Friday, November 30, 2012

Irons in the Fire

(Part 3 of the series, "Iron Man.")
Chapter 95
In this, the third part of what shall surely be known as the Great Iron Rebuild of 2012, we'll turn our attention to the refurbishment of the soleplate, complete the disassembly, and prepare for the final cleaning and reassembly next week of our venerable General Electric F50, which will then be ready for another half century of dependable service. 

As with any restoration project, (as anyone who has ever owned a classic car will tell you,) the only limit to perfection is how much time and money you want to spend. You can build a hundred-point concours d'elegance winner, or a just a driver to cruise around town. As we saw last week, the soleplate has some, well, issues: viz., the hex-head mounting screws are rusted in place, and the steam lid is warped. We've gone as far as electrolysis can take us. If I were truly inclined to make this perfect, there are tricks to use to get those screws out. I could soak the screws in penetrating oil for days, freeze the soleplate, then expand the metal around the screws with a butane minitorch. If all else failed, I could just drill out the screws and tap new threads. 

Regardless, the "pretty" way is to remove all the bits, take all the steel down to shiny metal, flatten the steam lid, polish all the aluminum to a smooth gloss, machine the mating surfaces, make a new gasket, and put in new stainless machine screws. It would look better than new and last for a hundred years...but you'd never know it was there. 

Well, we're not going to do that. We're making a runner. It'll look good on the outside, but everything "under the hood" will just be made to work, aesthetics be damned.

First, we'll patch the blown-out steam box gasket. For this, we will use the best metal bonding material known to man: JBWeld. If you're not familiar with it, it's a two-part high-temperature, high-stress epoxy. Before it cures, it's like thin putty. When it's dry, you can machine it like metal. The Kwik-Weld version here has a six minute working time, and cures in six hours. Get a wooden skewer, and something to mix on (I'm using tinfoil).

Dispense a small and equal amount from both tubes, and mix them together. The clock is now only have a couple of minutes to work with it.

Using the pointy end of the skewer, pick up a bit of the putty, and roll it in along the gasket line with a pull-and-twist motion to the skewer. You'll probably get three or four inches along before the putty starts to cure. Just smooth it down in the crack and make up another small batch.

Don't forget the bit down inside, under the mounting plate. With a steady hand you can get the skewer in and roll the putty just where you want it.

The lid sealed, using just enough material to close and seal the gaps. After it cures, you can sand off the excess along the sides for a neater finish...but functionally, the steam box will now work like new and direct all the steam down...instead of up, out, in, and every direction except down.

Now let's turn our attention to that sole. Ugly you will agree.

Here's where the elbow grease comes in. If you don't have an orbital sander of some sort, a sanding block will do the job -- eventually. Start coarse, say, 60 grit or so, and using longitudinal strokes, start shaving away. The sole is warped somewhat, and sanding against a flat block will get everything on the level -- again, eventually. (This is a slow and messy process. Black aluminum dust will get everywhere, so be warned.)

You can go as far as you want to with this. You can just take off the scorch and discoloration if you want. You can take it to the next stage and rub out the major scratches and knock down the high points. Or, you can spend a week, get it dead-level, and progress through finer grit paper until you are wet-sanding with 2000 grit and the sole is mirror-smooth. It's up to you. This pic is the tail-end of the knock-down stage. Minor scratches don't worry me, so I won't go much further than this point.

With the soleplate sorted out, let's turn our attention again to the top end of the iron. The only visible fastener is a hex fitting under the steam dome, so let's take that off.

The hex fitting, it turns out, is a plug with a small hole in it. The hole is stoppered with a needle up inside the reservoir. Releasing the steam button on top of the iron retracts the needle, permitting the water to drip slowly through the plug onto the soleplate, where it flashes into steam. The fitting also holds on the steam dome. The dome presses tightly down onto the hole in the steam box lid, preventing steam leakage.

There's no apparent visible way to remove the reservoir...but push lightly against the reservoir with one hand against what feels like spring pressure, and with the other hand, rock the fill funnel back and forth...

...until it works free. The fill funnel is the only thing holding the reservoir in place.

The reservoir pulls straight down out of the housing.

Now we see the source of that spring resistance: a spring ring at the bottom of the fill neck. It pulls right off. That spring insures that the steam dome presses firmly down against the soleplate once the housing is bolted in place.

Pull the spring-loaded needle straight out of the fill neck.

Keep the needle safe, don't let it get damaged! It looks a bit like a gravity-feed carbureutor's needle and jet, but a more accurate parallel would be the stopper in a bathtub. It doesn't have to be a perfect fit to work.

With the reservoir out and stripped, test it for leaks. Fill it up and see if there's any seepage. If there is, and you're handy with a soldering iron, that's the "proper" way...or you can break out the JBWeld again and plug any pinholes.

Turning to the underside of the housing, the handle is held on by three hex-head screws. Remove those...

And the handle lifts right off.

Then, we can remove the controls. The thermostat lever is held on by a friction fit. Put your thumbs on either side of the handle like this, press down and slide forward...

...and the thermostat assembly slides right out of the handle.

The assembly is stacked as shown: lever on the bottom, setting display on top, with a spring plate sandwiched between. The spring plate holds the display in place, and gives some drag resistance to the lever.

And finally, the Big Red Button.With everything else out of the way, the button simply drops out of the handle.

And that's where we'll leave off this week: with the top half in bits, and the bottom half ready to go. Next week, we'll clean and detail the showy part, button everything back up, and take our new car --er, iron-- for a test drive!

Friday, November 23, 2012

Ion Iron

(Part 2 of the series, "Iron Man.") 
Chapter 94
This week continues our mini-series detailing my little holiday project: the inspection and restoration of an early '50s vintage model F50 General Electric steam iron. When we're done, we'll hopefully have brought a world-class shirtpresser back from oblivion, and ready for another lifetime of service.

Last week, we'd gotten the soleplate off, with its electric components, and figured out how said components work. The steel parts are all very rusty, and any attempt to remove them from the aluminum base is fruitless. We'll try to remove the rust somehow, and the easiest way to remove rust from parts that are rusted together, is electrolysis

Rust is the oxidation of metal -- a natural electrical process that can thus be reversed by artificial means. Basically, if the rust is negatively charged, (in other words, ionized,) and the rusty item is submerged in an electrolyte with a positive electric source, then the rusty ions will boil off the negative side and be attracted to the positive side. It's the same theory as with a vacuum tube, or an electric battery cell.

What we need to do first is to assemble a non-conductive container, an anode, some wire, the electrolyte, and a voltage source. Fortunately, all of these things can be made with simple household items. 

The container is simple enough -- a plastic office trash can can be used as a bucket. 

Next, we need a sacrificial anode, something made of iron or steel. The simplest and easiest anode is a simple tin can, cut apart and spread out like this, to expose the largest amount of surface area. Don't use anything stainless steel for the anode: the process will pull the chrome out of the stainless in the form of tiny amounts of chromium trioxide. It's very, very toxic. 

We need a hanging wire, to suspend the parts in the bucket, and attach the electric leads. A wire clothes hanger is perfect for this. Straighten it out with a pair of pliers, and bend it to shape. Suspend the anode inside the bucket, about an inch off of the bottom, like this.

Check the continuity from the end of the wire through the can, to make sure the electricity will flow...

...then bend a wire to suspend the soleplate inside the bucket. You want the entire surface and all the components to be electrically charged, so hang it from two points: one on the thermostat side and other on the base side. Use the continuity tester to make sure all points of the iron are continuous through the wire.

Next, we need to make the electrolyte. The best (and safest) electrolyte for the process is sodium carbonate, also called soda ash, washing powder, or Na2CO3. If you don't have sodium carbonate washing powder, don't fret: there is an easier solution. Baking soda is sodium hydrogen carbonate, also called bicarbonate of soda, or NaHCO3, which is a little less effective, but still usable. Better yet, take a quarter-cup or so of baking soda, scatter it on a cookie sheet, and bake it for an hour at 300° F. The heat releases water vapor and carbon dioxide from the sodium bicarbonate, and you're left with soda ash. If you remember your high-school chemistry, what you're dong is 2 NaHCO3(s) = Na2CO3(s) + H2O(g) + CO2(g). Voila, you've just made sodium carbonate!

Dissolve your newly-made soda ash in warm water, and submerge the soleplate completely. Now you're ready for the application of mass quantities of free electrons.

If you have an automotive battery charger, you're all set. This one is user-selectable to push 10 amps of direct current at either 6 or 12 volts. (This is another vintage item of mine; it's been ready to keep my batteries charged since the 1970s.) Newer chargers, with computerized innards that are designed to detect the battery's state of charge and modulate its voltage output for optimum charging, may not let you "repurpose" it the way we plan to do...

...which is this! Hook up the charger's clamps to the wires, outside the bucket. Remember the negative side is the cathode, (the iron's soleplate,) and the positive side is the anode, (the tin can,) since the goal is to move the negatively-charged iron oxide anions off the cathode onto the anode. Hooking it up backwards will run the process backwards, so make sure you have it the right way 'round.

Turn on the charger; start at six volts. You should soon start to see bubbles rising from the cathode, and the froth on top will start circulating around the anode. Rusty scum will float to the surface, heavier particles will collect in the bottom of the bucket.

Safety warning -- keep the charger well separated from the bucket. You're playing with electricity, so keep your hands out of the water. Do this in a well-ventilated area, or preferably even outdoors: electricity also cracks water into hydrogen and oxygen, so you want no stray sparks. Needless to say, turn off the charger before you remove the clamps. Better safe than exploded. 

Check the mix every twenty minutes. Strain the scum off, rinse off the anode (it will accumulate scum as well,) pour the electrolyte into a second bucket and discard the rusty buildup at the bottom. Add extra water as needed; you don't need to replenish the soda ash as it doesn't get used up. Electrolysis is largely a line-of-sight process, so turn around the soleplate to face the bottom toward the anode every other cycle, as shown here. 

If this were a solid chunk of iron, we could leave it boiling for days; when all the rust is gone the reaction stops. Since we have a chunk of aluminum in the mix, we have to be a little more observant -- the aluminum will keep boiling off without end. ("Boiling" in the sense of boiling off ions from the metal. The water may get warm, but it will not reach an actual thermal boil.)

After several hours of boiling in 20-minute segments like this, I noticed that the topside of the plate was not getting as clean as the rest of the plate. I checked the ohms again, and found that the top plate had lost continuity. This necessitated a shift in the wire, hooking it 'round the top plate until all points of the iron were again continuous. It's important to inspect your work every so often for this reason: if any part isn't getting electricity, it won't shed its oxidation.

As the anode collects rust, it will pass less electricity, and the amps will fall. This is the tin can after just a couple of hours. Keep an eye on the cathode -- when the bubbles start slowing to a trickle, bump the charger to 12 volts to keep things vigorous. When even that doesn't work, you might need to replace your tin can.

A sure sign that the rust is still falling off is thick yellow scum at the top of the bucket. Keep an eye on this as well. There will come a point when the yellow scum will stop in favor of grey scum. At that point, the steel de-rusting has stopped and the aluminum is boiling off. There may still be black rust on the steel parts, but the aluminum has become the easier reaction. There's nothing you can do at this point but keep a careful watch on the aluminum -- let it go too long, and it will start to pit and degrade!

How long to let the process go is a matter of judgement. I stopped after about four and a half hours of total boil-time. There's still a bit of black rust on the mounting plate and leads, but closer inspection shows that the loose rust and scale are gone. The aluminum is largely clean, but I daren't go any further for fear of pitting and degrading the base. When you've decided electrolysis time is over, rinse off the soleplate thoroughly, and dry it immediately under a hairdryer to prevent anything flash-rusting again. Dump out the water (there's nothing toxic there: just rusty water and washing powder,) and clean up -- you're done!

Now we can get a closer look at the soleplate, and do a bit of sleuthing. The reason this iron was donated to the secondhand store is becoming clear: it had at some point badly overheated. Perhaps the pivot got out of adjustment, most likely through the mounting arm becoming weak over time through innumerable heatings. Eventually, the thermostat was unable to cycle on and off: the pivot would simply give with the flexing of the bimetallic strip, and the iron was full-on all the time -- even when it was turned off.

The triangular steam box lid, held on by seven screws, and insulated with a steam-tight gasket, warped badly in the excessive heat. So badly, it sheared the head off of the foremost screw, and cracked the lid at the left-front screw. The pressure created by the warped steam lid on the point of the sole cracked it at the button slots as well, just adjacent to the steam outlets; (but these are hairline cracks that don't extend all the way through the base.)

The damage was probably caused slowly, and the iron used for a time in this condition, but the steam wore through the gaskets, and blew out and inside the body of the iron, rather than down through the sole. This caused the excessive rusting of the mounting plate just behind the steam lid, and deteriorated away the asbestos insulation. So from the original owner's point of view, the iron stayed on high and wouldn't steam well, and limped along until it was thrown out. Alas, a simple adjustment of an eighth of a turn on one screw would have prevented this.

Too bad for her, great for me...for this is very fixable. And next week, we will fix it, and get on with the project of restoration. Stay tuned!

Click here to go to the next essay chronologically,  Part Three of Iron Man.

Click here to go back to the previous essay chronologically, Part One of Iron Man.

Click here to go back to the beginning.

Friday, November 16, 2012

I Am Iron Man

(Part 1 of the series, "Iron Man.")
Chapter 93
These next few weeks, I am embarking on an enjoyable little project, and I am going to take you along for the ride. As you know, one of the essential tools for being Dressed Like a Grownup is to be in possession of an iron: and yet, I have said precious little on the actual subject of irons thus far. 

I have briefly mentioned irons before, if only to mention that you need to have one and learn how to use it. Shirts need to be pressed; it's not an optional sort of thing. The process of wearing fabric pulls and stretches and wrinkles it, and washing said fabric pulls and shrinks and wrinkles it again. Ironing isn't just to make your shirts look good -- it is essential to take that mangled and distressed fabric, especially cotton and linen, and put things right again, straightening the fibers with heat, moisture, and pressure, aligning the warp and weft so that your shirts fit just as well on the thousandth day as they did on the first.

Fortunately, although they are essential devices, they are also very simple ones. One needn't purchase the largest, most expensive iron on the shelf -- the lowest-priced one you can find at the Big Box Store will work nearly as well as any other, for very little money.

The problem with new low-price irons is that they are largely light in weight and cheaply made. That's just the world we live in. Heavier irons are better, because the iron itself does more of the actual work of pressing. Older irons are also better, because they are made of a much higher build quality. And used, heavy, old irons are best, because they can be had for nearly nothing. So let's look into the world of Vintage Ironing.

Specifically, the venerable old standby, the General Electric F50. One of the first electric combination steam irons, the F50 first appeared in 1950, and it is still made today, in a slightly modernized version sold under license by Black and Decker, as the Model F67E.

Its longevity reflects its many benefits; it's rugged, simple, and heavy enough to give a good press, but not so heavy and cumbersome that it's a chore to use. At the time it was marketed as "light, light," since it was a fifth the weight of the old sad-irons, but it's still easily double the weight of most modern irons.

Another benefit: G.E. made them in vast numbers for more than a half-century, so they are plentiful to find, and if you do find one, the chances are it still works, even if it looks like it's been through a war.

Which brings me to my own newest acquisition: a G.E. 53F50! It was sitting, alone and forlorn in a shop, and even at two dollars, no one wanted it. It looked like it had a long and hard life, but I found its charms irresistible.

The G.E.'s soleplate is a little discolored, scorched and scratched, and there is some hard-water scale in the steam holes, but that's nothing that can't be smoothed out and re-surfaced with a little elbow grease.

Besides, who could resist those mid-century aerodynamic lines, that chunky ergonomic handle, the cloth cord, and all that polished stainless steel? That's when I decided to give it a good going-over and restore it as best I can. It will most likely be the last iron I'll ever have to buy, and as a bonus, you'll get a guided tour of it as well, so if you ever come across one yourself, you'll know just what to do!

Before we even plug it in, let's check it out electrically. The cord is the old cloth-wrapped two-lead type, and the plug is unpolarized and ungrounded. Nothing wrong with that in and of itself: appliances were wired like that for decades. But time and wear may have taken their toll, and if the cord is internally shorted, or if an internal connection has shorted to the chassis, it may make for a Very Bad Day -- especially for an appliance that keeps water and electricity in close proximity. So better safe than sorry! 

At the back of the iron, there is a plastic hatch held on with a single flathead screw. Undo this screw, and remove the hatch. 

Behind the hatch are two more flathead screws, that hold the wires coming from the power cord. The wires terminate in spade connectors.

Unscrew these slightly, enough to work loose the spade connectors and slip them free. Be careful; the wires are probably stiff after a half-century of doing their jobs.

The rubber boot at the end of the cord is press-fit into the slot at the rear of the handle. Rock it forward and back gently to loosen it up...

...and pull it straight back to free it. Be careful not to catch the spade connectors on any edges along the way.

Now that the cord is loose, give it a good inspection. See if the plastic plug is burnt or cracked, or if the plug blades are loose. Feel carefully along every inch of the cord, through the cloth. You're feeling if the wires inside seem to be kinked or broken, or if the cover is frayed or burnt. Unless the iron has led an unusually hard life, there shouldn't be any problems: cloth-covered wire is very robust and over-engineered.

Now you'll need something to test the continuity; I'm using the ohmmeter setting of my trusty multimeter. You'll want to test each leg through the length of the cord to make sure there are no internal breaks or high resistances along the wires: you want to see something close to zero Ohms. (I'm reading 0.6 Ω on this leg, which is just fine.)

Then do the same thing, but with opposite legs. You're testing now for a short across the wires, so you want to see infinity Ohms (in other words, no reading.) This cord is good: each leg runs true and independently of the other.

With the cord vetted and out of the way, we can turn back to the iron itself. The only other visible screw is a small Phillips at the base of the soleplate. Remove it...

...and pull the base plate off.

The other fasteners are hidden under the stainless-steel trim plate under the handle. It is clipped in place along the edges, under slight tension. To release it, push on the center of the plate with one hand, pull one edge up with the other hand...

...and remove the plate. Underneath, you will see two nuts and a hole. The reason for the hole we will see shortly.

Loosen and remove the nuts. These two nuts are the only thing holding the body of the iron to the soleplate.

Lift the top half directly up to remove it. There is a long rod that runs all the way up to the top of the handle, so be prepared for it. The top half is now free. That hole we saw from the top side is a little access port to an adjusting screw. The first thing that strikes us is that the mechanism seems very simple. The second thing is that it is very rusty! And the third, is that there is no asbestos insulation between the top and bottom halves to protect the connections. Unexpected, and a little odd...It would seem this iron has a story to tell.

This is a peek inside the top half. The brass bit is the water reservoir. We'll deal with this later.

Turning our attention to the soleplate, let's see what secrets it holds. That long rod is a cam turner. It connects the thermostat lever on the handle to that round, wedge-shaped cam. On top of the cam is a follower, connected to a bimetallic strip. The other end of the follower is a switch contact, with an adjustable pivot point between the two. It's pretty difficult to see amidst all the rust, so let's take a more schematic view.

That's better! As you can see, most of the rusty metal is just the mounting plate for the cam and the thermostat, shown here in grey. The thermostat is electrically insulated from the base by ceramic spacers, shown here in orange. The only electrically "live" part is in green. I've simplified the actual position of the Hot and Neutral leads at the rear of the iron for further clarity. (Since the plug is unpolarized, the leads could actually be in either position.) Follow the path starting from the Hot side: electricity flows through the line to the bimetallic strip, in dark green. It passes through the strip, across just behind the wedge cam, and back down a rigid arm beneath a ceramic pivot (in orange) to the contact switch, in red. If the switch is closed, the electricity flows to the heating element, a U-shaped electrical resistor that is embedded in the foot of the iron and runs around its perimeter, to the Neutral leg of the cord, and back into the wall.

Now let's see how the thermostat works. Put the cam turner into the cam and rotate it fully counterclockwise. This is the "off" position. Notice that the cam follower is at the highest point of the cam, and the bimetallic strip is flexed like a spring. The pivot in the middle of the arm is the fulcrum that holds the switch end down off its contact, and no electricity flows.

Rotate the cam fully clockwise, which would be the hottest, or "linen" setting. The cam follower is now at the lowest point of the cam. The bimetallic strip is relaxed a bit, the arm is sitting just clear of the pivot, and the switch is firmly in contact; in other words, the fulcrum is now the switch and not the pivot, and the electricity flows. 

The thermostat works because of the unique property of that bimetallic strip: it turns thermal energy into motion -- in other words, heat makes it bend. The hotter it gets, the more it curls upward. When the iron is turned on, the soleplate heats, and the strip starts to bend. The cam-end of the arm slowly moves up, until it comes into contact with the pivot. Further movement upward at the cam-end then pulls the switch-end down, and the switch opens, breaking the circuit. The soleplate and strip cool off slightly, lowering the cam-end of the arm until the switch closes, completing the circuit, and the cycle starts again. When the thermostat is on a hot setting, the follower starts low on the cam, and the arm has longer to travel before it makes contact with the pivot. So its on cycle is longer than its off cycle. When the thermostat is on a low setting, the cam-follower is already near the top of its travel, so very little heat will break the circuit: its off cycle is longer than its on cycle. So by simply switching its power on and off, the iron modulates its own temperature. It's simple, elegant, bulletproof, and completely computer-free.

This is all fine in theory, but we have to make sure everything is still working as it should be. Get out the ol' multimeter again and let's starting checking the continuity. First, put the connections on each end of the resistance element. It shows 12.4 Ω. Plugging in the numbers to Ohm's Law, 120 Volts at 12.4 Ohms gives 1160 Watts of power. We know this is an 1100 Watt iron (as seen on the first pic) so we can call our heating element in spec. (This also gives us a taste as to why what we're doing is so important: for Ohm's law also tells us that this thing will pull 9.68 Amperes, which is more than enough to kill you very dead.)

Now we'll check the off switch. Here's where you use that adjustment screw on top of the pivot. Put your testing leads at each end of the thermostat, as shown. Rotate the cam to the "off" position and make sure you get no reading on the multimeter: if not, adjust the pivot down until the switch just opens.

Now turn the cam slightly; the switch should close in less than an eighth of a turn. I'm showing 0.6 Ohms through the thermostat circuit, which is fine. You might have to fiddle with the pivot adjustment a bit to make the switch open and close just right between "off" and "not-off."

Put the testing leads on the cord attachment screws, and test the resistance through the entire circuit. (Make sure the cam is in the on position!) 12.9 Ohms looks good.

This next one is important: move one testing lead to the soleplate itself and make sure you aren't getting any power leaking to ground. I'm showing no reading here, so we're good, and I probably won't electrocute myself.

So, we'll leave off this week knowing that electrically at least, our new/old iron will work as well as the day it came off the assembly line. Next week, we'll see what we can do about clearing off the rust and scale, so it will look as good as it works, on the inside as well as the outside!