Category Archives: Techniques

Retrofitting a Classic Desk Fan With Leather Blades

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A close shot of the EMERSON ELECTRIC logo medallion on the front of a wire fan cage, with the replaced leather blades out of focus behind.

I’ve been on a “they don’t make ’em like they used to” kick lately, replacing a bunch of my new, flimsy, designed-for-disposal household appliances with old, battle-tested, designed-for-repair type stuff scored on eBay. Whether it’s the Cord-o-Matic retractable clothesline I snagged for my mom, the 1984-vintage Panasonic Auto-Stop electric pencil sharpener I bought for myself, or the cast aluminum Porter-Cable Model 136 I bought to replace my dad’s cheap Harbor Freight belt sander (which literally ground itself apart), I almost inevitably find that buying a used product with a proven track record gives a better overall experience than a new product that, as a friend on Facebook recently put it, “has had all the cost taken out.” Older stuff is usually easier to open up, refurbish, and repair, too, and it always has better stories.

So when my cheap plastic box fan recently self-destructed, I “retrograded” to this lovely chunk of metal—a model 94646-E “Northwind” oscillating electric fan by Emerson Electric, which appears to date from around 1955. You can see that it’s pretty beat-up, which is fine; I wasn’t looking for a carefully-preserved collector’s item, just something that worked and would be easy and fun to refurbish. I paid $45 plus shipping through eBay.

A front view of an all-metal oscillating desk fan with a wire cage. The cage is bent out of shape and the blades show some rust around the edges.

When the package arrived a couple weeks later, I cut it open and looked the fan over. There was some cosmetic damage—the cage was bent out of shape and the paint was peeling here and there—but when I plugged the thing in, it ran like a cheetah. The range of the oscillating motion was weirdly offset to one side, but it didn’t take long to figure out that somebody had reassembled it with the motor hub backwards on the base, and that flipping it around would center everything up again. Piece of cake.

Ten Minutes Later…

…I had cut myself, on the spinning blades, so badly that I thought I might need stitches. If I’d had more presence of mind I would’ve snapped a picture of the injury, but it’s amazing how preoccupied you can get when your body suddenly has a new orifice, oozing blood in time to your rapidly-escalating heartbeat. Once the cursing stopped and the bleeding was under control, I started laughing at myself. Apparently, in some cases, there are pretty good reasons why we don’t make ’em like we used to. When I told my mom, she smiled and said, “It’s amazing anyone from my generation grew to adulthood.” Which, I think, was her nice way of saying, When I was your age, we knew better than to stick our fingers into a spinning fan.

I wore an ugly mess of band-aids on the tip of my thumb for the next 10 days, and it was almost a month before the wound fully healed. I’m lucky things didn’t turn out any worse, since the fan had been stored who-knows-where, who-knows-how-long before coming to me, the edges of the blades were visibly rusty, and it had been waaaaaaay too long since my last tetanus shot.

What now?

So I sat, nursing my aching thumb, and wondering what to do with the fan. Would I remember cutting myself on the blade? Definitely. Was it nonetheless possible that I would eventually do it again? Also definitely. Given that it had taken less than ten minutes the first time, I gave it about even odds. Besides which, I was not the only one who might be exposed to this hazard. There was my girlfriend to think about. My nieces and nephews. My cat.

I had seen recently-manufactured fans with blades made of semi-rigid foam, silicone, or other soft polymer intended for safe use around a child, but I just couldn’t stomach slapping plastic blades on such a beautiful slab of post-war American industrial design. I’d sooner sell it to somebody else and go back to a modern appliance. But was there a more authentic, tasteful material that would also be softer and safer?

Of Course: Leather.

A desk fan, in front view, with no cage, and large free-spinning blades made of brown leather. The base is also brown and has attractive Art Deco styling elements.I had worked with vegetable-tanned belt and strap leather before, and knew I could buy it with weight and stiffness suitable for fan blades. What’s more, a bit of Googling revealed that this had been done before. To right, for instance, is a beautiful Art Deco-styled 1950 Robinson-Myer desk fan manufactured with leather blades, for safety, that was pictured in the July 2011 issue of Indianapolis magazine.

I started sourcing leather on the Tandy Leather Factory website, and though they taught me enough about how leather is cured, graded, and sized to figure out what I needed, they did not sell that material in quantities that were reasonable for this use. So it was back to eBay, which eventually lead me to Distant Drums, who sold me four pieces of their 10-11 oz. veg-tan tooling leather, each of which was just about the right size for a single blade. That set me back another $25, including shipping—the price of my “retrograde” was getting worse, but then the story was getting better, and that’s usually a trade I’m willing to make.

The Deets

First, you’ll wanna take off the blade assembly. In my case, this involved loosening a set screw that held the fan hub to the motor shaft, removing the two bolts that held the wire cage to the housing, separating the blades and the cage (together) from the rest of the fan, and then holding my mouth just right to rotate the blade assembly free of the cage. Second, you’ll need to remove the old blades. Mine were riveted to the hub, and were easily removed by drilling, from the back side, with a 3/16″ diameter bit. Once you’ve got the blades free from the hub, proceed as follows:

1. Put a piece of scrap wood down on your work surface, and then put your leather stock on top of that. Top the stack off with the template fan blade, then drill pilot holes through the blade mounting holes, through the leather, and into the wood. Secure the blade and leather to the wood with three small wood screws.

1. Put a piece of scrap wood down on your work surface, and then put your leather stock on top of that. Top the stack off with the template fan blade, then drill pilot holes through the blade mounting holes, through the leather, and into the wood. Secure the blade and leather to the wood with three small wood screws.

2. Trace around the perimeter of the fan blade with a sharp hobby knife, cutting through the leather as you go. It will likely take a couple of passes.

2. Trace around the perimeter of the fan blade with a sharp hobby knife, cutting through the leather as you go. It will likely take a couple of passes.

3. Remove the screws and separate the leather.

3. Remove the screws and separate the leather.

4. Repeat steps 1 - 3 three more times to cut four identical leather blades. NOTE: Be sure to identify two pairs of blades that are balanced to within 0.5g before proceeding (see below).

4. Repeat steps 1 – 3 three more times to cut four identical leather blades. NOTE: Be sure to identify two pairs of blades that are balanced to within 0.5g before proceeding (see below).

5. Apply leather dye to the front and back of the blades, per the dye directions, until the color pleases your eye. Let the dye dry thoroughly.

5. Apply leather dye to the front and back of the blades, per the dye directions, until the color pleases your eye. Let the dye dry thoroughly.

6. Rub extra virgin olive oil into the front and back of each blade to act as a finish and preservative. Allow excess oil to evaporate before proceeding.

6. Rub extra virgin olive oil into the front and back of each blade to act as a finish and preservative. Allow excess oil to evaporate before proceeding.

7. Attach the finished blades to the hub using pop rivets and a pop rivet tool. To avoid tearout, the wide flange of the rivet should be against the leather, not the metal of the hub. Be sure opposing blades are weight-matched to within 0.5g before riveting.

7. Attach the finished blades to the hub using pop rivets and a pop rivet tool. To avoid tearout, the wide flange of the rivet should be against the leather, not the metal of the hub. Be sure opposing blades are weight-matched to within 0.5g before riveting.

Make Sure to Balance the Blades

My first assumption was that the leather was pretty homogeneous and that, if I cut four identical blades from it, they would each weigh about the same. Not true. The first time I put the hub and leather blades together, the fan wobbled horribly, and I had to drill out the pop rivets and break out my postage scale to weigh the blades, at which point I discovered that one of them weighed 46 grams, while the others all weighed about 40. I used a micro-plane kitchen grater to remove leather from the flesh side of the heavy blade, and then had to re-apply stain to replace the color I’d scraped off. If you try this project, learn from my mistake: weigh and balance the blades before applying any finish.

The refurbished fan, with handsome brown leather blades, touched-up paint, and straightened wire cage.

Tactile guitar cues applied with tape embosser

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I’ve been playing Rocksmith a lot, lately, and the “Ducks” minigame has me moving up and down the length of the fretboard pretty quickly and pretty accurately, now, without looking.  But I’m still concerned my 30-something reflexes will never be able to keep up with the obsessive Japanese preteens I just know are monopolizing the top ten spots on the leaderboard.

Not without an edge, that is.

This trick—using a Dymo embosser to put tactile indicators on the backside of the neck—works pretty well. At least so far as the physical hack itself, goes: The labels are cheap, don’t look awful, stick firmly even after a lot of use, and yet can be removed easily enough without damaging the neck or its finish. In use, they index against the thumbpad on the fretting hand.

The strips are centered behind each of the “dotted” frets: three, five, seven, nine, and 12. Originally, I embossed the corresponding number characters into the tapes, but found in practice that my thumb cannot really feel the difference between a “5” and a “3.” But this ternary scheme (using capital letters “O,” dashes, and a single blank strip of tape at the seventh fret) works pretty well. These are easily distinguishable by touch. So far it hasn’t made too much difference, in practice, but I think in the long run it will.

So look out, IEatzBilletzNomNomNom.  I am coming for you.

Using a kitchen canister as a small trashcan

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Last weekend I celebrated my birthday with a small party. There was a buffet, and we needed a wee tabletop trash can for grape stems, toothpicks, used napkins, marijuana seeds olive pits, and so forth. This was my handy-dandy improvisation: pop the acrylic top out of the lid (they’re just press-fit on the cheap canisters), pop in a plastic grocery bag, cuff it over, replace the canister rim, and, just for looks, cut around the bottom of the rim to remove excess plastic.

Yours truly in C&E News

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Chemical & Engineering News is the American Chemical Society’s print organ, which is mailed to each of its 160,000-plus members weekly. Their back-page human interest column is called Newscripts. The most recent issue, dated November 21, 2011, features two chemistry-related projects from my grad-school years: my trick for using starch packing peanuts to build nil-cost molecular models, and my organic chemistry tutoring business card featuring a reversible cyclohexane chair drawing template. Always fun to see my name in actual, physical print! Thanks to C&EN staff writer Jyllian Kemsley for the ink.

Duplicating flat steel parts on the cheap

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This method gives good results with simple hand tools:

  1. The original part is affixed to a piece of blank stock of appropriate thickness. Double-sided “carpet tape” is very useful for this purpose. Excess tape can be trimmed away with a hobby knife.
  2. Any round holes in the original part are drilled through the blank with a hand drill, using the original as a guide/template.
  3. Close-fitting bolts are passed through these holes and fitted with nuts and or washers to clamp the original and the blank in close alignment.
  4. A hacksaw, a hand nibbler, and/or a file are used to trim the stock down to the original part profile on all sides. For hacksawing, it can be useful to secure the stacked blank and original part to a piece of scrap wood.

Shown here are two admittedly rather boring examples: A replacement hasp for my outside breaker box in stainless steel, and a duplicate strike-plate for a lockset on my rental property door. Both parts have performed flawlessly as replacements.

Lens cap clip mod

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Inspired by The Nice Clip’s recent successful Kickstarter, I modified the lens cap for my Canon SX10 by sticking a small lapel clip to it with Loctite-brand outdoor mounting tape (chosen over regular double-sided foam tape for additional strength). The lapel clip was a junk box find, removed from the cord on a freebie wired headset that came bundled with a long-dead cell phone. The metal clip on one of those clear vinyl ID badge holders would also probably work.

How I modded my Xbox 360 to run 10 degrees cooler

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Briefly, I did the three things suggested by ClickClick 5:

  1. Rewired one of the two fans to run at a constant 12V.
  2. Installed a small heat-sink on the graphics coprocessor.
  3. Added an aluminum foil duct over the processor heat-sink.

The hardest part of the entire process was getting the Xbox itself open, which I did by carefully following iFixit’s excellent teardown.

Rewiring the fans

This may or may not have any effect. Initially, my understanding was that the Xbox 360 fans are not run at full voltage/speed all the time, but that the driving voltage is dynamically varied depending on the console’s internal temperature. The idea behind rewiring one or both of the fans to a constant 12V source is to forgo this dynamic temperature control and just run the fan(s) at full speed all the time.

This rewiring job was easy enough. Instead of soldering to the motherboard (as ClickClick 5 does), I just spliced a short wire jumper between the fan power cable and the DVD-R power cable (which provides a constant 12V) using small wire nuts. I had to cut one wire in the DVD-R cable and one on the fan, and strip three wire ends (both ends of the cut DVD-R wire and one end of the cut fan wire), but no soldering was required. The nice part about doing it this way is that the parts you modify—the DVD-R cable and the case fan—are easy to replace if you mess up or for other reasons want to restore things to their original condition. Like ClickClick 5, I only modified one of the two fans in this way, but it would be straightforward to do them both.

However, I am not entirely sure that the Xbox does, in fact, dynamically adjust the speed of the fans. Per speedy22’s measurements of the motherboard fan connections, “V+ Starts at +5.4 VDC and climbs to +11.8 VDC within 30 sec of power on.” Which suggests that the fans may be running at 12V pretty much all the time already, and that the cooling effects both ClickClick 5 and I have measured is due only to the other two parts of his mod.

If I were to do it again, I might forego the whole splicing operation and just pop in aftermarket fans rated to move a higher volume of air than the OEM fans.

Installing a heat-sink on the graphics coprocessor

This chip is small (about 20mm square), and I didn’t have a small enough heat-sink on hand. I did, however, have an old cheap graphics card in my junk box with a ~50mm square heat-sink, which I pried off and cut down to size using a fine-tooth hacksaw blade. Aluminum is easy to work this way. I cleaned the top of the chip and the bottom of the heat-sink with Goo-Gone, followed by 91% rubbing alcohol on a cotton swab.

I had some old unopened tubes of Arctic thermal adhesive that I intended to use to secure the heat-sink in place, but when I opened them I discovered they had turned to rock on the shelf. So I substituted a drop of thin cyanoacrylate super glue, which seems to have worked out just fine.

In this case, too, it is impossible to separate the effect of this modification from the other two modifications I performed at the same time, and it would probably have been smarter to do them one at a time. The 360 case is such a PITA to open, however, that I didn’t want to mess with cracking it open and closing it up any more often than I had to.

Adding an aluminum foil duct over the processor heat-sink

This is by far the simplest of the three mods, and in retrospect I wonder whether it might not also be the most effective. Quite simply, it amounts to Scotch-taping a small rectangle of aluminum foil (shiny side down) to the plastic fan duct, so that the foil extends over the junction between the duct and the heat sink, and further about halfway along the length of the heat sink itself. The idea is that partially covering the grooves in the heat-sink forces the cooling air to be drawn more from the front of the case, thereby moving more air across the heat-sink’s cooling fins, and at higher speeds.

If I were to do all this again, I would start with this mod, reassemble the Xbox, and measure the effect before bothering with the other two mods above.

Measuring the effects

I had on hand a cheap digital indoor/outdoor thermometer. It is battery operated, with one thermistor-based temperature sensor on a 6-foot wire lead. The idea is, you set the unit on your windowsill and run the remote temperature sensor outside the window. The readout on the unit then reports the outside temperature from the probe, and the indoor temperature from a second sensor which is integral to the case.

The tip of the remote temperature sensor wedged nicely into one of the holes in the grille covering the fans on the back of the Xbox case, right in the path of the outgoing vent air. All I had to do was make sure I took all my measurements with it wedged in the same hole to be confident of fairly consistent readings. I draped the lead across the tabletop as far as it would reach and into a clear plastic peanut butter jar where I kept the temperature readout with its internal sensor. This was my room temperature reference point.

My Xbox is on almost all the time. I took seventeen measurements of the vent air temperature and the room air temperature at pseudorandom intervals over the course of about three weeks. Over these measurements, the average vent air temperature was 102 +/- 1 degrees F, the average room temperature was 76 +/- 1 degrees F, and the average overtemperature was 26 +/- 1 degrees F.

After performing the three modifications described here, I took another fourteen measurements at pseudorandom intervals over the course of about two weeks. Over these measurements, the average vent air temperature was 90 +/- 1 degrees F, the average room temperature was 73 +/- 1 degrees F, and the average overtemperature was 17 +/- 1 degrees F.

These three mods, in other words, resulted in a vent air temperature 9 +/- 1 degrees F cooler, on average, than my OEM Xbox.

Anecdotally, this cooling effect was accompanied by a marked performance improvement during processing-intensive gameplay.

My dried orange peel box

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Here’s a link to the fantastic British brainy-toys site Grand Illusions that I’ve been hoarding for awhile, hoping to someday reproduce the process and post it as a tutorial. I have tried sun-drying several of the largest orange peels I can find on suitable forms, and shown above is the one functional round box that I have produced. As you can see, it is quite small and ugly compared to these:

Just posted this over at MAKE, but I wanted a dedicated page to show my progress towards reproducing the process so far. The original description mentions that the peels are “squeezed thin” after soaking, but before forming and drying, which is something I haven’t attempted yet. How, I wonder, do you squeeze an intact hemispherical citrus peel into a thin layer without damaging it?

Parafilm keeps bugs out of porch light

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Note parafilm wrap sealing globe to fixture.

One week's accumulation of bugs before Parafilm wrap.

Same fixture, 6 months after sealing with Parafilm wrap.

If you’re sick of dumping dessicated insect bodies out of your outdoor light fixtures, and your fixtures are of a type which is amenable to the process, you might consider sealing them with a couple turns of Parafilm laboratory film. Shown immediately above is my front porch light, six months after sealing with Parafilm wrap. Above that is the same fixture, before sealing with Parafilm, just one week after emptying. Note that this process only works with relatively cool bulbs, like CFLs or LEDs. Bulbs that get too hot will melt the Parafilm and/or cause it to break.

If you’ve ever spent any time in a chemistry or biochemistry laboratory, you are probably familiar with Parafilm, which is sold by the roll and is somewhere between wax paper and cling wrap (but considerably pricier than either). Parafilm is waterproof and resists many solvents, and sticks to itself to form air- and moisture-tight seals that hold up under most conditions for months, if not years. And while it’s probably not worth keeping around just for this use, once you play with it a bit you are apt to discover all kinds of non-laboratory uses for it.