Things are looking up - delta calibration wise

[fcwilt]

Hi,

I was having a hard time calibrating my delta printer and getting the kind of good results that other folks were reporting.

So I took my printer apart and re-built it, measuring various dimensions along the way, checking for level, plumb, perpendicular as appropriate - basically doing everything I had read about and thought about to get the printer mechanics right.

Then I decided to eliminate the z-probe (dc42's IR unit) as a source of my problems and try to manually calibrate the printer.

I was not aware of the new manual calibration features in the latest versions of RRF so I decided to resort to "old school" methods.

To get an idea of where things stood I took a spare effector plate and mounted one of my dial indicators on it. I use these in my metal work and they are accurate to 0.0005 - what is commonly called "half a thou" - which works out to about 0.01 mm.

I then set about using that arrangement to set the endstop offsets first.

I carefully lowered it to the center (X = 0, Y = 0) until it read exactly zero.

Then I moved it to each tower in turn making a note of the readings. Using that information it was simple to get the endstop offsets correct.

Once that was done a little trial and error got the delta radius set.

I repeated the process many times looking to see if the results were repeatable - they varied more than I hoped but were not too bad.

THEN I read about the manual calibration feature in RRF and decided to see what it came up with.

Starting with the results I got my first way I was pleased to see the RRF reported that things were very good. A couple of runs of that resulted in some minor changes to the M665 and M666 settings and viola, my printer was well calibrated - from my point of view.

I wasn't getting the accuracy that some folks reported (deviations of 0.001 mm) but I was getting in the 0.02/0.03 mm range and that seemed to be good enough. In my metal work if I can keep things to +/- 0.001 I am happy and that 0.02/0.03 mm deviation is close to that.

In any case it is much better than I have ever gotten and I am satisfied for now. For the first time I was able to print and have the first layer look really good - no scraping and no gaps.

Thanks too all who provided assistance and to the Duet folks who have made their fantastic hardware/software combo work so well.

Frederick