3rdpig

@Link I started with .4 and went to .5. I also changed my shells from 3 and a 1.2 thickness to 2 and 1.0. I think this is going to work out well for my existing parts since I tend to like to leave 3.0mm between holes and between holes and walls. I also upped the number of top layers from 3 to 4. Mainly due to the white filament I'm currently using, it shows imperfections much more than colors and the fourth layer really helps that. But the fourth layer doesn't add as much print time or filament use as I'm saving by only using two walls so I may use it for everything going forward. I haven't printed enough parts yet to be sure, but all the test blocks and the one full sized part suggest that this might be a big improvement. I'm sure hoping so. If nothing else, this is the first really good looking part of this type I've made with Cura. Others have been ok, but not up to what I'd get from S3D.

@smartavionics I tried that back when I was originally trying to solve the issue, I kept increasing it until I started getting blobs and still had the cracks. I haven't tried increasing it again since I increased the line width. I may try it on a test piece later, but right now it's working really well. I'm printing a full size piece sliced in Cura and, with the exception of a tiny gap at the small hole, it's better than the S3D sliced part. I'm very happy with the results, the top surface is the best I've ever gotten and that's without ironing. There is another problem but it happens in Cura but not in S3D, and that's a tiny gap around smaller holes and neither the line width or adding a fourth top layer has fixed. Here's a picture, this is an 8mm hole, 7mm deep. If it was on the surface it would annoy me, but down inside another hole it's almost unnoticeable unless you're looking for it. I'll also attach the gcode for that test block. I wonder if "Outside before inside walls" would help? @Link I've tried changing this setting just to get rid of the necessity of removing the seam when the part is done. I usually have Hide Seam and Sharpest corner selected. Let me know if you find any difference in that. I may play more with it later to see if it helps cure the problem in the photo above. og test 3.gcode

@Link Yes, I rotated the models, it changed the location of the gaps but didn't fix it. I did find out what's causing this new issue. It's not the same as the old issue, this is worse and different. It's not just thin cracks, it's larger gaps, large enough to stick a pencil point in. Somewhere along the way top/bottom pattern got changed from Lines to Zig Zag. Changing that back put things right. Looking at it in Craftware the outer "zig" would sometimes happen over the open area between infill lines (I'm using Grid and 20%) and didn't contact the inner wall enough to support it, so it dropped into the infill. I suspect one of the "expand" settings would probably fix this, but just setting it back to Lines did the trick. And now that I have Craftware installed I'm going to print a test with it later and see how I like it. Gotta another job to kick out first though.

My problems haven't ended. I decided to print a section of a normal part and not only were the gaps back, they were worse then ever and in more places. I'm printing some more test pieces out now and I'll know more when they finish. At least I found a use for all those mostly used spools of filament I've got laying around. But I'd rather be making money.

@smartavionics When I changed the line width from .4 to .5 my wall thickness stayed at 1.2 but the number of walls went from 3 to 2. In this circumstance should the wall thickness and number of walls stay a multiple of .5?

I printed another one with Ironing 10% turned on, (something I found helped minimize the cracks but didn't totally cure them) and the results are really good. A tiny bit too much plastic, but I bet I can get it dialed in even better. And TBH I'd rather take a fine sanding sponge or an emery board and remove a bump or a ridge than try to fill cracks with a 3D pen then sand it down. Although the whole thing has improved my skill with a 3D pen, it's still something I'd rather not do if I can help it. This really made my day, thanks again!

Great information everyone, thanks so much! @smartavionics here's the Cura project. Funny thing, back when I was originally trying to solve this I'm almost sure I tried a wider line width and rejected it for some reason that I can't remember now. But that's a moot point, here's the print with a .5 line width, it seems to have totally cured the problem. Thanks everyone! P.S. Smartavionics, I owe you a beer or six. hole tier test v1.3mf

@smartavionics I didn't save the original gcode files, but the STL file is in my first post and I recreated the gcode in Cura from that and my friend sliced it in S3D for me, files attached. I printed the Cura gcode to make sure the problem was still occuring, pic below. cura gap test.gcode S3D gap test.gcode

@smartavionics Sorry, I was under a lot of pressure at that time to get a particular job done and this problem got shoved to a back burner. I've got two prints to get shipped today and another one to get started printing and as soon as that's done I'll either find or recreate those gcodes and attach them. I'd really like to use Cura because some of the new features like "Make overhangs printable" are awesome. Thanks again for your help with this. I'll have those gcodes up asap.

@James2858 No, I have never completely resolved it. And yes, it's very frustrating. I tried some Cura profiles from Facebook and some printed my test pieces without the gaps, but when I print the things I really need to print the gaps are back. So for now Cura is not usable for me for those items. I was hoping that the upgrade to 3.5 would improve it, but if anything it made it worse. This is happening to me across 4 printers, my own 2 Ender 3's, my Alfawise U20 and a friends CR10. I've upgraded firmware multiple times without any changes. Bugs the heck out of me, but for now I've got better things to do so it's gone on the back burner.

I typically run the part cooling fan at 80% after the second layer for PLA. One of my original thoughts was that the gaps were only on one side because the part cooling fan on the U20 blows from one side only. So I ran the same part on my Ender 3 with the Petsfang cooler and had the same result. I've got prints in progress now, but as soon as one is done I'll try lowering the fan speed and see if that helps. There's no bridging on this particular part so a high fan speed probably isn't necessary But it still brings up the question of why among 3 slicers, Cura, Ideamaker and S3D, why Cura is the only one exhibiting this problem?

Thanks for the help, I appreciate it. I had to get that one print done by Friday, so I had my friend slice in in S3D for me and it's printing now, but what I'm making is personalized so I'm either going to have to figure this out or buy S3D, but that's just admitting defeat, and I'm not there yet. lol I made the chances to both wall line width and some of the changes in the gcode above including a large jump in skin overlap and while it's different, it's still there. It's just odd that it's in the same place almost every time. Maybe I should rotate the part 180 on the bed and see if it moves with the part. Ideamaker gets the top surface right, but messes up the inner walls and floor in the hole. I haven't tweaked it much, I don't care much for the UI. I'm going to work more on this over the weekend, I'd really like to get this figured out, if only for my own sanity.

The parts in the pictures were both sliced in Cura 3.4.1, one was printed on an Ender 3 and one on an Alfawise U20. Yesterday I had a friend print one on his CR10 that I sliced in Cura and all 3 have almost identical gaps in pretty close to the same places. He also sliced the part for me in S3D and the top surface came out perfect (but the side walls of the holes weren't any where near as good as Cura). I sliced another one in Ideamaker and while it had problems elsewhere, the top layer was fine. With the above in mind it seems unlikely that it's a backlash/play issue, but I will check to make sure. I really want to use Cura, with the exception of the top layer it's producing the best parts and in the fastest times. It's ability to hide the Z axis hop makes me very happy. I also find it very easy to work with. But the top layer issue is killing it for me. It doesn't do it on everything I design, but where I have holes near straight walls it does it most of the time. I will try your suggestions, I've increased flow to 105% (110 was way too much) and I've increased the skin overlap, that produced the parts in the pictures, by far the best I've gotten. And no, it's really not that bad, but I don't want it there at all if possible. Tomorrow I'll try your suggestions about line and wall widths and see if that helps. Thanks very much for responding!

This has been driving me nuts for days. These small gaps where the upper layer meets, or fails to meet, the inner wall. I've got a project for a client and need to get this resolved. This has been repeatable on 3 different printers, CR-10, Ender 3 and Alfawise U20. The picture below is a small test piece I created to try to solve this problem. I've tried every setting I could think of including over extruding by 10% and even with obvious signs of over extrusion it still hasn't fully solved the issue. I'm putting a picture below and a link to the STL file. The original model was created in Fusion 360. I appreciate any assistance, I've probably got 20 of these pieces printed now and still haven't completely solved it. hole tier test v1.stl