Welcome to the SeeMeCNC Community

I've been struggling with my calibration drifting. One day it will be spot on, the next it will be off by a few tenths of a millimeter. I know that hot head and bed temperature changes are part of it, but even when they're at the same temperatures I see drift.

It seems important to know just what's happening, so that I can a) know what adjustments I can expect to need, or even b) prevent the drift altogether.

Here are my guesses as to causes:

• Hysteresis in the mechanisms (e.g. when I manage to ram my nozzle into the glass)
• Wear and tear
• Other parts changing dimensions with room temperature (e.g. belts, towers)
• Schmutz in the extruder's hobbed gear changing the extrusion ratio
• Eddies in the space-time continuum ("ah... is he. Is he.")

Any thoughts? What parameters seem to drift for you? How do you control it?


Thanks,
Dan

Now that I've got everything dialed in, I'm seeing maybe a 50 micron adjustment needed which I'll notice on the first print of the day. Haven't tracked the source of that down yet. yet.

From some recent experiences with my own machine, where is what I'd suggest.

With 170 posts, I'm assuming you've had your machine for at least a couple of months now, so many of these may apply.

- Check your screws. All of them.
I've been printing now for more than a year. I went through my machine last week. and every. single. screw. was loose. Go though and check all of them, the ones in each compartment, the ones on the bottom of the machine, the ones that connect your heated build plate. all of them.

- Check all the bolts for the idlers and tensioners for your belts and cheapskates

- Belt tension

- Check your idler pulleys for grime
Maybe not an issue for you, but I did a couple of really silly things earlier this year. I applied aquanet to the glass while it was on the machine, and had been cleaning off the glass plate, also on the machine. the aquanet transferred to the belts, which transferred to the idler pulleys, which then collected all the dust and dirt. That was fun.

- Check your setscrews for your cheapskates
if they're loose fitting, I guess they could wriggle about over time. maybe get them to within a few hundred microns of level and use locktite if they were loose

If I can think of any more

If you start losing Z height on the effector and it won't stay adjusted, check to make sure your stepper motor pulleys have proper flats ground into the shaft and use fresh blue loctite to hold the set screws tightly in place. If those slip even a little bit, it will make printing miserable and almost impossible.