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My wife's T-fal steam iron appears to have expired; it doesn't heat up. The thing has lasted way beyond its warranty period, and it's probably not worth looking into, but I'll look into it anyway.
The only fastener I can see is a single screw in a deep well at the rear of the iron. It looks to me like like the screw has a T25 security Torx recess head on it, and that presents a small challenge. I have security Torx bits, but they're the short style that go with a 1/4" hex socket driver. The well that the screw is in is too small a bore to accept a 10mm diameter driver shank. Here's a view of the situation.
I'll bore out the well to 13/32". There should be enough surrounding material that that will do no structural harm to the part.- - -
That worked well.
You just have to go lightly with the drill's speed control. (And it turns out that the screwhead's recess is T20, not T25. Torx recesses are a devil of a thing to gauge by eye.)- - -
Here it is with the rear end cap removed.
One of the 'claws' at the lower edge of the cap snapped off -- no big deal.Now I've got some 'digging' to do to find the fault.
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And here's the source of the trouble.
The thermostat's contacts have had one too many make/break cycles, I suppose, and they're not conducting current when closed. The heating element is ok -- it's showing a DC resistance of 9.8 ohms.Never use a file on thermostat or relay contacts. Cut a strip of N0. 600 silicon carbide paper, and use that to burnish the contacts. Give everything a good blow out with compressed air when you're done.
I'll reassemble the iron, and see if it works and doesn't leak. If it looks good, I'll append a detailed teardown procedure to this post.
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MONDAY, DECEMBER 26, 2011
Ressembly
I've decided to do this backwards. Since the iron is already apart, I'll document the reassembly sequence, and hope that it turns out to be worth the effort. For the disassembly sequence, just begin at the end of reassembly. (The screw dealt with earlier was the only security Torx item. The rest of the screws are all regular T20 Torx.)
1) Tank and Sole Plate w/Steam Chamber
- One M3.5x24mm pan head screw at the very front.
This screw was a bit difficult to get out. It's a thread-rolling screw[1] that was installed in the relatively soft metal of the sole plate, and it took metal with it as it was unscrewed. Here's a view of it.
That metal embedded in the screw's threads is stuck there like it's welded. M3.5 is something of an orphan in the metric screw sizes. It's seldom used, and neither of my two tap and die sets have an M3.5 die in them, so I can't chase the screw's thread to clean it up. By way of a serendipitous fluke, I happen to have some salvaged M3.5x24mm screws on hand, so I can just replace the screw with a new one. (The female thread is not so badly damaged that it can't still do its job.) Were it not for that, I'd have to tap out the hole in the casting to M4 or inch 8-32, and replace the screw with a more common size.Note the two holes in the top of the steam chamber. There are seals associated with those. Here's a view of that.
Given the age of this iron, I'm going to use a silicone RTV gasket compound[2] on the seals to ensure they don't leak. A curious feature of this iron's construction is that the only secure fastening of the tank to the steam chamber is that single screw at the front. The rear of the tank just perches -- there are no fasteners at the rear to clamp it firmly in place. (There's an electrical insulation wafer that acts as something of a 'wedge', but there are no screws.) With the tank reinstalled, I'll set this aside for a full day for the gasket compound to cure.There are two more items associated with the tank's installation that will have to go back in place at the same time as the tank. One is a little shield that goes on the stem of the thermostat. Here's a view of that.
The other is a rectangular insulating wafer that keeps the electrical leads spaced apart at the rear of the iron. Here's a view of that.
- - -Here it is with the tank back on.
That single screw at the front does not inspire confidence. It's a good thing my wife bought a new iron, because the odds of this working out well are looking slim to me. We'll see.- - -
TUESDAY, DECEMBER 27, 2011
Completion
'Time to finish up and try it out.
2) Knob
- It's just a straight press fit onto the thermostat's spindle; pry gently to get it off. It comes off more easily than it goes back on. There are three little 'claws' around the knob's hub that snap into the hole once you press hard enough.
3) Shell/Handle
- Set it back in place. It just lifts off at this point.
4) Three Shell/Handle Screws
- One M3.5x16mm pan head threading screw at the front.
- Two M3.5x16mm pan head threading screws at the rear.
5) Spray Nozzle
- Press its barbs back into their rectangular opening; squeeze them together to pull them out.
6) Water Spray Pump Check Ball
- One loose 3mm diameter ball in right side pump chamber. The 'steam burst' pump chamber on the left has a captive check ball.
7) Water Fill Opening Sliding Door
- Tape this item in place so it will stay put for now.
8) Bezel w/Pump Plungers
- This is mystifying. I'm going in the reverse order to how it came apart, but there's a snag now that I'm putting it back together. Here's a photograph of it.
Above and at either side of the two pump chambers, there's a protrusion interfering with reinserting the pump plungers.Much as I hate to admit it, I'm baffled. I see no other practicable reassembly sequence, yet this can't work. 'Beats the bleep outta me. I see no purpose that's served by those two protrusions, so I'm going to just lop them off with small sidecutters and get on with this.
I'll smear some silicone grease on the pump plungers. It appears that you have to force the plungers to go up beyond their normal 'up' position to be able to get this assembly back in place. Here it is, finally.
9) Steam ControlHere's a view of the steam control.
It's set now at position '0'. That probe lowers as the paddle is moved to its higher numbered positions.I'll smear some silicone grease on the probe and get this item back in place.
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That went back in easily.
10) Line Cord Receiver w/Indicator Light
- This item just perches; the iron's end cap secures it, although there are two places for screws to go. I installed two N0. 6 x 1/2" pan head sheet metal screws, to take some of the load off the end cap, like so.
11) Three Terminal Blocks and One Indicator Light Wire- The third photograph above shows the terminal blocks and line cord and indicator light wiring.
12) Line Cord and the Other Indicator Light Wire
- Thread the cord through the loose end cap and through the strain relief. Connect it as in the third photo above.
- The neutral conductor (the one with a rib on it) goes to the centre terminal block.
13) Line Cord Clamp
- Two M3.5x16mm pan head threading screws.
14) End Cap
- One No. 6 x 5/8" pan head threading screw, T20 security Torx recess.
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And there we are; it's all back together.
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Outcome
It works. Burnishing the thermostat's contacts got it going -- for how long I can't say.
The 'steam burst' pump works fine. The water spray function appears to have retired; the odd dribble is all it can manage. There may be something amiss with the seating of its check ball.
Was all this worth it? Not really, I tackled this out of curiosity. Canadian Tire has new equivalent T-fal irons on for half price this week -- $29.99.
It was interesting to see all the innards, and satisfying to get it more-or-less working, but economical repairability has been engineered out of modern appliances like these. They're quite intricately constructed, and disassembly is fraught with mystery and peril. They're well designed and made, they last a long time in normal use, and then they're landfill. So it goes.
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Notes:
[1] Thread-rolling screws are very hard screws that form their own thread as they're first installed by displacing metal, not by cutting metal as a tap does. They're recognizable by their vaguely 'triangular' cross-section appearance. This is the first time I've ever seen one used in a soft casting like this. They're normally used to thread holes in mild steel sheet metal. They're very common in the construction of laser printer chassis.
In steel, they make a very strong female thread because no material is removed in forming the thread. Manufacturers like them because they eliminate separate threading operations. In this application, the soft metal of the casting galls and adheres to the screw's threads -- not good.
[2] I'm partial to Permatex Ultra Grey; it's excellent stuff, and it's good for continuous exposure to temperatures as high as 450 degrees Fahrenheit. (At least, so I'm told by Permatex, and corporations never lie, do they?)
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So well explained with practical approach to repair. Thanks.
ReplyDeleteSo well explained with practical approach to repair. Thanks.
ReplyDeleteThank you for the Torx size.
ReplyDeleteYou're welcome. 'Glad to have been of help.
Delete