Dimensional Inaccuracies

Matrix2721

Hi, i have recently completed my delta printer and successfully setup repetier firmware and got it so the head moves flat over the bed, however, the size accuracy of the parts varies depending where it is printed on the bed, for example, printing something small in the center will be within 0.05mm of the correct size but printing larger or towards the edges of the bed the parts can be millimeters out, which setting do i have to change to correct this?

Thank you for your time

Repetier

That is a big problem if you calibrate with z probe to get a flat bed. You might neglect real geometry adding distotion in x/y direction. See

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

and also comments (one from me on how to adapt it to repetier).

Maybe it helps getting better geometric calibration.

Matrix2721

Hi Repetier,

I have printed that object already and all the angles are correct and when measuring the thickness they are all within 0.05mm of eachother, All of the lengths are too short ranging between 0.3mm and upto 1.2mm short. I am not sure what to adjust to correct these sizing issues since the angles are exactly what they should be. I did try using the zprobe but this had no effect on the sizing issues.

Matrix2721

I have just read a post where someone has given instructions on how to calibrate a delta printer using repetier firmware and they have said to adjust the 'printer radius' to correct flatness issues and to adjust DELTA_DIAGONAL_ROD to fix dimensional issues, however, when i originally changed the printer radius it had no effect on the flatness and i was able to get it flat by adjusting the diagonal rod length in eeprom, have a made a mistake doing it this way? i did try changing the printer radius but no matter what figure i put in it it had no effect on the flatness?

Repetier

Printer radius is just printable radius, no calibration parameter.

What they meant is diagonal rod length and horizontal radius. Both have an effect on the dome and can be sued to adjust it, but diagonal rod has great influence on geometry. And it should be mush easier to measure, so normally you measure that and adjust horizontal radius to fix flatness.