Hi, I have been using an A1 AMS with PLA for about 18 months and generally there have been no major issues, however this problem has me stumped. The only difference from the standard spec purchased is that I have started using a Smooth PEI Plate instead of the Textured one supplied with the printer and I have been using the Smooth plate for about 6 months with great results.
I was printing the second copy of this job with no changes. The first job was fine but about 25% of the way into the second job the printer stopped with a “nozzle blocked” message.
I replaced the nozzle with a new one, changed the filament to a different one which I had successfully printed with before and cleaned out the filament drive gears in the Hotend and tried again. This time the nozzle started to drag on the bed plate so I re-checked the nozzle mounting and it was fine. On start-up the filament is extruding fine, but when it prints the “test line” at the top of the bed it is clearly dragging on the bed to the point of damaging the bed.
I read a report online that some screws behind the nozzle mount can become loose with use, so I removed the nozzle and its mount and tightened all of the screws that I could see. Some I could get about half a turn on so I thought I had found the problem but no it was still the same.
I also read that changing the Z Offset to raise the nozzle might help but there is no facility to do this on the printer. I also read that the Z Offset could be changed in Bambu Studio, Printer Settings, Machine G Code. But the only Z offset shown in the Machine G Code relates to the Textured Plate and when I tried to put in a similar piece of code to relate the the Smooth plate it goes through the motions of saving it but later the changes are no longer there.
If I understand correctly, changing from a Textured plate to a Smooth plate without changing the Machine G Code should in fact result in the nozzle riding higher above the bed, but that’s not the case. Also the setting for the Textured plate is Z{-0.02}, is it correct that positive numbers raise the nozzle and negative lower it? Is 0.00 actually the surface of the plate?
Personally I have my doubts about the problem being related to the Z Offset because everything was working fine and the problem appeared to happen suddenly on a job that had already printed fine earlier.
I have tried three different filaments from different makers but its still the same. I have replaced the nozzle three times (all new) from different sources but its still the same.
I’ve carried out a full Factory Reset, but its still the same.
I’ve got the Bambu Studio set to trigger an automatic Bed Leveling every time.
Sorry for all the questions but I’ve run out of ideas!
Cheers
Rambler
Thank you for your response, yes those four and all the screws that I could see when that was removed. I got about a half turn on some but it made no difference.
Cheers
A further update, I figured out what I was doing wrong when I tried to change the Z Offset and have got it to save the changes. I started by changing the original Z{-0.02} to 0.00. No difference.
Then I changed the value to 0.02. No difference. Then I changed the value to 0.04. No difference. Finally I changed it to 0.06 and still no change.
Granted, I’m not sure I know what I’m doing, but a difference of 0.08 overall I would have expected some change in the printer’s actions, but there wasn’t. As it started to lay down the first layer the Extruder kept clicking and the rotor kept slipping backwards.
Ignoring the autocalibration issue and commenting on the workaround, If your symptom is “nozzle is dragging on the plate layer 1”, your Z offset needs to be more than +0.15, and likely +0.20 or more. If there’s contact, and the original setting is to say initLayer=0.20, then you need +0.20 [or more]
If you want to give autocal another try, clean and regrease the Z rods especially down near where it rests at z=0. Make sure there’s no PLA poop wedged in the nut, motor, or thread. Also can maybe benefit from a factory reset → then calibration
Sorry to say it’s me again. OK, I have cleaned and lubed the Z screws, the X rails and the Y rails, which incidently I frequently do. I also changed the Z Offset to 0.30 (the original setting was 0.02) saved it and synced it but the actions of the extruder has not changed. The squish on the initial test strip along the top of the bed plate looks the same and there is nothing being laid down when it starts the first layer. In addition the extruder continues to make the same skipping noise.
I can’t help but think that something is moving in the Hot End which is neutralising the adjustments that I’m making to the Z Offset, but what it may be I do not know.
Just a further update, I’ve now changed the Z Offset to 0.50. Tried it again, with the ABL turned on in case it makes any difference and the result is the same. Interestingly there is no “Skipping” noise when it is doing the test line but as soon as it starts the first layer it starts skipping and nothing comes out.
In despiration, with the Z Offset still at 0.50 I have set the Initial Layer Height to 0.30 and for the first time since the failure it has formed a first layer without “Skipping”. However, as you can imaging with those settings the layer resembled a farmer’s ploughed field.
I’ll try incrementally scaling down the settings to see if I can find a magic setting. I just wish I knew what caused the issue in the first place, I feel like I working on the symptoms rather than the cause.
OK, the original Initial Layer Height was 0.02 before all this started, so I started reducing the 0.30 setting where it worked without skipping and got down to 0.27 any lower caused it to skip.
I then did the same with the Z Offset and scaled down from 0.50 and got down to 0.45 any lower caused it to skip.
The problem is that with an Initial Layer Height of 0.27 and a Z Offset of 0.45 it may well print without skipping but the quality is less than bad, I could use a different word but some people may object.
OK another day spent trying everything I can think of. I have worked through all of the normal again such as the retaining screws on both sides of the nozzle heater, cleaned all around the cooling fan, but the extruder is still skipping. I’ve run a full re-calibration and bed leveling but its made no difference. I have manually operated the extruder and the filament comes out cleanly with a steady flow. However, when the printer starts it produces a “test strip” at the near end of the bed and then moves into the middle to start printing the job. No matter what setting I use for the Z Offset the printer produces the test strip fine but then gets so close to the bed plate that it is actually rubbing and there is just a few wisps of filament coming out and as it moves the extruder skips backwards, which is shown by the rotor going backwards.
I get the impression that the nozzle is too close to the bed plate but I can’t find any way to get it to work at a higher level. I have set the Z offset to 0.98 but it made no difference.
I thought that there may be a problem with the Eddy Current Sensor, so I carefully cleaned all around the sensor and checked the continuity across the sensor and got a reading of 3.2 ohms, which I understand to be correct.
What should the Z offset be set at when using a smooth PEI plate? The original setting for a Textured plate was -0.02 and that worked fine with the smooth plate until this problem happened.
For the record the printer has 840hrs clocked which I would have thought was not a great deal.
Well now, with a bit more investigation I’ve discovered something odd. with the bed temp set at 50 Deg C I’ve checked with a laser thermometer and get a reading of 49.8 C. However, with the nozzle temp set for 150 C the highest reading I get is 52 C and then it appears to fluctuate between 52 C and 49 C. I’ve checked the thermometer on the cooker and it reads above 100 with ease.
Question: Would a faulty nozzle heater cause the problems that I’m seeing?? The filament is being melted but when manually extruded the extruder starts skipping after about one minute.
And the answer is, YES. The nozzle heater was heating enough and for long enough to start melting the filament and them it would start to cool and nothing would come out. So it didn’t make any difference changing the Z Offset or the initial layer height because there was nothing coming out of the nozzle after the first 30 seconds or so.
Bought a new nozzle heater assembly with the thermistor and hey presto it works as good as new.