I decided I needed to roast my own coffee. Not wanted. Needed. Disgusta (Augusta), GA is singularly bereft of affordable sources for coffee one wouldn't have moral qualms about giving to a squirrel (if indeed squirrels could be induced to drink coffee), and Sweet Maria's has every exotic coffee worth drinking, green.
Skillet roasting? Too hit-and-miss for an introductory method. Oven-roasting? Possibly, but I'd rather roast outside. Aha! Popcorn poppers! Whodathunk you could roast coffee in a popcorn popper? Apparently, quite a few people, as it's the number one intro homeroasting method.
If you've got a BigLots nearby, you can have a fantabulous little roaster for eleven bucks (well, plus tax, of course...), and it even almost looks spiffy! This one's been christened the "Tom Servo One", for reasons which, with a little imagination, ought to become apparent.
Step 1: Round Up the Gadgetry!
Okay, you need two gadgetries. The first is the Toastmaster TPC3 Hot Air Popcorn Popper 1200W, available at BigLots for eight bucks flat. You'll have to remove it from the box and check the label on the bottom to ascertain the wattage. This particular popper has been used semi-popularly in the homeroasting community for several years. The model you can find at BigLots is a newer, sleeker design, but appears (from photos I've seen online) to be identical within. However, if you pick up a used, old-design TPC3, some specifics may not work out; general concepts remain the same.
The second gadgetry you'll need is actually a piece of foo-foo flim-flammery which you, if you're a red-blooded male, may be somewhat embarrassed to purchase -- and if you're of the opposite persuasion, you may be reluctant to cannibalize. Go to the Home Decor section, and look at the candles. What you're seeking is the Home Heritage Candle Holder by Alco. It looks like a little porcelain filigree base which holds a votive, topped with a small glass chimney. You want the chimney. Shell out three bucks for the pointless thing and we're on our way
Step 2: Eviscerate!
Second order of business, of course, is to make your nice, shiny new popcorn popper look decidedly (a) not nice, (b) not new, and (c) not popperly.
We take care of this by getting rid of the "modern kitchen chic" housing. First, toss that insipid yellow lid/chute from the top. We don't have any use for it. Figure out something to do with it and make your own Instructable later.
While you're looking at the top, peer into the popping chamber. Notice the air vents in the sidewall arranged along the bottom. If you don't get the Toastmaster, those vents are the feature to look for: they produce an upward swirl of hot air that aids in evenly roasting the beans. Poppers which force air from directly below will at best scorch your coffee, and at worst burn down several hectares of old-growth forest: well, your house, at least.
You'll need a T7 (Torx) screwdriver for this, unless you actually dismantle enough things to have triangular security bits lying around. No matter, though, since the T7 fits perfectly in the screws. Using the T7, remove the two security screws on the rear top surface of the black cover, and those on the front holding the cover on from below.
Now, with a Phillips bit, remove the cord spool from the bottom. Then pull/pry/spindle/mutilate the little rubber feet out of their seats so you can get to the next round of screws (You don't need the feet, but be nice to them: they may come in handy for some other DIY project someday). These screws are deeply-recessed (as are the set following), so a long-shanked screwdriver will be much more help than a standard ratchet-driver.
With the bottom now removed, set about the screws actually holding the heater/blower unit into the case. Be careful not to dent the popping chamber walls once the unit is freed, as it's rather important later on.
Step 3: Inflict Lasting Damage.
Until now, you can put everything back together and show yourself a wise consumer who always complies with the labeled uses of electrical appliances. And if you're careful enough to leave no trace, the warranty will probably remain intact. But the bold will press on. The bold will take a cutting implement and open up enough room in the bottom panel to ease the plug through, thus freeing the roaster-to-be of yet one more scrap of plastic detritus. The lazy will not want to go find a proper tool, and will instead grab a steak knife from the kitchen.
Now that you've taken the bold step, unscrew the strain-relief and chuck the now-useless bottom panel. You won't be wanting it.
Step 4: Putz Around the Popper Innards for Fun and Profit.
Admit it. You won't be satisfied until you completely take the thing to pieces, will you? Okay, mayhap you've less a curious streak than myself. This step is entirely optional -- for the sating of curiosity only -- and if you don't get things back together properly, you may have all sorts of bad things happen -- not limited to bad roasts or dire chain-letter-esque vengeances.
Okay, pop out the three screws holding the blower (bottom half) to the heater/chamber (top half). Carefully separate the two halves, taking care to not tug at the wiring. Set the mating ring to the side.
There, that's the blower. Not much to look at, is it?
On the other side is the heater. Gingerly remove it from the shroud, and look at it. It's made up of two sheets of some sort of heat-resistant-yet-flimsy-and-paperboardesque carding, with the nichrome element wound between them. Lining the shroud is a strip of this same material.
Now your curiosity is somewhat propitiated. Put it together how you found it, making certain that (a) the heater is fully seated within the shroud, (b) it bounces a little on the spring, indicating full seating, and (c) the strip of heat shielding is intact. Align the holes on the shroud with the holes on the mating ring and the holes in the blower, pop the screw back in (ensuring the lock washers are still in place), and whistle and look innocent, so no one will think you opened it up unnecessarily.
Step 5: Part of Your Base Are Belong to the Roaster.
We do still need a base for this. I toyed with the idea of making a spiffity metal base with miscellaneous hardware and some quarter-inch soft copper pipe, but I decided that I wanted to be able to say that the thing only cost me eleven bucks.
Hold the body section of the housing over a lamp, and mark the height of the four posts upon which the unit was mounted. Then, stretching a string from mark to mark, line off the circumference to ensure a straight cut. Now hacksaw the bejeezies out of it.
Well, not really, but carefully cut along the line with a hacksaw (cutting around the entire housing, rather than straight through). When you've separated the bottom ring from the housing, deburr it with coarse sandpaper.
Re-mount the unit on this ring, and congratulate yourself that it already looks pretty darn good.
Step 6: Mounting the Chimney
Here's where the chimney comes in: increasing the height of that dinky little roast chamber. I'm supposing you found the little piece of kitsch that I found. If not, you just need a glass chimney of some sort with a bottom outside diameter of 2-3/4 inches (the diameter of the chamber).
Ruler in hand, put your trusty Sharpie to work marking 1/4-inch slots 1/2-inch apart along the rim. Then, make six or seven marks spread around the circumference of the chamber 1/4-inch below the rim. Using your string again, mark a line around the chamber at that 1/4-inch depth.
Now pull out a set of side-cutters or diagonal cutters (seriously, don't worry about the tin-snips for this), and cut from each mark on the rim down to the depth mark. This may not cut completely through, but the metal is soft enough to allow for tearing along these almost-cuts.
With a set of pliers, bend down out the 1/4-inch tabs perpendicularly to the axis of the chamber, and bend the 1/2-inch tabs in to about 45 degrees.
Put the chimney over the chamber, and bend the outside tabs (opposite tabs together) in to firmly grip the sides of the chimney. Then, with a stout stick, reach inside the chimney and push the inner tabs up as well as you can, holding the chimney down firmly while you do so.
Step 7: Mounting the Switch
Yes, I realize that the switch mount was split between the upper and lower segments of housing. Calm down and grab your trusty tube of Duco cement. Slide back the insulating sleeves and detach the spade lugs connecting the switch into the circuit.
After a suitable period of time, reconnect the spade lugs.
Voila, and stuff.
Step 8: Does the Chimney Need an Insulated Grip? Yes.
Of course it does! So grab a roll of jute or sisal (or cotton, if you wish -- just not nylon or anything else that might melt), wrap the "neck" of the chimney in whatever creative fashion you wish. The point here is to have something to grab onto the chimney by when the roast is complete and you're trying to take it off to dump the beans out of the roast chamber.
Now is also the point where, if the forward-cant of the roaster bothers you, you can add some "feet" made with long wood screws to the front bottom screw-holes. It's really up to you, as "leveling" the machine isn't necessary for proper operation.
So ya wanna actually roast in it now? Pending an appropriate Instructable, I'll refer you to Ed Spiegel's excellent Popper Roasting Tips.
There is one possible modification you may wish to make to this design. While the problem with most hot-air roasters is overly-fast roasts, at times (such as in cold weather) it may be desirable to speed up the roast by restricting airflow through the chamber, allowing higher temperatures to develop. If this is the case (i.e. if the weather is cold enough that your roast is taking fifteen minutes with no sign of finishing), simply remove any "feet" you may have put on the bottom and re-mount the entire roaster on the original bottom plate.