CoreXY Calibration

Update: New Calibration Octagon. (Calibration OctagonV2)

• Prints faster
• Updated extruded instruction text
• Updated V notches

This procedure makes use of three calibration objects. An Extrusion Cylinder, a Calibration Octagon and a 100mm Calibration Column. This is probably not the only way to calibrate but it's the process I used when calibrating my CoreXY.

A caliper is required to perform this calibration.

There are eight steps to complete the calibration:

1. verify the printer's frame is square.
2. Level bed and adjust the Z offset.
3. Calibrate the extruder.
4. Calibrate the Extrusion Multiplier of the slicer.
5. Identify the Alpha and Beta stepper motors.
6. Using the Calibration Octagon adjust belt tension.
7. Using the Calibration Octagon adjust steps/mm of the Alpha and Beta Motors.
8. Using the 100mm column adjust the steps/mm of the Z stepper motor.

**Prior to starting calibration verify that the printer's frame is square, the bed is leveled, and the Z-Offset calibrated.

These first steps are important to guarantee accurate calibration.**

Print Settings

Printer:

HyperCube Evolution

Rafts:

No

Supports:

No

Resolution:

.2

Infill:

20%

Filament:

Notes:

• Extrusion Cylinder is printed in vase/spiral mode.
Calibration Octagon is printed slower than normal to lessen any artifacts in the outer wall. I printed at 50 mm/sec. Layer height .3mm. 100mm Calibration Tower is printed with a first layer of .2mm and layer height of .2mm.

How I Designed This

I designed this after reading CoreXY Tuning on the RepRap Forum. It made sense. I applied the instructions to the Calibration Octagon I had previously designed. After seeing the results I needed to share.

I think I've edited out all my typos and fine tuned the calibration steps. If there is something I missed, or needs more explanation, please leave me a comment.

First Steps

1. Verify the frame is square.

Using a tape measure verify the diagonals (corner to corner) of the frame are the same measurements. 2. Adjust the Z-Offset and level the bed.

There are many online videos showing the procedures. 3. Calibrate the extruder.

Again, there are many online videos demonstrating the procedure.

Basically, mark off 100mm on the filament and then extrude 100mm. If the extruded amount is different than 100mm, adjust the steps per unit to fix.

Extrusion Multiplier Calibration

1. Print the Extrusion Cylinder in vase/spiralize mode.
2. Using calipers measure the thickness of the cylinder wall.
3. If printing with a .4mm nozzle it should be around .43 to .45 mm
4. If adjustments are required adjust the extrusion multiplier (Cura: Flow) of the slicer.

Adjusting Belt Tension

Calibration Octagon

How to perform measurements.

Place the octagon flat on a table when measuring. Use the table top to keep the caliper nibs aligned and measure dimensions from "V" notch to "V" notch. The Octagon is chamfered to prevent inaccurate measurements due to an elephant foot.

Place the Calibration column flat on a table top when measuring to align the caliper nibs.

Adjust belt tensions

1.Identify which of the X/Y motors is the Alpha and Beta motors.

Turning only one X/Y motor while keeping the other stationary, observe which diagonal the X carriage moves along. If it moves along the "A" diagonal then the motor that's being turned is the Alpha motor. The belt that is attached to the Alpha motor is the Alpha belt. If it moves along the "B" diagonal then it's the Beta motor and the Beta belt. 2.Print the Calibration Octagon. 3.Allow the Calibration Octagon to cool. 4.Measure along the A and B diagonals. * If "A" diagonal measurement greater than the "B"
Alpha belt tighter than the Beta. Either loosen Alpha belt or tighten Beta belt. * If "B" diagonal measurement greater than the "A"
Beta belt tighter than the Alpha. Either loosen Beta belt or tighten Alpha belt. 5.Repeat steps 2-5 until satisfied with result.


Adjust X Y steps per unit

1.Print the Calibration Octagon. 2.Allow the Calibration Octagon to cool. 3.Measure the "X" dimension and "Y" dimension of the octagon.

They should be very close to equal. Using the following formula calculate the new steps per unit.

100 / Measured Dimension x Current steps per unit.

Example:

If measured dimension is 101.3 and Current steps per unit is 80

100 / 101.3 = .98717

80* .98717 = 78.97

Set the steps per unit for both X and Y to 78.97 4.Repeat steps 1-3 to verify and/or adjust.

Adjust Z steps per unit

1. Print the Calibration Column

First layer should be at .2 mm and layer height set to .2 mm. 2. Allow print to cool. 3. Measure the Calibration Column. 4. If required, using the same formula as in the X Y steps per unit, calculate the new steps per unit for the Z axis. 5. Repeat 1-4 until satisfied.