Sunday, August 26, 2012

Computer I/O shield Experiment, Take 2

I just wasn’t happy with the experiment, so I tweaked the file a bit and milled a second one. This is on the back of the computer and nobody will even give it a second thought, but it was annoying me nonetheless.
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Milling
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Done.
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Comparison, old one on top.
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In place. I probably could have moved the USB cutouts over another .01” but it’s much better now.
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Happy kitchen PC. Running Xubuntu.

Friday, August 24, 2012

Computer I/O shield Experiment

I recently came across a large pile of new in the box computer parts at a garage sale ("at pennies on the dollar", said I to my suffering wife). I ended up with a processor (Core 2 Duo, 2.2Ghz), 120 GB hard drive, 4 GB DDR2 ram, Antec case w/ power supply, all of which were hypnotically commanding me to make a complete PC.
So I looked around online for a cheap Socket 775 motherboard and bought one from Geeks.com. It was refurbished and I didn’t notice that the description stated “Cables, I/O shield and Driver discs are not included.”. The I/O shield serves several functions, blocking off excess airflow, grounding the I/O ports and most importantly, shielding RF noise (these are all the fodder for much debate on computer forums). This last become apparent as a buzz on the audio line when I hooked the PC up to the kitchen TV.
Small detour: Did you know that most flat panel LCD and plasma displays usually have standard PC VGA inputs? Yup, they are all waiting expectantly to be hooked up to a computer. You can watch online content (Youtube, Hulu, Netflix, etc) as well as streaming audio from your network or the internet. In most cases all you need at a VGA cable and a 1/8” audio cable. (leaving aside the subject of HDMI which has vexed me of late on our living room TV).
So I figured I would attempt to make an I/O shield. I have come across this problem (missing I/O shield) several times before so I figured that what I learned from the experience would probably pay off later on. I did learn several things, most importantly to not buy motherboards without the I/O shield. (Mom, I/O means “input / output”.)
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I took a picture of the back of the case. That curve to the motherboard is not a camera artifact, the motherboard is warped. What did I expect for $20?
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I cropped and tried to get the sides parallel in Paint.net
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I brought the picture into Rhino and scaled it to suit the ATX standard (6.25” x 1.75” +/- .008”) for the I/O shield hole. Then I drew some boxes around the various components.
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I generated the toolpaths in MadCam (an excellent CAM plugin for Rhino, which was generously donated to yours truly by the fine folks at MadCam.
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Beginning the milling operations on the Taig CNC mill.
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Almost done.
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Attached to “sprues”.
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Cut free and cleaned up. I spent some time deburring.
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It didn’t quite fit in spite of being within the specifications. So I filed the edges a bit and got it into place. So my second lesson learned is to reduce the edge dimension by .004” on all sides. Still within specifications but with some wiggle room.
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Not quite what I was expecting…Seems that I miscalculated or otherwise managed to locate the cutouts slightly to the right of where they should have been. This is with the motherboard shifted left as far as possible. I said it was an experiment…My third lesson is to take some other reference measurements, which I thought I could avoid by working from the picture.
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But the USB cable fits in the connector so all is good. I may remove it and file the openings slightly larger on the left side, or I may just leave it. Maybe I’ll make a new one later.
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So there it is. Hooked it back up in the kitchen and there is now an absence of buzz on the audio output.
UPDATE: I decided to try again with better results, link to post.

Friday, August 03, 2012

To LA And Back, Part 3

On our way back home.
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Victoria drove us to the train station. LA traffic is wonderful.
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Outside Union Station.
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Henry had a Wetzel’s pretzel for lunch. He enjoyed it.
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Coming back along the coast at high tide.
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It was  a bit gloomy but beautiful.
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Some lunch.
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Another stop. The couple in the foreground live in Oakland and were coming back from LA. He works at a large US Mail distribution center in Oakland.
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The guy walking towards me is on his way up to UBC to study for a masters in Forensic Psychology. His main field of research is surfer and skater culture.
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The “horseshoe” curve between San Luis Obispo and Paso Robles.
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That’s highway 101. The train is pretty high up on the hill.
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Back in Oregon, so green. The train was late getting into Klamath Falls so we were able to enjoy views of Mt. Shasta. I had a long conversation with a sheep farmer from New Zealand as we wended our way through the cascades.
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Goodbye parlor car. That’s Angelina, our porter on the left.

To LA And Back, Part 2

Morning in LA, or Alta Dena.
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Peter, Charlotte and Shadrach relaxing on the couch.
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Their back yard has a nice view of the mountains.
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Harry, Max & Henry playing Wii.
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Peter shoveling out the chicken coop.
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We went to their swim club.
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That guy on the right is an actor I recognize but I can’t place his name or what he’s been in. Which probably explains why he belongs to a relatively inexpensive swim club rather than some posh country club. Harry is enjoying a shaved ice.
Edit: Peter found out who he is, it's John Michael Higgins. He was Mentok the Mind Taker in Harvey Birdman Attorney at Law! Not that I recognized him from that role.
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The next day we went to the California Science Center.
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The kids enjoying a zoetrope.
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Some thermal imaging.
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Charlotte in a hurricane chamber.
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Felice learning to fly.
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Hanging out by the fountain.
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Peter is really excited.
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Everyone shoehorned into the Odyssey for the trip down to Legoland. I will stress at this point that the idea of visiting a theme park was none of my doing.
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Such a happy guy.
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Ewok and my nostrils.
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I’m happy I can deny piggyback rides.
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At least there was something cool there.
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It’s a nice mold.
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I can only imagine how many molds Lego uses.
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Some girl vandalizing Churchill.
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I don’t think that’s the Vietnam Veterans memorial. It’s the tomb of the unknown hot dog.
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The models were pretty cool.
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And it was a dream come true for Henry.
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I need to get one of those for home.
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Still having fun…
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A girl and her droid.
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More steamboats. There was also sunburn and puking.
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Shadrach
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He has three legs, as do all cats, but is missing the fourth one.
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Peter and I cobbled together a simple launcher for paper rockets.
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Charlotte counted down from 100.
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Harry donned safety gear.
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There was a bit of dribbling as well.