Got into ceramics class

I got into the beginning ceramics class for Watsonville/Aptos/Santa Cruz Adult Education (at Santa Cruz High) for this fall! The online registration for the first session opened at 9 a.m. on August 11, and for the second session at about 9:01 a.m.—by 9:03 a.m., both sessions were full.  The classes themselves start in a couple of weeks (August 29).

I’ve been thinking a little about what projects I want to make this time:

• I have a mold (resin printed at UCSC through BELS) for the little sauce dishes that I discussed in 3-D printed test pot.  I’ll want to test making sauce dishes with that mold and playing with the glazing.
• I plan to design an extruder die for mug handles—probably a two-part die with a rotating upper part to select between different handle cross sections in the lower part.  I’ll probably try to match the handles of some of my favorite mugs, which vary from 18mm to 23mm wide, with different cross sections. I should be able to fit 4–6 different shapes on one die.  I’ll have to print the outer part at UCSC, as my 3D printer is too small for the flange, but I might be able to print the funnel/selector upper part at home, as it would only be about 101 mm in diameter.
• I’ll want to make some mugs to go with the handles—some thrown and some hand-built.
• I might want to 3D print a roller for patterning a slab for hand-built mugs.  I’ve not yet figured out the best way to convert a flat pattern to a cylinder.  I can write a program easily enough to map points, but I’m not sure how best to communicate the pattern to OpenSCAD (or other 3D modeling software that can produce the STL file).  Should I do the 2D-to-3D conversion in OpenSCAD itself?
• I want to try hand throwing a suribachi (a Japanese ceramic mortar with a textured interior). Last Spring I did not succeed at throwing any large bowls, and all my little bowls had very thick clunky walls, so this will be a considerable challenge for me.
• I want to try making some more of the tiny trilobe planters, to see if I can make the feet a bit shorter and put the planters together in a single class period, rather than having to take the extrusions home.  I want to play with some of the other glazes on them also. Some of the planters were a bit wobbly, so I want to work on a way to make them more level (probably more care in cutting the extrusions).
• I may want to 3D-print a soap-dish die for the 4″ square extruder, so I can make soap dishes big enough to be useful.
• I’d like to make some cereal bowls, about 140mm in diameter and 60mm high, with flat bottoms and walls about 4mm thick.

3D-printed test pot

I’m looking ahead to this Fall, when I hope to take the pottery class again.  I was thinking of designing a form for making small sauce dishes.  We have one vintage one (which my wife inherited from her grandmother) that I thought would be fun to make more of. The dish is small—about 80mm across and 23mm high and has a somewhat complex pattern on the inside.

I plan to make a two-part press mold that I can squeeze a slab between to make the pot, but to check whether the design is any good, I first did the design to make a positive model of the pot. I expected the interior design to be difficult, but it turned out to be really easy, while getting the right profile on the outside with roughly constant wall thickness took me much longer.

I made an SVG file of half the cross-section of the bowl, then used “rotate_extrude” in OpenSCAD to get the basic shape.  To get the raised pattern on the inside, I intersected a slightly raised bowl with a set of twisted linear extrusions.

The outside has a number of steps that should become more visible as glaze flows a bit.

The inside has a raised network of curves that I had originally thought would be hard to create, but turned out to be really easy.

My main remaining concern is determining how difficult it will be to get the clay out of the mold intact. Will I need to switch to a 3-part mold (to push the clay out from the bottom of the slump mold)? Will I need to mold it with a flat bottom and trim the pots when they are leather-hard to make the foot? Should I use a mold-release spray (like https://glaserceramics.com/index.php?route=product/product&product_id=2194)? Should I use a powder mold release (like cornstarch)? Or a light coating of oil? How dry does the clay have to get before I can remove it from the mold (most of the advice I’ve seen calls for letting the clay dry to leather hard on mold, but that could take quite a while with a plastic mold)? Should I let the slabs dry a bit before using the molds like stamps?

I can see that I’ll have to do a fair amount of experimenting to get something that works.  I may play around with polymer clay to see what I can get to work there (though it tends to be less sticky than real clay).

3D-printed clay-extruder die

In UCSC’s soon to be fab lab (and an existing one), I talked about two of the fab labs on campus and mentioned that I was planning to try using the DSI studio in the basement of the “Science and Engineering Library” (which no longer has any science or engineering books or journals, so should be called the “Study Space on Science Hill” instead). On Monday, I got certified to use the Ultimaker 3 printers and attempted printing the clay-extruder die I had designed:

The Scott Creek extruder is designed to work with ⅛” aluminum dies, with no allowance for different thickness of dies. So plastic ones have to be made with an ⅛” flange, with the body of the die as a plug that goes into the extruder tube.

I printed the design in PLA with a 0.4mm nozzle and 0.2mm layers, with 4 walls, 20% gyroid infill, and 20% infill overlap.  I chose gyroid infill, because the stresses on the die would be both compressive and bending. I was worried that the 3mm flange might not be strong enough, especially as I expected some stress raising around the inner edge of the ring that holds the die in place.

The die printed fine, with no visible blobbing and only tiny amounts of stringing, easily brushed away.

On Tuesday, I took the die to my ceramics class and tried extruding some clay with it (I had a scrape on one of my fingers and did not want to get my hands wet practicing throwing pots). The die worked just fine and showed no damage from being used—the photo above was taken after the die was used and cleaned. So it seems that the 3mm flange is thick enough not to cause problems (at least for a few uses—I’ve no idea how long the die would last in production use, and I don’t really care). Next week I’ll trim the soap dishes, stamp them on the bottom, and leave them to dry on the greenware shelf.  Trimming should not take too long, so I should have time to try throwing again.

If I design other clay-extruder dies, I think I’ll make the bevel on entrance to the die bigger, so that there is more “wedging” of the clay as it is pushed through the die.  I had intended a wider bevel, but I had a bug in my OpenSCAD code, where I had used a constant “3” instead of the parameter “extend” in one function, and I had not noticed that the bevel was narrower than intended in the final STL file.  Of course, there wasn’t really room on the die for more bevel (unless I made the soap dish even smaller), so perhaps the bug was not such a bad thing.  I’ll have to think about how I could modify the OpenSCAD program to make the bevel large in the middle of the die, but reduce it near the edges, so that the die entrance does not get too close to the sides.

UCSC’s soon to be fab lab (and an existing one)

Yesterday, I took a tour of the space in the basement of Baskin Engineering that is being converted to an “Experiential Learning Facility” (a name only a bureaucrat could love—but at least they are looking for a new name!). The space used to be two machine shops: a professional one that only the lone machinist was ever allowed into, and a student machine shop that was never used, because you had to get someone with a recharge number to pay several hundred dollars for the once-a-year training then $12 an hour to step into the room.

Most of the old machine tools were sold as surplus, because they were too difficult to use for a student space. Some of the more basic metal working tools were kept (a bending brake, a large shear, an arbor press, a Rotex punch).  There is also a small CNC mill and a lathe.  There are some basic woodworking tools and a laser cutter, and some 3D printers will be moved in once they get the next room over (before March, I think).  I believe they will also get some sewing machines, though what sort is far from clear.

The space looks like it could become a fabulous maker space for students, but I suspect that it will not, because of stupid policies by the administration.  They outlined 4 uses for the space: a first-year design course, 1-year group projects (like senior capstones), thematic areas (like the S-lab on sustainability that has moved into much of the space and provided equipment for that portion of the space), and engineering clubs.  The engineering clubs will get permanently (or at least annually) reserved spaces for the club to meet, work on their projects, and store their projects and tools.  The lion’s share of the space is reserved for 4 clubs, which will have to apply for the space, but it is expected that FormulaSlug (car building), SlugBotics (robot building), and Rocket Club (rocket building) will get 3 of the 4 spaces.

Note: what is missing?  There is no provision for someone to come in and use any of the tools unless they are in one of the classes or clubs! You take the freshman design course (which has not been created yet) and learn to use some tools—great!  Now you never get to use those tools again until your senior design course—too bad!  Unless you are interested in one of the 4 things that the 4 clubs are doing, in which case you are set up in style!  Why the administration omitted such a critical part of the facility is a mystery to me.

I urged the few students who were there (interns working on helping create and advertise the space) to get students to start a new Maker Club and apply for one of the club bays.  That way anyone could join the Maker Club and (after getting suitable safety training) use the space and tools! The Maker Club could also provide “super users”, who could help maintain the facility, providing training and safety supervision. It would also be good to open the tool use up to faculty, staff, and emeriti (again, with appropriate training), so that a community can be built that has some continuity from year to year. With the current administration, though, I’m not holding my breath waiting for a sensible outcome.

If the administration gets their heads out of their behinds and figures out how they are going to make the space actually useful to individual students (rather than just instructional space and a clubhouse), then I’d be glad to help out with things like short workshops, 1-unit courses, and even some scheduled supervision of the space.  But I fear that the administration is going to silo it up so that very few students and no faculty or staff have access—repeating the mistake that PBSci made with the old machine shop (though not quite as badly, since a few hundred students will have access, instead of 1 or 2).

This bad management is not an essential part of creating a makerspace at UCSC.  The Digital Scholarship Innovation Studio (DSI) on the lower level of the Science and Engineering Library has a much more open policy—anyone with a ucsc.edu address can take their training (online), do a simple in-person assessment, and use the equipment. Actually, I’m not 100% certain about alumni—they can take the training and sign up for the assessment, but they may need a current ID to actually use the equipment. The answer in the FAQ for “Who is allowed to use DSI equipment?” is “Any UCSC affiliate (students, faculty, and staff) who has completed Library training.”  That is a little ambiguous about affiliates who have retired or graduated.

DSI has 4 Ultimaker 3 (2-nozzle) printers and plan to get 2 Mini Prusa printers with a Mosaic Palette accessory (for 8 colors) set up during Winter quarter. They also have 4 small GlowForge laser cutters (11″×19.5″), but lack the ventilation to cut acrylic—so just cardboard, MDF, and thin plywood (or engraving on some harder materials). Currently you need to use materials provided by DSI, but they don’t have a recharge mechanism: they provide a small amount free to students. They provide PLA filament (the 3mm Ultimaker filament, not the more common 1.75mm filament) and sheets of birch plywood. I imagine that they’ll have to set up a way to charge for materials if they get really popular.

I took the online training for the 3D printer this evening—it is fairly simple, though there are a few bugs in the Canvas course that I pointed out in the feedback form at the end.  I suspect that they’ll get those bugs cleared up soon. I’ve signed up the in-person assessment Monday morning, and I’ll see if they let me use the 3D printer.  If they do, I’ll take the online training for the GlowForge laser cutter and get checked out on that also.  I’ll also find out if there is any role for me to play in their space—I’d be glad to help students learn to use Cura or OpenSCAD—perhaps even FreeCAD, once I’ve learned how to use that myself.

I have something to print that is too big for my little Monoprice Delta Mini: a die for a clay extruder, to fit a 4″ round Scott Creek extruder. Unfortunately, the extruder die design I had to match my broken soap dish will not fit—the biggest dimension is more than the 4″ diameter.  I decided to try scaling the design down, making a soap dish only 80% of the size of the existing one.

The Scott Creek extruder is designed to work with ⅛” aluminum dies, with no allowance for different thickness of dies. So plastic ones have to be made with an ⅛” flange, with the body of the die as a plug that goes into the extruder tube. I think I like the NorthStar extruder design better, but I’m not about to spend $400–500 to get one.

If they let me, I’ll try printing this on Monday (it uses 50g of PLA, for a cost of about $3.33, or about 13 minutes of minimum-wage staff time).