Micrometer inconsistencies in z-offset probing causing waviness?
Hi.
I've been doing some experimentation on finding a suitable z-offset value in my slicer for my kit MK4 printer. I occasionally have some issues with wavy first layers due to the z-offset being too low, and I've landed on adding +0.025 mm to the z-offset to eliminate the waviness / waves. Surprisingly enough, just 0.005 or 0.010 mm difference in z-offset is enough to cause or eliminate waviness in the first layer.
When printing many +0.025 mm z-offset samples to ensure consistency, I encountered a problem. The same piece printed with the same +0.025 mm z-offset are on the same print bed different in waviness (see attached picture). I guess this is due to the automated z-offset probing itself has some inconsistencies. (To clarify, I have not seen a pattern in previous prints of the right object being more wavy than the left object.)
I could in theory remedy this and just add a much larger like +0.05 mm z-offset to all my prints, but I'm concerned adding too much of a positive z-offset will lead to a decreasing print quality in other ways.
Have you faced this issue before? Do you have any tips or advice?
RE: Micrometer inconsistencies in z-offset probing causing waviness?
No attached pictures. I believe you have to have a certain number of posts before you can attach anything.
I do not have a MK4 but I do have a MK3 along with a few other printers. As with ANY printer you have to take thermal expansion into account. The bed as it heats will expand. It also takes awhile for the heat to soak in thoroughly. Now the Mk3's PINDA probe is also temperature dependant so even without bed variances for it expanding the sensor would also give different readings when it is at different temperatures.
On the Mk3 the answer is to do a preheat for 10 minutes or so before printing and to also make sure the pinda probe is also at a set(minimum) temp before proceeding. Which is handled by specific start gcode modifications first introduced by the much missed Bobstro several years ago. Since doing that I get a very consistent first layer every time. It just requires a degree of patience , especially in winter to get everything up to temp.
Not sure how the MK4 handles that, however seeing as there are several posts on here complaining about this very thing it looks like it doesn't, at least in all cases. Sometimes newer does not always equal better.
You can at least take bed temp variance out by doing your tests and coming up with your value with the bed heated up to a specific temperature (your most common printing temp) for at least 10 minutes before you start. That way you have less variables to worry about.