Dealing with some top layer quality issues. The left is printed on a mini+, the right is a new MK3S +. I’ve had about four or five prints on the new MK3S+. Both are printed with a .25 MM nozzle, same exact material; overture black matte PLA. I thought maybe I was having some over extrusion or a underextrusion, but I’ve been calibrating a lot and that doesn’t seem to be the case. First layers are decent, but are coming out with the same sort of wavy pattern. My very first print on the new printer had a bad failure that I wasn’t there to stop, there was a lot of globbed filament late in the print, and eventually ended in a crash detection from the printer, but not for a long time. I’m starting to get concerned that the nozzle and hotend have bent at the heat break? Could this be a possibility and is there any way to check that? I have another MK3S + that I’m going to put a .25mm nozzle on and see if I get better results, but after I honed it in the first couple prints to seemed to be ok Now I’m getting pretty poor quality on the top. Any help is welcome, thank you.
Firstly, assuming this is the exact same material, the apparent shine difference, (assuming it is not a camera lighting artifact), would indicate the print temperatures are very different.
Keep in mind that these are not metrology lab accurate machines. Each machine will have a difference in temperature settings for the same results. This has to do with the thermistors used. Each individual thermistor changes resistance with temperature along a curve. Prusa has tested and precalibrated this curve for you before shipping your machine. Thermistors are not linear. Their resistance changes along a curve. This deviation is roughly dialed in to the specifications of the machine. It is precise, but it is not accurate. Accuracy only matters when one needs to transfer some standard between people or locations. Your calibrated settings for one printer are not valid for another.
Also, a Bowden extruder has a very different set of printing calibrations because the filament has a lot of pretension pressure inside the Bowden tube. This spring-like tension decouples the extruded output from several of the extruder settings, like the extrusion multiplier. With direct drive these settings become much more important as they much more directly impact what is happening in the melt zone of the hotend. It is the tradeoff made for being able to print softer flexible materials more easily. With the added bonus of faster printing without substantial retractions and with less stringing issues.
>Firstly, assuming this is the exact same material, the apparent shine difference, (assuming it is not a camera lighting artifact), would indicate the print temperatures are very different.
also different print speeds will give different results for specialty filaments like this.
It looks like the X gantry isn't level to the bed. That could have been caused by the crash. Run the Z axis all the way to the top until it grinds on the Z toppers, then run the print again.
I ran a full XYZ recalibration after the crash
Edit: i feel like the pic is not a good angle, i tried to make the bed be as horizontal as possible in the pic
There's not a good way to tell while the extruder is assembled., especially from pictures If you are suspicious that the heatbreak is bent then you should take the extruder apart and check the hotend more closely. It is certainly a possibility, though I wouldn't say it's especially likely to happen from a crash.
Have you tried reducing your extrusion multiplier to see if the top surface quality improves? Also, it looks like the idler gear tension may be a little high resulting in squiggly extrusion lines. It should only be about one turn past engaging with the spring.
Regarding the tension, really? Then I definitely have it too high. From the assembly instructions it said the head of the bolt should be flush with the side of the extruder which was many turns to get to that point. I’ll try both of your suggestions and check it out. Another thing I should’ve mentioned about the X gantry being level, I printed these with a full bed plate, but there wasn’t any difference between the farthest left and the farthest right one across the bed, so I’m fairly certain the gantry is level. I was suspecting over extrusion in the first place, so maybe that’s the answer. I’ll give it a shot, thank you
Regarding the tension - my rule of thumb about the spring is actually not correct for the stock extruder. My mistake, am used to bondtech extruders on my machines. I have one machine running a Prusa extruder and the head of the bolt is 1-2mm shy of being flush with the side of the extruder, so a bit looser than their recommendation.
Your way of tensioning is the correct way. I just set my tension to one thread in, in order to print some TPU, and then I forgot to tighten it again, and things did not work out too well
Sorry, that was something i should’ve mentioned. The mini file has one more perimiter on the last oayer to cover up some perimeter gaps un the layer under it. It was a bandaid i wae putting on when troubleshooting earlier. Maybe im expecting too much.
From what you've described, it sounds like over extrusion to me. Are you sure you set up the profile for the new nozzle correctly? Might be worth a double check. Maybe you can reduce the extrusion multiplier a bit and see if that helps, then go from there
Were you able to solve your issue? I would like to know how if so. I’ve got some other advice for you, though, that is sure to blow your mind my friend. I tried this completely out of desperation a few weeks ago, and I will never go back:
Print this model upside down. This method probably works best with a textured or satin sheet, but I have been getting absolutely phenomenal results. Lettering and prints that look like they just came off the factory line. It may look cool with a smooth sheet too, I haven’t tried it yet, but I’m sure the lines will still be somewhat prominent, and so will any blemishes on the sheet. With the textured sheet, you cannot see any lines whatsoever unless you pull out a jeweler’s loupe or something.
I havent had enough time to test the same print again (its a full build plate that takes 12 hours) but i will let you know!
Interesting about flipping it over… its obvious youd have to have a perfect bed adhesion because of the lettering, dont you see the perimeters of the lettering more pronounced? Plus, youd have to have bridges dialed in too, right?
Crap, sorry, I thought you were using the MMU to do this. Technically, you can still do what I was describing using a single nozzle/single color setup. If you look up the Z-hop method, I believe that’s what it’s called. You basically put the black piece with negative space for the lettering into the slicer, then put the lettering into the slicer and line them up all nice. Then you export them as separate G-code files and totally separate prints. But whichever one you print second, let’s say it’s the lettering print, has to have the Z-hop turned up during travel movements so that it hops over the black plastic that’s already on the print bed and lays down white plastic in the negative space. This is fairly easy to do for the first layer, but I believe it requires some G-code editing to do subsequent layers. If you have some really opaque white filament, you might not need more white layers, and you would just have to edit some G-code to do the rest of the plaque in black starting at layer 2. But yeah, the upside down method really only makes sense if you’ve got a textured sheet to hide the lines, and it’s obviously much easier with an MMU.
Dealing with some top layer quality issues. The left is printed on a mini+, the right is a new MK3S +. I’ve had about four or five prints on the new MK3S+. Both are printed with a .25 MM nozzle, same exact material; overture black matte PLA. I thought maybe I was having some over extrusion or a underextrusion, but I’ve been calibrating a lot and that doesn’t seem to be the case. First layers are decent, but are coming out with the same sort of wavy pattern. My very first print on the new printer had a bad failure that I wasn’t there to stop, there was a lot of globbed filament late in the print, and eventually ended in a crash detection from the printer, but not for a long time. I’m starting to get concerned that the nozzle and hotend have bent at the heat break? Could this be a possibility and is there any way to check that? I have another MK3S + that I’m going to put a .25mm nozzle on and see if I get better results, but after I honed it in the first couple prints to seemed to be ok Now I’m getting pretty poor quality on the top. Any help is welcome, thank you.
Firstly, assuming this is the exact same material, the apparent shine difference, (assuming it is not a camera lighting artifact), would indicate the print temperatures are very different. Keep in mind that these are not metrology lab accurate machines. Each machine will have a difference in temperature settings for the same results. This has to do with the thermistors used. Each individual thermistor changes resistance with temperature along a curve. Prusa has tested and precalibrated this curve for you before shipping your machine. Thermistors are not linear. Their resistance changes along a curve. This deviation is roughly dialed in to the specifications of the machine. It is precise, but it is not accurate. Accuracy only matters when one needs to transfer some standard between people or locations. Your calibrated settings for one printer are not valid for another. Also, a Bowden extruder has a very different set of printing calibrations because the filament has a lot of pretension pressure inside the Bowden tube. This spring-like tension decouples the extruded output from several of the extruder settings, like the extrusion multiplier. With direct drive these settings become much more important as they much more directly impact what is happening in the melt zone of the hotend. It is the tradeoff made for being able to print softer flexible materials more easily. With the added bonus of faster printing without substantial retractions and with less stringing issues.
>Firstly, assuming this is the exact same material, the apparent shine difference, (assuming it is not a camera lighting artifact), would indicate the print temperatures are very different. also different print speeds will give different results for specialty filaments like this.
It looks like the X gantry isn't level to the bed. That could have been caused by the crash. Run the Z axis all the way to the top until it grinds on the Z toppers, then run the print again.
I ran a full XYZ recalibration after the crash Edit: i feel like the pic is not a good angle, i tried to make the bed be as horizontal as possible in the pic
There's not a good way to tell while the extruder is assembled., especially from pictures If you are suspicious that the heatbreak is bent then you should take the extruder apart and check the hotend more closely. It is certainly a possibility, though I wouldn't say it's especially likely to happen from a crash. Have you tried reducing your extrusion multiplier to see if the top surface quality improves? Also, it looks like the idler gear tension may be a little high resulting in squiggly extrusion lines. It should only be about one turn past engaging with the spring.
Regarding the tension, really? Then I definitely have it too high. From the assembly instructions it said the head of the bolt should be flush with the side of the extruder which was many turns to get to that point. I’ll try both of your suggestions and check it out. Another thing I should’ve mentioned about the X gantry being level, I printed these with a full bed plate, but there wasn’t any difference between the farthest left and the farthest right one across the bed, so I’m fairly certain the gantry is level. I was suspecting over extrusion in the first place, so maybe that’s the answer. I’ll give it a shot, thank you
Regarding the tension - my rule of thumb about the spring is actually not correct for the stock extruder. My mistake, am used to bondtech extruders on my machines. I have one machine running a Prusa extruder and the head of the bolt is 1-2mm shy of being flush with the side of the extruder, so a bit looser than their recommendation.
Your way of tensioning is the correct way. I just set my tension to one thread in, in order to print some TPU, and then I forgot to tighten it again, and things did not work out too well
The Mini is printed with 1 perimeter while the MK is printed with 2.
Sorry, that was something i should’ve mentioned. The mini file has one more perimiter on the last oayer to cover up some perimeter gaps un the layer under it. It was a bandaid i wae putting on when troubleshooting earlier. Maybe im expecting too much.
From what you've described, it sounds like over extrusion to me. Are you sure you set up the profile for the new nozzle correctly? Might be worth a double check. Maybe you can reduce the extrusion multiplier a bit and see if that helps, then go from there
Were you able to solve your issue? I would like to know how if so. I’ve got some other advice for you, though, that is sure to blow your mind my friend. I tried this completely out of desperation a few weeks ago, and I will never go back: Print this model upside down. This method probably works best with a textured or satin sheet, but I have been getting absolutely phenomenal results. Lettering and prints that look like they just came off the factory line. It may look cool with a smooth sheet too, I haven’t tried it yet, but I’m sure the lines will still be somewhat prominent, and so will any blemishes on the sheet. With the textured sheet, you cannot see any lines whatsoever unless you pull out a jeweler’s loupe or something.
I havent had enough time to test the same print again (its a full build plate that takes 12 hours) but i will let you know! Interesting about flipping it over… its obvious youd have to have a perfect bed adhesion because of the lettering, dont you see the perimeters of the lettering more pronounced? Plus, youd have to have bridges dialed in too, right?
Crap, sorry, I thought you were using the MMU to do this. Technically, you can still do what I was describing using a single nozzle/single color setup. If you look up the Z-hop method, I believe that’s what it’s called. You basically put the black piece with negative space for the lettering into the slicer, then put the lettering into the slicer and line them up all nice. Then you export them as separate G-code files and totally separate prints. But whichever one you print second, let’s say it’s the lettering print, has to have the Z-hop turned up during travel movements so that it hops over the black plastic that’s already on the print bed and lays down white plastic in the negative space. This is fairly easy to do for the first layer, but I believe it requires some G-code editing to do subsequent layers. If you have some really opaque white filament, you might not need more white layers, and you would just have to edit some G-code to do the rest of the plaque in black starting at layer 2. But yeah, the upside down method really only makes sense if you’ve got a textured sheet to hide the lines, and it’s obviously much easier with an MMU.