How calibrate axes in a delta printer?

peirof · 1 Dec 2017, 16:14

Hi,

i have followed the guide to calibrate steps of extruder motor, and ok, but…. when print, there is a dimensional error, not vey big, but sufficient for disturb.

The answer.

HOW I CAN CALIBRATE DE X,Y AND Z AXES? (extruder i have it)

Remember i have a delta printer.

i have not clear if M92, can be used in Delta printer, is the system i have use for extruder....
https://reprappro.com/documentation/commissioning-introduction/calibration-duet/#X_Y_and_Z_axis_calibration

peirof · 1 Dec 2017, 16:36

hi,

Searching in google i have find in:

http://minow.blogspot.com.es/

This:

 [[language]]
4- Calibrate the firmware to print to correct dimensions.
 
At this point the printer probably prints, but the results are dimensionally wrong.  Printing something 100mm long results in a printed object that is not exactly 100 mm long.  This also, can be corrected in firmware.  Adjustments to DELTA_DIAGONAL_ROD in the firmware control the size of the printed object.
 
Create a simple calibration object in openscad, slice it, and print it. By measuring the actual size of the object as printed and comparing it to the size in the design, the accuracy of the printer can be assessed and adjusted.
 
Here is my sample openscad object:
 
cube([100,2,2]));
 
If the length of the object is wrong, adjust DELTA_DIAGONAL_ROD:
 
new DELTA_DIAGONAL_ROD =
100 / measured_length * original DELTA_DIAGONAL_ROD
 
then re-upload the firmware, and print and measure again.  When the printed object measures 100 mm, the printer is printing accurately to size and is fully calibrated.

This valor… can be used here????

M665 RXXX L[HERE] BXXX Hxxx

Martin_S · 1 Dec 2017, 17:50

This guide is great:
https://www.thingiverse.com/thing:1439048

But, how far off is your dimensiona error? 0.05mm? 0.1mm? more?
is it consistent with all the axes or the error is way more in X than in Y for example?

First I would make sure that the steps/mm for X, Y and Z are correctly set.
So, post your config.g file and:

motor step angle, 1.8? 0.9?
16 tooth pulleys, 20?
gt2?

peirof · 2 Dec 2017, 15:52

I have follow this guide… But the problem in my case is the dimensional error is different in X and Y axes... And I don't kwon how compensate this...

I have only ocurrs correct with slicer, applying a scale different in X and Y axes...

All systems I have see correct the same in both axes.

I will try dimensional construction errors, difficult to compensate.... I think

Martin_S · 2 Dec 2017, 17:58

If it's very low, it could be because of the belt tension. If one axis is way more tight that the others it could cause what you are having.
I would also check that all your arms are exactly the same. For testing, rotate them and check if the dimensional issue rotates too.

We still don't know how much the error is.
Share more info so others can jump in and help.

Billhc83 · 2 Dec 2017, 18:40

Could you be more specific about the size of error in x and y. There are many things that can contribute to this on a delta. Knowing the size of each error would be helpful…..I would go through the entire printer again with a measuring instrument. Making sure everything is exactly the same. Or as close to it as you can get.

peirof · 2 Dec 2017, 19:33

ok,

i have do some print test…. this prints: https://www.thingiverse.com/thing:1439048

With this results

PRINT OBJECT MESURES REAL PRINTED OBJECT SCALE FACTOR TO SLICER
X Y Z X Y Z
35 x 35 x 3 mm 34,8 35,05 2,83 100,57% 99,86% 106,01%
50 x 50 x 5 mm 49,45 50,34 5,41 101,11% 99,32% 92,42%
100 x 100 x 5 mm 98,22 100,5 ??? 101,81% 99,50% ???

In the test can see, how the scale is diferent in X and Y axes…

dc42 · 2 Dec 2017, 21:26

You can make small scale corrections using the M579 command. See https://duet3d.com/wiki/G-code#M579:_Scale_Cartesian_axes.

peirof · 2 Dec 2017, 22:03

ok, I will try…

In Delta printer...How is the maximum deviation that I can correct?
Where I have to put? In some line of config.g(is the same)?

dc42 · 3 Dec 2017, 09:06

Put it in config.g. You can correct as much as you like; however if the scaling error to be corrected is large then the underlying geometrical issue that is causing it will give rise to other issues, such as straight lines coming out slightly curved and the scale not being uniform over all areas of the bed.

Martin_S · 3 Dec 2017, 18:31

If your printed part was supposed to be 5.00mm tall and came out 5.41mm then don't use M579.
That might be too much. It looks like your step/mm are wrong, the error keeps scaling up.

If you have a delta, first dial in Z dimension. It's the easiest one. X and Y are also determined by rod lenght.

EDIT:
Post this:
1). Your config.g
2). Motor step angle
3). Type of belt
4). Type of pulley

	[[language]]
	4- Calibrate the firmware to print to correct dimensions.

	At this point the printer probably prints, but the results are dimensionally wrong. Printing something 100mm long results in a printed object that is not exactly 100 mm long. This also, can be corrected in firmware. Adjustments to DELTA_DIAGONAL_ROD in the firmware control the size of the printed object.

	Create a simple calibration object in openscad, slice it, and print it. By measuring the actual size of the object as printed and comparing it to the size in the design, the accuracy of the printer can be assessed and adjusted.

	Here is my sample openscad object:

	cube([100,2,2]));

	If the length of the object is wrong, adjust DELTA_DIAGONAL_ROD:

	new DELTA_DIAGONAL_ROD =
	100 / measured_length * original DELTA_DIAGONAL_ROD

	then re-upload the firmware, and print and measure again. When the printed object measures 100 mm, the printer is printing accurately to size and is fully calibrated.