X Y Compensation

duetlover

Hi everybody

After several tests and adjustements, I get, on a CoreXY e3D toolChanger a difference betwenn X and Y dimensions.

When I print x 10x10x10 mm cube I get :
on X : 10 mm
on Y : 10.1 mm

And for 20x20x20 mm:
on X : 20 mm
on Y : 20.1 mm

I learned that with a CoreXY this issue is due to belts tension/aligment but I tried severall on this without success.

That's why I was looking for a software compensation.

I tried M579 but this seems to be "proportionnal".
So this does not help me.

Is there a config.g configuration to tell : "print Y axis -0.10 mm" ?

Thanks !

Best regards

Phaedrux

If you can't solve it mechanically you could adjust the steps per mm slightly in M92.

duetlover

@phaedrux Thanks for you reply.

But I think I will get the same as M592 : il will be proportional.

I need something not proportional :
10.1 => 10.0
20.1 => 20.0
30.1=> 30.0

Hope I'm clear

Thanks !

SIam

@duetlover i didn't think that this issue came from the printer. if this were so you should get the following results
10.1
20.2
30.3 .....

I think that your slicer add this offset, look there if you have set something like X/Y compensation maybe check it with another slicer.

o_lampe

@duetlover
You should print something 'not square' to avoid having the seam on one edge of the cube. (I guess, that's where the 0.1mm difference comes from)
I think of an hexagonal shape.

mrehorstdmd

@duetlover 10mm is too small to calibrate anything or to check calibration (so is the 20mmm so-called calibration cube that so many people use).

How are you measuring it?

Every time you measure anything with a caliper, you introduce some user error in addition to the error limit of the caliper itself. If you make a 0.1 mm error on a 10 mm object and use the that value to calibrate the axis steps/mm, when you print an object that is 100 mm long it will come out 101 mm long.

If you make the same 0.1 mm error on a 100 mm object, calibrate with that, and then print an object that is 10 mm long, the error will divide down to 0.01mm. This is why you want to calibrate with a large object, not a small one.

That covers the user and the caliper, but 3D prints are made of molten plastic. If the plastic is very close to the bed, the plastic can "elephant foot". If you measure there, the object will be larger than if you measure 10mm up from the bed. If you use a very small print, the layers don't have time to cool and shrink before the nozzle comes around and dumps more hot plastic on the previous layer. The prints start to look like mushrooms. Where are you going to measure that?

Always calibrate using the largest object you can measure and measure it well above the bed. Be sure the layers take long enough to print that you're not getting the mushroom effect. The print you're measuring to calibrate should look as close to perfect as you can get. Print slowly - a little ringing will throw off your measurement. Measure the print in multiple places, well above the bed and calculate the average value and use that to calibrate.

If you print a rectangular or square object you can check squareness of the X and Y (and even Z) axes by measuring diagonals. if the axes are square, the diagonals will be the same length. If you print a 100 mm cube, you'll be able to measure the diagonals with a common 6" caliper.

psychotik2k3

use this one to calibrate, it is specifically made for core xy calibration
https://www.thingiverse.com/thing:4018438