0.1 layer gets knocked off at about 6cm

I've made many 0.3mm layer prints with no problem, but 5 of 5 prints at 0.1mm quality have failed at about the 6cm mark. As it approaches 6cm (starting around 4.5 maybe?) the extruder starts grazing against the previous layer, making a very audible click sound. By the time it gets to 6cm (more or less) it catches on the print and physically rips it up.
As I said, 5 out of 5 prints at 0.1mm quality have done this, always at about the same height of 6cm, not once have I printed something taller than that at that detail to completion. This leads me to conclude that there is something very wrong somewhere, like it thinks it is rising 0.1mm and laying down the right amount of plastic but is really only raising 0.099mm, or it is rising 0.1mm but laying down plastic for a height of 0.11mm maybe? Is that a thing that can be? And if so how do I go about fixing that?
Thank you! I'd really like to make a few things at 0.1mm quality as Christmas presents.

 

How does your print look like? From what you're saying you could try to reduce the filament flow in your slicer to like 90% and also try to measure the first layer height an specify it in the slicer as well.
In my early prints I figured that the flow rate was too high so that resulting in too much filament layed down.

Is your bed properly levelled in all directions (left-right-front-back)?

I think if it would move only 0.099mm, you'd run into issues much earlier. with 6cm, this is about 6mm. Your hotend would probably chrush into your object quite badly..

 

The print actually looks more or less perfect right up until the extruder catches on it and pulls it off.

The bed is as level as I can make it using a stock card at all four corners.

In another thread I discovered that I may not be printing hot enough or with enough cooling so I'm trying some things. I'll also try reducing the filament flow; where do I find that? Is that "extrusion multiplier"? That seems to say it does what I need it to do.

 

Trying is always good

Yes, the extrusion multiplier is probably what you need. On Slic3r it should be around 0.9 to 0.95. In Cura (what I use) it's somewhere between 90-95%. You should also try to measure your filament. If you go from 1.75 to 1.8, you already get 3% less extrusion.
Can you check if your z-axis threads are tight to the steppers? I wouldn't know why the layer height would make a difference, but anyway, one more thing to rule out.

 

I have a theory, try setting your layer height to 0.09878, let me know how that goes.

 

You're thinking of a different thread gradient? Like M8x1 instead of M8x1.25?

 

the robos use imperial threaded rods, everything else on the printer works in metric, so every so many layers it will cause an error in the print, this is often the cause of z ribbing. I'm thinking that maybe since he is using such a small layer height that there is less forgives and that's what is causing is problem. But probably not.

 

Interesting, I was implying those were metric. If I were to change those to metric, I'd probably need to tweak the firmware, right?
I just realized that my tallest print is about 50mm so far, so I may not have hit this issue.

 

I increased the temperature of the extruder and actually completed a print at almost 7cm without issue. It still grazes it a little, got really worried, but it is definitely much better. I'm going to try reducing the flow to 90% on my next attempt, see how that behaves, and throw in some more powerful cooling later.
My problem now is that the bottom warped pretty heavily, as a result of the hotter temperature I would assume. Two steps forward, one step back.
It's only a matter of time though, I'll get it perfect eventually.