Beer Bottle Master Mold via 3D Printing

April 2024: Version 3 of this method is underway and promises to be much simpler and better than 1 or 2. And no rubber is needed! Stay tuned.

This project is being done to demonstrate the amazing power that 3D printing brings to ceramic slip casting. People are amazed by these beer bottles more than piece from any other project I have done in ceramics.

It is now possible to quickly draw 3D objects on a computer, 3D print block or case molds and have working plaster test molds within a couple of days. The more pieces a mold needs to have the better this system works. It is interesting to note the precision that is possible using this process - and that achieving that precision can be done by simple trial-and-error recreation of test molds. Additionally, a potter can create partial or small-scale molds to prototype and then make full-size rubber masters.

Ceramic beer bottles were made historically. They are a very difficult shape for jiggering, needing to be done in two parts and joined. Thus, many companies even had teams of potters making them by hand. Slip casting using traditional mold-making techniques was never practical compared to the metal molds used in glass forming. That being said, ceramic bottles have some important advantages over glass - these include decoration and customization options, practicality for potters to make, flexibility to retool size and shapes, flexibility in glazes and colors and options for stamping and embossing. Ceramic glazes, especially stoneware glazes, also have the potential to be more durable. So it is easy to see why we are excited at how easy it now is for potters to take advantage of the ceramic process in ways industry cannot.

Version 3 coming: While a case block mold is ideal for a factory situation I am targeting this at potters. I found that the rubber picked up every imperfection of the 3D printed block mold and transferred them to the working molds. More fixup was thus required. And the rubber required reinforcing to produce right angles and perpendiculars. A plaster case mold seems to be better.

This project has long are arduous. I had to make just about every mistake to learn better and better ways of doing things. In the end the best way turned out to be the cheapest one: Using the equipment that I have. My ability to do whatever was needed in 3D design was the single most important key to success.

Related Information

A glass beer bottle with the stopper I want to use

This commercial bottle is 25cm high. The wire mechanism is attached very firmly. I measured it to derive starting dimensions.

These stopper mechanisms are a commodity item, millions are made and a wide range of bottles work with them. They are easy to find oneline and go by a variety of names (e.g. "Grolsch style flip top stoppers", "Swingtop Grolsch style bottle cages", "Porcelain swing top cap").

Making a mini bottle just to demo the concept

PLA is the most common filament used in consumer 3D printers. It has a very low melting point so even hot water can soften it. The PLA printed mold-mold (lower right) has vertical sides and it would be pretty well impossible to remove the plaster mold from it without significant damage to the corners. So I just heated them a little and they peeled off easily. Making these two mold halves confirmed how accurate 3D printers are nowadays, the pieces mate precisely. Notice there are no notches, I feel they are not needed (lining up the outer edges perfectly positions the pieces).

How to draw a mold-mold for slip casting using Fusion 360

Drawing your objects in CAD software is the most difficult step in leveraging 3D printing for slip-casting mold making and production. In this 11 minute step-by-step video we will draw a mold-mold, using Fusion 360, that can be 3D printed. Plaster can be poured into it without even a need for mold soap. It is the best fitting and most dimensionally accurate mold we have ever made. This is well within the reach of almost any potter.

Re-calibrating the fit for stopper wiring assembly

In Fusion 360 I sliced off the top of the bottle and formed a small box around it to be able to quickly 3D print a test mold of just the upper neck. Two of these mold-molds printed in about 3 hours, the next morning I cast the plaster molds. After drying on top of a firing kiln overnight they were ready to use the next day. Making a hole in the middle of the wire mounts was easy at the leather hard stage. The wire is 2.8mm dia, a 9/64 drill bit is 3.5mm. Simply twisting it to create a hole in the center of the pads takes seconds. Firing these to cone 6 will enables testing the fit for the swing assembly and seeing the amount of shrinkage that happens.

Trying the stopper in a fired test of the bottle neck

The centre one is M370 + 10% raw umber - leather hard out of mold. The other two are fired at cone 6. Comparing the lengths of these two enables calculating the total shrinkage (drying and firing). I can use that to adjust the parameters in the drawing. The 9/64" holes made at leather hard are big enough for the wire but too snug a fit, they are breaking (as you can see on the right). The pad also needs to be bigger, 8x8 mm will be the next test. The hole being 21mm down from the rim is about right, the mechanism is locking well.

Do it again: Dissect a portion of the mold in Fusion 360

Here is version 2.0 of the neck (to test stopper fit). The link below links to a step-by-step in Fusion 360 of how to save a temporary copy of the mold drawing and modify it to isolate just the top portion of the neck.

Beer bottle calibration mold demos some casting process improvements

Plaster molds held together without straps

This is another example of the flexibility potters have compared to manufacturers. These 3D-printed gizmos are stuck on to hold the mold halves together. The casting slip itself adheres them. Dipping the flat surfaces and attaching them takes seconds. The 3D printed pouring spout is likewise attached using the slip (it also helps hold the mold halves together). Another feature: There are no notches (the halves were poured into disposable 3D printed PLA masters - and mate perfectly). Initial use of a rubber band to hold them together was not ideal because realignment of the halves damaged the inside corners. By using this method the mold halves can be aligned accurately. These three things are great for potters. They simplify mold design and production, reduce mold size, improve the fit of parts and simplify pouring, demolding and cleanup,

Printing my own version 1 block mold in two pieces

Of course, this is far too large to print in one piece on my printer so I sliced it in two and added tabs to clamp the halves together. Notice the size rails are part of the print. The 3D rendered version was, of course, smooth but there is quite a bit of stair-stepping on the 3D printed surface, I did not worry about smoothing it and it did not prevent casting two plaster molds. No mold soap was even needed, the plaster molds came out using compressed air. The long side rails did require some stabilization (they were flexing with the weight of the plaster).

Slip cast leather-hard full-sized beer bottle

This is a black buring porcelain (it has 10% raw umber), the L4768D recipe (I also use a red burning one, the L4558A recipe). As a starting point I use water/Darvan proptions outlined in the "Casting Recipe" section of the M370 data sheet. This piece is leather hard, just out of the mold. By the time it is fired it will be 10% smaller and will match the glass one on the right. The pads are positioned firmly and correctly for the swing-top stoppers. These are presenting few problems, I am making bottles by the dozen (from multiple molds). The narrow neck causes issues for fast-casting clays if drained too quickly - inverted draining creates suction that can pull the soft walls away from the plaster. I made a large 3D printed pour spout to provide a reservoir to accommodate the fact that the slurry level drops during casting, that turned out to be a double benefit because it acting as a gauge of when the drain.

Finished cast v1 stoneware beer bottles

The center bottle is a standard glass one, the other two are ceramic, cast out of the version 1 plaster mold. The stopper fits perfectly. The clay is Plainsman M370 + 10% raw umber, it fires black. The glaze is GA6-B. They were fired using the C6DHSC firing schedule. The slightly larger size will enable inserts at the bases to inlay a logo or other info. These bottles are a testament to how 3D printing and 3D design now make it possible for even casual potters to make pieces never before practical or even possible.

Version 2 ceramic beer bottle block mold

Casting a rubber case mold for the beer bottle

This time I printed the block mold, rather than the case mold, in six pieces on my consumer 3D printer.
Top: I printed the two halves upright (creating them in the slicer rather than Fusion 360). Because the print lines run concentric the quality is so much better than the previous version printed flat. The ribbing inside made the halves strong so they did not go out of shape when filled with plaster (to give them weight).
Second: The mold halves were simply laid against each other - they mated perfectly (and stayed in place because they are full of plaster). The four rails were then clamped in place.
Third: The PLA was soaped (using Murphy's Oil Soap) and rubber poured in (Smooth-On PMC-746). The next day it easily pulled out.
Fourth: The finished rubber case mold. The sides are pretty flabby so I make them rigid using the four rails (placed upside down).
Right: Using a plaster mold created from this rubber case mold I slip-casted a bottle using my L4768D recipe, glazed it with GA6-B and fired it at cone 6.

Yikes - Version 3 ceramic beer bottle drawing mold obsoletes previous

Something I love about 3D parametric CAD is how a drawing can evolve to be both simpler and better. While my version 2 drawing had about 20 steps, this one is down to nine. No more ribs, no offsets or mirrors in the sketches, no double-revolves and no seams across the mount ads. Printing will be dramatically faster. The quality of the side rails is now the key factor in final mold accuracy (these stabilize it while filling with plaster from the back).

I now draw the simplest repeatable shape: A one-quarter slice. Step 5 cuts the bottle profile from the solid block extruded in step 4. The preceding steps were a sketch of the bottle and block outline and a plane and sketch for the pad. Steps 6 and 7 are the extrusion and corner rounding of the pad cutout (near the rim). The last two steps mirror this quarter upward to create the block and then shell it to hollow the back side.

The drawing is now fully parametrically resizable, I have taken advantage of that to make a stubby bottle test. Neck spline points are now spaced vertically as a percentage of the neck height parameter - set at "70" here. The body and neck heights are separately set now so the full height is now a driven dimension - it is 146 here.

Underside shelled at 0.8mm

The quarter has been mirrored and then shelled, not at the top life the last one, but at the back. This is flimsy. And that is an advantage because it means the side rails will be able to impose perfect right angles and perpendicularity.

If you have this printed by someone else they will advise you against this. Don’t listen.

Links

Media	Make a precision plaster mold for slip casting using Fusion 360 and 3D Printing In 11 minutes you will learn a new way to make complex plaster molds for slip casting - faster and more precise than ever before. Anyone can do this.
Media	3D Print a Test of the Beer Bottle Neck In 4 minutes you will learn how to modify a copy of the existing drawing to print only a narrower part of the top 8cm
Media	Slip cast a stoneware beer bottle I will mix the slurry, assemble the mold, attach the 3D-printed pour spot, pour in the slip, pour it out, remove the spout, trim the lip, split the mold, extract the bottle and drill the holes for the swing-top stoppers.
Projects	Medalta Ball Pitcher Slip Casting Mold via 3D Printing

By Tony Hansen
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