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Hey all. I've been printing with my Rostock MAX without issue for almost a year now. I've got the E3D V6, the nice aluminum mount with carbon stand offs, carbon arms, and a few other basics. I've had perfect bed leveling and have been able to print with a 0.25mm nozzle anywhere on the glass with no issues.

However, the other day, about 2mm up in a print, the printer lost position and the print failed. I figured something got bumped... But now, it is just waaaaaay off on the bed. I've tried recalibrating to no avail. What's odd is that I can get the printer "level" at X0 Y0, X0 Y120, X103.925 Y-60, and X-103.925 Y-60 (the center and the base of each tower). However, in order to do that, I had to add 1.5mm to the delta radius value, otherwise the center would hang high. In this scenario though, if I go to X103.925 Y60 (between Y and Z tower), it crashes into the glass. If I go to X0 Y-120 or X-103.925 Y60, it's almost 1mm high off the glass.

I have checked the squareness of the towers with extremely expensive digital equipment (I work in a machine shop) and they are totally square to within +/- 0.1°. I've verified that the height of each tower is the same. I've verified that there's no twist to the towers. I checked tightness on everything which hasn't provided any improvement. I rotated the effector plate and the arms to different towers with no change. I did find that the belt on the X tower was pretty loose, so I fixed that, but again... no change.

I am at a complete loss right now. Is there something I may be overlooking, or some "oh when that happens, it's this" event? I'm about to chuck this thing in the garbage and build a Cartesian to replace it.

Did you happen to see exactly how it failed?
If there is no sign of something mechanical that failed I would try re-uploading the firmware. Do an EEPROM Clear first.

That might solve it when some voodoo curse takes possession of the Rostock Max. I've been there, my EEPROM got mysteriously messed up.
It's good to name your machine, they tend to work better when named

HA, this turd is named. It seemed to shift towards negative X and positive Y during the failed print.

Reloaded the firmware... No change.

Small update... I found a heim joint popped apart, so I flipped that rod 180°. It's better, but still not right. I guess I'll go back through and flip every rod. I think those straps that are intended to remove lash have just a little too much tension because every heim joint is bent.

I flipped every rod, and it's still not acting right. I'm totally lost at this point.

Have you checked the endstops and the screws that contact them to see if either are loose? (I realize you said you checked everything for tightness, but those seemingly aren't a high priority for that.) Have you checked for any sticking points in the travel of the carriages? It may be that when your part failed, that a mechanical failure manifested that is not visually evident (As the teeth on the belts face inwards most of the time)

I did check every end stop, and they all check out OK. After flipping the rods, I'm down to just a high spot between X and Z towers and a low spot between Z and Y towers. Everywhere else checks out perfect. If I take the arms off of the carriages on the towers and rotate the whole effector/arm assembly, the problem will rotate. I've ordered totally new arms to see if that corrects it. The next step after that is going to be drawing up a new platform and throwing some metal in the Haas to cut something extremely precise.

There's no carriage sticking, and they're adjusted nice and tight (but still move). I took the belts out, and they check out.

I presume given your registration date, that you had the white U-joints. Did you order a like replacement, or the cup and ball arms? If you went for the cup and ball arms, unless you also have the IM carriages, you'll need some form of adapters, but both the IM carriages and cup and ball arms are tangible upgrades. If you want to save some time putting together a design, 713Maker is getting ready to release his own aluminum effector.

Now, as a bit of a machining geek, I'd like to ask, what sort of Haas are you referring to? (I've worked with a VF-1, VF-2, VF-E, HL-2, SL-10, and another lathe I can't remember right now)

I have the carbon fiber arms from Trick Laser. I junked those plastic things a while ago.

We have a Haas VF5SS, Haas SL40, two Okuma LAW-V24, and a DMC 80 H from DMG.