Delta Calibration Migration over Time



  • Hello everyone,

    I know it's common practice to calibrate every time you turn on the printer, or even before every print. But it got me thinking - assuming the build of the printer doesn't change and isn't mishandled, what factors contribute to calibration drift over time?

    Here's a list I can think of:

    • Non-rigid bed
    • End stop movement
    • Electrical noise
    • Ambient temperature?
    • Thermal expansion / contraction mechanical movement

    Assuming a rigid bed, I'm thinking the next largest factor of error will be end-stops?

    Has anyone tracked their calibration results over time to see how they're changing and possibly tracked down what the issue is?



  • Cartesian printers really don't need much precision in X/Y homing. If the print is in a fractionally different part of the bed, it doesn't really matter.

    They DO need precision in Z, and most are arranged so the Z-Stop is physically at the same end of Z travel as the bed/nozzle 'zero' relationship. This is OK-ish on cheap printers. Better printers use a probe to calibrate Z. Every time. This ensures that IF anything changed, everything still works.

    Delta/Kossel have a higher need for a probe every time for two reasons: The stops are (almost always) as far away from the bed as you can get, and all three motors participate in making Z correct. Again, cheap printers can get away with no probe (manual calibration every so often) and this is again OK-ish. Probes just make everything better. Probes that can be fully automated to work every time, even better.

    I realize I didn't answer your question (yet). The fact that cartesian and/or Delta can be calibrated without a probe, and hold that calibration from hours to days to weeks, indicates there is not much shifting (from all sources combined). The fact that they will eventually lose calibration indicates there is some... so... probe... 🙂

    Also, probing means that endstops need even less precision, so stall detect on Triaminic chips suddenly becomes much more useful.

    Still didn't really answer your question. Given that probing is going to be "required" for quite a number of reasons, I'm not sure it is worth the time/effort to really explore. I'd advocate: Make the printer rigid (for many reasons); make the endstops be stall detect (which is really imprecise); probe; achieve fantastic first layers.

    Just MHO.



  • my delta had mechanical end stop. after i switched to optical ones it became more consistent


 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.