Frustrating calibration issues

[Shizuma]

So recently I've been trying to chase down some calibration issues with my Rostock MAX, I didn't have these problems when it was first built but now it's driving me crazy. I'll go thru and calibrate the towers one at a time per the assembly manual, and when I have the 3rd one calibrated properly the 1st one is off again, adjust that and the 2nd is off, and so on, eventually it will randomly get to be all correct and i'll check center and it will be off, so I start going and adjusting the printer radius, it will be high, lower by .5, repeat, still high, still high, etc, then bam, too low, then I start going back the other way, too low, too low, etc, the exact same printer radius that had the hotend too high in the center is now too low and I can get it to equalize and be correct.

Does anyone know what could be the problem? I verified the adjustment screws are all hitting the end stops correctly and I checked to make sure all the towers are square and they are, I'm not sure what else to check.

[guanu]

I'll post the calibration procedure I do here at the shop when I calibrate all the orions, but I'll change the gcode for the size of your max... hopefully this makes calibration easier, its easier for me and faster....

for pictures of what you should be looking at look (starting at page 25) at the 0.91 firmware version of the orion manual at http://download.seemecnc.com/orion/Orio ... -2ndEd.pdf" onclick="window.open(this.href);return false;

1) Preheat hot-end and bed to the material you use. If you use both, just use the “Preheat ABS”
in the printer settings menu on the LCD.

2) Once the hot-end and bed are up to temp, on the LCD, click the knob to bring up the menu,
go to Advanced Settings (at the bottom of the list). Click the knob.

3) Go to the bottom of the next menu to Calibrate Z Height. Click the knob.

4) Now you are in the calibration menu. Click Home Towers. The machine will go up and hit all
the end-stops.

5) Go down to Z Position and click the knob.

6) Turn the knob Counter-Clockwise to lower the nozzle. Bring the nozzle down till its a couple
millimeters from the glass like the following pic.

7) Turn the knob counterclockwise SLOWLY and look eye level with the bed, and bring the
nozzle down till it just barely meets the glass (this is easiest with a white wall in the background
so you can watch the reflection of the nozzle – if you don't have a white background to use, you
could tape a sheet of paper between the towers to give you enough contrast). When the nozzle
touches the glass, click the knob.

8) Go down to Set New Z=0.00 and then click the knob.

9) Go to Home Towers. Click the knob. You have now set the z height, and now it is time to
calibrate the towers.
The next steps can be done through a computer or SD card. I find it is easier on a sd card so
you can keep close to the machine to watch the movement.

10) Open notepad or a text editor of your choice.

11) Paste the following into the text editor: ***modified for Rostock Max!***
; Tower endstop calibration script
G28
G1 Z.2 F15000
G4 S1
G1 X-77.94 Y-45 F2000
G4 S2
G1 X0 Y0
G1 X77.94 Y-45
G4 S2
G1 X0 Y0
G1 Y90
G4 S2
G1 X0 Y0
;

12) Save the file as “Towers.gcode” and place it on an SD card, or if you are going to be using
a computer, load it into your host software that you use.

13) Again with the bed at eye level and looking close, Run Towers.gcode from either your host
software or SD card. Watch closely as the machine will home, then the nozzle will drop to
0.2mm ABOVE the glass.
After it drops to the center like that, it will travel to the X tower. DO NOT pay attention to what
the nozzle does while traveling, what you must pay attention to is when it pauses.
The nozzle will pause at the X corner, then return to the center, and move to the Y tower and
pause. After the pause, it will again move to the center, and move to the Z tower, pause, and
return to the center.

14) What you want to remember is the nozzle when it pauses. You want to compare the
movement to the gap at the center.
– If the nozzle at the tower RAISES (compared to the CENTER), you want to adjust the screw
that hits the end-stop by turning it counterclockwise (moving the screw up).
– If the nozzle at the tower LOWERS (compared to the CENTER), you want to adjust the screw
that hits the end-stop by turning it clockwise (moving the screw down)

15) After you have adjusted the screws, You have changed the Z height, so you want to go back
and re-set the Z height the way you did earlier in this guide.

16) Re-run Towers.gcode and watch as you did before, again noting the changes in the nozzle
at each pause. You will run through these steps till the nozzle remains the same height at each
tower when compared to the center.
If the nozzle goes the same direction on all 3 towers (such as you have the gap in the center,
and at every tower the nozzle lowers. Or you have the gap at the center and at all 3 pauses the
nozzle raises), you will adjust the radius in the following way

17a) If from the center gap, the nozzle goes DOWN toward the glass at ALL 3 TOWERS, load
your host software and bring up the EEPROM information. You will look for Horizontal Radius.
You want to RAISE that number. I suggest raising it by 0.2 and run towers.gcode to see the
change, and keep raising the number till the gap evens out (changing this number will not make
you need to re-set your z height, it will just raise the outer edges where the nozzle pauses).

17b) If from the center gap, the nozzle goes UP away from the glass at ALL 3 TOWERS, load your
host software and bring up the EEPROM information. You will look for Horizontal Radius. You
want to LOWER that number. I suggest raising it by 0.2 and run towers.gcode to see the
change, and keep raising the number till the gap evens out (changing this number will not make
you need to re-set your z height, it will just lower the outer edges where the nozzle pauses).
After doing this, you will see any changes where one tower may be higher than another, if this is
the case, go back to adjusting the end-stop screws as before.
Typically it can take anywhere from 5-10 or so re-runs of the tweaks to get the gap to remain the
same at all 3 pauses compared to the center of the machine. Once the gap is the same at each
tower compared to the center, your machine is calibrated and ready to print!

[Shizuma]

That's essentially what I'm doing for calibration, though the guide I'm following is the one from seemecnc that's for the Rostock MAX, the end result is the same though in what it's doing. The problem is I'm not getting consistent results now, sometime with the printer_radius at 197.5 the hotends movement profile is concave, other times it's convex with the exact same settings, so I can run thru the calibration procedures going back and forth with the printer_radius for hours (which I did last night) and still never get properly calibrated because things keep changing like that with the same settings.

[guanu]

the reason I posted that procedure was so you can see the 3 movements along the bed in one script, doing it one tower at a time can get frustrating and takes longer to do, this lets you see the concave/convex movement parallel to the bed in one gcode file and you adjust all the towers at the same time... and watching the 0.2mm gap is a lot easier than lots of tweaking, and lets you watch it all across the bed, when you change horizontal radius in the eeprom, the nozzle when it goes to the center, should not move.. only the outer edges should go up or down when you change that value, but the gap in the center should remain the same.

Guanu

[Shizuma]

I know, my problem I don't believe is in the calibration procedure though, when I first got my Rostock I used the procedure in the assy manual with no problems at all. Something has to be either wrong with software or mechanically out of wack since the printer_radius adjustments simply aren't working right as if I set the printer radius it should either always be properly adjusted, concave, or convex, it shouldn't bounce back and forth with the same radius settings, I'm just not sure what could affect that. My thoughts were the towers being square and the end stops hitting correctly but that's not it, until I hunt down the inconsistency a different calibrating procedure would still give me the same issues since printer_radius isn't working correctly, I will try that procedure next time I calibrate it to see if I like that better though.

[Shizuma]

Basically what's happening is this, I go adjust my towers, then adjust the printer_radius, I started at 197

197 = center is higher than edges
196.5 = center is higher than edges
196 = center is higher than edges
195.5 = center is higher than edges
195 = center is higher than edges
194.5 = center is higher than edges
194 = center is higher than edges
193.5 = center is lower than edges
194 = center is lower than edges
194.5 = center is lower than edges
195 = center is lower than edges
195.5 = center is lower than edges
196 = center is lower than edges
196.5 = center is lower than edges
197 = center is higher than edges

That's exactly the type of behavior I'm seeing which shouldn't be happening.

[guanu]

what firmware are you using? if 0.91, then in the eeprom it should be called horizontal radius, and when you adjust it, the center should not be what changes... center should be the same no matter what you set it at, and only the outer edges should change.. and a 3mm change is huge, at most I've only ever had to tweak a max up to about 1mm from default...

Guanu

[Shizuma]

I'm using the 0.91 firmware, I'm also adjusting the radius directly in the firmware per the assy manual using Arduino IDE, inside there it's printer_radius, which is also what the assy manual says it's called.

And yes, technically the edges are what's changing, I just chose to say the center was high as opposed to the edges were low.

Yeah, the adjustment is huge and with no consistency which is what's driving me crazy, my initial calibration was 1.25 of adjustment and it was good, I went by .5 increments till I overshot and then backed up the other direction by .25 and I was golden.

[guanu]

ahhh see changing it in the firmware will not alter the eeprom, with the 0.91 firmware you are changing one set, while the horizontal radius stays in the eeprom... use eeprom to change the horizontal radius, you dont need to reupload the firmware with 0.91... so I would suggest put it back to original, upload, then only tweak the eeprom horizontal radius...

Guanu

[Shizuma]

I didn't even knew that setting was available in the eeprom till you mentioned it, kind of frustrating that the assy manual wasn't updated to reflect that. however while i'm doing the radius calibrations I do have eeprom_mode set to 0 so the eeprom settings aren't actually taking effect and the eeprom was disable thru that entire sequence of adjustments I posted.

[joecnc2006]

I wonder when you make the changes to the eeprom if the read/write light flashes on the Rambo Board? If so this could be a way to ensure it is working properly.

[Shizuma]

I've never specifically looked to see if the lights were flashing, but Arduino IDE does say done and doesn't spit out any errors, and I had a RAMBo 1.2 with the static discharge issue, so I know it tells you when it can't write, also it definitely resets the RAMBo because the display goes blank for a second and it resets and it turns off the bed and hotend when it does.

[joecnc2006]

yes the lights do flash with ardiuno software, I was thinking about the eeprom config in repetier-host.

[slashthedragon]

I had a problem with the end stop microswitches being loose. Tighten those and then try again. Good luck.

[Shizuma]

Thanks, I'll check that when I get home tonight. Fortunately I have no problems at all printing with it how it is, it's just the perfectionist in me wanting to chase down the calibration to be perfectly calibrated.