how are there no lines on these prints?

Any tips on printer tuning? Or maybe theres a whole tutorial i missed?

Not sure about bad camera focus for the first two videos. Seems fine by looking at the detail on the disc the print is on. But video is only 480p though...

Anybody got some macro photos of 0.1mm prints with good tuning? These videos are honestly all i could find that look good.

ultimaker+14hours+.1mm

that's how this was accomplished

At .05mm layers, I doubt the lines would be easily distinguishable, but they are still there.  There is an article somewhere out there examining high-res prints with a microscope in order to show that even high resolution prints can get bits of food stuck in them, even if the eye cant see them.  Something else important to note: that single print took 11 hours to make and is smaller than his hand. Also he has a delta machine, which usually runs faster than a Solidoodle, so it would take even longer on a Solidoodle.  Honestly, the lines don't bug me.  I print at .2mm and the lines are only just noticeable to the naked eye, and if others notice, it's a cool conversation point "Yep, that really was made on my bedroom desk!".  With my Solidoodle, the z-banding was so bad that it usually overshadowed the thicker lines making my high-res prints look worse than low-res ones, so if you do try to go that high-res with a Solidoodle, the fine threaded z-rod is going to be the first step to making the prints look that good, then a new extruder (E3D is amazing), and then possibly some linear bearings for the other axes.  It seems that usually people who do those really high resolution prints have an Ultimaker (probably because of its speed).

If you want line free printing.. buy an SLA printer. Someone was infact offering up their Form 1 for sale.
FFF/FDM printing is not the appropriate tool in this instance... By definition, it will have deposition lines. You can counter this by using an appropriate material for the end-state.. for example, if surface finish is important, but fine surface detail is not present - just use PLA at anything <.25mm and you wont see lines...

Refer to Blue coloured Yoda on the left in this pic:

Thats just old fashioned .25mm with PLA and a slight hotter nozzle to make it a tad runnier... The transparent yoda is in ABS, and consequently, highlights the occasional deposition lines as its pretty static once laid down...

Now - knowing I printed that at .25mm as a test piece... lets have a look at the time comparisons between the different layer heights for the same printer using that STL : Yoda-Lite.stl (mesh reduced Yoda bust https://www.thingiverse.com/thing:10752 from faberdasher )

1h 37m .40mm
1h 55m .30mm
2h 09m .25mm
2h 28m .20mm
4h 32m .10mm
8h 43m .05mm

Massive difference there in time to print exactly the same piece ultimately. And there is no quality benefit in switching below .25mm .. it literally just takes 4 times as long! (I say this for this model, as it has no fine surface texture or detail, so there is no quality improvement. If you were printing a lifelike textured sandstone wall - then sure, .1mm etc might bring you much greater detail than .25mm would. For the models in the video, and for old Yoda here - it don't do nuthin' but stretch the print time.... yes theres a tiny bit of extra face craginess you can eek out - but it doesn't really effect the final product....)

As for leaving the machines running and 11 hours for a tiny print 'not so bad'..... the bigger issue is it wears very very thin the 4th time at around hour 6 there is a slight fault in the print...

Ultimately if you are concerned about layer lines, move right along to SLA and forget worrying about FFF/FDM. Especially when you consider the time taken to print the (relatively) small model at 0.05mm to avoid any layer lines, you  could have printed 4 other models in the mean time... Or put another way - The pic in this post would have taken 22+ hours to produce, vs the 4 hours it actually took

Worrying about layer lines on FFF/FDM printed objects is like fretting over the most appropriate way to use a teaspoon as a screwdriver (i.e, you've already started with the wrong implement ..... it can be done, but its often not worth the effort of just using a screwdriver in the first place ) 

Old post, but I have a strange update over this topic.
I'm facing a strange behaviour. Half of my prints has visible layers, the other half has an almost perfectly smooth surface.

It shows that is possible to have not visible layers, but I can't understand how!
Moreover, I noticed if I raise the temperature layers are more visible If I reduce the temperature surfaces seems smoother, but If I reduce too much the temperature surfaces become much smoother but also surfaces become deformed and bent.

How is it possible?
How can I have 100% of the piece perfectly smooth?

Has someone faced the same?