Ironing on every or/and N layers

[megablue]

I would like to request Ironing not being exclusive to top-most layer but ob every layer or selected interval. The idea being, ironing fills the microvoids between lines, ironing on every layer will make the parts super strong since the microvoids between extrusion lines are basically eliminated/reduced and bond together better.

[ChrisTerBeke]

Thanks for re-opening here :)

[JonasLehmke]

I would love to have this feature to do more transparent prints!

[e-dervieux]

This feature would also make sense to print gas- (or at least water-) tight containers, and I would love to see it implemented as well ! Any update on this?

[Ghostkeeper]

Currently this is, I think, a case where the user thinks they want this but actually doesn't. I've tried printing with ironing every layer (by disabling a check in CuraEngine) and the result is terrible, producing weaker prints with more air gaps than when not ironing, due to massive overextrusion. That's why this is not implemented at the moment. It'd need more research.

[e-dervieux]

@Ghostkeeper, indeed, the extrusion setting should probbaly be tuned and the fan setting as well. I recently stumble onto this paper : https://www.mdpi.com/2073-4360/11/9/1487/htm and as you can see on Figure 11 for instance there is some significant air gaps inside the structure. (You may also have a look at this )

I guess the idea of ironing at each layer may be a solution to this porous structure, and may as well reduce anisotropy (and improve transparency in case of transparent prints). But this might not be the solution to simply iron at all layers indeed.

By the way, if you have a blog / website where you posted these tries of yours, or some experimentation results along with the parameters that you used, I would be more than happy to have a look at it!

EDIT: apparently, those guys managed to 3D print sealed ABS vessels. But their printing settings are not that detailed... Maybe ABS prints are less porous that PLA ones? In addition, they did not give any SEM pictures of their prints. Alternatively this guy also seems to have found something–without ironing–but I did not try his parameters.

[nubnubbud]

Currently this is, I think, a case where the user thinks they want this but actually doesn't. I've tried printing with ironing every layer (by disabling a check in CuraEngine) and the result is terrible, producing weaker prints with more air gaps than when not ironing, due to massive overextrusion. That's why this is not implemented at the moment. It'd need more research. @Ghostkeeper

as I said in a previous study, I don't actually think overextrusion is necessary for this. just proper ironing technique and proper mid-print heat treatment using the nozzle. a little overextrusion definitely helps, but you can get most of the way there with only slight differences.

also, because you can set the number of top surface skin layers, and the ironing feature specifically says "irons top surface" I would consider it a difference in expected vs actual functionality, but I don't wanna be semantic and why limit users for some arbitrary reason? if we get ironing every layer like all the other slicers, we shouldn't need it to be a hack.

though in slic3r it's a hack, they DID implement it as a bespoke shape for infill https://github.com/supermerill/SuperSlicer/issues/38 however it still needs some work as it doesn't work with concentric infill, doesn't iron the skin, and you can't set ironing density like in Cura

indeed, the extrusion setting should ... they did not give any SEM pictures of their prints. Alternatively this guy also seems to have found something–without ironing–but I did not try his parameters. @mranvick, ironing can definitely produce these sorts of results, but I would iron at least 2mm thick walls for it. your biggest issue will be keeping your nozzle going over it multiple extra times/layer.

I'm regularly printing things mostly clear now, but it's a crap-shoot if I've calibrated any print just right, as it's completely dependent on the shape of the model, without slicer compatibility. You can see in the slic3r post above that given various settings, it's definitely possible, and works fine and reliably, given various concessions! https://community.ultimaker.com/topic/26593-please-include-an-iron-every-layer-option-for-clearer-prints/ was my first attempt, in my first week of PETG several year back, with hand-made ironing gcode that proved ironing was helping.

https://user-images.githubusercontent.com/7472816/139210376-0115ff10-a162-48b8-80c7-8e9178ecf05d.mp4 this print is simply what comes out of supermerril's prusa fork which has it (maybe the main one does too now) set to iron every layer. it's a hack and ironing doesn't include perimeters and only works with zigzag- so sides will have a consistent .4mm knurling on them, but the lightplay is fantastic inside.

https://user-images.githubusercontent.com/7472816/139211309-bce76ea6-2ed1-4cd7-a829-499afcf3112a.mp4 This is a special one. I was able to futz with Cura enough to get it to spend extra time on every printable area. I was even able to make sure the base of the statuette was opaque while the dragon was clear by varying printing and fan speeds! of course, this only works with certain models of certain shapes and sizes.

ironing every layer would just make it easier to do with any model. it still won't be the easiest, but its limits will become a material issue more than a software issue, and that's how it should be. You get the material to do what you need.

[nubnubbud]

@mranvick

edit turned post to make sure you see it: I actually have had some luck with printing clear stuff without ironing! They always, however, have a tapering profile, which led me to a new conclusion altogether. Notice how in those tests, all the layers are ALWAYS laid, top-to-top. what if there was a protocol to lay down lines between the ones from the previous layer? I use concentric in all the tests that work, so a shrinking model from layer to layer would also give such results. They would naturally fill in the gaps, and with a wide nozzle and small layer size, we could likely see any gaps disappear completely, as cooling air can shrink them if pockets exist by pulling the plastic in as it shrinks.

This should be readily possible in the new arachne engine I'd imagine, as halving the width of every other outer perimeter would do the job... at least for concentric. if it was an option like "optimize paths for solid prints" it would indeed need some algorithm to trace the previous layer's internal lines with an offset, and perimeters with the aforementioned "alternating half width outer" every other layer. even a post processing preset that "change setting every even layer" would be able to manage it, if a hack is appropriate for testing.

[e-dervieux]

@nubnubbud

Well thank you for your detailed answers, though I think they may benefit from schematics to clarify what has been done and what your proposals are (just a suggestion, no offense meant, but I had to re-read them a couple of times to grasp their meaning).

If I got it right (please correct me if it's not the case), what you're suggesting in your last comment is:

• a 100% infill
• a concentric layer pattern
• a slight expansion / compression of the layer patterns from one layer to the next, in a fashion similar to what is already done by Cura with the "Alternate Extra Wall" to catch the infill with an extra wall. But in your suggestion it would be one layer that is "caught" by the next one by positioning the layers in quincunx.
• the latter expansion / compression should be accompanied by a reduction in layer height so that the layers better git with one another according to the quincunx scheme.

Seems interesting. I would love to see SEM / microscope pictures of your prints to see their inner structure. Although I think it will be difficult to cut a slice thin enough to be placed on a microscope slide if you have one... I would be interesting to compare the porosity you get with that reported by the authors mentioned in my previous post.

Also, I am mainly interested in the gas-tightness rather than in the transparency of prints. I do not know whether you had the chance to test this as well?

[nubnubbud]

@mranvick

well, it's still all experimental at this point in time. as it stands, even testing if something would help requires a significant amount of work for programming and refining, and as is the case with things like adhesion, there are probably multiple ways to produce satisfying results.

When it comes to airtightness, you can get what you want from significantly thick walls. if you're willing to put gaps inside the walls, and include surface ribbing of the right shape- it should work fine, unless you want zero leakage. in that case good luck with most any plastic polymer.

I'm out of a microscope, but those images I took were simply through an old lens-in-tube microscope from the 60's or earlier. You just shine a light from the bottom, and focus just beneath the surface. if the specimen is clear enough to warrant study, it shouldn't matter how thick it is~... and just to note, those image rulers are in micrometers-crystallization of the brightest looking ones are almost 100% and visible porosity is at almost 0 at that scale. in this image, the small imperfections are little gaps left over from sanding. (just below the 40 mark is a gash from a large grain from a 100 grit piece of sandpaper). While there is an occasional bubble or spot of dust, as far as I could tell, it's completely solid to gasses, unless they can invade the crystalline material itself, of course. I feel though we are looking for different things, we can both achieve them through more crystalline prints. clarity = purity and lack of gaps, therefore in this case, clarity can be a test for airtightness as well... supposing the part is thick enough to actually have the right qualities and structural needs as a pressure vessel. (I have luck filling pressurized enclosures with balloons. not only does the balloon keep it airtight, but make dangerous catastrophic failure via explosion far less likely!)

• a slight expansion / compression of the layer patterns from one layer to the next, in a fashion similar to what is already done by Cura with the "Alternate Extra Wall" to catch the infill with an extra wall. But in your suggestion it would be one layer that is "caught" by the next one by positioning the layers in quincunx.

yes! this is exactly what I mean, but note that it's liquid and lightly pressurized the very moment it's laid down... so this would be more accurate. There will still be gaps, though, so it's not a perfect solution.

• a concentric layer pattern

actually, if you look closely at my tests, you can see the best results were from rectilinear with no perimeters! no clue why, but from what I can tell, it might be that the open ends of the lines allow the air to be pushed out by a piece of plastic, and be replaced like in the drawing above, basically filling it in... but there's also no reason that wouldn't happen with concentric I can tell, so my only theory is shaky at best.

we have to remember though that any pressure in the system is negligible. it only represents flow and force, but the actual material is still not in a compressible state, disallowing such physics for the most part. bargain bin PETG, what I use, is sticky and highly viscous. I've never tried, but it's likely I could easily make PLA clear at this point. it might be that we simply can't avoid the overextrusion method, but I think there's always a way around it. Our ideal here is reducing the need for overextrusion to 0%

[Ghostkeeper]

edit turned post to make sure you see it: I actually have had some luck with printing clear stuff without ironing!

The best results I've had with transparent prints have always been without ironing. Key is to get the material to melt properly into all the crevices, not having any flow changes (e.g. by having both walls and skin) and sanding/polishing well. Ironing adds new air pockets when it puts another "layer" on top (even if that layer is just dragged material from previously printed lines)

Notice how in those tests, all the layers are ALWAYS laid, top-to-top. what if there was a protocol to lay down lines between the ones from the previous layer? I use concentric in all the tests that work, so a shrinking model from layer to layer would also give such results. They would naturally fill in the gaps, and with a wide nozzle and small layer size, we could likely see any gaps disappear completely, as cooling air can shrink them if pockets exist by pulling the plastic in as it shrinks.

Staggering linear patterns improves strength, too, but it's better to keep the focus in this thread to ironing multiple layers instead of just the top one. I don't think this has anything to do with Arachne either.

[nubnubbud]

Staggering linear patterns improves strength, too, but it's better to keep the focus in this thread to ironing multiple layers instead of just the top one. I don't think this has anything to do with Arachne either.

I agree, but do note that clear prints both allow you to see gaps and have no internal porosity, which is central to the theme here, as a clear print MUST ALSO "fill the micro-voids between lines", which was his primary interest. Maybe we should simply start a thread on clear/solid/nonporous printing research,

back on subject-! The only way I could imagine doing this with ironing correctly, now, would be a combination of quincunx layering and slight overextrusion with a particular nozzle geometry: I have experience accidentally raising the bed, and causing ridges to form from one line getting mashed against the side of the previous. If the nozzle had a thin tip and allowed this more readily, then ironed to cause it, you could theoretically put ridges for the next layer lines to rest in, eliminating the gaps between lines. but even then, it's not too different from normal overextrusion: it could feasibly done more accurately without ironing (there's an upper and lower limit to accurate extrusion speeds, I've found) is the primary issue here. The only thing I have been able to think of, that ironing could do but other passes could not, is annealing/stress relief, or affect crystallization, which WOULD affect porosity.

[fvrmr]

We are constantly working on making Ultimaker Cura better. Our community is a big part of that by requesting new features and reporting bugs.

To be able to focus on the most requested and needed features and bug fixes from our community and from Ultimaker, we have decided to remove this bug from our backlog. We believe we will not work on this anytime soon and will therefore defer this issue.

Since Cura is open source, you or anyone else is more than welcome to work on this issue and create a pull request yourself.