iMac intel fan stuck on

We had a short power outage, and when the power resumed, the fan in our iMac (intel core duo) was stuck on full speed. It sounded like a jet plane. I waited a minute or two for it to slow down, but it didn’t stop. Even rebooting didn’t affect it.

After some Internet searching, I found that there is a chip which controls the fans, which can get stuck like this. Fortunately it can be reset also.

I eventually found the iMac intel reset procedure at the Apple support web site. The procedure varies with the model, but this was the correct one for my iMac core duo.

The basic procedure is:

  1. Unplug all cables from the computer, including the power cord and any display cables.
  2. Wait at least 15 seconds.
  3. Plug the power cord back in, making sure the power button is not being pressed at the time. Then reconnect your keyboard and mouse to the computer.
  4. Press the power button on the back to start up your computer.

Thirty seconds later, it was fixed. I like nice simple solutions.

Submitted by amillar on Mon, 2008-12-22 13:15

Art deco LED desk lamp

Flat panel TV swing-arm mount

Flat panel TV mountJessica bought a flat panel TV, and wanted to attach it to the wall with some sort of swing-arm mount. The prices at the store were outrageous. Armed with my moderately-trustworthy arc welder and couple of discarded bed frames, we set out to construct one ourselves.

Mock-up

We started by building a cardboard mock-up model. We needed to determine the proper size and shape to fit the TV and wall. First we made a rough model by just bending the cardboard where we thought the joints should go. Then we made a second cardboard model which accurately fit the exact shape and size. We used bamboo skewers for the hinge pins. Once we had everything right, we were ready to build the real thing.

Cardboard TVFirst rough cardboard armSecond refined cardboard armSecond cardboard arm


Construction

Construction mostly consisted of copying the cardboard pattern onto the angle iron. Most of the arm was fairly simple. The hinges were a challenge. I could not find nylon bushings at the hardware store to match the size of the bolts, so I used polyethylene sockets for caster wheels and trimmed them to fit.

The TV was made to stand on a large foot; it did not include anything for a wall-mount bracket type of configuration. However, it was made with an aluminum frame around the perimeter. We removed the foot and made an X-shaped metal bracket, which we screwed to the frame at the outer edges.

After the sections were welded and filed down smooth, we painted it black with semi-gloss spray paint. We bolted it to the wall with concrete anchors (since this wall is a solid concrete wall behind the panelling) and it works great.

Arm piecesArm piecesFirst hinge
Hinge bushings
Bushings
Wall bracket
TV pivot
TV frame bracketBracket on TV
Arm on wall
Arm on wall
Finished
Finished
Finished
Finished
Finished


Submitted by amillar on Sun, 2008-09-21 22:43

Baldor Grinder Restoration

Grinder restored
Grinder restored

I received a Baldor metal grinder with 10-inch wheels, on its own pedestal floor stand, discarded from a school metal shop program. Several owners before me did not know what to do with it, mainly because the motor is wired for three-phase industrial power which is not found in U.S. residential homes. My job was to fix it up and get it working.

There were two major tasks to the restoration: cleaning/repainting, and making the three-phase motor work.

Cleaning and Painting

I started the cleaning process by removing all attachments that I could, including the wheel shroud side covers, the wheels themselves, and all electrical boxes and covers. I remove all of the old flaking paint and minor rust spots using a wire wheel brush on the electric drill. Some of the paint was still good, but much of it was stripped down to the bare metal. I could not remove the riveted-on motor label and didn’t want to paint the wheel axles, so I covered them with masking tape.

I spray painted the entire grinder and all the separate parts with primer for a good base coat. I followed it with a few coats of grey paint.

Stripping paint and rust
Stripping paint and rust
Priming parts
Priming parts
Painting parts
Painting parts
Priming body
Priming body
Painting body
Painting body


Polishing hardware
Polishing hardware

I cleaned up the hardware to make it look a little nicer. I filed and sanded the heads of the screws and bolts while spinning them in the drill press. I buffed all of them with a cloth wheel, which made them nice and shiny. I finished it with some clear spray varnish.

I reassembled all the pieces, back in the order they came off.

Painted well
Painted well
wheel reinstalled
wheel reinstalled
Shiny screws
Shiny screws


Electrical

Originally this grinder was hard-wired to the wall using “BX”-style flex conduit. There was a power relay and circuit breaker box, which engaged and disconnected all three phases in sync, using start and stop push buttons.

For the 3-phase power, I built a
static phase converter using capacitors.

I rewired the relay box to supply single phase power to the phase converter. I attached it to the pedestal stand of the grinder. I drilled holes in the pedestal and tapped screw threads into them, and screwed the relay box in place. Instead of flex conduit for the power line, I added a standard power cord. Since it uses 240 volts, double the US standard, I used a different plug and outlet.

The phase converter needs an extra momentary push button to start the motor, so I added that to the front of the grinder next to the main on-off switch.

Tapping holes
Tapping holes
Switch boxes
Switch boxes
Converter and relay boxes
Converter and relay boxes
Relay
Relay
Power to relay
Power to relay
Start button
Start button
Converter in box
Converter in box

3-phase motor static phase converter

Start buttonsI received a Baldor metal grinder with 10-inch wheels, with a motor wired for three-phase industrial power. Three-phase power is not provided in U.S. residential homes, so I needed to power it from normal single-phase power. My solution was to build a balanced static phase converter, requiring only a few relatively inexpensive capacitors. (Much less expensive than the nuclear reactor I was considering.)

Research and Testing

Electric Motors in the Home Workshop
cover
Amazon | Powells
IndieBound

I knew I had some homework to do, to figure out how to make this work. I had ignored much information on 3-phase motors in the past, thinking that I would likely never need it. When would I ever come across any 3-phase equipment that would fit my miserly budget? Well, now, it seems.

The first resource I turned to was Electric Motors in the Home Workshop by Jim Cox, my favorite book on the subject. This book is written specifically to address reusing various industrial and appliance motors for home-built tools and uses, which fits my crazy schemes. It covered the basics of 3-phase motors, but did not go into great details. It did describe a very common method of generating 3-phase power from single phase, which is called a rotary phase converter. In this method, you use a single-phase motor to mechanically drive a 3-phase “idler motor” which generates the other 2 phases. This is a robust and flexible method which can handle multiple varying 3-phase loads. It also takes up some room, and requires two large electric motors dedicated to it. If you had a variety of 3-phase motors to run, it is a good solution. But it seemed like overkill for just my one grinder.

Phase converter schematicI did some more Internet searching, and came across another idea: the static phase converter. This is a very simple converter which uses capacitors matched to the amperage draw of the motor to generate the extra two phases. As long as your amperage draw does not vary much (meaning you can only really use it for one motor), this is a simple and inexpensive solution to the problem.

I found the best explanation and description in Rick Christopherson’s page on
building a balanced static phase converter. I used his guidelines to determine the likely capacitor values I would need for my converter.

Run capacitors
There are two run capacitors for the extra two phases. The two capacitors create pulses 120 and 240 degrees out of phase with the primary, so the second capacitor is twice the size of the first. Based on his tables, I guessed that my motor would require about 6 uF and 12 uF for the two phases.

I went to a local surplus store, and was able to find smaller capacitors of 2.2 uF. My electricity textbook said that capacitors can be combined in parallel to add them up, so I just combined 3 for one phase and 6 for the other, providing 6.6 uF and 13.2 uF.

Just putting the run capacitors in the circuit would get it to run, but it would not start from a stand-still. With my dad helping me, we were able to spin the motor axle with a rope to get it started, and then turn on the power to make it continue running. It worked! I checked the power draw of all 3 phases with an inductive ammeter, and they were all nearly identical within 0.2 amps of each other.

Final start capacitorTo bring the motor up to speed under power, it needs a large starting capacitor, connected in with a momentary push button. They are readily available, sold simply as A/C start capacitors. I had a capacitor from an old washing machine motor, which worked to start it as a test. I ordered another one of 86 uF from an Internet mail-order surplus place. Holding the start button for about 3 or 4 seconds is all that is needed to bring the motor up to full speed.Run capacitorsTest start capacitorStart button


Construction

Figuring out the capacitor schematic and values was the hard part. The rest of the construction was relatively simple. The grinder already came with a large magnetic relay contact switch and circuit breaker, previously wall-mounted separately. I attached it to the back side of the pedestal stand, and put the push-button on/off switch on the front. I added two new electrical boxes: one on the front for the momentary start push button, and one on the back to hold the capacitors.

Since the voltage is double at 240v, I needed a different plug and outlet. But the amperage is low at 5 amps, so did not need a large super-heavy-duty power cord and plug like one might use with an electric clothes dryer or kitchen stove. I found a plug and outlet the same size as a standard US power plug, but with both prongs rotated at 90 degrees from standard, so neither side could be accidentally interchanged with a normal plug. Since the total amperage draw is only 5 amps, a 14-gauge power cord was adequate.

Tapping holesSwitch boxesConverter and relay boxesRelayWiring switchesWiring switchesPower to relayPower to relay
Converter in boxConverter in box


Result

Start buttonsConverter closed and labelledI created some labels using Inkscape, printed them on photo paper, and attached them to the various boxes.

The end result was very satisfying. The motor only takes about 4 seconds to spin up to speed, and the grinder works great.

Submitted by amillar on Tue, 2008-09-16 12:08

Professor Calorium’s Pyroelectric Metalurgical Liquefaction Apparatus

Lawn aerator (upside down)
Lawn aerator (upside down)

The handle broke off my manual lawn aerator. It had been welded in place, and since I have an arc welder, I figured I should weld it back on. This was the first time I attempted to arc weld something with a real purpose to it. There were a few details to work out, such as the fact that I don’t know if the welder works right, and I don’t know if my welding rods are any good, and what was the other one? Oh yeah, I don’t know how to arc weld. Well OK then, time to get started.

Actually, I do know the arc welder works, at least nominally. I got the arc welder from my friend Tim when he got a better one. It is your typical “stick” AC arc welder, with no fancy features. He used it at least once. I think. It’s a solidly-built big old monster with a giant transformer inside and a hand crank to turn the amperage up or down. The amperage indicator needle was missing; I replaced it but don’t know how close it reads to reality. My dad helped me make a few practice welds with it last year, so someone who knows what they are doing should be able to make it work. Ahem.

I got the welding rods from my dad, who had a bunch of these sticks left over from his previous job. I’ve heard you have to keep them dry and in good condition for them to work right. They’ve been inside in a plastic bag to keep them dry, and they don’t look obviously bad to me. That’s pretty easy since I don’t know what a bad welding stick looks like.

Then there’s that knowing-what-you-are-doing part. I did some oxy-acetylene welding back in the dark ages, I mean the 1980’s, but not arc welding. So last year when I got this beast from Tim I figured I should learn a little and read up in I Can Do It All By Myself: My So-Big Book of Arc Welding or maybe it was called Introduction to Arc Welding, I forget which.

My dad bought me a cool welding helmet which automatically darkens in bright light and lightens again in normal light. If you don’t know what you are doing, it really helps if you can see it. I think.

I did read up on the safety stuff, and made sure to wear boots, long sleeves, and thicker denim jeans, along with proper welding gloves. Hot molten metal, no matter how small a splat, is not fun to feel. I also turned on a big box fan right next to the work, because these fumes stink! Oh, and they’re toxic too, I hear.

I put some protection around to keep the splattering metal from flying onto everything else. (Don’t weld over a pile of sawdust.) When I first tested the welder last year, we set up a shield using cement backer board, the kind you use as an under-surface for tile counters. This time I used some scraps of “HardieBacker”, which has cement in it but is a little more like sheetrock, so it is easier to cut and shape. Works great for a welding shield. And for laying tile, too.

So it was time to melt metal with fire using a blazing lightning bolt of electricity. Can you do anything cooler than that? Of course not. I figured I should do some practice welds on a piece of junk steel before mangling the lawn aerator. I grabbed some scraps from a discarded bed frame (awesome source of free angle iron) and set to work. I spent a long time getting the rod stuck to the piece, over and over, without getting an arc. Clearly I was not getting this arc thing figured out right.

I gave up after half an hour. Something wasn’t right. Either the welder was bad, the rods were bad, or I didn’t know what I was doing. Hmm. It could be any of the three, so I went into standard cheapskate troubleshooting mode: which of these variables can I improve or eliminate for almost no time or money? Buying another welder would not be cheap, unless I wanted to take forever, so that was out. Despite being the highest probability culprit, learning how to weld properly was not going to happen within the weekend, and would likely require known-good equipment, so that was out too.

Fortunately, a box of arc welding sticks was only ten dollars at the big orange home improvement store, and they were open. With new rods in hand (or rather a new one in the electrode holder), I had an arc and an acceptable weld on my test piece within a few minutes. The new rods were smaller than the ones I already had, and the box had a recommended amperage range for them which worked fairly well. That makes me think that the old rods may not have been bad; I just may have been using them with the wrong amperage setting. There’s that know-what-you’re-doing thing again; curses!

Welded joint with bracket
Welded joint with bracket

I cleaned up the broken parts of the lawn aerator on the grinding wheel to make a clean face and bevel the edges. After all the prior drama, it actually welded pretty easily. I also added a steel bracket to the joint, to reinforce it. I don’t know whether my new weld in the joint itself is a strong as the original factory weld (probably not), but I expect that the new bracket makes the whole thing stronger than before.

Once it was welded, I cleaned it up with the grinder and a wire-wheel brush on the electric drill. Success. I finished aerating the lawn, and it worked just fine. I melted metal using a white-hot electric arc, and I did it without burning down the house or injuring myself. You can’t beat that.

GPS for OpenStreetMap

Magellan GPS for Palm VI bought a cheap GPS on EBay. I got a Palm Vx with a Magellan GPS Companion attachment for ten dollars. By PDA standards the Palm Vx is completely obsolete, but it works fine as a GPS data logger.

The accuracy is pretty good. I don’t know how to measure it explicitly, but it usually matches Yahoo aerial photos and Google Earth within a few feet. That is for open skies, either from my jacket pocket while bicycle riding or on the dashboard of the car. Looking at my tracks in Google Earth, it does correctly match the parking space in which I parked the car at the shopping center. Scary.

It didn’t come with any software, so I’m using cotoGPS as the track logging software and converting it to GPX with gpsbabel.

It appears that all the Palm-related GPS or map commercial software companies are no longer selling the products now. I would like to find a map viewer that will work with it, but I don’t know what I will find at this point.

Still, as a simple data logger for 10 dollars, it is a fun toy.

Submitted by amillar on Tue, 2008-03-11 15:53

OpenStreetMaps


Mapping Hacks
cover
Amazon | Powells
IndieBound

I’ve recently come across two interesting projects and web sites: openaerialmap.org and openstreetmap.org. These two projects are efforts to collect and share freely-available map information.

One may wonder what the point is, since you can get all kinds of free map tools through the likes of Google Maps, Google Earth, MapQuest, and the like. But although those tools are available at no cost, they have limitations on what you can do with them. Because the underlying data is owned and copyrighted by commercial companies or governments who spend money and manpower surveying and updating the information, you are restricted from copying the data and you are limited in using it for other purposes. In Europe, even the government-created map data is copyrighted and you can’t copy it for your own use. And if you find mistakes, you can’t fix them.

But simply knowing the names of streets and where they are located cannot be copyrighted, and anyone can make their own maps if they want to do so. A futile and daunting proposal for an individual, but what if you could harness other technology like GPS and the Internet?

Like the open-source software movement, there is an open data movement happening. The world is full of data, but making is useful and accessible has been the hard part. The Internet is changing that.

The OpenStreetMap project is working toward making an entire street map of the world, freely accessible to everyone and freely copyable for anyone’s use.

In the United States this doesn’t sound too unusual, since all federally-produced data is by law public domain. The freely-available data from the US Census is not quite accurate, though, and needs corrections. In other countries, it means starting from scratch.

The OpenStreetMap (“OSM”) software infrastructure is designed around the idea of collecting GPS data logs (“GPS tracks”) and then drawing and labeling streets and features on top of them. Where aerial or satellite photos are freely available, they can be used as tracing sources also.

I’ve been working on fixing up the map for my neighborhood. While the vast majority of the streets are there already, many of them are out of alignment or proportion, and recent developments are missing. Although I have had an interest in maps my whole life, this is the first time I’ve been able to make or work on a map that other people may actually find useful. Fun stuff.

Submitted by amillar on Tue, 2008-03-11 15:40