Bed not levelled after Auto Level
Posted by RVE
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Bed not levelled after Auto Level May 18, 2016 08:30PM |
Hello,
I would like some advice on a recurring issue I am facing with my Prusa i3 (with inductive sensor and auto bed-levelling).
So, my issue is that when I start a print with autolevel, autolevel mesure is performed without issue, but when printing, the level is not perfectly corrected by the autolevel function :
I can see some correction being performed (both Z axis lead-screws are slightly moving when printing the extruder moves on the X or Y axis).
As a result, the first layer height for the center of my printing area is good, but it is getting smaller as the extruder move to the right part of the bed, and higher as it moves to the left part of the bed.
This leads to issues with my first layer adhesion for big prints, and on prints longer than one hour, it leads to a lot of wrapping on the left side of the bed (always the left side).
Obviously, I don't really want to print without the auto-level, trying to set the right side of the bed higher won't fix that (auto-level detect the new position of the bed, and correct it with the same error once again).
I also tried to change the firmware on my printer, without any result (current firmware is Marlin 1.1.0-RC6).
Behaviour is the same with both the "3-point" autolevel and the "grid" autolevel (3 points grid hence 9 measurements) functions.
Did any of you faced the same issue, or at least do you have any idea where this kind of issue can come from ?
Thank you in advance for your help
Romain
I would like some advice on a recurring issue I am facing with my Prusa i3 (with inductive sensor and auto bed-levelling).
So, my issue is that when I start a print with autolevel, autolevel mesure is performed without issue, but when printing, the level is not perfectly corrected by the autolevel function :
I can see some correction being performed (both Z axis lead-screws are slightly moving when printing the extruder moves on the X or Y axis).
As a result, the first layer height for the center of my printing area is good, but it is getting smaller as the extruder move to the right part of the bed, and higher as it moves to the left part of the bed.
This leads to issues with my first layer adhesion for big prints, and on prints longer than one hour, it leads to a lot of wrapping on the left side of the bed (always the left side).
Obviously, I don't really want to print without the auto-level, trying to set the right side of the bed higher won't fix that (auto-level detect the new position of the bed, and correct it with the same error once again).
I also tried to change the firmware on my printer, without any result (current firmware is Marlin 1.1.0-RC6).
Behaviour is the same with both the "3-point" autolevel and the "grid" autolevel (3 points grid hence 9 measurements) functions.
Did any of you faced the same issue, or at least do you have any idea where this kind of issue can come from ?
Thank you in advance for your help
Romain
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Re: Bed not levelled after Auto Level May 19, 2016 10:47AM |
The aluminium bed is brand new, so I think that it is OK, plus the issue was already present with my previous bed, so I guess it doesn't come from there.
The probe doesn't shift, and I am sensing the same surface during all the auto level process (the aluminium bed).
The offset I had to set in my firmware was -0.65mm.
I just thought about one thing though, the metal structure supporting the aluminum bed is bigger on the left side than on the right side. Would it be possible that the inductive sensor would somehow detect the metal structure through the aluminium bed, and as a result detect the bed from a little further distance (we're talking about tenth of millimeter here) than on the right side (I don't know precisely how inductive sensor works, so I guess maybe more metal will mean earlier detection) ?
I also have a capacitive sensor. I think I will try to install it on my printer and see if the results are any better
The probe doesn't shift, and I am sensing the same surface during all the auto level process (the aluminium bed).
The offset I had to set in my firmware was -0.65mm.
I just thought about one thing though, the metal structure supporting the aluminum bed is bigger on the left side than on the right side. Would it be possible that the inductive sensor would somehow detect the metal structure through the aluminium bed, and as a result detect the bed from a little further distance (we're talking about tenth of millimeter here) than on the right side (I don't know precisely how inductive sensor works, so I guess maybe more metal will mean earlier detection) ?
I also have a capacitive sensor. I think I will try to install it on my printer and see if the results are any better
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Re: Bed not levelled after Auto Level June 07, 2016 07:19AM |
Hello,
I'm experiencing probably the very same problem with my Sintron Kossel Mini (delta printer). Initially my z-Probe assembly was very wonky and the spring that pushes the probe against the bed was way too strong, possibly twisting the whole hotend a bit during the individual probing movement. Recently I redesigned it and also made it simpler thus more precise. I'm positive that now it's much more precise, but the result ist the same: after the auto bed level procedure the bed seems to be still more than 0,5 mm higher on one side than on the other (it doesn't look like a delta typical bowl deviation). For big prints the head scratches the bed with no filament flowing on the one side an on the other it doesn't adhere due to the big gap. In the middle however there is an area where it works fine.
I'm wondering if the recorded bed z information actually gets written or retrieved from the eprom. I can't see if there is any corretion happening at all or not (because auf the delta design).
Shouldn't the bed at x=0, y=0 read z = 0 after the level procedure ? I'm asking because I still have to set a z height correction in slic3r. Might that be a hint that the bed leveling doesn't get stored? Does it get stored on all boards anyway or am I supposed to not turn off the printer after the procedure?? That thought ocurred to me just recently, I'll test that later today. I think I never testet that (again) because I once got dangerous movements and head crashes after the auto level procedure and not resetting the board afterwards. Maybe that was just coincidence? I could build a 3 point adjustmend for the bed, but that would make the auto bed levelling pretty obsolete, wouldn't it (except the bed is no perfect plane) .
My questions in short:
Does the usual Arduino Mega 2560/ADK with Ramps 1.4 retain auto level information after a reset/power off?
If so, why does it still look like no correction is done?
Should the z value (retrieved by the m114 command) after level procedure defiantely read 0 at the bed center? (or does it still read the "uncorrected" value and the correction is done without showing?)
Regards
Edit: I tried bed levelling today without turning the board off afterwards - same result. Now that I think of it I already mechanically levelled the bed twice in the past. It should be 1 mm higher on the side that was too low. But it isn't. It's the same like alsways since I got the printer. That must mean that the error is introduced by be electronic auto bed level. My only idea here so far: could the delta rods have different lengths? (although I measured them an screw them to equal length - I'll re-measure them today)
Regards
Edited 4 time(s). Last edit at 06/08/2016 02:54AM by TheYear2525.
I'm experiencing probably the very same problem with my Sintron Kossel Mini (delta printer). Initially my z-Probe assembly was very wonky and the spring that pushes the probe against the bed was way too strong, possibly twisting the whole hotend a bit during the individual probing movement. Recently I redesigned it and also made it simpler thus more precise. I'm positive that now it's much more precise, but the result ist the same: after the auto bed level procedure the bed seems to be still more than 0,5 mm higher on one side than on the other (it doesn't look like a delta typical bowl deviation). For big prints the head scratches the bed with no filament flowing on the one side an on the other it doesn't adhere due to the big gap. In the middle however there is an area where it works fine.
I'm wondering if the recorded bed z information actually gets written or retrieved from the eprom. I can't see if there is any corretion happening at all or not (because auf the delta design).
Shouldn't the bed at x=0, y=0 read z = 0 after the level procedure ? I'm asking because I still have to set a z height correction in slic3r. Might that be a hint that the bed leveling doesn't get stored? Does it get stored on all boards anyway or am I supposed to not turn off the printer after the procedure?? That thought ocurred to me just recently, I'll test that later today. I think I never testet that (again) because I once got dangerous movements and head crashes after the auto level procedure and not resetting the board afterwards. Maybe that was just coincidence? I could build a 3 point adjustmend for the bed, but that would make the auto bed levelling pretty obsolete, wouldn't it (except the bed is no perfect plane) .
My questions in short:
Does the usual Arduino Mega 2560/ADK with Ramps 1.4 retain auto level information after a reset/power off?
If so, why does it still look like no correction is done?
Should the z value (retrieved by the m114 command) after level procedure defiantely read 0 at the bed center? (or does it still read the "uncorrected" value and the correction is done without showing?)
Regards
Edit: I tried bed levelling today without turning the board off afterwards - same result. Now that I think of it I already mechanically levelled the bed twice in the past. It should be 1 mm higher on the side that was too low. But it isn't. It's the same like alsways since I got the printer. That must mean that the error is introduced by be electronic auto bed level. My only idea here so far: could the delta rods have different lengths? (although I measured them an screw them to equal length - I'll re-measure them today)
Regards
Edited 4 time(s). Last edit at 06/08/2016 02:54AM by TheYear2525.
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Re: Bed not levelled after Auto Level June 08, 2016 04:54AM |
Quote
TheYear2525
Hello,
I'm experiencing probably the very same problem with my Sintron Kossel Mini (delta printer). Initially my z-Probe assembly was very wonky and the spring that pushes the probe against the bed was way too strong, possibly twisting the whole hotend a bit during the individual probing movement. Recently I redesigned it and also made it simpler thus more precise. I'm positive that now it's much more precise, but the result ist the same: after the auto bed level procedure the bed seems to be still more than 0,5 mm higher on one side than on the other (it doesn't look like a delta typical bowl deviation). For big prints the head scratches the bed with no filament flowing on the one side an on the other it doesn't adhere due to the big gap. In the middle however there is an area where it works fine.
I'm wondering if the recorded bed z information actually gets written or retrieved from the eprom. I can't see if there is any corretion happening at all or not (because auf the delta design).
Shouldn't the bed at x=0, y=0 read z = 0 after the level procedure ? I'm asking because I still have to set a z height correction in slic3r. Might that be a hint that the bed leveling doesn't get stored? Does it get stored on all boards anyway or am I supposed to not turn off the printer after the procedure?? That thought ocurred to me just recently, I'll test that later today. I think I never testet that (again) because I once got dangerous movements and head crashes after the auto level procedure and not resetting the board afterwards. Maybe that was just coincidence? I could build a 3 point adjustmend for the bed, but that would make the auto bed levelling pretty obsolete, wouldn't it (except the bed is no perfect plane) .
My questions in short:
Does the usual Arduino Mega 2560/ADK with Ramps 1.4 retain auto level information after a reset/power off?
If so, why does it still look like no correction is done?
Should the z value (retrieved by the m114 command) after level procedure defiantely read 0 at the bed center? (or does it still read the "uncorrected" value and the correction is done without showing?)
Regards
Edit: I tried bed levelling today without turning the board off afterwards - same result. Now that I think of it I already mechanically levelled the bed twice in the past. It should be 1 mm higher on the side that was too low. But it isn't. It's the same like alsways since I got the printer. That must mean that the error is introduced by be electronic auto bed level. My only idea here so far: could the delta rods have different lengths? (although I measured them an screw them to equal length - I'll re-measure them today)
Regards
Are you using Marlin? Are you homing after doing a bed level? If so then there's your problem.
Scroll down to "Firmware setup" on this page:
[www.thingiverse.com]
for more information on how to set up a working autolevel.
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Re: Bed not levelled after Auto Level June 08, 2016 05:56AM |
I'm using Marlin and I'm homing before and after levelling. I have no servos, so at least part of the linked firmware setup isn't for me. It doesn't seem to be a problem of software endstops either, because I hear the switch clicking every time it probes. Software endstops are set about 0.5 mm below the actual bed, in addition to that the probe protrudes 2 mm below the extruder. I set all probe offset values according to my actual probe setup already.
I'm currently not at home but will check some things from that firmware setup later. Currently I'm not sure if these lines are true in my firmware
#define min_software_endstops false
#define EEPROM_SETTINGS
// #define Z_PROBE_ALLEN_KEY
What does the latter one even do?? (or rather: what would it do, if it was un-commented?)
Are you implying that homing annihilates bed level data, or am I supposed to home? (I never tried without homing!)
The m500 command to write the data into the eprom is totally new to me
never saw it mentioned in the manual or elsewere. I'll definately try that!
Thanks so far .
p.s.: Maybe I should mention that in the "manual" I received with the printer, a bed level routine is listed. Like "execute g29 [...]". In my Marlin firmware there is already a 37 point routine predefined and in use. It includes deploying the allen key probe by touching the belt and retracting it by pushing it against a screw head.
Edited 3 time(s). Last edit at 06/08/2016 06:22AM by TheYear2525.
I'm currently not at home but will check some things from that firmware setup later. Currently I'm not sure if these lines are true in my firmware
#define min_software_endstops false
#define EEPROM_SETTINGS
// #define Z_PROBE_ALLEN_KEY
What does the latter one even do?? (or rather: what would it do, if it was un-commented?)
Quote
nebbian
Are you using Marlin? Are you homing after doing a bed level? If so then there's your problem.
Are you implying that homing annihilates bed level data, or am I supposed to home? (I never tried without homing!)
The m500 command to write the data into the eprom is totally new to me
never saw it mentioned in the manual or elsewere. I'll definately try that!Thanks so far
.p.s.: Maybe I should mention that in the "manual" I received with the printer, a bed level routine is listed. Like "execute g29 [...]". In my Marlin firmware there is already a 37 point routine predefined and in use. It includes deploying the allen key probe by touching the belt and retracting it by pushing it against a screw head.
Edited 3 time(s). Last edit at 06/08/2016 06:22AM by TheYear2525.
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Re: Bed not levelled after Auto Level July 23, 2016 01:37PM |
I ditched that whole autolevel stuff and levelled the platform physically. After that I noticed it to be bent pretty much in one direction - like 0.5+ mm or so . I used an angle grinder to flatten it and checked with a metal bar whether there is a gap when it lies on the bed. I didn't completely remove the gap because I have the tendency to make things worse when I try too hard xD . So my circular bed ended up like that at 8 cm print radius:
[mm]
........0.1
0.0...0.0...0.1
.......-0.1
I think that is close enough when using a layer height of 0.3 mm for the first layer.
I still don't understand why someone writes a 39 point autolevel routine when it doesn't correct for a bent surface
.
I actually got the same idea, putting a glass plate on top. But naah, not yet ^^ .
Edited 2 time(s). Last edit at 07/23/2016 01:41PM by TheYear2525.
. I used an angle grinder to flatten it and checked with a metal bar whether there is a gap when it lies on the bed. I didn't completely remove the gap because I have the tendency to make things worse when I try too hard xD . So my circular bed ended up like that at 8 cm print radius:[mm]
........0.1
0.0...0.0...0.1
.......-0.1
I think that is close enough when using a layer height of 0.3 mm for the first layer.
I still don't understand why someone writes a 39 point autolevel routine when it doesn't correct for a bent surface
.I actually got the same idea, putting a glass plate on top. But naah, not yet ^^ .
Edited 2 time(s). Last edit at 07/23/2016 01:41PM by TheYear2525.
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