[Solved] Calibration problem  

RE:

I hope this video helps show the issue.

RE: Calibration problem

@joantabb did you write on op post as your response see picture below

RE: Calibration problem

@kvlasblom Ok thats weird so if I understand from video the extruder doesn't home probably so I would suggest that you move extruder all the way to the left so it hits the plactic then run calabration after that do first layer calabration and see if it still isn't homing it correctly 

RE: Calibration problem

I'm afraid that they did. They edited my question instead of posting a reply, I think. But the video shows the problem anyway, the carriage crashes into the side when it wants to calibrate Z in the far right corner. The left corner is too far to the right....

RE: Calibration problem

I can't believe I didn't try that, that worked. Heating up now for the first layer test.

RE: Calibration problem

Bad news, what seems to be happening is that when the printer starts something it is not first sending the carriage to X zero. So then it wants to level Z first, but does not start at the left, and goes too far right. It then crashes and forces Z leveling, which then forces the nozzle into the bed because now the carriage is on the far right, where the pinda is not above the bed....

RE:

@Hello,
i intended to post that info. did I put it in the wrong place?

Joan

RE: Calibration problem

Hi, the original video link had some formatting information before and after the video title, which stopped the video link being visible. 

My intention was to edit the link, save the post, then write another post. unfortunately I messed it up. 

My sincerest appologies, 

Joan

RE: Calibration problem

the mk3 series printer uses sensorless homing on both X and Y axis,  there are no end stop switches. 

the Printer einsy controller, monitors the axis movement during homing, to identify where the end of travel is. and then sets a virtual endstop just a little short of the end of travel, 
If something causes resistance to motion during homing, then the home position may be mis reported which will offset the X axis to the right, and the Y axis slightly to the front. 

As you have noticed, if the X axis is too far to the right, the Pinda, can move past the side of the build plate and fail to trigger.   so you are looking for smooth movement of the X axis to the left hand side and all the way across to the right. 

Many things can influence the home position, including 
Bearing misalignment, 
Bearing covers causing binding, 
Wire bundles sagging and snagging on other parts of the printer
Over tight belts
Over tight idler bearing retaining screw, 
Damaged or faulty linear bearings, 
Damaged or faulty idler bearing, 
Misplaced Zip ties (usually found during XYZ calibration)
there could be a combination of the above items, 
Lack of lubrication can also be an issue. 

regards Joan

RE: Calibration problem

Thanks. I can cross a lot of those off the list as the printer has been working for a year. When does it set the home positions for X and Y?

RE: Calibration problem

I switched the printer on and went to the move option in the settings. X was at zero, whilst the carriage was nearly in the centre of the X axis. Switched off, moved the carriage to the left manually, switched back on again and went to the move option in settings again. Now X is at 0 with the carriage at the far left hand side, and turning the dial moves the carriage left and right fine. Went to do print, it starts to level Z. Front row of three points went fine, when the carriage wanted to go left on the second row, from the far right a crash was detected. So I think you're right, it is sensing resistance somewhere. There is no visible obstruction though. What should I lubricate with?

RE: Calibration problem

...yet it is perfectly happy to move X, using the move axis option in the menu, over the full range of travel, as long as the carriage is on the far left at power on. I just tried to do the same for Y, but as that was not at the travel limit at power on was now a problem. And when I moved it in the direction it did want, it detected a crash and started to automatically move (I assume Z leveling but did not see a message, probably because I was in the menu) then crashed and also tried to continue to move beyond where it could, making scary noise.

RE: Calibration problem

prusa recommend White Lithium Grease, and they usually supply a small tube  with every printer. 

When you turn the printer on, it has absolutely no idea where the extruder is, at this stage it sets X, Y and Z to ZERO. so your Move Axis tool will only move the axis in a positive direction. 

If you use Home All, the printer should attempt to search for the home position... extruder to the front, left corner of the build plate, it should use sensorless homng for the X and Y axis, and use the Pinda for homing Z. 

Once homed, the printer will reset X and Y to Zero again, and IIRC it sets Z to 0.2mm (Never really looked... )

the fact that your printer has been working for a year suggests that something has changed. have you done any repairs or changes?

regards joan

RE: Calibration problem

I upgraded the firmware a couple of days ago, but did print after that. When I switch it on, it does not home, I don't remember if it used to, should it?

RE: Calibration problem

I got home this afternoon and went through the steps described to lubricate the smooth rods. The printer has always been in an enclosure and they seemed to have been very clean. After that I did the homing option in the menu and all seemed fine so far, then I did the Z levelling and that also went fine. It is now printing, thank you!!

One thing I did notice is that when I had applied the lubricant (yes, this was in the box of bits that came with the printer kit) and moved the y axis to and fro using the menu, I had forgotten to manually push the carriage to the home position first, and something weird happened; it allowed me to go into the negative a bit. I think I remember hearing a noise after moving into the extreme positive first, I guess it did this due to not knowing that the extreme was there, due to the Y zero position now having an offset. Anyway, I will keep an eye on it with the next few prints. Sorry for not performing proactive maintenance properly!