T-FAL Ultraglide Plus Steam Iron Repair

[Note: You may want to scroll way down and read the 'Outcome' section before embarking on a repair effort on one of these irons.]

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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.

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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.)

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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.

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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.

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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 Control

Here'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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FEEDBACK

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Moisture Meter 'Repair' and Maintenance

Someone brought me this moisture meter with the complaint that it wasn't working.

There's not much to these things. All this one consists of is a little DC millivolt meter and a probe. Here's a view of the back of it opened up.

The meter's full scale deflection value is 330 mV -- a very small amount of electrical energy will deflect the needle.

The key to the meter's operation is the probe. The shaft-tube and tip are made of dissimilar metals, electrically insulated from one another.

The shaft-tube is connected to one terminal of the meter; the tip is connected to the other terminal. That's all there is to it.

Here's a view of the end of the probe.

I don't know what the tip is made of, but it's prone to oxidize, and tip oxidation is what impairs the operation of these units. Note how dull the tip's surface is in the photograph. I cleaned it up with sandpaper, and the meter is back in working order.

Theory of Operation

I've always wanted to write the heading, "Theory of Operation", so I could swear never to do it again. That phrase, "theory of operation", makes me gag every time I see it in a machine service manual; it's so pretentious and patronizing -- as if the writer is delivering 'special' knowledge from the podium of a university lecture hall. As far as I'm concerned, there's nothing 'theoretical' about it; the thing operates. If we need a heading for an explanation of how a thing works, what say we just use, "How it Works"; or, "Characteristics". Or, if we want to appear all techno-corporate, "Functionality". I'll leave 'theory of operation' to all the technical writers who haven't a clue about what they're writing about, and there are more than a few of those out there.

How it Works

When the probe is inserted in moist soil, the soil and the two metal elements of the probe mimic the operation of one of these.

The combination comprises a rudimentary primary voltaic cell. (A 'primary' cell is one that can't be recharged. Rechargables are 'secondary' cells.) The shaft-tube is the positive electrode, the tip is the negative electrode and the moist soil is the electrolyte. (Soil that plants can grow in is not 'dirt'; it's quite complex stuff with many ingredients and micro-organisms.) Within some limit, the moister the soil, the more energetic is the resulting cell, and the higher is the meter's reading.

Maintenance

Never leave the meter in soil as a 'monitor'. A characteristic of primary cells is that one electrode sacrifices itself to the cell's operation; in this case, the tip of the probe. A probe tip left in soil will erode.^[1]

After taking a reading, wipe the probe clean. A smear of WD-40 on the tip wouldn't hurt at all. When the tip looks dull from oxidation, brighten it up with abrasive paper.

And there we are -- nothing 'theoretical' about it.

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Note:

[1] Note the pitted appearance of the probe's tip in the photo. This is not the first time this moisture meter has been in the workshop. It was once brought to me after having been left for quite a spell in soil. The tip looked awful. Its appearance was clear evidence of the electrode 'sacrifice' phenomenon that's typical of primary voltaic cell operation. Scraping and abrading the tip got it working again.

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FEEDBACK

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An N. Slater Co. Ltd. Woodworking Vise

My son has been clearing out my deceased father's garage, so he'll have a place to restore an old car, and he's been finding the odd interesting bit of gear, like this woodworking vise.

On the front it says, "THE N. SLATER CO. LTD. HAMILTON CAN".

N. Slater currently exists as Slacan Industries Inc. I don't think they make woodworking vises any more, though. I emailed them to inquire about the vise's likely age, and they never replied. I should thank them for reinforcing my opinion of the corporate world.

This thing is just begging me to restore it to pristine condition; I guess I'll have to comply. Consider it a work in progress. I'll update this post as I go along with it.

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MONDAY, DECEMBER 26, 2011

The Dog

This leaves a bit to be desired.

A vise dog is something I never have use for, but this is a restoration so I have to come up with a sound facsimile of the original part.

I'll have to find some steel bar stock, 1/2" x 3/4" in cross-section, and 2 5/8" long. That's going to be a challenge; I have nothing like that on hand.

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The Jaw Facings

What's currently on it for facings is two wretched, undersize pieces of 10mm plywood. That has to go and be replaced with proper hardwood facings, 3 1/2" x 7 1/4". I have two excellent pieces of oak on hand for that.

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The Rail-Rod End Terminations

Yuck. A couple of folded over nails.

I'll replace those with the correct size of cotter pins, and add two close-fitting flat washers or something for a more elegant rod end termination.

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The Handle

See the first photo above. It's currently a 12 1/2" length of 15/16" diameter hardwood dowel, with a screw in each end for retention. It's actually not bad; the length is good and the diameter is about right. I might keep that, but I'll have to come up with a better-looking treatment for handle retention.

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WEDNESDAY, DECEMBER 28, 2011

The Rear Jaw/Foundation and the Nut

The nut is interesting; I've never seen this done before.

The nut is self-retaining. Its length is it's axial retention, and the 'wings' are its angular retention.

The nut's overall length is 4 1/2". The thread in it is only at the front (under the wings); the thread extends back 1 3/8", then the rest of the nut's length is just hollow.

That metallic paint looks pretty chintzy -- I'll paint it the same colour as I paint the jaws. (I haven't decided on a colour yet. For a restoration, I should stay true to the original, but that grey looks dismal to me. A dark blue similar to Record blue would look good.) Anyway, the next stop for the nut is the parts washer tank for a thorough degreasing.

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The Screw and the Crank-Tee

The only way to get the screw out is to grind the peening off the end of a big rivet.

Here goes.

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THURSDAY, DECEMBER 29, 2011

Stymied

That didn't work out worth a bleep.

It's not often that I have to say I'm stymied, but I'm stymied. It looks to me like that rivet was installed with an extremely tight interference fit, then peened only to look right. They could have forgone peening it; nothing would budge that rivet. I'll have to clean the screw and paint the front jaw and the crank-tee with the screw still in place -- clumsy but doable.

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TUESDAY, JANUARY 3, 2012

The Screw

That bit of failure behind me, I must point out an interesting feature of the screw. It's an Acme, two-start thread. Here's a view of the end of it.

The photograph reveals it poorly, but what's pictured is two interleaved threads -- hence, 'two-start'. (I've daubed the starting points with correction fluid to make it clearer what I'm on about here.)

Linearly, the thread appears to have a pitch of 4 tpi (four threads per inch). A 4 tpi thread would have a lead (linear advancement per revolution) of 1/4". But this thread has a lead of 1/2" -- one revolution of the screw moves the front vise jaw 1/2". That's because it's actually two interleaved 2 tpi threads (two threads per inch gives a lead of 1/2"). The apparent 4 tpi thread is really two 2 tpi threads -- hence, a 1/2" lead.

This outfit, Roton, has some excellent information on screw threads.

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The Rail-Rods

The big 1 1/4" A/F hex nuts at the front came off fairly easily. Before loosening them, I scribed 'L' and 'R' on the rear ends of the rods, and made punch marks at the back of the front jaw to identify the rods' angular position. That may have been overly cautious of me, but it never hurts to anticipate the possibility that the factory might have done a bit of selective fitting here and there. And unless you mean to make alterations for some purpose, making arrangements to ensure that a machine goes back together exactly as it was is a good practice regardless. Here's a view of the threaded ends of the rods, and the hex nuts.

The rods are 7/8" diameter by 16" effective length. The reduced diameter at the front is 3/4". The threads are 3/4"-10.

The rods show quite a bit of evidence of rust-pitting through the paint. Painting the rods may not be a bad idea, really, but not that cheesy-looking 'colour'. If I do repaint them after stripping them, it'll be black.

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Trial 'Installation' and Assembly

After a thing's been painted is most emphatically not the time to discover an oversight or a flaw that needs correcting. The only way I know of to guarantee a smooth final reassembly is to 'begin at the end', so to speak. I'll rig an installation mockup with the help of my press, and make certain that final reassembly will contain no surprises. Here's what I've come up with.^[1]

And I already see a little problem that I'd best resolve right now -- the front left corner of the foundation doesn't want to tuck up against the undersurface of the 'bench' as it should. There may be no fix for that aside from shimming somewhere, but I need to work that out before proceeding.

When I have that settled, I can fully reassemble the vise and evaluate every aspect of it, and I can fabricate the new jaw facings and do a trial installation of them.

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'Found It

As I suspected, the foundation casting isn't quite true -- tightening the screw at the right rear corner forces the front left corner downward. A bogus American Express card that came in promotional junk mail will make just the shim I need to correct it. (I keep those things for just this sort of situation; they make great shim stock.) Here's the shim washer I made from the card.

Now I can remount the foundation correctly and get on with it.

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SATURDAY, DECEMBER 31, 2011
Trial Assembly

Here it is back together less the nut.

It doesn't show well in the photo, but the jaws are not parallel vertically -- they only actually meet at the top edges. That's a very good thing, and a sign of a well-designed, well-constructed vise. When forcefully tightened on a piece of work, flexure and deflection of the rail-rods won't result in grip being lost at the tops of the jaws -- the work will remain secure.

I've added a thin flat washer under each hex nut; a nut will tighten nicer on a steel flat washer than directly on a solid cast iron surface. The slight loss of thread engagement is unimportant, but I will see if I can find even thinner stainless steel shim washers for the purpose.

After taking the above photograph, I backed out the front jaw assembly and installed the nut.Were I doing that on an actual final installation, I think I'd want to have help with it so I wouldn't mark up the paint; the nut is a clumsy thing to install unassisted.

Here's a good way to treat the rail-rods' end teminations.

3/16" cotter pins with 7/8" snap rings added for 'bumpers'.

Next up is to fabricate and install the new facings.

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SUNDAY, JANUARY 1, 2012

The Jaw Facings

Installing jaw facings on these things is not as staightforward as it may look, especially if you're after a very fine outcome.

It would be nice to do it with flathead screws countersunk to just below flush, but flathead screw installations have zero latitude for adjustment, and getting holes drilled and countersunk at exact locations in a material like oak is not easy -- I don't trust myself to accomplish it. Also, I'm not dealing with precision machinery here; one of the 1/4"-20 threaded holes for attaching the rear facing on this vise was bored and threaded at an angle -- it's not perpendicular to the jaw face. That's a further complication.

In light of all that, I'll do it this way. I'll use low-profile, pan head screws with flat washers set in counterbores. I'll make the counterbores and the holes for the screws' shanks slightly oversize; that will give me some adjustment latitude. And I'll spot the screw holes empirically, rather than try to take measurements off the jaws. Here's a view of my setup for spotting the holes for the rear facing.

With the jaw and its facing in position, I clamped the two in place. In each of the two pertinent holes there's a cup-point setscrew. Running down the setscrews firmly spots my screw hole locations. Now I can dismantle that arrangement and make the holes and counterbores.

There's an order to be followed for the counterboring and drilling:

1) Drill a 1/8" pilot hole clear through at both places with a brad-point bit. Those will be the pilot holes for counterboring with a 5/8" spade bit.

2) Counterbore the facing's face side to the requisite depth (7/32" in this case). [Later deepened to 9/32" to accommodate split lockwashers.]

3) Drill through with a 9/32" twist drill.

And here's the rear jaw with its facing in place.

I had to increase the right side screw hole's diameter to 5/16" because of the angled threaded hole there. It's really off at an angle from perpendicular.

I'll remove that facing now, remount the jaw/foundation on my 'bench' mockup and reattach and adjust the facing. Then, I can slide in the front jaw assembly, reference its facing to the rear facing and spot its hole locations the same way I did this one's.

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MONDAY, JANUARY 2, 2012

And here it is with both facings installed.

You can see better what I mentioned earlier; that the jaws are not parallel vertically -- that's as it should be. The maximum opening with the facings installed is just shy of 8 3/4".

That's all the truly crucial trial assembly work done, but I still need to resolve the dog and the handle. Then I can dismantle it, strip the paint and repaint it, knowing that final reassembly will turn out to be final reassembly.

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SUNDAY, FEBRUARY 5, 2012

The Handle Ends

This may not be the greatest idea I've ever had, but I'll give it a try. Here's a view of a pipe cap handle end treatment part way done.

That's the original handle and two 1/2" NPT galvanized caps.

At the left side end, I've turned a shoulder down to just over 23/32" diameter. That lets me 'thread' a cap on with difficulty, so it's a good, snug fit. I'll pin that cap with a 1/8" x 1 1/4" roll pin, and it will be the permanently attached cap.

At the right side end, I've turned a shoulder down to 23/32" diameter. A cap can be 'threaded' onto that more easily. That will be the removable cap, so I'll 'pin' it with a 4-40 x 1 1/8" screw. 'Be back shortly with the pinning done.

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That turned out reasonably well. Here's the roll-pinned end.

And here's the screw-pinned end.

I turned down the head diameter of that round head screw so it would fit in a 3/16" diameter counterbore. Ideally, I would have used a hex socket head screw there, but I don't have any the required length.

At the opposite side of the cap where I threaded 4-40, I used a larger tap size drill than the chart calls for. The chart calls for a No. 43 (0.089") drill. I used No. 42 (0.0935") to lessen the risk of breaking the tap. I don't hesitate to do that sort of thing in a case where great thread strength is not required, and that's certainly the case here. All the female thread has to do is hold the screw in place; there's no great load on it to speak of.

So, the handle is well and truly dealt with. I can set that aside and get serious about fabricating a dog. (That reminds me of a joke about how you turn a cat into a dog. I'll do the right thing and not relate it.)

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MONDAY, FEBRUARY 20, 2012

The Dog

There's an outfit name of Metal Supermarkets that came through for me on this beautifully. They deliver the goods as advertised. For a very reasonable price, they sold me a bit of 1/2" x 3/4" mild steel bar that will make an excellent replacement for the missing dog. Here's a view of the blank after I'd trimmed it to exact length and ground its ends square on my disc sander.

It doesn't get any better! This is going to work beautifully.

It needs a 1/4"-20 threaded hole through it at one point for a clamp-screw to secure it when it's raised. Threading with a tap through material that thick is fraught with peril -- I'd rather not try it. There are two less perilous ways to go about it.

a) The thread needn't run the full thickness of the bar. I could drill clearance diameter (1/4") half way through, then tap size diameter (No. 7) the rest of the way. That would make for much less thread cutting, yet still give me all kinds of enough thread for a clamp-screw.

b) The rectangular opening in the vise jaw is oversize enough to accommodate the flange of a tee-nut. I can take the spikes off a regular tee-nut meant for installation in wood, and install it in a hole sized for an interference fit. That will give me an entirely adequate thread with no tapping to be done at all. I quite like that option; I think I'll go with it.

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Pictured below is an unmodified 1/4"-20 tee-nut, alongside one that I've modified for my purpose here.

Tee-nut barrels are not precise cylinders, and interference fits are a delicate bit of business to get right. The nut's barrel measures about 0.300" diameter. I'll go with a letter size M drill (0.295") and see what sort of fit I get. First I'll drill a 3/32" pilot hole through, then follow up with the letter size M drill.

- - -

I've slightly countersunk the hole to accommodate the trace of a fillet that's at the base of the nut's barrel. In the following photo you can see that the barrel has a slight taper to it -- it inserts part way easily before it becomes an interference fit.

The hex-head screw is there for me to hammer on.

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And here it is with the tee-nut fully set in place.

That turned out reasonably well. I've got the 1/4"-20 thread I was after, and no tap suffered in making it. With that flange protruding, the dog just makes it into its opening in the vise jaw. Now I have to come up with a suitable thumbscrew, and the dog will be done.

- - -

And here we are.

The dog's height is 11/16" when fully extended. When 'parked', it sits just below flush with the top of the vise jaw.

The screw's 'grip' element is a salvaged timing belt pulley from a business machine. It had a 6mm bore, and was easy to tap through 1/4"-20. It's installed on the screw with red Loctite. A 5/16" hex nut serves as a spacer, and a 1/4" SAE flat washer finishes it off.

All that's left prior to final reassembly is paint stripping and repainting.

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Painting The Rear Jaw -- SUNDAY, JANUARY 27, 2013

I quite enjoy spray painting; I find it pretty easy to get excellent results. At times, though, getting an object rigged up so it's manipulable for painting can be a bit of a challenge. That was certainly the case for the rear jaw of this vise. Here's a view of what I've come up with.

That turntable and vise arrangement has often served me well for this sort of work, and will serve nicely for this job. Here's the primer coat done.

And here it is after two coats of enamel.

That can go aside for the paint to harden. Next up is painting the front jaw -- that will require a very different rigging method.

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Painting The Front Jaw -- SATURDAY, JUNE 22, 2013

I finally got the front jaw paint-ready and rigged for spray painting. Here's a view of it with the primer coat just completed.



It's suspended from a hook in a joist overhead by a chain. I screwed two 1/4" rods into the rear of the jaw to give me something in the way of 'handles' for manipulating it. That arrangement worked fairly well. Two coats of enamel to follow, and I'll let it harden for a week. Then, I should be ready to do the final reassembly.

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All Done At Long Last -- MONDAY, JULY 1, 2013

Here's a view of the completed vise closed up.

And here it is wide open with the dog raised.

Quite a decent vise.

Following are some miscellaneous notes that may be helpful.

Mounting Fasteners

The two front-facing holes in the face of the rear jaw are sized to comfortably take No. 14 flat head screws. The two holes at the extreme rear can take the same, or even larger.

Screw Lubrication

I won't grease the screw. In my experience, grease on a woodworking vise's screw just turns into dust-laden sludge that makes the screw's action sluggish. I'll lubricate the screw with WD-40.

The one point that should be kept well oiled with something more substantial than WD-40 is where the crank tee bears against the front jaw; that's where all clamping force is brought to bear as torque.

Washers For The Rail-Rod Nuts

I've mentioned this before, but I'll reiterate with a little more detail.

Adding thin, hard washers under the big hex nuts in front is a worthwhile little assembly aid. Here's what I used.

That washer is 1/32" thick, 3/4" bore x 1 1/8" O.D. 1 1/4" O.D. would be even better. Lubricate the washer and the nut's threads with WD-40 just prior to assembly, and the nut will tighten down sweetly without turning the rod.

Jaw Facing Counterbores

I deepened them to 9/32", so I could add split lockwashers. The lockwashers make it easy to gently snug up the facings so they're adjustable at final mate-up, but will stay put as you fully tighten their screws. Here's a list of the jaw facing fastener hardware for 3/4" thick facings:

a) Qty 2, 1/4"-20 x 1" pan head screw (front jaw).

b) Qty 2, 1/4"-20 x 1 1/8" pan head screw (rear jaw).

c) Qty 4, light No. 14 split lockwasher (0.047" thick); Spaenaur P/N W-115.

d) Qty 4, 3/16" nominal flat washer; CTC P/N 61-3196-0. (These serve as light, close-fitting flat washers for 1/4" screws.

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So there we are; that was a delightful project. Now, I just have to find this thing a home. I quite like the Record No.53E quick-acting vise that I already have, so unless my son wants this one, it's a spare piece of gear to me.

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Note:

[1] A hydraulic press makes a great 'horizontal vise' at times, but a word of caution is in order.

Some hydraulic jacks leak down slowly and 'relax'; the jack on my press does that. The plank in the photograph is hooked to the press' cross member at the back so it can't tumble. That's something to bear in mind should you ever make use of the work-holding method pictured -- be certain it has 'fail-safe' security.

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A Rotary Switch Repair

The style of switch-fitted light bulb socket pictured below is widely used in articulated desk lamps and the like.

This one has gotten stuck 'on', and doesn't want to switch off. These switches often respond well to a bit of reconditioning. The worst part of the job is usually getting the lamp's line cord slackened off so you can get at the thing.

Undoing two small threading screws gets you access to the switch's innards, like so.

The slot in the end of the knob engages and turns a rod that shorts two contacts to turn the light on. The spring keeps the rod firmly pressed down.

Here's a view of the rod inside and the contacts it works with.

[I've already cleaned up the inside parts.]

The switch is shown in its 'on' state -- the rod is bridging two contact 'ramps'. Ninety degrees of CW rotation of the knob will cause the rod to climb the contact ramps, and then it will fall across two insulator ramps and be in its 'off' state.

The contact ramps can be scraped clean with a jeweller's screwdriver. The rod can be chucked in a portable drill and burnished with synthetic steel wool. Blow out any dust, reassemble, lubricate it with WD-40 and it should be back in business.

This switch worked fine once it was back together. I'm actually a bit mystified that it was so stuck; I really didn't see a reason for it when I opened it up.

Anyway, it's working, and it looks to me like it should be trouble-free for a long time.

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Air Compressor Drain Valves

Where I work, we have a big Campbell-Hausfeld air compressor. It's a 5 hp, 80 US gallon unit, and we tend to be a bit lackadaisical about draining the condensed water out of its tank. Every couple or three years we get around to thinking about it.

The other day, the boss came in with a new drain valve for it. (The drain valve that's in it leaves a bit to be desired.) I quite like the looks of the valve he bought; it looks to me like a well-thought-out, well made bit of gear. It's a Porter-Cable "PDRAIN-14M". Here's a view of it.

When I first looked at it, I wondered, "Where are the 'wings' for cranking it open and closed with? There's just that knurl on the end of it." I cranked it open and it made sense.

It's fully open in the photo. Note that the valve has an O-ring doing the sealing, not a metal-on-metal stem and seat, so no great amount of torquing is needed to open or close it -- a very nice bit of engineering, that.

There was just one little problem with installing it -- it has a 1/4" NPT threaded body,^[1] and the compressor takes a 3/8" NPT bodied^[2] valve, like so.

A reducer would be needed to install the Porter-Cable item in place of the original, and that would bring the valve even closer down to the floor, which it's quite close enough to already. The boss will take the Porter-Cable valve back to the store, and see if they have a 3/8" NPT Campbell-Hausfeld part.

The original valve in the above photo has a nicked valve stem, so it leaks a bit. Wrapping the stem's end with Teflon tape before reinstalling and closing it takes care of the leak, but with that bit of hassle thrown in, the thing may as well be replaced by a plug. When the tank needs draining, unscrew the plug and there's your drain opening.

Anyway, the tank is now drained. I got about 1.5 litres of remarkably clean water out of it that had accumulated in about three years of operation.

If we all get past 2012 intact, maybe I'll have another go at it come 2014 with a replacement valve that fits -- or maybe just a 3/8" NPT plug. Whatever.

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Notes:

[1] Hex is 9/16" A/F.

[2] Hex is 11/16" A/F.

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Compression Fittings

There are compression fittings, and there are compression fittings, and they're not all created equal.

At the left in the above photo is a pre-fabricated, gasketed fitting on the end of a faucet supply hose. Those are superb -- absolutely fool-proof and reliable.

In the centre is a plastic faucet supply tube and compression sleeve. I get fine results from those as well.

At the right is a length of plated soft copper tubing with a loose sleeve and nut that one assembles in situ. My hat is off to anyone with the skill to consistently get those things assembled correctly -- I have a devil of a time with them.

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I installed a hose faucet by my workshop's sink recently, and learned a few things.

First off, compression fittings and soft copper tubing are useless for creating any sort of rigid, mechanical structure. I was attempting to add a tee fitting to a faucet supply valve with a very short length of tubing, like so.

That was fallacious to start with. Compression fittings have little tolerance for mechanical stress. They're strictly for making connections where the only load on them will be the weight of the undisturbed tubing itself. Just tightening the two hoses attached to the tee introduced stresses that were more than the lower two fittings could cope with. They leaked.

Even when correctly applied, though, compression fittings can be an iffy affair.

For a pressure-tight seal, the sleeve must compress straightly and truly at both ends. The least bit of crookedness in the sleeve's compression will result in a leaky fitting that no amount of tightening will correct. I tried a little experiment that I hoped might yield an improved fitting. It didn't work out, but here's what I did, for what it's worth.

At the left in the above photo is a standard 3/8" compression nut and sleeve. Note that the nut has the same bore as the sleeve. That strikes me as fallacious. It seemed to me that if the nut's bore were bigger, the assembly might be much more inclined to self-align correctly, so I bored out a nut to 27/64". It's shown at the right.

That turned out not to work any better, but a subsequent discovery told me I was on the right track.

While rummaging about in my little drawer of 3/8" compression fittings, I found some items that I'd paid no attention to in the past -- compression nuts with captive sleeves. Here's a view of one next to a standard nut and sleeve. (Down in front at the right is a captive sleeve that I knocked out of a nut.)

'Captive sleeve' nuts are also known as 'self-aligning' nuts. As you can see, they have a very different sleeve construction, one that makes a lot more sense to me than the conventional style.

I still wouldn't attempt a fallacious assembly like the one in the second photo above with these, but if I ever have need of a compression fitting on a legitimate soft copper tubing installation, I'll do it with captive sleeve nuts.

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One last point about compression fitting installation; lubricate the fitting before assembling it -- WD-40, salad oil, spit, something to help it go together smoothly and snugly.

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