Printing problems when model is centered on bed

I managed to succeed with my first print using ColorFabb XT last night. I used the Laybrick profile and adjusted the temperatures:

However I had to move the print job off the center of the bed to get it to print properly. You can see the outline of a previous attempt on the bed in the center. Essentially what happened is that the print head would move over the close and left side of the bed but not extrude anything. When it moved over the far and right part of the bed, it printed normally. As a test, I moved the model to where you see it now, and it printed normally (so I let it finish).

This is happening again this morning with the next piece I intend to print:

Can anyone explain why this is happening? I looked online through some common problem guides but found nothing similar.

The piece currently printing is this one: https://github.com/zdayton/DeltaThrottle/blob/master/stl/Base_rev2.stl

Yesterday’s piece that did the same thing until I moved it on the bed is this one: https://github.com/zdayton/DeltaThrottle/blob/master/stl/Handle_2_bottom.stl

In the log the following errors can be seen, not sure if they’re related as yesterday’s successful print also had some errors like this:

< Bed x: 0.00 y: 0.00 z: -12.00
< Bed x: 160.00 y: 0.00 z: -8.42
< Bed x: 160.00 y: 160.00 z: -8.18
< Bed x: 0.00 y: 160.00 z: -7.92
< Eqn coefficients: a: 0.01 b: 0.01 d: -11.04
< planeNormal x: -0.01 y: -0.01 z: 1.00
< Probing done!
< echo:endstops hit:  X:0.70 Z:-7.92
< Error:No Line Number with checksum, Last Line: 54
< Error:No Line Number with checksum, Last Line: 116
< echo:Unknown command: "66"
< Error:No Line Number with checksum, Last Line: 327
< Error:No Checksum with line number, Last Line: 340
< Error:No Checksum with line number, Last Line: 350
< Error:No Line Number with checksum, Last Line: 350
< Error:No Checksum with line number, Last Line: 359
< Error:No Line Number with checksum, Last Line: 392
< Error:No Line Number with checksum, Last Line: 401
< echo:Active Extruder: 0
< Error:No Line Number with checksum, Last Line: 420
< Error:No Line Number with checksum, Last Line: 441
< Error:No Line Number with checksum, Last Line: 456
< Error:No Line Number with checksum, Last Line: 472
< Error:No Line Number with checksum, Last Line: 489
< echo:Unknown command: "8"
< Error:No Line Number with checksum, Last Line: 505
< Error:No Line Number with checksum, Last Line: 525
< Error:No Line Number with checksum, Last Line: 535
< echo:Unknown command: "33"
< Error:No Line Number with checksum, Last Line: 579
< Error:No Line Number with checksum, Last Line: 586
< Error:No Checksum with line number, Last Line: 594
< Error:No Line Number with checksum, Last Line: 594
< Error:No Line Number with checksum, Last Line: 610
< Error:No Line Number with checksum, Last Line: 626
< Error:No Line Number with checksum, Last Line: 642
< Error:No Line Number with checksum, Last Line: 656
< Error:No Line Number with checksum, Last Line: 669
< Error:No Line Number with checksum, Last Line: 681
< Error:No Line Number with checksum, Last Line: 693
< echo:Unknown command: "41"
< Error:No Line Number with checksum, Last Line: 916

Also you can see damage to the bed that happened when I tried to remove yesterday’s piece. I waited until the bed was less than 30C in temp before I even started to remove it (which took far longer than 20 minutes), based on how long it took to remove even the single layer failed prints from yesterday. I had to take a razor blade around all the edges and then carefully pry with the clam knife, and it still ripped the bed. What can I do about the bed damage, and how can I get this material to not stick so strongly?

The Mini is now “printing” the second layer and the problem continues, by the way.

Edit: Here’s a picture taken as the second layer nears “completion”:

After aborting the print I can get a better image:

This is a bigger problem than I thought. I’m attempting to re-print the first piece from my previous post here. Any time I have it on the far side of the bed, it selectively prints only the furthest part of the piece, the rest it traces but doesn’t extrude anything. So its not just when the piece is centered. So far I’ve only had luck when I move the thing to be printed to the close half of the bed.

Can anyone else duplicate this problem?

The only time I’ve seen this is when I had an old ~/.cura configuration file. This is different from the filament profile. If you have the latest LulzBot Cura and a fresh config, it will be in the center by default.

I downloaded Cura from the Lulzbot web site on Wednesday. And the prints are centered by default, they just don’t print properly unless I move them off center to the close side of the bed.

Are you printing straight to glass? No PET sheet? No PEI? Something else?

When the areas that are supposed to be printing are not printing, what’s going on with the extruder? Are the herringbone gears still turning? Is material still coming out of nozzle just not sticking to bed? Is your filament somehow getting caught or pinched if the extruder head is in a certain position in the x or y direction? If you simply place the extruder in a spot where it’s currently not printing and you make the printer squirt out 10mm of material, does it do what you ask? Do you get a nice long spaghetti string of material coming from nozzle?

Have you tried using Slic3r and Pronterface? After the gcode is created, and you load the gcode into Pronterface you can preview each slice before you print. I’m not sure if you can do the same thing in CURA.

I would check to see if there’s a problem with the creation of the gcode first by using that preview of each slice.

As for the parts sticking to the bed, you’ll first need to explain what you’re doing, and on what. From the pictures it looks like you’re printing straight to glass. Are you using hair spray? Elmers glue stick? Lulzjuice?

He’s printing on PEI, afaict.

It almost looks like the bed is not leveled properly. Before each print is the printer running the auto leveling procedure? If not you may need to add the Gcode for the leveling process in manually.

I’m printing on the stock PEI that comes with the Mini: https://www.lulzbot.com/products/lulzbot-mini-pei-sheet

Every print other than the one where I didn’t load a profile first has been auto-leveled: https://forum.lulzbot.com/t/filament-profiles-and-auto-leveling/1205/1

I wish I knew.

Yes.

Material is not coming out over the areas where there is no printing.

No.

Yes and yes.

No and no.

This is a separate issue so I'm separating it.

"As for the parts sticking to the bed, you'll first need to explain what you're doing, and on what. From the pictures it looks like you're printing straight to glass. Are you using hair spray? Elmers glue stick? Lulzjuice?"

I'm printing directly to the stock PEI that comes with the Mini, untreated with anything.  It sticks incredibly strongly, enough so that it rips the PEI when I try to remove the piece using the clam knife, assuming I can even get the clam knife under the print in the first place.  I have to go around the perimeter with a razor blade as carefully as possible just to get the clam knife under the print, then try to wiggle it around.  I more recently did another print with a different material and it came up ten times easier.  I think this is a problem with Colorfabb XT, next time I use it I'm going to try running the bed without any heat at all.

Edlink, I think I must explain the problem better. When the 3d model is placed in Cura in the center, or on the far side of the bed, the printer selectively doesn’t print parts of the thing to be printed. When the 3d model is placed on the close side of the bed, the thing to be printed prints normally. The print head travels over every part of the print as it should, it just doesn’t extrude anything over parts of it. This is repeatable. I’d like someone to attempt to duplicate this problem with their Mini. .Stl files that I’m using have been linked earlier in this thread.

The fact that I can get it to print normally on the close side of the bed indicates that it isn’t a mechanical problem with the printer, but a fault with the firmware or software telling the extruder when to extrude.

Let me provide another picture of a successful print:

As you can see, there is a great overlap of between the last picture of my first post and this picture. Areas that were traveled over yet nothing extruded printed fine in this second attempt. The only difference is that instead of the job being centered on the bed, I moved it to the close side of the bed. If there was a mechanical problem with the printer, this would not have happened.

Make sure the nozzle is clean prior to running the next print. Load a file in Cura, bring up the controls and bring it to extrusion temp, then wipe the nozzle with a dry clean natural fiber cloth/paper towel. Then try this print: http://devel.lulzbot.com/mini/test_prints/stl_files/bed_calibration/bed_calibration_print.stl

Pay attention to it as it probes the bed corners. Look for bed deflection/movement when it’s contacting the corners. Take a photo of the print.

The Mini uses a default 140C nozzle cleaning temperature. Your ColorFabb filament may need a higher nozzle cleaning temperature (30C less than your extrusion temperature perhaps).

I’ll try that, but its plainly obvious this has nothing whatsoever to do with nozzle cleanliness. It prints just fine over certain portions of the print, and fails over other portions. If the nozzle was dirty, this wouldn’t happen.

If the nozzle isn’t clean when the printer homes and probes (completing an electrical circuit to determine contact) the first, front left corner it’s going to have to push deeper onto that corner than it should. If that happens, then it’s going to think that front left corner is lower than it physically is. When it tries to print, it’s going to compensate for that perceived lower corner, and place the nozzle lower in that portion of the bed than it needs to be.

When that happens, the nozzle is sitting directly on the bed, keeping the filament from flowing out until it reaches the other portions of the bed, or the internal pressure allows the filament to seep out between the nozzle and the bed.

Please try it again while watching the probing process contact points, as this is the most crucial part of the print. If the bed is being pushed down while probing it will change how well it performs the first few layers.