DivingDuck

I feel totally misunderstood 😂 You are right and you are not. No one with a little bit knowledge ask for this kind of resolution for printing one layer with 0.0075mm hight with a 3D printer (and that is for sure not a matter of Chinese quality or not. They also can do very precise things...) The impact is an complete other story. Think about a technical design with more than one plane stacked involved and where you have to match these planes to fit into other parts. And also think about that this dimensions don't follow a given fix layer height, especially if in addition tolerances have to be part of this too. Then a "stupid" single step become a huge impact to get the dimensions correct within a more complex technical part. And that is usually not one or more printed single layer of 0.0075mm but maybe a combination of layers that do not follow a "normal" layer hight of 0.1mm, 0.15mm or 0.2mm but maybe like x + one or multiple steps more. Example: 0.165 (= 0.15 + 0.015) for a next layer, what is in full steps 20 steps + 2 steps = 22 steps for a TR8 with pitch 1.5mm. I guess you get my point. That is for what I use adaptive layers usually. Back to your Chinese style printer, this mean that you have usually a TR8 pitch 2.0mm lead screw. This means a general resolution of 0.01 mm for each full step and increments of it. And also here, you don't want to print 10 single layers with 0.01 but maybe you need something like 0.23mm, what is 23 steps or 0.13mm (13 steps) - and that is what your and all other printer do absolutely precise, no matter if your printer is expensive rocket science or a cheap one. 🙂 What means this for your example? You need to think in steps first and then find a relatively good setup for a printed part with spherical objects include as there is no one click solution. The only way I know is to play with all 3 parameter to come as close as possible to a good print. In addition there is a hidden 4. parameter ... you: for fine tuning / polishing the print if needed. 🙂

Agree for aliasing and flow, this can be a challenge. Micro stepping isn't a problem because it isn't involved (for the same reason you mention). It is pure full step for a DIN TR8 with pitch 1.5 for standard 1.8° stepper's. The main problem is that Cura limits the input value to 3 digits and I need to use increments of 0.0075 mm to match the conditions. I never understood why this decision was taken, as pitch 1.5 is an standard value in DIN wold. Please correct me, if I forgot something that have to be consider: I my case for Cura I can use 2 steps as minimum Z hight, 0.015 mm. Then the flow calculation can follow w/o having a calculation problem (hopefully).

Nice. Please make a photo from your calibration cube. I like to see how it looks now :)

You maybe overlook the impact of bed mounting. When you fixing a aluminum plate on all 4 corners with a screw so that it can not expand/move evenly in all directions, what will happen? Usually it will put expansion forces to the screws and try to bend them, screws it self will put forces against the plate too because they can't move too. And not to forget that the thermal expansion of the heat bed isn't consistent everywhere too. In reality it will bend both, screw and bed. In the end this will always have a measurable effect on distance between nozzle and bed. This effect will be more noticeable as bigger a bed will be and even more if the plate is thin.

The only way I know is to move the parts manually while check the result in the print simulation.

Why? Make the math. Lets assume you have a normal setup with an Trapezoidal Lead Screw e.g. TR8 with 1.5 or 2.0 pitch and a standard Nema 17 motor with usually 200 steps per revolution. This means for pitch 1.5 mm / 200 steps = 0.0075 mm / full step. That is what the resolution for Z is for a TR8 with pitch 1.5. For pitch 2.0 it is 0.01mm / step

Correct but not only thickness, it also start to wrap. You can easy check this for your printer. Level your bed for PLA (maybe 60 °C) and then heat up the bed to 80°C and check the distance between bed and nozzle. That's what happen.

That's a simple story: There are two points to consider . The first one is the fast heating capacity of silicon plad's. For fast heating you calculate between 0.33 to 0.9 W/cm², optimal is ca. 0.5 W/cm². That is for an 300mm x 300 mm heater plate 450 W and this will heat up a plate within 3 to 4 min from 20 to 80 °C. While a usual 12V/24V heater plate need much longer, the controller have more time to control the heat up process and that is what the usual firmware setting is. In that time the silicone heater will easily overshot by 20 to 40 °C what will cause a significant expansion for the heat bed. The second point is how printer manufacturer fasten the heat bed. They usually fix the bed on all 4 corners with an spring loaded screw. Well, this ask for even more deformation as this is a stupid design with problematic impact (as you can see). 😉 @VladimirK, it is ok to have a slight overshooting, as this is how adaptive control works in combination with thermal inertness of the aluminum plate . Check if you can increase the PWM slightly. (I use 20 Hz for my SSR's with 600 W pads)

Thanks for keep us informed. 👍

wegen dem anderen Tread? 🙂

This is something where the Cura team can improve the software as this problem is well known and often reported since Adaptive Layer was implemented. 🙂 I don't want to complain, but find it remarkable that Slic3r can do that easily (they implement it 2017). Cura implement it, but isn't able to summarize layer heights correctly. I know, easy to say, but how long exist Cura 4? And there is no time and/or priority to correct this software failure - the only thing that a FDM-Printer can easily achieve in exactness and the slicer isn't able to do it. I am still hoping that someone from the development team take this issue and repair it. Because this is showstopper for technical prints where is the need for minimum one exact measurement.

There is even more to do for controlling the bed heater. Bang-Bang-Control or PID-Control and setting PWM frequency for the SSR. https://duet3d.dozuki.com/Wiki/Choosing_a_bed_heater#Section_Bed_heater_driven_using_a_Solid_State_Relay

Statt Raft ist Brim ebenfalls eine gute Variante. Bei PETG auf die Bett-Temperatur, Druckgeschwindigkeit für den ersten Layer und Lüfter achten. Für den 1. Layer setze die Druckgeschwindigkeit eher in Richtung Hälfte der normalen Druckgeschwindigkeit und Lüfter aus. Bei problematischen Teilen (wie z. B. spitze Winkel und 90° Ecken) kann man sich bei eigenen Konstruktionen kleine Eselsohren als Brim-Ersatz hinzufügen. Das ist sehr hilfreich, falls ein Brim für saubere Außenkanten problematisch ist. Bezüglich Tisch gibt es ebenfalls noch einen weiteren Punkt, die Rollen betreffend (zumindest bei früheren Modellen), dort wandern die Kugellager in den Rollen nach innen weil man an einem passenden Spacer gespart hat. Dies führt dann ebenfalls zu einem wackelnden Tisch, insbesondere, wenn die Platte heiß ist und die Wärme mit der Zeit dort wirkt. Als Interimslösung kann man die Miniaturkugellager aus der Rolle nehmen und mit sehr sparsam dosiertem Sekundenkleber auf der Innenseite der Rolle wieder verkleben. Oder neue Open-build Rollen kaufen - die funktionieren dann garantiert, da sie einen passenden Spacer zwischen den Lagern haben.

You are setting the maximum variation to .16 and that is the problem. 🙂 What does this mean for your layer hight? You are advising Cura explicit to variate your normal layer hight of 0.2 mm between 0.36 mm (0.2 mm + 0.16 mm) and 0.04 mm (0.2 mm - 0.16 mm). So said, if you don't want to have a smaller max layer hight, you need to reduce this value. In addition you maybe want also change the original layer hight to a value that match to your needs. E.g. when you want a max layer hight of 0.2 mm and a max. variation of +/- 0.5 mm the matching regular layer hight should be 0.15 mm. Edit: Oh, @ghostkeeper was a bit faster. 🙂

The problem shouldn't come from the SSR. 220 V Silicone heating pad? This looks more like the temperature is over- and undershooting too much. How is your setup for temperature control?