otto9otto @otto9otto@makerdon.org

This container is for use in working with a terrific new material that I am investigating: a mixture of chopped glass, sodium silicate, and water (more on this in a later post). This mix tends to get lumpy when mixed. I like to press out the lumps to create a more homogeneous mixture. This strong, flat-bottomed container will work well for that.

I created the flat-bottomed, straight-walled container from stainless steel. I used a carbide-infused fiberglass cutting disk mounted to a Dremel for both tasks.

All-State 11 FC Nickel-Silver coated brazing rods seemed like just the ticket, but it didn't work. Finally, I called the local Air Gas (where I get my gas cylinders) who sold me Radnor Safety-Silv 56 coated brazing rods. 😀 I used a natural gas-oxygen torch.

Commercial HEPA flow hoods are expensive. I made a small HEPA filter from a catch basin (Lowes Item # 118877), a vacuum bag, wood, adhesive, and a squirrel cage blower.

I used the wood to mount the filter fabric.. The installed finished assembly works great. By that, I mean that the air flow is what I wanted: not too much or too little.

I discovered thi wonderful book when it was only expensive and hardbound. Now the author has made every chapter of the book available in PDF format - FREE! This book is readable, with a minimum of extraneous (not useful to a maker) math. My most recent insight from this book is that, for slow-changing data, a moving-average filter is most suitable. This is easily implemented on most microcontrollers.

The Scientist and Engineer's Guide to Digital Signal Processing

https://www.dspguide.com/

A long time ago, I worked on a vaporizer design that would heat air on-the-fly prior to entering a pipe. The four leftmost objects are casting fixtures. The four little round thingies in the middle are cast ceramic shapes. The right two are fully wired to function as (12V) air heaters. The three things on the right are functional vaporizers - pipe not included. The one on the end is what I have used personally for many years.

The center axle of my top was going to be 4 mm. I am trying to keep everything metric. But a 4 mm drill bit in the center hole of my aluminum master part wobbles. Well, my drawing states that all tolerances are +/- .1 mm, and maybe it is within tolerance, but that wobble doesn't make me comfy. Also, upon examination, 4 mm seem a bit slim. So: I am expanding it to 3/16", but I can't drill it on my lathe - too big. Sweating bullets attempting to exactly center the drill on my drill press.

I have a question: when making a drawing of a disk shape for machining, is it sufficient to draw only one-half of a cross section (with dimensions, of course)? Or, should one draw both cross-section halves, but only dimension one of them?

@jmwright Hi Jeremy, can you tell me what happened to my post wherein I told the tale of my final success in producing a workable DXF file via LibreCAD?

Digikey has created a Kicad parts library:

https://hackaday.com/2018/05/01/digikey-tips-its-hat-to-kicad-with-its-own-library/

A funny thing happened on the way to a working levitating top prototype: Modelling this in FreeCAD led me to the realization that the powerful Nd magnets I am using can be lined up with all poles in the same direction IF they are press-fit into the top structure.

So now that I have the moving part fully drawn (sans magnets), I also realized that I don't have to make the first article by machining. All I need to do is make a mold, which is sort of a 3D version of a photographic negative.

My long-promised introductory post:

I am an experienced EE. My talents include switching power supplies, analog design, and microcontroller programming - most recently from TI (MSP 430 and TM4C12X). No experience with Arduino or Raspberry Pi, though. I am willing to answer questions, but presently I doing something completely non-electronic: a levitating top. They exist now, but mine will be way cooler. Details (and probably a video) at a later date.