delta printer calibration

I built a delta printer. Metal structure. All parts are measured correctly and entered into the firmware. I leveled the printer. I do not find errors in the data and yet ... I print 1 mm less in x and almost 1 mm more on the X and Y plane. If I move the trolley 10 cm and measure on the tower ... it's right!
I tried to print a calibration object, but I do not know how to intervene. Can someone help me?

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I print 1 mm less in x and almost 1 mm more on the X and Y plane.

That doesn't make sense.

If I print an object x = 60mm y = 60mm and z = 20mm becomes 64x64x19.5 mm approximately

Edited 1 time(s). Last edit at 05/05/2018 09:59AM by mga.

Scaling Z-axis is easy. Just change steps/mm.
That also influences XY scale, so you have to increase the diagonal rod length by ~8-10%

thank you. But the diagonal rod value should not be exactly what measured? I think there must be an error somewhere in the geometry. Of course I will do as you say ... I have no choice ... but if I could I would prefer to insert the exact geometry. In fact, with the Cartesian printers it is enough to act on the steps / mm and everything is solved. In my case then I have a complication: X and Y are not the same. But the corners are all 120 ° and I can not find a mistake but certainly there.

However, increase the size of the rod by 10% ... and then for the differences between X and Y how do I do?

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x = 60mm y = 60mm and z = 20mm becomes 64x64x19.5 mm

You didn't say anything about X/Y-differences. But you come up with different numbers every time?! The first post said something about +/- 1mm.
It's time to come clear and also post some pictures.

Yes you are right. I wanted to solve the macroscopic problem first. Now I'm printing a 30x30x30 cube that I find X 30.2 and Y30.3 (z I do not know yet). This is the result I have after increasing the 5% rods

There is a list of common geometrical errors that result in calibration difficulties on delta printers at [duet3d.dozuki.com].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].