Gas station without pumps

2023 February 24

Monogram stamps

Filed under: Uncategorized — gasstationwithoutpumps @ 16:11
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In addition to the extruder dies that I mentioned for soap dishes, I’ve 3D printed a few other tools for my ceramics class:

I printed some stamps for marking the bottoms of the pots. The large stamp is 17mm in diameter, the NS stamp is 15mm, and the small one is 10mm. The small one was printed on an Ultimaker 3 at UCSC, because my Monoprice Delta Mini could not really cope with the fine detail. The “NS” stamp is for “night school”, as we are required to put an NS on every pot to distinguish ours from the high-school students.

Here is a mirror-image of the large stamp to show my KJK monogram. This is the only stamp with a rectangular base—all the rest have a trapezoidal base, so that the top is easily determined (the narrow end of the trapezoid).

I also printed some 6mm thick sticks on the Ultimaker 3, for controlling the thickness of clay that I roll out. The printing on the Ultimaker 3 was not very good—perhaps because the PLA filament was not the Ultimaker brand and may have been a bit undersized. The sticks were printed diagonally on the bed of the printer to make them 25cm long, but the ends show a little warping—I suspect that the build plate was a little too cool in the corner, though it may just have been insufficient adhesion.

I printed three of the NS stamps on my home printer and gave two of them to the instructor for the classes to use. I also offered to make simple stamps for anyone in the class. One person gave me a scrap of paper with her monogram written on it with a pen several times—I scanned the paper, selected the best-looking of the copies, and cleaned it up (making the stroke width nearly constant) with Photoshop elements. I then used Inkscape to convert to SVG format (doing a little more smoothing and adjusting of the thickness of the lines). I used OpenSCAD to scale, mirror, and extrude the SVG design.

The leftmost stamp was printed on the Ultimaker 3, but the quality was much lower than I expected (much lower than the more difficult tiny KJK stamp). I had to clean up a lot of blobbing and seams. I tried printing on my Monoprice Delta Mini, but the first attempt detached from the printbed about half way through. It looked ok (other than being too shallow) once I removed the rats’ nest of filament that was the remnants of the second half, so I printed a third one with glue stick instead of hairspray for the adhesion.

Here is a mirror image of the 3rd printing, to show the CM monogram. I’m a little worried that the C and the outer circle may be too close together. If that turns out to be the case, I can reprint either without the outer circle (which is 15mm diameter, like the NS stamp) or with the CM slightly shrunk. After taking this photo, I noticed the blob on the inside of the C by the M, and I removed it with a riffler.

For future designs, I’ll try to keep all open areas at least 1.3mm wide, since that is the diameter of my pottery needle, which I’ll use for clearing clay out of the crevices.

Another student sent me a design, but it was way to detailed to make a stamp out of—the stamp would have had to be the size of a dinner plate! I hope that she will try again with a less ambitious design.

2023 February 17

Soap dishes

Filed under: Uncategorized — gasstationwithoutpumps @ 18:33
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In My first pot, I promised a post about the soap dishes I extruded. The extruder-die was presented earlier in 3D-printed clay-extruder die.

Here is another picture of the extruder die that I designed and made.

The soap dishes did shrink as expected. I had designed for 80mm wide soap dishes after 12% shrinkage, and the soap dishes are about 80–82mm wide, so the design was about right.

I made four of soap dishes from the extrusion, but only three were trimmed, bisque-fired, and glazed in time for last week’s glaze firing.

Here is a view of the tops of the soap dishes.

And here is the view from the bottom—you can see that I did a really sloppy job of applying the wax resist to the feet.

Here is the top of the cracked soap dish I was emulating, side-by-side with one of the new dishes. The original did not glaze the ribs, which seems to be a necessary feature—the glazed ribs are too slippery to hold the soap well.

Here are the bottoms of the old and the new soap dishes, showing the difference between a skilled person and a rank amateur.

The scaled-down soap dishes are a little too thin and warped a bit in the kiln. (This is the worst-warped of the three.)

The end of this dish shows how sloppy I was with the wax resist. I hope I did a better job on the 4th soap dish.

Although the soap dishes are the size they were designed to be and are about as big as I can make them with the 4″ round extruder, they are really too small for bath-sized soap bars. The outer width is 80–82mm, and the widest bar of soap that could fit on them is only about 63mm. The lengths of the soap dishes are about 82mm, 91mm, and 92mm in the center and about 91mm, 100mm, and 100mm on the outer rims.

The soap dishes were made of Bravo Buff clay from Clay Planet. I glazed the soap dishes with two dips—first in shiny, milky white, then in noxema blue. The tongs left marks in the middle of each soap dish. In the last 2 photos, you can see the monogram stamp mark, as the glaze filled in the stamp area making it darker.

I don’t think that these soap dishes were very successful, but it was interesting making them.  I might try to make a die for the square extruder that could duplicate the original soap dish better, but I want to play around with hollow extrusion some first, and I also want to spend some time trying to do wheel throwing, so I don’t think I’ll get around to a bigger soap dish in this set of classes.

My first pot

Filed under: Uncategorized — gasstationwithoutpumps @ 17:06
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No, I’m not toking—I’m talking about my ceramics class.  We got our first glazed pieces back on Tuesday, and I had one wheel-thrown pot and 3 extruded soap dishes in the firing.  I’ll do a separate post about the soap dishes later—this post is just about the wheel-thrown cup.

The inside is glazed with “shiny milky white” glaze, applied by pouring the glaze into the cup, then pouring it out. The outside glaze is “noxema blue”, applied by dipping the pot into a bucket of the glaze.

The splash in the previous picture and the dots in this one were not intentional (a bit of sloppiness dipping the pot), but I rather like the result.

The outer glaze has a few flaws near the base. I don’t know whether I splashed a little wax there when protecting the foot or the dipping was poorly done—possibly both.

Some of the outside of the cup has white glaze under the blue glaze (due to sloppy glazing of the inside), but I actually like the double layer of glaze better than where there is just the blue glaze.

The foot has “NS” for “night school” scratched into it—a mark we were required to make to avoid confusion with the work by the high-school class.  I also have a stamp with my monogram, which did not come out as clear as I had hoped—I think I need to stamp deeper.  I should probably make an “NS” stamp also.

The cup is 58–59mm high and about 100mm in diameter at the rim, and the inside depth is about 45mm. The foot is about 66mm in diameter. It weighs 264g, which is rather heavy for such a small cup. The cup’s capacity is about 150mL, but the usable volume is more like 100–110mL, filling to about where the white glaze ends.

Although this cup is rather clunky and not one I would buy even at a seconds sale, I’m still quite pleased with it as my first attempt.  I would not be surprised if it turns out to be the best wheel-thrown pot I make in this course.

2023 February 13

Fifty-ninth weight progress report

Filed under: Uncategorized — gasstationwithoutpumps @ 14:14
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This post is yet another weight progress report, continuing the previous one, part of a long series since I started in January 2015.


My weight is about where it was a year ago—perhaps a couple of pounds lighter.

I still want to lose about 13 pounds, though I’d probably be satisfied with 10.

The very careful observer might notice that more of the weight curve has moved into the “overweight” category than in previous reports. That’s because I updated my height for the plots—I’ve shrunk about 1 cm since 2010.  I should probably change the plot scripts to use a time-dependent estimate of my height, rather than a constant, but that is too much bother for now (plus I don’t really know how my height varied over time).

Since my last report in mid-October, I’ve cycled an average of 2.23 miles/day, bringing my average over the last year up to 2.12 miles/day (a very small number).  I’ve averaged about 6.4k steps per day—down from earlier in the summer. I no longer have the Verily Study watch to keep track of my steps, but my walking was definitely reduced during the winter rains that we had, so I suspect that my exercise is way down overall.

2023 February 8

Science fair judging videos

Filed under: Science fair — gasstationwithoutpumps @ 21:05
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This post is not about judging videos submitted to a science fair, but about some videos I created for providing some guidance to new science-fair judges.  I’m not happy with all the videos, and I still plan to redo at least two of them, but I felt I needed to release the videos or miss the 2023 science-fair season entirely.

The four videos are at and are now public. If you find them useful, feel free to share them with others.  If you have constructive criticism, either leave comments on the YouTube video or on this blog post.

Thumbnail image from one of the videos.

I don’t know how soon I’ll get around to doing new videos or redoing the existing ones—I’ve gotten busy with other activities (ceramics class, improv class, 3D-printing clay-extruder dies, readers’ theater, … ). 

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