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Okay, recalibrate the material flow setting seems to reduce the scratching. It seems that my previous print might have an over extrusion issue. So maybe that is what most people do and there is no need to do Z hops.

https://github.com/Ultimaker/Cura/issues/5226 https://github.com/Ultimaker/Cura/issues/6470

Why does Cura make "Combing" and "Retraction" mutually exclusive options? Can't they exist at the same time to increase user flexibility? "Combing" keeps the stringing within the print, but at the same time, I want to use "Z Hop" to avoid scratching the surface, and "Z Hop" must exist with "Retraction".

The print comes out okay, but now I found that the disadvantage is that the print has more stringing, even though it is only a PLA print. I guess the advantage of "Combing" is to have the stringing stay within the solid area of the print.

Okay, "Combing mode" is actually enabled by default. So the problem is fixed by disabling "Combing mode". But doing so will make the print very slow since it will retract all the time. Setting the "Retraction Minimum Travel" to a higher value such as 5mm will make it print almost as fast as the default, but of course, now the diagonal line is gone. So although the problem is fixed by changing this setting, it still does not make sense that filament are spitting out during a travel in "Combing mode". I think something is wrong with the G-code output from Cura.

Upgraded the Cura to the latest 4.8.0. Now the diagonal line becomes a horizontal line. Yes this line does not really affect the print quality that much, but the problem is that when it travel across the print, it scratches the layer with a loud sound. This seems more like a software bug than a hardware problem.

Hi, I just start printing with Cura and Ultimaker 2. I have built-plate adhesion set to "Raft", and after printing the first raft layer, it travels to the next raft layer but seems like the nozzle is still extracting. I already have retraction enabled. I tried different settings such as "Combing mode", "Z hop", etc, and it does not change anything. If I have retraction enable when layer change, it does retract but it retracts only after drawing the diagonal line. See the pictures. The nozzle travel very quickly in the diagonal direction and you can clearly see the diagonal line with print material on it.

Thanks for all the replies. I did some test on my materials and the end results are similar to what this person did in youtube. Seems like PETG is really hard to catch fire compared to ABS. But I rarely see PET being used in electrical enclosure, maybe of its lower melting point. I heard that PC is a better material for engineering application, but I guess PC will be even harder to print as my ABS warping problem is already hard to solve. I will try the ABS+ material in my next project to see if it can improve on warping.

maybe there is a way to just modify the gcode? I think Cura should add this feature.

Hello, To avoid warping when printing ABS, I would like to keep the air temperature high and avoid any large air temperature fluctuation . I already have an enclosed top and door for my UM2E+. But the print still slightly warp after printing, so I suspect that the build plate homing creates a large temperature shock to the model since the air temperature at the bottom of the UM2E+ is usually lower just after printing. The fact that it is an "extended" ultimaker makes it even worse. I want to be able to let the model cool down slowly first before homing the built plate down to the bottom. Is it possible? Actually I do not know if the warping happens during printing or during the cooling after printing, but I would argue that a gradual air temperature change will always be better to the model than an abrupt temperature change. I have another 3D printer and it does not home to the bottom after print. It is harder to remove the print but it is better for the model.

Hello, I am using 3D printing to make electrical enclosure. We all know that heat resistance of ABS is a little better than PETG. But besides the Tg value, I want to make sure the material will not burn at high heat which will increase the safety factor for using it in electrical application. In that case, would anyone recommend PETG over ABS?

Yes, it worked! Attached is the code. UM2_bed_check_v1.1.gcode

Thanks and the code was tested okay. The only thing is I added one more z-hop before the first move. Also it should go to the left side before the right side to make it the same as the normal calibration steps. I was trying to add a statement //action:pause without success. I want to be able to manually push the button to proceed instead of wait for a fix number of seconds.

Hi CarloK, Thanks for your code. I wonder can this code be used in UM2E+ ? Because I do not understand how to change the head positions. Do you mean I should modify the Gcode myself?

Actually I wonder if there is a way to generate a G code to home the print head to the three points without printing?

Hi, Is it possible to verify the build plate calibration without going through the adjustment process again? That means I just want to home the print head to the three points for checking. Thanks.

Hi, I cannot find the "UltiGcode" selection in G-code flavor. Is it the same as the "Ultimaker 2" selection?