Tuesday, April 12, 2016

Waxed Paper 'Washers' For Finish Protection

If you attach anything securely to a painted or varnished surface, the attached thing is likely to 'weld' itself to the surface tenaciously, no matter how well hardened the finished surface appears to be. Future removal of the attached thing will result in damage to the surface underneath. That may or may not matter to you, but if you'd rather preclude such damage, install waxed paper 'washers' at the interface of the attached thing, and the painted or varnished surface.

I recently removed the mechanic's vise from my workbench, so I could refinish the workbench's hardboard surface with polyurethane. Where the vise base's mounting washers had been in contact with the bench, the washers had bonded themselves to the bench with a vengeance. The washers came away with great shards of hardboard stuck to them, like so.

I filled in the damaged spots on the benchtop, refinished the bench's surface and cut three waxed paper washers for the reinstallation of the vise.

And here we are with the vise's base bolted back in place.

The reason for placing washers underneath the vise's swivel-base mounting ears is to preclude breakage of  the swivel-base casting. Tightening down a cast swivel base directly onto a benchtop's surface is unwise -- irregularities in the surface, and/or the casting, can result in stresses that may break the casting. I've seen it happen. The washers serve to concentrate all the attachment force directly at the ears, isolating the rest of the casting from untoward forces.

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Saturday, April 2, 2016

On Salvaging Old Gear

On the face of it, salvaging old gear of any kind seems like a paying proposition. Retail prices of anything new these days are sky high, and are unlikely to ever come down. But are there really savings to be had in salvage?

Much as I'd like there to be, and much as this blog has often featured salvage projects as subject matter, I'm not so sure that salvage effort is always, or even often, worthwhile.

Over my years of servicing laser and impact printers, and working closely with printer subassembly remanufacturing operations, it dawned on me that there seems to be nothing quite like factory 'newness'. No matter how meticulously an old mechanism is refurbished, its service life and reliability are unlikely to equal those of new replacements.

Anyway, for want of anything better to do, I thought I'd refurbish an old water supply shut-off valve, and test it out to see if it could still be trusted to give leak-free service. Here's a view of the valve.

It's a common 1/2" copper pipe to 3/8" compression fitting shut-off valve, as is typically installed for a faucet's water supply. This one appears to have been installed by a DIYer -- there's evidence of some sort of sealant having been applied to places where there ought to be no need for sealant. DIYers are notorious for gratuitous application of sealant.

I'll clean it up nicely, and devise a test fixture. If it doesn't leak at its valve stem when fully opened, I'll consider my refurbishment to have been a success.

Following are a few noteworthy points:


The washer in this type of valve is not replaceable. Water supply shut-off valves are so seldom closed that washer wear is not an issue. An embrittled, cracked washer would spell the end of a valve's usefulness, unless one wanted to undertake the machining necessary to make the washer replaceable.

The Valve Seat

Like the washer, the valve seat is not replaceable. A corroded valve seat (unlikely) might be salvageable by reaming and/or burnishing with valve-grinding compound. See this post.

Valve Stem

The valve stem ought to be cleaned with fine steel wool prior to removal of the gland nut and seal. One wants nothing to abrade the lip of the valve stem's seal as the seal is removed.

The 1/2" Copper Pipe Socket

I've been meaning to acquire a 5/8" reamer to help me salvage 1/2" copper pipe fittings, but the price has been scaring me off. Meanwhile, I've been making do with an X-Acto knife and steel wool.

The socket must be clean, and must easily accept a pipe end to the full depth of the socket.

The Valve Stem Seal

There are two parts to the seal -- a thrust washer, and the ring-seal itself.

The thrust washer is concave; the concave side goes outboard. The ring-seal is asymmetrical face-to-face; note its orientation as you remove it.

The ring-seal must be resilient and undamaged, else the valve is a write-off. The seal pictured here looks a bit distorted on one side; it remains to be seen whether that will be detrimental.

Note the discolouration of the valve stem near the stem's thread. That's evidence of slight corrosion that may cause stem sealing to be iffy.

The Test

I assembled the cleaned up valve, using silicone grease on the valve's threads, and all its stem-sealing surfaces. I rigged a test fixture that allows me to install the valve onto a faucet that has a 3/4" hose-fitting thread on it. Here's a view of the valve in 'operation'.

The photo shows the valve pressurized and fully opened. The valve's output end is closed, as it would be if it were supplying a closed faucet.

It looks good. There's not a hint of weeping at the valve stem.

So, that turned out well. It would be safe to put that valve in operation in an actual faucet installation.

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