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!

1 comment:

  1. So, this site lead to me upping my act dress-wise. Which lead me to want to want bespoke. Which lead to me wanting to learn it. Which lead to learning about the Iron work (stretching and shrinking you'd mentioned in the Jacket Project). Which lead to the purchase of a fully functioning 15 lbs. Dry Iron from the early 1930's at the cost of $37 when all was said and done. Next acquisition is a mechanical sewing machine. You'd be entirely surprised how many vintage Singers can be had in Phoenix, AZ off of Craigslist. Not just treadle either. Electric and fully functional and relatively inexpensive.

    But, I digress. Back to my original point and that about my New York Pressing Company dry iron that is more than half the weight of my Two-year-old son. It was quite the steal as well as being better than new but, it has some scorching on the quite hefty soleplate. What would you recommend as a good way to get the scorching/rusting on the very bottom? Progressively finer sandpaper? Mr. Thompson, I am in need of your sagacity, sir.

    P.S. Also, quite coincidentally, I was reading through Cutter and Tailor and found some of your old posts. It seems I was destined to stumble across your tutelage and that it would lead me to Tailoring glory (but, it the least, some nice, self-bespoke, clothing. Now to figure out the finer points of hand sewing one-handed. That and getting my Wife to wrap me in duct/duck tape so I can FINALLY build my Tailor's form. But, I made her promise to do it this Sunday, so that's a plus.