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3D printing problems

3D design and printing for mold making in ceramics bring exciting new capabilities. Awareness of the issues and knowing how to mitigate each is a must. 3D is resetting all fabrication industries and engineers are solving every problem, you can too.

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Poor plaster release from 3D printed mug handle case molds

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My objective was to continue skipping the making of a rubber case mold and 3D print them directly. Since 3D printed surfaces naturally part well from plaster and the artifacts, although visible, do not show on the final fired pieces, I even wanted to do this whole process without any sanding or oiling. However, despite printing a dozen or more variations, carefully controlling plaster/water ratios and waiting/mixing the recommended time periods, few good plaster molds were extracted without corner-breaking. Even painting the inner surface, oiling over it and beveling corners did resolve this issues. It seems that a combination of the printing artifacts, sharp corners, the handle perpendicular (because of the oval cross-section) and the inside negative shape all enabled the plaster to get a very firm grip on the PLA print. Although I could have resorted to a heat gun to soften the PLA material enough to pull it away I relented and decided to switch to making a block mold (for rubber) rather than a case mold (for plaster).

Warping during a large print - one solution is multiple pieces

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I am attempting to 3D print a shell for making a rubber block mold (the base of a Medalta ball pitcher). This is almost at the limit of what will fit on the print-bed. It would take 30 hours. But at about 10 hours it did this: All four outer corners warped upwards. I have a larger printer but it will do the same thing! What is the solution? Cut it up into smaller pieces and print each of them at the best orientation (bottom right), this saves significant printing time and achieves better quality. For this piece, the inside surface on the center section is most important, printing it upright with printed support took about 4 hours. All the other pieces print in about 1 hour each. Tape (either masking or MicroPore) can be used effectively to hold everything together for super-gluing or epoxy. Much of the tape can be left in place during the pour. The rubber form has thin 1cm walls, but these are supported by side-rails when plaster is poured.

Infill and support issues with 3D PLA prints

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Top: The left one has a rectilinear fill, the right a square grid fill. Notice the fill on the left has buckled part way up - this piece is too tall for that type. While the grid fill on the right is far more stable, it is not as easily removed (although it can stay in place here).
Middle: The piece on the right printed in half the time because the only fill needed is at the bottom. The fill is rectilinear and easily removed - it affects the smoothness of the surfaces but they are not a finished ones so it does not matter. However that method is risky, notice the failed print on the lower right - upward pull of the flat section pulled it away. This happened twice more so I chalked up the one success to luck.
Bottom: Took about 16 hours. Like others, the grid of printed support out past the edge - that part has to be cut away with a sharp blade knife to enable mating with the other pieces.

Assorted problems with 3D printing PLA molds

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I am 3D printing a block mold - rubber will be poured into it to make a case mold for beer.bottles. It is an amazing process but there are still issues to deal with:
-Stringing (top left). This usually happens when the nozzle is running too hot. This new batch of filament needs a slightly lower temperature, so I adjusted from 215 to 207.
-Size constraints: This is too big to print as one mold so it has to be done in multiple sections (two mains, two end-caps). Pieces fit precisely and can be glued or taped.
-Experience shows where glue, tape or special brackets (e.g. corners lower left) are needed.
-Special tools must be made (lower left is a clip-insertion tool).
-Corner lifting: Happens mid-print (the large thin pads on the lower right are to prevent that).
-Pressure bowing: The stabilizer bars spanning the two mid-pieces (lower left) and the triangular lip (upper right) keep that edge straight despite pressure from the liquid rubber inside.

Warping of PLA under heat of plaster set

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When cutting a larger object into multiple pieces it is important to have an assembly plan.
In this case I have glued at the pieces together (and filled and sanded the joins) and plan to fill the two on the left with plaster to make them rigid.
I should have 3D printed inserts to cap these ends instead. The printer can produce a very precise fit and they can be super-glued in.

Glue-sticking the 3D printer bed for better adhesion

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Many objects are unprintable due to plate adhesion issues. Some objects print successfully when done alone, but doing many of simultaneously can fail when one releases mid-print. In these cases, objects can be guaranteed to stick using a hot bed PVP glue stick like this one from Amazon (even a paper glue stick can be used, it sticks pieces even better but does not apply as evenly).
-When applied to a heated bed using long strokes it goes on evenly and dries hard.
-It can be washed off and replaced after several prints.
-The glued surface sticks pieces very well, this enables reducing the area of contact and lightening objects (giving success even when the slicer issues a "low bed adhesion" print stability warning. For example, these spacers and clips would normally release from an unglued plate.
-Objects having a large contact surface may not be removable without damaging them or the plate. Or, pliers may be needed to pull objects off (flat-bottomed pieces giving the most difficulty).
-The ten clips (right) are quite delicate, having 0.8mm walls and 0.4mm thickness base flanges. When adhesion is too great these can be damaged when removed with pliers, when not enough they release during printing. We adjust for this by increasing flange diameter when adhesion is too low and reducing it when it is too high.

3D-printing artifacts on a slip cast M370C bottle. A problem?

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Here is why the stair-casing artifacts are not the problem many people think. These are stonewares fired at cone 6 oxidation. The dark one is M370C with 10% added raw umber. The other is M370C. Both are glazed using GA6-B Alberta Slip amber transparent. The wood-grain texture on the right is an artifact of 3D-printing - the case mold was printed flat rather than upright. Strangely, that is the bottle people want! But the production prototype bottle is the one on the left and the stair casing is barely visible. Additionally, these are prototypes, the production molds would either be made by printing the model upright or by casting a plaster model of a bottle half, smoothing and soaping it, attaching it to a clamping baseplate and then setting up 3D printed railing around it.

Why 3D design and printing is a better way to make slip casting molds

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I dread the traditional mold making process, the mess, all the supplies and tools involved. I am a potter, I make functional ceramics. I am not a mold-maker, but 3D design and printing have put it within my reach. This way more fun! There is no stopping this, it’s the future.
-I spend most time on design, pouring the plaster or rubber takes minutes.
-Many fewer tools and supplies are needed, the process is less messy, as easy as downloading a file, printing it and pouring in plaster - this is doable in my kitchen!
-Sanding of flat mating faces is possible (for better seams than I've ever had). This is because natches can be added later (using embeds).
-I can make my own natches and interlock schemes.
-No spare is needed, the 3D-printed pour spouts work better.
-The range of shapes seems limitless. Especially because designs can be split up into pieces, each printed in optimal orientation (and glued together).
-I make molds through multiple design-print iterations. 3D makes do-overs or changes in design as easy as a reprint and plaster pour. So, I can make a mold just to test an idea!

3D printing artifacts on a bowl model. Are these a problem?

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3D printing is resetting and revolutionizing all fabrication industries. It has taken hold because it brings exciting new capabilities we never had before, especially in ceramics. Each disadvantage is being addressed and solved. This stair-casing, or more correctly, "printing artifacts", are often cited as a reason not to adopt 3D. But these are not an issue here. First, most of the surface on this case mold is not exposed on the final piece. Second, near vertical and fully horizontal printed surfaces, such as the shell around the outside and the spacer ring, don't have artifacts. Third, this bowl model is not 3D printed, it is plaster that was poured into a 3D printed shell. Before use, this will be stuck down onto a potter's wheel and tooled smooth. It is then attached to a clamping baseplate and the 3D printed railing clamped around it.

3D printer printer poop

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This is not technically printer poop (waste generated when 3D printers change filament color), it is just waste. This is an important problem in 3D printing. Much of this is a result of mistakes that I will not make again. I want to absolutely minimize waste and filament consumption. First, an editorial: 3D Model sites are an obstacle to DIY and environmental responsibility. Their FAQs make no mention of any earth-impacts of printing plastic. They ignore the issues of printer poop, model weight, infill and support waste, excessive print times and the likelihood of print failure on many models. They are uncurated and foster passive consumption and the print-and-dispose culture. And they foster the STL file format so that wasteful models are not easily edited. We make models that print quickly and are as light and reusable as possible, ones that you open in a CAD package and edit yourself, ones with a design history and support pages, projects, videos, etc.

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