Tolerance and O2

tol·er·ance   [tol-er-uhns]
1. a fair, objective, and permissive attitude toward those whose opinions, practices, race, religion, nationality, etc., differ from one’s own; freedom from bigotry.
2. a fair, objective, and permissive attitude toward opinions and practices that differ from one’s own.
3. interest in and concern for ideas, opinions, practices, etc., foreign to one’s own; a liberal, undogmatic viewpoint.
4. the act or capacity of enduring; endurance: My tolerance of noise is limited.
5. Medicine/Medical, Immunology .
a. the power of enduring or resisting the action of a drug, poison, etc.: a tolerance to antibiotics.
b. the lack of or low levels of immune response to transplanted tissue or other foreign substance that is normally immunogenic.
6. Nowhere in does it say anything about machine tolerance in this definition, how just .001″ off of flatness of a PCB can totally ruin a board, and frustrate your evening.
7. I need to learn some … or machine some.

This post will have to go into both CNC and Electronics. Currently, I’m working on milling PCBs, to complete the first steps of my final O2 analysis project. I have some big plans in the works for a SCUBA product for analyzing Nitrox bottles. I will not divulge any details, as I hope to have a patent when it is done. You know, making money from projects is a goal of mine.

This, however, is testing milling PCBs using the power-stage of my current O2 circuit, which will be a generic O2 analyzer when (and if) it’s done.

What do I now know:

1. Copper Clad board is not flat. It looks flat, but it’s far from flat.
2. .001″ if height fluctuation will completely destroy a circuit you are trying to mill.
3. The bits I purchased are very brittle. I’ve broken 3. Must order some more.
4. I’m having a VERY hard time mounting PCB flat, even though I have flattened my table surface.
5. Carpet Tape still sucks!

The photos are of the latest version. I did not include the other tests I tried to do without carpet tape to “mostly” get the PCB flat on the sacrifice board. But, I know from testing acrylic with carpet tape, this stuff is impossible to remove. So, why did I use it on the PCB? Well, I wanted to see a circuit! So, sacrifices had to be made.

Things to do:

1. Mill flat a sacrifice board (both sides)
2. Figure out some kind of stock pin register system for flipping the boards (I’ve worked at a newspaper for years. I should be able to figure this out, having dealt with pin registers for a few years)
3. Figure out some way to hold the PCBs flat, without having to resort to carpet tape

I read on another post ( about using a machined aluminum plate to hold down copper clad with super glue. This might be something to try, if I can find aluminum. But, that’s expensive and I’m notoriously cheap. So, I’ll keep experimenting with MDF, until I’m satisfied I can not use that material. The Chugerizer sent this over, which might be a good source of inspiration for the hold-down mechanism (

Sorry for the rambling, but this is my notebook today, so I can remember where I’ve come from and where I’m going. Once this step of the O2 project is completed, I can move on to final patentable circuit design and prototyping.

Christmas 2011 Round-up

Well, it’s finally after Christmas (well, New Year’s for that matter), so I can put these photos up. It’s not like the kids look at my website, so I probably could have posted my progress as I went, but, better safe than sorry.

I think most of these turned out okay, and it was a major learning process along the way. The biggest thing I learned was you need more time than you originally plan, so add a couple of weeks in the future, Tracey.

I built a box for Chugs. This was supposed to be out of acrylic, but I’m have a tough time learning how to get that done properly. It might have to wait for the creation of X-CNC:Gen.2, which will be much more rigid than my prototype machine. He liked it, so I guess that counts for something.

The halftoning process into wood it a really great effect. After a bit of software research to complete the project, I finally settled on Halftoner. It’s a great app! Thanks you Jason Dorie for cloning software into a better version! (

Last but not least, the photos: