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The bottle should be doing the talking! Glass bottles are just a container, ceramic bottles elevate beer, they bring sustainability and style to beer drinking. Ceramic bottles bring local craftsmen to your beer experience.
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").
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).
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
I flush the edges around the mating surfaces, that automatically lines up the inner sections. This is easy to do so mold natches are not required. This clay body, an M370C test, is made by substituting Opticast kaolin and KT#1-4 ball clay, materials intended for use in casting slips. The slip only needs to stay in the mold for about 10-15 minutes to get a good thickness. Within ten minutes after pour out the mold splits and the bottle releases.
Slip only needed about 12 minutes in the mold. Within ten minutes I can extract the piece. I am using a new recipe from M370C that uses Opticast Kaolin and KT#1-4 ball clay.
These 3D printed mold slide into side rails for each pouring of plaster to make pieces of a working mold. The bottom piece eliminates the seam across the base (characteristic of two-piece molds normally used for this type of item). And it enables putting embossed logos on the base. The holes enable mounting embeds that fit flush with the plaster surface - making it possible to sand the mating surfaces flat before gluing the natches into the embeds. This is so cool I can't stop picking up the pieces and assembling them to try. The custom side rails, their precise fit and simple plaster pouring process make it so easy I can do this in my wife's kitchen. And she doesn't mind! Want to hear any other lies?
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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. |
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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
A project to make a reproduction of a Medalta Potteries piece that was done during the 1940s. This is the smallest of the three sizes they made. |
Projects |
Nursery plant pot mold via 3D printing
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Glossary |
3D Design
3D Design software has revolutionized traditional ceramic manufacturing, now it is accessible to hobbyists and potters. |
Typecodes |
Mold making using 3D printing
An ordinary consumer 3D printer has many exciting possibilities for making many types of molds, it is a place where people having both artistic and mechanical abilities can get a double the dopamine! |
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