Delta printer calibration (size of the print) step per mm by Bob-In

Last crawled date: 3 years ago

Hello, i would like to share how i calibrated my delta printer. The problem i had was about the size of my prints, it was not enough accruate (100mm square give me 102.xxmm101.xxmm99.xxmm*100.xxmm).
Im not telling you this is the best way to fix this but i would like to share how i fixed it by myself. With this methode, the biggest difference between the lengths of the square sides was 0.2mm/0.3mm maybe i can have better result but it is fine for me.
So, i calibrate it in the firmware (marlin) with this line :
define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 80, 100} (x,y,z,e)
What we want to change is the x,y,z value but depending on how you assembled your printer the order may be different, in this case changing the value one at a time, this will change the speed of the step motor movement and you will found the right order for your printer. If you lower your hotend height, you will notice that one of the step motor moves differently. so it can be (x,y,z,e) / (z,x,y,e) / (y,z,x,e) ...
Ok for calibrate your Delta printer...
What you need to do is to print my calibration test, it should be right in front of the 3 towers. The 3 rods should mesure 30mm by 3mm. If not, fallow this step :

Print and Mesure the lenght and the tower associate with each rod. Exemple:(Tower x: 31 y:29 z: 30)

You will need to do a little bit of math.. Take the lenght it was supposed to be "30" multiplied by the current step per mm value "80" (3080=2400) and you divide it by the mesure of the rod. So for the Towe X it should be (3080)/31 = 77.42 Tower Y: (3080)/29 = 82.76 Tower Z: (3080)/30 = 80
Enter this value in arduino so it will be : #define DEFAULT_AXIS_STEPS_PER_UNIT {77.42, 82.76, 80, 100} (x,y,z,e)
At this point you will need to adjust your endstop and do Z height calibration (paper test)
Print again.. What we want is that the sides should be as much as possible of the same length. Even if the side does not measure exactly 30mm, this is not important since we can resize with DELTA_DIAGONAL_ROD
If the sides the same or enough closer to be the same lenght you will only need to resize the print dimmention with delta_diagonal_rod.... if not redo the steps.
*Is this tutorial enough clear ? what can i change or add to make it better ?
is that helped ? not enough ? do it again and again until it is