Site repair/update

While the site displayed, I wasn’t able to manage it for a while. I finally hunted the issues down, updated DB passwords, cleaned things up, and have it working again. Happy New Year!

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Thoughts on focus and gas pressure

Focus depth and gas pressure

Many materials require high pressure assist gas for effective laser cutting. These materials include stainless, mild steel with air, and aluminum with N2.

Usually these call for a focus set well below the surface of the material. The adjustment is generally a percentage of the thickness of the material – focus halfway into the material, or at the bottom of the material, etc.

All this is empirical, because we have no way to actually see what’s happening in there, really. Anyway – this is production – the result is all that matters.

I wonder, though – how much of the focus adjustment is due to deflection of the lens and/or lens mounting due to the pressure? And, what about gas lensing?

Gas Lensing

In certain circumstances, gas pressure gradients can act like a lens. I don’t see much info about this. There are a few papers and studies about “gas lensing”, but those are aimed at using lensing effects to replace standard optics.  Nevertheless, gas flow into the area below the focus lens can affect the beam shape drastically.

A real-life occurrence

In one of our Optimo systems, we made some test burns below the nozzle in plastic. The system had a 5″ lens, and I positioned the target about 5″ away from the nozzle. The burn should have looked like it did at the lens – but it didn’t.

There was a shallow burn the size of the raw beam, then a very sharp spike perhaps half the diameter of the beam. As we tested with lower gas pressure, the spike became smaller. At 20psi or so, it did not show at all. See gas lensing illustrations.

Gas port configuration

The gas was ported to an annular slot, and a series of holes allowed gas from the slot into the area just below the lens. All the holes pointed at the center of the beam path just below the lens.

What cured the problem

We had some stainless steel mesh available, and we just rolled a cylinder of several layers and put it in the head to diffuse the flow of gas. It solved the problem nicely.

The manufacturer (Prima Industries) revised the design of that part of the head. I don’t recall what else was changed, but it fixed that issue.

So what?

If you have a cutting head / lens / gas system that is unproven, or if you are trying to operate at a much higher pressure than usual, watch out for strange cutting issues – you may encounter gas lensing.

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The job I took at Apria Healthcare went well. I got along well with my managers and co-workers, and they appreciated me.
Unfortunately, due to changes in the healthcare industry, Apria has decided to downsize. I’m told it was a tough choice, but they kept my fellow Technical Writer and are releasing me. If nothing else, the guy they kept has nine years more seniority at Apria than I.
Ah, well – it was great experience. I got to work closely with another experienced TW and an experienced manager/editor. Together, we supported quite a number of “process content specialists”. I got to exercise and expand my VBA skills, creating utility macros that the teams have come to depend on.
So – onward, to the next great adventure!

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What’s happening in early 2015

After years of being a contractor and sometime freelancer, I am now a captive employee.
I landed a perm position with a healthcare company as a Technical Writer.
Benefits, paid vacation, etc. And, it is a remote position. I work from home.
And, for only the second time in my professional career, I am working with another technical writer.

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What I did in 2014, part two

After Magellan, a brief pause. Then I landed a project (through an agency) for the City of Carlsbad. They needed a suite of IT security policies and procedures. Great – they wanted someone to gather best practices from other cities or other government organizations and create a set of policies for them. Wow, that was pretty cool.
That went well, then back to the hunt. The next project came in early 2015 – a topic for next post.

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What I did this year, part one

Recently, I worked at Magelllan GPS for about six months. I got to brush up on my FrameMaker skills, and learned to use InDesign pretty well. Also learned something about crop and bleed.
And learned something about Android, BTLE, and aspects of GPS and vehicle navigation.

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Drowning in resources

So many opportunities, so little time…
There are videos, and blogs, and forums, and galleries. It takes real focus to pick relevant items, and stay away from all (most?) of the rabbit holes.

Actually, one decent on-topic item is better than any number of wonderful presentations that I don’t need.

The real challenge is determining What’s Important Now.
And realizing that almost anything else can be found again later, if it is really important.

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Connectivity Challenges

Recently, one or two of my email addresses seemed be flaky, so I tried to login to my hosting provider to check settings.
I could login to my account, but cpanel – the real management interface – refused to accept my credentials.

After submitting a trouble ticket, and several rounds of testing, it developed that cpanel would respond just fine from anywhere we tried – except for my own home DSL account.
I examined settings for my router, disabled my A-V and firewall entirely, with no improvement.
I went to a public WiFi just to test for myself – and in fact I could administer my account just fine from the free WiFi at McDonald’s.
(Yes, I know that is poor practice, and I did change my account password when I got back home. I can change the password from the Lunarpages account page, without going to cpanel.)

I then submitted a trouble ticket to my ISP.

I don’t see any response from Covad, but it mysteriously started working again.

I’m torn between annoyance and relief.

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Found – Optimo memorabilia

I found a number of software manuals for the Windows MMI systems we developed for Optimo.
There are some odds and ends as well, including two CD-ROMS.

It looks like the CDs include software and manuals for most of our Optimos, including the DOS systems.

Wow – I was afraid that was all lost.
Great techwriting samples, too.

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Vintage Computing

Time to clean out some of the junk/old computer stuff. I looked around, and it looks like there’s a bit of activity in old computers and parts.
So, maybe I can make a few dollars and save some of this from e-waste.
Here’s a place to sell for free:
“vintage computer marketplace”
vintage computer forums
Surprise – there’s still interest in old Commodore computers:
Commodore fan site
And someone is building/marketing new ones:
Commodore USA
Other sites:
Note that these (.com and .net) are two entirely different sites!

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