20120423 ... .small.jpg

on the floor when people ask this. They haven't broken yet. And now are losing a bit of strength because of the many times it has been disassembled. But strength wise it's as strong as any other plastic.

I really like PLA. It feels tough, it smells nice when extruding, and it prints very well. The only disadvantage is that it breaks before it bends. So snap together designs are sometimes a bit harder to pull off (but still possible)

 

I’d like to eventually do some items that have ball and socket armatures but unsure if I could pull it off without having a thick clumsy design.

I haven't tried ball&socket yet. But I have done pin connectors, for example in the screwless rotating cube gears. I'm not sure what you find thick and clumsy. The normal connectors are like 7mm width, but I think they can work smaller. However, when I printed them at 50% scale they didn't snap that well anymore and that small cube falls apart.

[gibbons 0]

Thanks for all the helpful answers.

Couple more questions while I have you.

How well does PLA age? For example, colors get sun bleached, or it becomes more brittle?

Have you played with anything like printing interlocking parts that clasp? Where it requires a little bit of flex in the parts to snap into place?

As for 'thick and clumsy' ball and socket parts, what I'm trying to nail down is the feasible size and thickness of a socket joint. Making things that don't need support and work without too much cleaning. After having a few designs printed on a uprint, wanted to see if I could pull off more detailed prints on a Ultimaker.

Thanks again for all the info.

[Daid 298]

I don't know how well it ages. We have a print laying in someones garden for half a year now, still looks the same. (dutch weather, lots of rain, little sun) But it's black, so it is hard to see if it loses color.

I've done these snap together things:

http://www.thingiverse.com/thing:12305

It can be done, but you need different designs for ABS then PLA. As ABS flexes more then PLA. It simply comes down to doing test prints. That's the only way to know your design works. Even with my experience, it took me quite a few tries to get my tiny gears printed correctly in a way they work. Which didn't have to do with clamping, but more with tolerances and part strength.

[gibbons 0]

Thanks again for all the info.

[chronoless 0]

I've done a bit of testing with ABS and I still prefer PLA. ABS also has some interesting pro's though. It seems to flow/fill better. It's difficult to describe how exactly . Also it's not as glossy as PLA. The glossiness shows the imperfections really well. Also ABS has a few material properties that can also be beneficial like strength and temperature resistance.

The reasons I don't use ABS most of the times: It smells bad. It wraps; a lot. You can solve this by using a raft but it depends on the design of the part if it actually works satisfactory. It doesn't stick as good to the tape as PLA. Also it's easier to mess up the filament drive. It almost never fails with PLA anymore but with ABS it sometimes just strips. But maybe that's just a matter of experience with fine-tuning.

The only thing I had to do to make a file ABS ready is to change the packing density in Cura.

[joergen 1]

I am one of the few who dropped PLA and went for ABS, because PLA wasn't working at all for my projects (360rig.com).

the main reason is that ABS is machinable (drill, cut, mill, sand etc) while all of this is extremely difficult with PLA, or impossible. if your PLA prints come out perfect, and you don't need to do anything, then PLA is fine. if you are planning to work on the print a bit more, go for ABS. a heated bed with a glass platform (110-115C) eliminates all warping and stick-to-the-bed issues.

also, ABS starts to get soft at 110C, while PLA gets soft at 58C (glass transition temperature), which was a big issue for me, since electronics get hotter than 60C

[gibbons 0]

Chronoless and Joergen thank you both for your material insight.

The real question I have is, out of the box can the Ultimaker handle ABS without too much issue. (Assuming that a raft would have to be made for each print.)

I'm cool with future modifications, but just want to make sure that I can experiment with different materials without too much worry.

Joergen on a side note I'd like to commend your camera project, quite nice.

[joergen 1]

The real question I have is, out of the box can the Ultimaker handle ABS without too much issue. (Assuming that a raft would have to be made for each print.)

I'm cool with future modifications, but just want to make sure that I can experiment with different materials without too much worry.

It depends on your part. generally, the more material you have in each layer horizontally, the more you have to deal with warping when it cools down. both plastics warp, ABS more than PLA. without a heated bed, it is impossible to print a perfectly flat bottom 6x6cm part with ABS or PLA. if you design around this issue (needs a bunch of failed prints to understand how the plastic is behaving), or if you print only hollow, tube like structures or vases, blue tape will offer enough adhesion to print with a cold bed.

 

Joergen on a side note I'd like to commend your camera project, quite nice.

Thank you, I am redesigning the rig from scratch right now to solve some fundamental issues, and will present it on the international panorama photography conference in 10 days here in NYC.

[gibbons 0]

Thanks amendaburls