The Ultimate "Calibration Cube"

A simple, yet effective solution for calibrating your printer's steps per mm that is unaffected by flow rate or PA.
Your search for a fast and reliable calibration has come to an end! This calibration is designed to easily raise the accuracy of your 3D printer without the excessive print times.

Compared with the more conventional six-sided calibration cube, this print offers three main advantages; it's faster to print and uses less material,* it's more accurate, and it is not affected by poorly calibrated flow rates, e-steps, or pressure advance settings. At 50mm, measuring errors are less severe than with the standard 20mm cube, and after taking the average of the inside and outside edges, it becomes far more accurate than even a 50mm cube. The Califlower is by far the more precise tool with larger measuring lengths and skew calibration, but this has the advantage of print speed.

Print Settings

It's pretty much drag and drop for most printers, but you can shorten the print by using only two walls and setting the infill to 0%. If you don't need to calibrate the Z axis, just pause the print when it starts on the Z axis tower. If you're having trouble getting it to adhere to the build plate, consider using a brim or applying some glue stick. Once the print is complete, allow it to cool before removing it from the build plate.

Print in a low-shrinkage material such as PLA or PETG, as this will reduce the effect of warpage on the results. If you have PLA-CF or PETG-CF, use these as the carbon fibers will help maintain dimensional accuracy.

Calibrating Your Printer

I won't go into detail on how exactly to calibrate your printer's steps per mm (hereafter SPM) because it is different for every printer, but I will provide an overview and the equations necessary.

-First, you will need to research how to find your printer’s current SPM values for your X, Y, and Z axes. This will be specific to your printer's firmware type (Marlin, Klipper, RepRap, etc.) and potentially your printer. If it is running custom firmware, take my advice and check first that changing your SPM value is possible on your printer as you could potentially cause damage or just waste your time if it's not. After you have these values, write them down as you will need them later.

-Here's the fun part, print the model.

-Once the print is done and has had time to cool, choose an axis and measure both the inner and outer distances on the model, recording the average. Do this for both the X and Y axes of the print. The Z axis is only one measurement as flow rate and pressure advance only affect the X-Y plane of the print.

-Now for the math. Take your measurements and put them individually into the equation below or use an online calculator.

(current_SPM x expected_measurement)/actual_measurement
Here's an example with "mm" added for clarity.

New X SPM = (80 x 50mm)/49.85mm
New Y SPM = (80 x 50mm)/50.18
New Z SPM = (400 x 50mm)/50.04mm
-Now apply and save these new values to your printer. Make sure that they have been permanently applied as it is possible to have the values appear to be saved, only to lose them after powering off the device.

-Congratulations, your printer is all set to start printing again! If you want to take it a step further, repeat this process over a few times to get an even more accurate steps per mm value. Using one of the larger models will multiply your printer's deviance, making it easier to measure. For most consumer 3D printers, a deviation of ±0.1 is considered acceptable.

Additional Notes

You may want to consider saving your new SPM and other printer related settings to some kind of document for future reference in the case that they get lost or you happen to need them after a motherboard replacement.

Some 3D printers use mm per step instead of steps per mm. This will mean that the number will be represented as a decimal fraction (e.g. 0.0125). The conventional math will not directly apply in this case. You must take your number and divide it by 1. This will convert it into the usual form (e.g. 80), after which you can solve it normally. With your new steps per mm number, divide 1 by it again to convert it back to mm per step.

*Compared with the equivalent 50mm³ calibration cube.