Sharp corner problems

[nirakara]

I'm having issues printing sharp overhang corners, specifically those of these heart gears. I thought it was an overhang thing or that it needed tweaking the temperature so I did a temperature tower - 225 to 210 and all of the overhangs look good. I thought it might be acceleration so I have gcode at the beginning to lower it to 1000, and the print speed is already at "Fine PLA" speed in Simplify3D which works fine for other things but it doesn't change things here. I even lowered the speed manually to 50% of that for the second half of the print I have in the pictures with the same result. The one thing I notice as it prints is that the print head sometimes stops at the tip of each corner and puts a little drop of material, which seems weird to me and I'm not sure what in the slicing would make it do that.

I was going to embed the pictures but its easier to tell in higher res.

I'm pringing with Simplify3D 2.2.2 on a Kittaz using InPla Taulman3D White.

Thanks for the help!

[JoeJ]

You definitely have some settings that you need to adjust. Those top layers also look really bad. Honestly, it looks like massive overheating and insufficient cooling all the way around.

Do you have a cooling fan on your printer? Is it running at full speed?

I would also try lowering the temp to 190C and see what happens.

[Holy1]

You definitely have some settings that you need to adjust. Those top layers also look really bad. Honestly, it looks like massive overheating and insufficient cooling all the way around.

Do you have a cooling fan on your printer? Is it running at full speed?

I would also try lowering the temp to 190C and see what happens.

I agree with Joe. Cooling fan not working? The layer under the layer being printed hasn't cooled sufficiently so it is blobing. You could set the # of skirt levels to 999 so that it prints a tall skirt to the finished height. This allows the part to cool before the next layer is printed. This is a good trick when you are printing a fine part....You are also over extruding.

[nirakara]

Thanks for the replies guys. I do have the fan going at full speed. I printed another temperature tower without the fan with not as clean results. Regarding the hot layer hypothesis I'm unconvinced since printing the tower (which is a much smaller area layer area) prints fine. The gear print spends tons of time on the in-fill so that those corners should be nice and cool before the head gets to them again - and it's only a single perimeter too. And again the tower shows 225,220,215,210 C temps with no visible difference. I'm not saying you guys aren't right, I'm just trying to reconcile the tower with the gear in my head, why would the larger part look worse.

This is a new filament for me so I do appreciate your help working out the kinks. Regarding over extruding i did another test which is just a hollow cube with a single perimeter and i measure the walls to be just under my 0.35 nozzle dimension, which I thought was what I wanted?

I'll try to print the gear at lower temp when I get a chance, thanks!

[jimc]

The difference between the gear and the tower is that the gear isnt just an overhang. Its an double overhang going out to a point. Those points have very little supporting them and are going to be prone to curling up slightly. Just a little curling at those tips will cause the blobbing. Try printing a lower temp and print 2 gears at the same time and see if things improve

[nirakara]

Sorry for the lapse but I tried a few more times with lower and lower temp with no success and I got frustrated and I haven't printed in a while now. I decided to go back to it today and I think I can still lower the temperature a little more but after looking at S3D closer I'm more convinced it's the slicing than ever. I did a slice with a single sidewall, no in-fill and no support to find what all the skipping around the corners was about and I've captured this picture of what the printer is doing:

The print should just go around making that star shape over and over but instead at the very inside tip of those corners and on the inside flat walls it's depositing extra material at top speed, which I'm almost sure is messing up this print and not affecting other things I do. There's absolutely no reason for those extra lines - what setting do I mess with to turn this off? Thanks.

[gatorNic]

One thing you could try with your current settings is "Avoid crossing outline for travel movements" in the Adv tab.

But if this is hollow in the center like a vase then I would rather try "Single outline corkscrew printing mode (vase mode)" in the Layer Tab. That would stop most retractions and big moves, but is only good for certain models like vases.

Overall though keep your temp lower, a higher retraction setting if it oozing at retraction points.

[dkightley]

The little bits you refer I believe are "bottom solid layers " fragments. The perimeter of the gear is at a fairly shallow angle and the slicer is deriving that there's just enough room to splash a spot or two of bottom solid layer.

You can get rid of these bits by lowering the value down....however as this is a gear and is likely to need some strength, I would increase the bottom layers by two or three so as to create even bigger bits in the narrow part of the gear. I'd also add some infill to give some strength.

[nirakara]

I purposely turned off the infill to figure out what those extra bits were. You are absolutely right that they are bottom layers, which I find extremely strange, as they are not in the bottom. I can turn it up and get what looks like extra internal perimeters so that they won't be tiny blobs. I'll give it a shot, thanks!