accidentally starting making a replacement for a previous shop built ER40 Collet Chuck when I mounted my three jaw chuck. That video can be found here:
https://youtu.be/Rr1vfegdKaAI'm honestly not sure what to think of the indicator runout readings, but i'm pretty sure it will be "good enough for what I do" as they say. I guess I say that too.
Here's a useful link with all the dimensions needs for various sizes of ER collets:
http://www.takayama-shoji.co.jp/rego/pdf/13_technical_information.pdfIf you like what I'm doing here and find some value in it, consider supporting my work on Patreon:
https://www.patreon.com/JeremymakesthingsI promise I'll still mostly make stuff out of rusty junk and not just buy shiny things with your money.