How do I calibrate the printed dimensions?  

Re: How do I calibrate the printed dimensions?

Hmm.. I suppose different materials might shrink differently. Maybe that is accounted for in the slicer instead of the printer?

Re: How do I calibrate the printed dimensions?

I often messed with the x and y dimensions with the steps/mm, but found the stock XYZ steps/mm very accurate.
calibrating for small objects will make big objects larger or smaller, calibrating for big objects will make smaller ones inaccurate, and nothing will really have their intended dimensions anymore.

The one thing that does something for accuracy is tuning the E steps.
It usually helps on every printer, but witht he MK3, well lets say the devs themselves are not sure wherever the E steps or the extrusion multiplier should be corrected. Currently they have this line in the starting gcode that tones down the extrusion a bit to avoid layer lines
M221 S{if layer_height==0.05}100{else}95{endif}

What this does is give you 5% less plastic, which can result in the smaller dimensions you see on X and Y.

For Z lower the nozzle by 50-100 micron.

Also different materials have different shrinking capabilities. Tune for one material, and it's off for the next.

Re: How do I calibrate the printed dimensions?

I just now noticed that the latest firmware release claims to have modified/corrected calibration. Not sure if it will matter or not:

new version of firmware 3.2.0-RC2 for MK3 is out!
What is new:

MK3:
- Modified XYZ calibration
- Printing area and calibration points corrections

Re: How do I calibrate the printed dimensions?

Same experience for me. It's not worth to calibrate the printer for a perfect dimension accuracy.
With FDM printing you have always a trade of. Should it look nice? Should it be strong? Should it be dimensional accurate? Should it print fast? ....
In addition the 1.75 diameter for a spool varies often somewhere between 1.65 and 1.85. And I don't even start with a shrinkage of the filament.

I always modify the print settings or the object scale, if proper dim. acc. is required. After couple iterations, I'm getting the correct values.

Re: How do I calibrate the printed dimensions?

I always modify the print settings or the object scale, if proper dim. acc. is required. After couple iterations, I'm getting the correct values.

Which print settings do you modify?

Re: How do I calibrate the printed dimensions?

Which print settings do you modify?

For small adjustments:
-> flow rate
-> number of perimeters
-> infill percentage
Big adjustments:
-> Scale