gr5

Yes exactly. If you make it infinitely thin cura really shouldn't be printing it at all as infinitely thin is the same as nothing at all. But it's seeing that the mesh goes all the way around and assumes it's a solid. As cura is meant to print solids.

If you are going to print it upside down like this then: 1) The curved surface - right where it leaves the print bed - is much steeper (more horizontal) than 45 degrees. You can't get good quality on surfaces that steep without PVA support. So: would it be so horrible to make it 45 degrees initially as it leaves the flat part? And then blend into a curve? 2) The brim of your "hat" is simply underextruded because it was over support and gently fell down onto the support. Not squishing out as normal. So again, PVA support is a good option here. It's okay (even recommended) to do 0.8 nozzle with PLA on the left extruder and 0.4 nozzle PVA on the right extruder (BB 0.4 seems to waste less PVA).

Is the mesh solid? Or is it infinitely thin? You have to give it a thickness. I recommend at least 1mm thick.

This is called "underextrusion". Search facebook or the internet for "anet a8 underextrusion". Hopefully someone has advice for you. Good luck. But for now try printing even slower. 20mm/sec. Or print thinner layer heights. If this was an ultimaker 2 I would say to replace the teflon part. I don't know if the A8 has teflon in it.

These are relatively common. Although it has never happened to me after years of printing with UM3 and S5. It's called a "head flood". Don't panic. Hopefully this is PLA. If it's a higher temp material you may need an entire new head. Contact your reseller. They can help you out. But basically someone has to get a heat gun and spend 30 to 60 minutes heating bits of pla and then removing with metal tools such a pliers, screwdrivers, etc. Heaflood causes One cause is that the head flops open because the magnets aren't making good contact. But this is rare. 90% of the time the problem is that the part came loose. If the part you are printing is wider than tall at the moment it comes loose from the print bed then this is exactly what you get. The part slides around like a hokey puck. Prevention Never ever ever ever let a part come loose from the bed. There are a lot of things to know. I detail them all in my video here. Yes it's long - but if you follow my advice you will never ever have a part come loose during a print. You can hit the part with a hammer sideways and it should not come loose. In the video I pick up the entire printer with a tiny print on the print bed (a normal size ultibot).

So cura is maintained by Ultimaker and none of their printers released in the last few years support USB printing. So unfortunately I suspect this feature gets low priority - especially for new features.

This is on purpose. Some printers when you move the Z value it moves the nozzle up and down. Some move the bed up and down. ALL printers have z=0 when the nozzle and glass are touching. ALL printers have it such that when z=10 the nozzle and the bed are 10mm apart. So pronterface and cura have it so that the "down" button make the nozzle come "down" to the glass (or the glass up to the nozzle). The Z value goes *down* towards 0. Does that make more sense now?

I don't understand what you were saying. I also don't understand what you are trying to do: 1) Are you trying to make it as big as will fit? 2) Are you trying to make it a certain size? 3) Are you trying to make the base a specific diameter? 4) Are you trying to scale it up in X and Y but not Z? Note that you have "uniform scaling" checked which means it will scale up all 3 axes equally. Note that you can choose a specific size (left column) or you can choose a specific scale (right column) but obviously not both at the same time.

Oh. You are resizing the Z. That's the height. If you want to set the diameter to a particular value put it in either X or Y rows on the left column. If instead you want to resize by an exact amount like 2X put a 200% in the right columns.

Everything looks good to me. 150mm is about 6 inches so your measuring tape seems to agree with the printed model. So I'm not sure what your question is.

It's very fast on most computers. Even old, slow computers. A lot of people complain that it is slow but most people find it just fine. Try a different computer maybe? It could be something to do with security (try turning off all security features for 10 mintues) or it might have something to do with the fact that it is always looking at drives (there was an older version of cura that was very slow if you had a certain kind of external drive plugged in - cura was trying to figure out if that was an SD card or something strange). So check all your peripheral storage devices (and network devices) and see if dismounting them all helps. I'd just try a different computer. It works great for me on both windows and linux.

Did you print this in PLA or a higher temp material? Because if it's a higher temp material there's a lot more you can do (you may have bad layer adhesion). 1) Well in the "hook" end of the tab where it gets thicker now, you could make that thinner so the tab doesn't have to flex as much. 2) You should make it thicker at the base where the most force is and have it thin gradually to just before the hook. The idea is instead of having all of the flexure at the base, you want all of the tab to flex equally - equal strain everywhere. The exact calculation I don't know but at least make it thicker at the base of the tab and thinner at the top. You are doing two things here - making it thicker where it is most likely to break and making it thinner where it is less likely to break so it flexes more there. 3) You can also make the tab wider at the base potentially and narrower at the tab. This might not be practical or too much work in cad. 4) Look at other materials. For example "tough" pla aka TPLA is designed exactly for this kind of thing. Many plastics are slightly more flexible without being weaker. The parameter you care about is best described by the "modulus" or the "young's modulus". Google any material and "modulus" to get the mechanical characteristics. All venders publish the modulus but pretty much all nylons are similar and all pla's are similar and so on. Here's a chart showing some materials - modulus is the horizontal axis: https://gr5.org/mat/

steps/mm is changed permanently on the printer, not normally in the slicer. Ask someone else who had to change steps/mm for your particular printer - maybe on the "anycubic" message board (if there is such a thing). There is also a way to change it possibly through gcodes. If so then add the M500 gcode which saves settings for after power cycle. But typically you do it in the menu system on the printer.

Woah! What the hell - it didn't even get close. I'm wondering if your z steps go messed up somehow or it thinks you have a smaller printer (an S3?)

There are a few things to check. One thing you don't need to worry about is the firmware or rebooting. That rebooting "fixed" your issue is probably a coincidence. 1) First and foremost, check the wires. Swing open the print head and check the wires. The sensor is a flat plate at the base of the print head (as close as possible and paraellel to the print bed when doing active leveling). There are 2 wires there (for me it's a red and white wire). Tug on each gently and if one is disconnected then this is the issue. Also remove the 2 screws at the back of the print head (very long screws). Don't worry - nothing will come loose if you only remove those 2. At that point the print head rear top pops off. Push down firmly on the connector that is now revealed to make sure it is seated (with the print head in a corner so you don't bend the rods). 2) keep electromagnetic energy away from your printer during auto level - make sure there is a 1 foot clearance around the printer during autolevel (e.g. no laptops within a foot of the printer). Other S5 printers side by side are fine. Most importantly keep your hands, head and fingers at least a foot away from the printer during auto leveling. 3) Since it sounds like your leveling failed before the nozzle touched the glass these last 2 things aren't related: Springs in the cores and bed can mess up autoleveling - you'll see the nozzle hit the glass and keep going - for a long long time (not just a half second but maybe 2 seconds). If that happens then the springs in the core are too weak and/or the springs in the bed are too strong. Loosen the bed springs by rotated CCW (from below) quite a bit or try different cores on the core that has the issue. DON'T DO THIS if the autolevel fails before it touches the build plate. 4) Finally contact your reseller. If they are not helping you, let us know here in the forum and let us know who your reseller is or at least what country you are in. We can direct you to better support if your reseller isn't helpful. Unfortunately for this issue they may want you to return the printer. If your printer is less than a year old I'm pretty sure you can get this fixed for free.

On linux just type "locate .def.json" Anyway you can see all of them here just as easily as ahoeben says: https://github.com/Ultimaker/Cura/tree/master/resources/definitions

Could you show a screenshot of your model in both PREVIEW and PREPARE mode please? I'm not sure what you mean by "in the middle". Do you mean that central cylindrical hole that is at the center of all the fins - do you mean that was not supposed to be empty? If so then you have an issue with your CAD model and posting the screenshots will help. Or do you mean about that tiny little hole in one of the fins? Again - it would help to see the PREVIEW screenshot.

Are the numbers sticking into the part (grooves) or sticking out (bumps)? Sticking in is usually better. If they are sticking out then the walls of the numbers are probably too thin for the nozzle - make sure the walls are double the nozzle width or larger e.g. 1mm wide. If you must go smaller make sure to check the box: "enable thin walls". And consider also lying about the nozzle size - if the nozzle is 0.4 you can set line width to 0.35 and that will work relatively well. Please show photos (screenshots).

By the way, if you are going to use blue tape, it helps a lot to clean it with isopropyl alcohol. Without doing this, the blue tape has a waxy surface (to keep the tape from sticking to itself I suspect). This comes off very easily with a single tissue half soaked with IPA.

If you saved it as a stl file then problem solved but if you saved it as a 3mf file then please upload the 3mf file here and then also if you have the energy, please report the bug in github (you have to create a github account but the rest is easy). This could be a very recent bug. This worked for me the last time I tried it (I have a version of cura a few versions ago). I could create the bug report for you but it's so much better if the devs can ask you questions on github as some of them don't come to the forums much: https://github.com/Ultimaker/Cura/issues/

Was @ahoeben correct? Did you save it as an STL by accident instead of a 3mf file?

No idea. I'd leave things as is. If I see someone contacting you as smartavionics I'll let them know.

Change "combing mode" to "not in skin". If you look at your part in PREVIEW mode and choose color scheme "line type" and check the box for "travels" (blue) you now get 2 types of blue lines - 2 colors - one color shows retraction moves and the other shows non-retraction moves. You will see that with default settings there is no retraction for the layer you show in the picture above (bottom and top layers are called "skin"). Retraction is very quiet on the S3. And fast. You have to hold the filament just below the feeder to tell if it is actually retracting or not. Or use the color trick I mentioned. What is combing? Combing saves a lot of time on a print - if for example you are doing infill you don't want it to retract hundreds of times as some stringing *inside* the part is usually fine. Unfortunately it is also enabled by default on top and bottom layers. Just change combing to "not in skin".

The next time it is doing anything strange on the bottom layer, push the bed up or down gently to learn what the issue might be.

Is this on a PC? What is the "com" port? I think there was a bug in most versions (all versions?) of cura where it only uses com ports up to around 10 or 20? You can use arduino software to load the hex file or other software - I think pronterface might be able to upload hex files onto a UM2. But easier to keep switching PCs or Macs until you find one that has the com port < 10 (e.g. COM3) Power cycle the UM2 occasionally also. Also for some people the USB on their computer just doesn't have the power that a UM2 needs so adding a USB hub could help - or again - just try a different computer.