Help … please
Hello
you could begin by searching a bit on internet. With keyword as “clay printing” Here I added “site:https://discourse.mcneel.com” in order to just have images from this forum.
Also
read that
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You are right one seems to have 2 or 3 or 4 paths per slice and the other just one.
Quan Li is correct - that is a seam line. The vase is NOT printed in “vase mode”, which is a mode in which the printer nozzle moves in a single continuous spiral path all the way from the bottom to the top. This produces a print that has no seam, but is only one nozzle-diameter thick. For regular 3D printers a result like this is quite fragile, which is why vase mode is seldom used.
This vase was printed in the standard 3D prier mode, which is a series of horizontal loops (called layers) stacked on top of each other. A vertical seam line happens when the printer nozzle moves vertically from the end of one layer to the start of the next. A standard method of eliminating seams is to randomize the start position of each layer, but this takes more print time and can leave tiny blobs at the start/end of each layer.
This vase is made from circular layers which have been tweaked to add an additional number of what looks like small elliptical loops at certain points around the layer. These points are rotated slightly for each layer as the vase is built up. What’s not clear to me is why these little elliptical loops don’t droop down, but instead stick out. My guess is that the consistency of the clay is stiff enough to keep the elliptical loops in place as they are printed.
The key to this print is the way the elliptical loops were added to the basic circle that forms each layer. Someone developed some very clever code to do that.
exactly 
and also the thing that, while when you are printing over a previous layer of clay, the extruded clay is forced to “splat” between the previous layer on the bottom and the moving extruder on top
as you start moving the path of the extruder even slightly outside the path of the previous layer, the extruded clay doesn’t find a solid bed on which it can splat, so it looks like it “expands” in the only possible direction (like in these areas)
it looks from the pictures that there is a single filling “standard” layer between those tentacles (that I use to call “slabbrini” in italian)
layer section would look something like this:
-------------------------------------------------
-oo–oo—oo—oo—oo—oo—oo—oo-
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—oo—oo—oo—oo—oo—oo—oo----
-------------------------------------------------
it’s importanto to put a “normal fill” layer in between the layers with protusions, because that pass will sort of fill the gaps created by the absence of material due to the protusions on the previous layer
if you see this pattern that flows regularly (most visible on the inside) it usually means the number of divisions used to calculate how many “tentacles” you get is constant for all layers
and the thing that some of these tentacles looks like going almost vertically, in my opinion is not “by design”, in the sense that the code ran by the machine was not changing Z coordinate while printing those
it’s just the result of having some of those on the bottom, over which the next ones are printed, they just happen to act as a scaffolding for the new ones being printed, and the final result may change a lot depending on how much water is mixed with clay, feed, extruder speed ecc etc
as last thing, it’s always more beautiful if you can avoid having printing seams
in clay -if the shape allows for that- printing with a spiral path always gives a very nice feeling
for this last vase it would be pretty easy to “hide” the seam between those tentacles, and I bet no one would ever see where the old path finished and the new one started…
but for the first image in this topic… welll… I would have avoided that 
believe me, it’s 100 times easier than what it seems 
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Good catch Inno - I hadn’t looked at the images closely enough to notice that. But I agree - it does look like there are alternating layers: one thin one and one with tentacles. (Actually a “tentacle” is a single flexible arm that is not connected to anything, i. e., it is not a closed curve. How about “protuberance” for these small loops?)
Oh really? It looks to me like there’s a pretty sophisticated technique for switching from a plain circle (1) to the start of some protuberances (2) to fully formed ones (3) and then back to a plain circle. Maybe this is done by reducing the nozzle speed, slowly increasing the material flow rate to make the protuberances, and then reversing that to get back to a plain circle. That’s pretty tricky business and I am not aware of any slicer that has anything like that capability.
MIT has a printer that uses molten glass - a bowl like this would be a great glass print if they can do it. I’ll see if someone in the glass lab there thinks making one is possible.
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Slicers are mostly needed for filling strategies, support, perimeters offset, retraction, overhang etc…
Here, most probably, it was not used a normal/common slicer, but a script or a specifically developed sliicer for this purpose.
For this result it is almost a vase mode: just the outer perimeter converted into a polyline… you transform it into a sequence of XYZE rows and that’s it.
On the “bulge” parts, i would move the extruder head slightly outside (to be sure the bulge fall outside and not inside) and increase the flow E , as you said…
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I know, it was the very same headache the very first time I approached the topic
the big “difference” I felt between printing Clay and Plastic, is that with Clay the extruder -usually- squeezes the clay snake that is being extruded
this way the layer you are printing usually becomes larger in size than the diameter of the nozzle, because the material “has to go somewhere” → you decide the height of each layer in such a way the extruder itself becomes also a “scraper” that splats the clay while it goes, knowing that the level of the previous layer was exactly the trajectory of the previous pass, because the nozzle also splat that
[edit: that is also because Clay is something of a more “stubborn” material than molten plastic, you need to force it to weld and settle on the previous layer so you need to apply some force and shared surface, and the splat helps for all of that]
I have this ancient video where the splat is very visible
when you get to this point, you’ll see that the material that is being extruded sort of “pushes” a little bit on the previous layer, that deforms a bit and has a sort of rubber-gummy-pushback effect (the first time I saw that with my eyes I was mind blown, as the printing of a layer somehow visibly deforms the previous ones for a split second, and the print looks “alive”)
and if you hover the extruder mid-air, it will just extrude perfect vertical same-diameter-as-the-nozzle snakes of clay of course
so the combination of these two things, that the top of the nozzle “scrapes” the clay, and at the same time the extruded clay doesn’t find a bottom surface that gives enough resistance to be squeezed in-between, produce by itself these kind of swellings here
a planar X/Y movement of the extruder, that goes slightly off-path than the previous layer is already enough to create evident surface patterns
then, the more you move off-path, you start printing over the void, there’s no bottom layer anymore to hold and squeeze in-between the clay being extruded, so it becomes the very same shape of the nozzle: a perfect snake
regarding slicers, creating G-code that you can use to 3D print Clay is really easy in GH, 100% feasible using just a small portion of vanilla components!
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Since all my experience has been with standard FDM plastic printers your description of how clay printers work makes sense. I’ve seen only a few videos of clay printers, but quite a few more of concrete printers making walls for houses and other similar structures. Those are even more complex - the ones with filleted rectangular nozzle openings rotate the nozzle when it comes to a corner. Needless to say this would add even more complexity to the required GCode.
I continue waiting for consumer oriented 3D printers to make the transition from 2.5D to true 3D, but I doubt this will happen anytime soon. As much as I admire what clay printers are doing now I stay happy printing things like this:
(Does that look famiiar?)
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Just thought I’d add this tid bit to the convo. Changing the nozzle orientation has a large effect on the outcome. In this video I specifically aim the nozzle at the previous curve instead of directly downward vertically out of the nozzle.
Inno, very well articulated on the process and its parameters.
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Very interesting Joseph, any chance you can show how the nozzle looks while it’s printing, or what the printer looks like?
hopefully in the coming weeks we are going to try printing our “imitation shape” of the awesome works of Alessandro Zomparelli and Bruno Demasi aka Clay Code Clay Code
[image from Clay Code Facebook page]
still work in progress, need to refine several things in the drawing, but everything (shape, toolpath gcode) is done through vanilla GH components only
this book is a solid and very well-structured starting point (at least it was for me ) https://www.amazon.it/gp/product/B086Y7CLLC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
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