Weird z-probing with Kossel Delta-Printer

03daniel11

Hi, 

recently I build my first 3D printer, a delta style printer.

For a few weeks I am having trouble with the calibration.

I calibrated the printer with the paper-method...all three tower and the centre. I think regarding this part, the printer ist calibrated quite accurate.

But when I want to print large parts (200 mm length) at one of the edges the printer prints above the print surface and at another edge the nozzle moves into the bed.

So I want to add z-probing and z-correction.

First question: Can anyone explain to me what z-leveling Exactly does andy why I need it? I have trouble finding any good explanations.

Second question: I have the endstops calibrated with the paper-method, what is the best order to go on now? G28 - G32 S2 - G29?

Third question: As is sad, I am sure having the enstops calibrated quite accurate.

But when I to G32 I get differences at about 0.4 mm what is totally weird in my opinion. 

Because I don't have any Idea what to do now I am writing to you.

Hopefully you can help me.

Thank you very much & greetings from Germany.

Repetier

The problem with deltas is that every imprecision gives you an error somewhere. At some places errors get bigger then on others. Simply measuring 4 points just makes sure that you are the right height there but we have 20 or more parameter influencing everything so you can still have errors somewhere.

The advantage of having a z probe is speed in measurement and you can create a height map seeing how z errors are distributed over the surface. Use the repetier-host height map function for this.

There are also some things you can not measure with a z probe resulting in errors in the print. This calibration piece

http://www.thingiverse.com/thing:745523

can help you fixing some very important parameter like angles and length. From there on z probing gets much easier and accurate. As a last resort for last z problems use z distortion correction from 0.92.4 firmware.