RE:
A somewhat heavy-handed thought, can you disable the print fan completely? I usually turn it off (with ABS/ASA, to err on the side of caution as cooling means warping means catastrophic head crash). It's probably suboptimal but might still be an improvement. The object in the picture looks quite robust, no bridging or the like.
Or a compromise, set a fixed fan speed min=max?
Heavy handed, yes, but simple to implement. Yes, this is a simple part. Definitely worth a try.
Wish there was a general solution, rather than hacks like this.
Hey, if it were simple, everybody would be doing it 🙂
I wouldn't even sell this off as a "hack", more like systematic troubleshooting. Frankly, I'm not convinced it's related to the fan.
Coming back to the original subject line:
>> Fine horizontal lines on exterior when an internal feature ends
If the fan can be exonerated, this would be the next angle to look into. Overextrusion maybe, pushing outwards?
Can you improve the CAD design to smoothen the edge e.g. assuming it's a (90-degree angle between bottom and vertical wall) create a cylinder ring, then subtract a torus (centered at its inner, upper corner) for a circular = filleted transition?
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
If the ridge is still there, it's not the fan...
That's another thought I had. If not the fan, then maybe slow down the flow rate in that area. It's like that layer is getting squished before it completely cools.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
A somewhat heavy-handed thought, can you disable the print fan completely? I usually turn it off (with ABS/ASA, to err on the side of caution as cooling means warping means catastrophic head crash). It's probably suboptimal but might still be an improvement. The object in the picture looks quite robust, no bridging or the like.
Or a compromise, set a fixed fan speed min=max?
Heavy handed, yes, but simple to implement. Yes, this is a simple part. Definitely worth a try.
Wish there was a general solution, rather than hacks like this.
Hey, if it were simple, everybody would be doing it 🙂
I wouldn't even sell this off as a "hack", more like systematic troubleshooting. Frankly, I'm not convinced it's related to the fan.
Coming back to the original subject line:
>> Fine horizontal lines on exterior when an internal feature ends
If the fan can be exonerated, this would be the next angle to look into. Overextrusion maybe, pushing outwards?
Can you improve the CAD design to smoothen the edge e.g. assuming it's a (90-degree angle between bottom and vertical wall) create a cylinder ring, then subtract a torus (centered at its inner, upper corner) for a circular = filleted transition?
Yes, I can make a filleted transition in the bottom, rather easily. Currently it's an abrupt 90 degree angle there, primarily because this was a somewhat quick design, and hey, I didn't think it was necessary to finesse it. Maybe I have to. So what kind of radius are you suggesting for the fillet? 1mm? More?
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
If anything, I'm slightly under extruding, at least for 0.2mm structural. I'm using Overture PETG, with a 0.95% multiplier, and reducing the MVS to 6. At Prusament like settings I was getting excess material on the nozzle which then deposited on the print with predictable results. Tall stuff got knocked over... With settings like this, the Overture PETG prints pretty good.
RE:
... So what kind of radius are you suggesting for the fillet? 1mm? More?
Here comes the "cooking" part... 1 mm sounds good for systematic debugging. It's smooth enough so if you still see an edge, it's something else.
If I had to put a number just for looks, I'd say three to four layer heights which may be slightly less than a mm. But I remember screw bosses for M3 screws that kept tearing off the base surface - for strength I've used larger radiuses.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
It's like that layer is getting squished before it completely cools.
That may be it, actually...
Prusa slicer:
Filaments / Cooling Thresholds / Slow down if layer print time is below (put number here).
Shouldn't hurt to use this for testing, just slows down the print.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
BTW, unrelated:
>> 0.95% multiplier ... getting excess material on the nozzle
the number doesn't look wrong but check whether the filament moves freely in the PTFE tubes. Ideally the extruded filament should be exactly proportional to the steps counted off on the extruder motor. In reality you can see friction in the surface quality / roughness. And the nozzle doesn't collide with the theoretical average value but the peaks.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
... So what kind of radius are you suggesting for the fillet? 1mm? More?
Here comes the "cooking" part... 1 mm sounds good for systematic debugging. It's smooth enough so if you still see an edge, it's something else.
If I had to put a number just for looks, I'd say three to four layer heights which may be slightly less than a mm. But I remember screw bosses for M3 screws that kept tearing off the base surface - for strength I've used larger radiuses.
I can put in a fillet of 2mm easily on the bottom piece. The top cover, I can't put in any fillet because my screw threads end at the flat face. The fillet would fail in CAD. I would need to redesign the piece. I think the bottom piece, with the male threads, would be an adequate test bench.
RE:
I haven't noticed any feeding issues. Don't think the Bowden tube is an issue, or at least isn't the major issue at the moment. The Overture PETG over extrudes at a multiplier of 1, big time. Terrible prints. 95% and below fixes the problem, at least with 0.2mm structural and a normal 0.4mm nozzle. Sometimes I'll even reduce it to 93 or 94%. I also run it slightly cooler, because it just prints better...
RE:
Worth spending 13 minutes of your time.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
thanks... but takes all the fun out of reinventing the wheel 🙂 ... layer times ...
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
I can report that using a 2mm radius fillet at the base didn't stop the line from forming. That's what the guy said in the YT video would help. Didn't work for me. Line was in the same place, 4mm from the bottom. Actually, the line was more pronounced.
Changing the perimeter stuff from baseline settings did nothing. I'm ready for fuzzy skin, but I'm not hopeful.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
I'm 8hrs into a 17hr print, but when it's done, I'll throw on a spool of Overture PETG and see what I can do with it.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
Might be a coincidence, but the ring defect mimics (roughly) the filament cooling shroud shape. The defect is roughly 240 degrees around the cylinder, with 120 degrees being basically defect free. It's close to the physical shape of the filament shroud, which is roughly 240 degrees around the nozzle.
Ok, tried fuzzy skin, and consistent surface cooling. Same model as before, with the addition of the 2mm radius fillet. No obvious line, but at the expense of a smooth surface. Personally it's too rough for my liking. I'll try something finer. It's odd to me that this works, but a smooth surface doesn't.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
Might be a coincidence, but the ring defect mimics (roughly) the filament cooling shroud shape. The defect is roughly 240 degrees around the cylinder, with 120 degrees being basically defect free. It's close to the physical shape of the filament shroud, which is roughly 240 degrees around the nozzle.
Ok, tried fuzzy skin, and consistent surface cooling. Same model as before, with the addition of the 2mm radius fillet. No obvious line, but at the expense of a smooth surface. Personally it's too rough for my liking. I'll try something finer. It's odd to me that this works, but a smooth surface doesn't.
RE: Fine horizontal lines on exterior when an internal feature ends, how do you get rid of this?
A smaller amount of RMS surface deviation reveals the line again. I halved the default fuzzy skin values. It's a nicer surface than the default in my opinion, but it doesn't eliminate the dreaded hull line. This is with the 2mm fillet. To be fair, you have to look for it and then it catches your eye. But it's right a 4mm, where the floor of the box ends, even though there is a fillet starting there. But the fillet does help some compared to the lid where the transition is abrupt. The lid (screwcap) line is a little more pronounced than on the bottom, where there's a fillet.
Dunno, seems to be the best I can get, which is disappointing. It doesn't change the functionality of my pieces, but the lines at the feature boundaries are a disappointment. Seems like a whole lot of fiddling, nerding about, and not much improvement to show for it.