Glaze Material Substitutions

This page provides a set of calculators to help with calculating common material substitutions in glaze recipes.

Warning: These calculators are based on theoretical UMF analysis of the materials, and I have not verified them experimentally. Oxide analysis isn’t the only factor that determines how a material will behave in a glaze.

Each calculator allows for conversions between two material forms. Click “Switch” to toggle the conversion direction. Red cells indicate that a material should be subtracted from the recipe.

Wrapping vector artwork around a conical object in Inkscape

Free vector editing tools are pretty lacking in intuitive ways to wrap a template around a conical object (i.e. mug or vase). I aim to produce a vinyl decal that can be applied perfectly to a ceramic piece without any stretching.

This post is not a step-by-step procedure, but rather a general overview of the steps that I use to fit vector artwork to pieces of pottery using Inkscape and a vinyl cutter.

Current development builds for KiCAD 7 include the new constraint keyword physical_hole_clearance for detecting hole and pad collisions within a common net. This is useful for detecting via-in-pads which are often undesirable, as some PCB vendors upcharge to plug vias that could cause wicking during assembly.

To set up the custom design rule, first install a nightly build of KiCAD (6.99). Please note that saving a project with a development version of KiCAD will prevent older versions from opening the PCB file. To prevent this, I run the DRC from KiCAD 6.99 and make the necessary changes from KiCAD 6.

I bought a spool of Protopasta iron-filled PLA to test in a project where I need to fit a flyback transformer into a confined space. The prototype will likely be 3D-printed in PLA plastic and contain some moving parts wrapped in magnetic wire for power transfer.

For optimal performance, flyback transformers are generally wound around a ferrite core, which has high magnetic properties but low conductivity to reduce eddy currents.

I came across an apparent bug in java.util.zip.ZipInputStream where reading a certain type of zip file causes an exception:

java.util.zip.ZipException: invalid entry size (expected 0 but got 199 bytes)
	at java.util.zip.ZipInputStream.readEnd(ZipInputStream.java:384)
	at java.util.zip.ZipInputStream.read(ZipInputStream.java:196)
	at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:122)

The file in question reads fine using archiving utilities and Java’s ZipFile, so the issue is likely rooted in ZipInputStream. My application requires reading the zip file sequentially, so ZipInputStream is my only option besides a third-party library. I decided to search for a solution using vanilla Java rather than pulling in a new dependency.

This post will be continuously updated with useful commands related to HTTP.

Python3 HTTP Server

Launches an HTTP server in the current directory for serving files

1python3 -m http.server [port]

cURL - Post Multipart Form

Post two files

1curl -X POST -F "file1=@file1.png" -F "file2=@file2.png" --no-buffer https://chandler.io/test