Teaching Tech 3D Printer Calibration
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This page serves as a companion for this video:
It aims to make calibrating your 3D printer as easy as possible. If you find it helps you and you would like to say thank you, here is a donation link: PayPal.me
Special thanks to my Patrons for suggesting this video and helping define the contents.
Watch the video and then work through each tab. I have created a custom gcode generator to assist in testing towers. Every attempt has been made to ensure this is safe but ultimately there always is risk in running presliced gcode from the internet. Preview the gcode in your slicer or Gcode.ws and print at your own risk.
To ensure there are no underlying problems with the frame or mechanical components.
Any time the frame or mechnical components have been disassembled or replaced.
It would be easy to use the techniques elsewhere on this page to try and fix problems that were actually caused by a problem with the physical components, so we will eliminate this first.
Many of these procedures are covered in this video: Complete beginner's guide to 3D printing - Assembly, tour, slicing, levelling and first prints
Move around the machine and check all fasteners. Crucial ones include those on the print head gantry such as those that hold the hot end on.
If your printer has a motion system based on V-roller wheels riding on V-slot extrusions, check they are properly tensioned. Each location will have one eccentric nut. This can be twisted to either add or remove tension on the wheels.
If the wheels are too loose: Wobble will be present in the assembly, which will show in the print as surface artefacts.
If the wheels are too tight: The assembly is will be too tense, which will wear the V-rollers prematurely.
Probably the most essential part of setting up your 3D printer. Most new users will trip up on this. My method is included in the above video and this diagram is a handy reference:
If your printer has PTFE tube, such as a bowden tube setup for the extruder/hot end, it is essential to make the tube is fully inserted and seated in the coupler. Also ensure the coupler is properly tightened. You may wish to use a small retaining clip on the coupler to prevent the tube working loose: Creality PTFE clip by morfidesign.
It is worth heating up te nozzle and pushing some filament through to see if it is exiting the nozzle properly. If the diameter is inconsistent or the extruded plastic shoots to one side, it may indicate a partial blockage in the nozzle that will be a pain in the future. It is also worth checking if the nozzle is properly tightened. Only do this when it is hot or you mau break it.
Ensure all belts are properly alinged and tensioned sufficiently.
Check all fans are spinning freely. This includes but is not limited to: mainboard cooling fan, heat sink fan, part cooling fan, PSU fan. It can be hard to diagose if a fan is performing at less than full capacity. It may be easier to simply replace than repair if you suspect a fan is failing.
To ensure the heating of the 3D printer nozzle and bed are safe, stable and consistent.
Any time the hot end is changed, including addng/removing a silicone sock or altering part cooling fan/ducts. Any time the bed is changed, such as adding a glass/mirror plate, magnetic spring steel sheet and/or under bed insulation.
This procedure is covered in this video: Two easy fixes for 3D printer temperature swings
In Marlin, this is a very straightforward process using M303.
Using a terminal such as Pronterface or Octoprint, enter the following for the hot end:
M303 E1 S200 U1
This will tune the hot end at 200 degrees. The S value can be altered to suit your most common printing temperature. The
M500
For the bed, PIDTEMPBED must be enabled in the firmware, then the command is quite similar:
M303 E-1 S60 U1
The bed is selected with E-1, and the temp set to 60 degrees. Substiture as necessary for your normal printing temperature. Once again save to EEPROM afterwards with:
M500
It may be preferable to have the printer as close to printing conditions as possible during these tuning prodecures. That means having filament loaded and the part cooling fan on for PLA temperatures.
To establish a baseline for comparison with later tests or before modifications.
Before general calibration or before a significant modification is to be fitted.
The form below will create a customised version of the XYZ 20mm calibration cube by iDig3Dprinting. It is fast to print and gives a good indication if there is any fundamental problem with the printer.
If there are no major issues, please continue to the next step. If there is a significant defect, the culprit will likely be found on the frame page.
To determine the correct amount of steps Marlin firmware needs to send to the stepper motor for a desired movement.
Base calibration, as well as any time there has been a change to the extruder/hot end.
For the X, Y, and Z axes, the steper per mm is usually consistent between printers and rarely changes with modifications.
For the extruder however, variations in extruder hardware and filament means it is worth properly calibrating the extruder steps per mm, or E-steps.
This can be achieved using a terminal such as Pronterface or Octoprint by sending a series of gcode commands.
Firstly, we need to know the existing E-steps value. To find this, enter:
M92
M92 is used to report or set the steps per mm for each axis. M92 by itself will report the currents parameters. We want to make note of the number after E:
Now heat up your hot end to whatever temperature you usually print with. Once the temperature is stable, enter:
G91
G91 puts the printer in relative movement mode. Which means asking for 100mm adds 100mm to the current position, instead of moving to the exact position of 100mm.
Now we take a permanent marker and put a mark 120mm from the entry to the extruder.
G1 E100 F100
G91 sends a move command to the printer, in this case asking the extruder to advance 100mm at a speed of 100mm/sec.
The filament will then slowly go through the extruder and hot end. Once the extrusion finishes, we masure the distance between the mark and the entry to the extruder.
Ideally, 20mm remains, which means exactly 100mm was extruded. If your distance is anything other that this, complete the form below to calculate the correct E-steps:
To determine the correct amount filament to be extruded by the 3D printer as directed by the slicer.
Base calibration, as well as any time there has been a change to the extruder/hot end.
Our E-steps are now correct so we will move on to calibrating the slicer. Each slicer has setting to control the overall amount of filament extruded by the printer. If the flow rate is increased, more filament will be extruded. If the flow rate is descreased, less filament will be extruded.
In Simplify3D and PrusaSlicer, this is called Extrusion Multiplier. Cura calls it Flow.
My method of determining the correct flow rate is to print a single wall thick hollow cube, measure the actual thickness of the wall and then adjust the flow ratre to suit.
Unfortunately, I can't provide gcode for this process. It is vital to use gcode generated by YOUR slicer. The basic steps are covered in the video, and are repeated here.
| Step | Cura | Simplify3D | PrusaSlicer |
|---|---|---|---|
| 1. Import STL | cube STL | ||
| 2. Turn off infill | Infill > Infill density: 0% | General settings > Infill percentage: 0% | Print settings > Infill > Fill density: 0% |
| 3. Turn off top layers | Shell > Top thickness: 0 | Layer > Top solid layers: 0 | Print settings > Layers and perimeters > Horizontal layers > Top: 0 |
| 4. Ensure wall thickness is a known value Substitute whatver values you like here |
Shell > Wall thickness: 0.4 | Extruder > Extrusion width > manual > 0.4 | Print settings > Advanced > Extrusion width > Default extrusion width: 0.4 Print settings > Advanced > Extrusion width > Perimeters: 0.4 |
| 5. Set outer wall thickness to single extrusion | Shell > Wall line count: 1 | Layer > Outline/Perimeter shells: 1 | Print settings > Vertical shells > Perimeters: 1 |
| 6. Set flow rate to default 1.0 / 100% | Material > Flow: 100 | Extruder > Extrusion multiplier: 1.0 | Filament settings > Filament > Extrusion multiplier: 1 |
Now slice and print!
Use vernier calipers to measure the outer wall thickness of the hollow cube. Take measurements in multiple places/sides.
The following calculator can then be used to calculate the new flow rate:
| Cura | Simplify3D / PrusaSlicer |
|---|---|
What you see with your eyes is more important tha a theoretical calculation. After you have performed this calibration, please adjust the flow rate higher or lower based on what you actually see.
For example, take the cube shown in the thumbnail of the XYZ 20mm calibration cube by iDig3Dprinting:
This print shows clear signs of under extrusion. Despite what any calibration procedure determined, the flow rate for this slicer/printer combination needs to be increased.
To set the correct amount of current supplied to the stepper motors of the printer. This is set with the stepper motor driver.
If steps are being skipped/missed. If the stepper motors are too hot to touch. When significant changes are made to the motion system (eg. heavier bed, conversion to direct drive from bowden tube).
Setting the stepper driver current is an important step in calibrating a 3D printer, although typically the value does not need to be exact. There is a window within which the printer will operate without issue. Although some exact methods are shown, the following rule of thumb is the most important factor:
If the stepper motor is missing steps or you are experiencing layer shifts, the stepper current needs to be increased. This will supply more torque to the motor but also make it run hotter.
If the stepper motor is too hot to touch, the stepper current needs to be decreased. This will remove torque and make the motor run cooling.
Unfortunately, some times a stepper motor may be running hot and still missing steps. The following may apply in these cases:
If tuning the stepper driver current is unable to find a sweet spot, the good news is you can upgrade to a larger stepper motor easily in most cases. Nema17 steppers have the same mounting pattern and output shaft diameter, however you should still check your machine to ensure there is enough room for a longer stepper before any purchase. With all else being equal, a longer stepper motor will be capable of more torque and handling higher current.
Depending on the stepper motor driver, there are two ways of setting the current:
For older stepper motor driver or TMC drivers running in legacy mode, the current is set by turning a trim pot screw on the top of the driver to raise or lower VREF, which in turns sets the driver current.
On TMC drivers, the current is set directly with gcode commands. This can be set in the firmware or via a terminal or the printer's LCD. This value should be saved to EEPROM to stay persistent.
We will cover these one at a time below.
Setting stepper driver current accurately relies on knowing two values: the peak current of the stepper motor and the sense resistor value. Methods for determining these are seen in the following snippet:
I have covered this in detail before, so please use the embedded videos below, queued to the correct time, to set the VREF. The VREF is just a reference voltage to assist us in setting the driver current. It is used because it is much simpler to measure voltage rather than current with a multimeter. Typically these drivers have the peak/max current set.
The general steps for setting current via VREF are the same between drivers, only the VREF formula changes:
Alternatively, you can use an aligator clip wire between the red probe and the metal shaft of the screwdriver, so that a VREF reading is available as you turn the screwdriver. This procedure is shown in this snippet:
The typical sense resistor value is 0.1. Please check your drivers to be sure.
VREF = 8 x max current x sense resistor value
Then use the video above as a guide to the process.
The sense resistor value should be 0.1. If it is:
VREF = max current / 2
The process is then the same as for A4988s as shown in the video above.
Like the TMC drivers covered in the gcode section, the current for the TMC2100 is set not as a peak, but instead as RMS. To determine this, divide the peak current by 1.41.
VREF = (RMS current * 2.5) / 1.77
The process is then the same as for A4988s as shown in the video above.
Like the TMC drivers covered in the gcode section, the current for the TMC2208 (legacy mode) is set not as a peak, but instead as RMS. To determine this, divide the peak current by 1.41.
VREF = (RMS current * 2.5) / 1.77
The process is then the same as for A4988s as shown in the video above.
When I tested these, there was no mention of a sense resistor. Therefore the VREF formular is simple:
The process is then the same as for A4988s as shown in the video above.
VREF = max current / 2
TMC drivers connected via UART or SPI serial can have their current set via gcode. This is not peak current, but rather RMS (root mean square current. Rather than the max, think of this as more a typical current, where the driver will be operating mostly. To convert a peak current from stepper motor specs to RMC, divide it by 1.41.
The gcode command to set current is
These drivers should have a sense resistor value of 0.11. This is the default in Marlin, so when compiling it should already be set:
Therefore you can set your RMS current directly in the firmware when compiling. After flashing firmware, remember that the previous value may still be stored in the EEPROM. Check your values by entering M503 in a terminal.
You can also set the RMS current via terminal with the M906. Please follow the link to see the reference. Don't forget to save the value afterwards with M500.
Finally, the LCD configuration menu can be used to set the RMS current. Don't forget to save afterwards by clicking on Store Settings.
The TMC5160 is the same as the other TMC drivers apart from one important difference: the sense resistor value needs to be changed from 0.11 to 0.075 when compiling the firmware.
After this change is made, the same procedures apply:
You can set your RMS current directly in the firmware when compiling. After flashing firmware, remember that the previous value may still be stored in the EEPROM. Check your values by entering M503 in a terminal.
You can also set the RMS current via terminal with the M906. Please follow the link to see the reference. Don't forget to save the value afterwards with M500.
Finally, the LCD configuration menu can be used to set the RMS current. Don't forget to save afterwards by clicking on Store Settings.
To set the correct parameters concerning retraction during 3D printing, including retraction distance, speed, Z hop and extra restart distance.
Initial calibration, any time the hot end or extruder is changed, when trying a new type/brand of filament.
FDM works by melting plastic filament and extruding it accurately one layer at a time to build up 3D geometry. By its nature, the plastic will continue to ooze and drip out of the nozzle even when not pushed byy the extruder. To combat this, our slicers use retraction, where the filament is withdrawn from the hot end, aleviating pressure and minimising ooze. When properly tuned, this has the effect of removing stringing, the unwanted oozing of plastic between two points of the model.
Temperature tuning and retraction tuning are related to each other. You could do them in either order, and it may be necessary to tune back and forth to reach an ideal result. A higher nozzle temperature will promote more oozing and stringing, whereas a lower temperature will reduce oozing and stringing.
Besides hot end temperature, there are four parameters we will be tuning relating to retraction. In the table is a description of each as well as where the setting is found n the most popular slicers.
| Retraction Parameter | Cura | Simplify3D | PrusaSlicer |
|---|---|---|---|
| Retraction distance: The amount of filament that is pulled away from the nozzle. | Travel > Retraction distance | Extruder > Retraction distance | Printer settings > Extruder 1 > Retraction > Length |
| Retraction speed: The speed at which this filament is withdrawn in mm/sec. | Travel > Retraction speed | Extruder > Retraction speed | Printer settings > Extruder 1 > Retraction > Retraction Speed |
| Extra restart distance: The retraction distance will be reveresed when the travel (non-extruding) movement is over. This is typicaly zero, but you can opt for extra filament to be extruded (a positive value) or less than than what was retracted (a negative value). | Travel > Retraction extra prime amount | Extruder > Extra restart distance | Printer settings > Extruder 1 > Retraction > Extra length on restart |
The following form will create a retraction tower to conveniently test back to back parameters in the same print. Of the four available parameters, it is best to change only one per test print. For example, keep the retraction speed, z hop and exta restart distance the same, but vary the retraction distance over each segment. Changing more than one parameter makes is hard to tell what made the difference. The print is quick, so repeat the test varying other parameters until you are happy with them all.