Repaired Harbor Freight digital caliper

Oh, those are your pages. Nice info and thanks.

The silicone and salt atmosphere problem is real. It forms sodium silicate, which is water soluable. Add almost any acid, and you get silicic acid. Heat and dry that you get silica gel, which is quite hard and not very soluable in anything. It takes a while, but it does happen.

I used to work for a marine radio manufactory in the 1970's. Customers would sometimes use various lubricants loaded with silicone to clean pots and switches. It would work, but about a year later, we would get the radios back with seriously intermittent pots and switches. No amount of solvent cleaning would fix them, so we just replaced them. We just assumed they were internally corroded or salt encrusted. I didn't discover the silicone and salt atmosphere problem until many years later (when I repeated the mistake on a consulting project).

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Olive oil works almost as well. It's about 50% oleic acid. My solution is mostly Coleman fuel (naphtha), some olive oil, and a little alcohol. It works and leaves the radio smelling "organic".

Well yes. Such cleaners (and Cramolin) are mostly mineral oil. Remove the volatiles and antioxidants, and what's left is mineral oil. There are different types of mineral oils: paraffin, naphtha, various petroleum distillates, and mixtures. The paraffin residue left after evaporation might be the gum that you're seeing.

It appears that Contaclean is the same as the old Cramolin Red (R-100). Mostly mineral oil (hexane) and isopropyl alcohol. MSDS:

Hmmm... looks like the oleic acid was removed.

I would blame the mineral oil instead, especially since there doesn't seem to be any oleic acid in the Contaclean reformulation. Oleic acid is much like corn oil or olive oil. It will leave a gummy residue under the correct conditions. However, there is only 5% oleic acid in the bottle, which isn't enough to leave much residue. If there's plenty of residue, it's probably the mineral oil.

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Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Oops. It's still there, but well hidden. It's listed as an "aliphatic hydrocarbon", which includes fatty acids such as oleic acid.

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Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

If I had one of these I'd fit onto the calipers a small solar cell and diode to trickle charge the original battery ie not specifically rechargeable , and replace the lid of its casing with a glass panel and leave on a bright position .

visibly

I'm inclined to disagree. Cramolin/DeOxit definitely work on tin- and nickel-plated surfaces. They are not as effective on gold-plated surfaces; ProGold does a better job. It isn't just a matter of mild abrasion; a chemical reaction of some sort is needed.

Hello, and DeoxIT is the best thing I've ever come across for cleaning and de-oxidizing electrical contacts. It also does wonders with scratchy volume and tone pots and it'll be long while before you have to apply it again. Sincerely,

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Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

WD-40 is mostly kerosene.

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Jim Yanik
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dot com

Close. It's mostly Stoddard Solvent, also known as mineral spirits.

50% Stoddard solvent (i.e., mineral spirits: primarily hexane, somewhat similar to kerosene) 25% Liquefied petroleum gas (presumably as a propellant; carbon dioxide is now used instead to reduce WD-40's considerable flammability) 15+% Mineral oil (light lubricating oil) 10-% Inert ingredients

Reverse engineering at its best:

USA MSDS sheet:

The key ingredient is a sulfactant (wetting agent), to reduce surface tension and make it "cling" to objects and "puddle" water. My guess(tm) the reason it took 40 trys is that they had a difficult time finding one that would work in a solvent solution.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Th 357 and the LR44 ARE NOT quite the same in experience, The LR44 seems to have a slightly domed top and it seems to make a difference in all of my products that use them. I can't find evident to support my claim, but experience, unfortunately.

In general, the LF357's fit a little looser in the holder and the LF44's are easier to insert.

Good info. Darn, I liked to use the can as a flame thrower to kill pests with the flammable propellant. Bags worms met their doom.

Greg

Harbor Freight Has the 6" dial Caliper on sale 11/24

Mikek

Nice, I like the metal cutting saw they have there just off to the right..

Think I'll do a stop in for that.

Jamie

Do note, it is pneumatic. Fine if your setup for it. Mikek

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It is an off switch to turn the *display* (only) back on. They sometimes make it also turn the display back off to make people feel better. :-)

The auto-turn-off time of the display is usually good enough.

Enjoy, DoN.

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[ ... ]

Actually -- there *are* some "solar powered" ones -- by Mitutoyo IIRC. They would probably be excellent used daily in a well-illuminated shop. In my shop, often dark for days at a time, until a project lures me there, the replaceable batteries are a better choice.

I did recently get an auto-darkening welding hood from Harbor Freight which is solar powered, and based on what I have read about them dying if not used regularly, I've put mine on a folding workstool facing out the window so it sees daylight to maintain the charge. I'll proably eventually have to perform surgery and replace the rechargeable cells in there. There is a temptation to provide a connection for an AC-powered trickle charger so I can store it more conveniently. What would be particularly nice would be an induction coupled charger like those for electric toothbrushes. Just put it on a stand and expect it to be fully charged when I come back.

If the charge is good enough to work on the first strike, it should work fine for the rest of the day, because it will be getting a charge boost from the arc -- close enough to vigorous sunlight. :-)

Enjoy, DoN.

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itutoyo

d

I saw a solar-powered Mitutoyo at a flea market and was intrigued, but resisted. Something about having a glass window on a machine tool close to all that hard steel just didn't sit well--it brought up memories of scratched and broken watch crystals.

OTOH, I paid $10 for most of my HF calipers. Those you can take chances with. Using the 8x25mm solar panel from a $1 calculator, a super capacitor for storage, and an LED as a regulator diode was my notion. $2 in parts, $500 labor ;-).

I fitted one to the lathe carriage--best thing I ever did. Removable. I fitted another to the tailstock ram. With it you can bore to 0.002" depth every time without even trying. Magic.

rbor

y y

it

Sounds like a LiIon cell. If so, those can't be allowed to go dead, as you've surmised.

-- Cheers, James Arthur

Still, there's no benefit to turning off the display, in this case. = Might=20 just as well have it display "OFF".

I bought a high-end headlamp from Coleman a few years ago

oduct_id=3D2000000265# and every time I went to use it the batteries (4 AA) were dead. I = measured=20 the current draw when turned off, and it was something like 300 uA, = which=20 should have provided 8000 hours (almost one year) for the 2500 mA-hr=20 batteries. But I was getting only a few weeks before finding them = exhausted.=20 Maybe the current increased as the battery voltage dropped. I usually = used=20 rechargeable NiMH and they might have been old and tired. But, still, = there=20 is no reason for 300 uA standby current on a flashlight. Even if it had = a=20 microcontroller, a typical PIC18F2420 draws only 11 uA while running, = and=20 only 100 nanoamps in sleep mode! So, I just pop out one of the batteries =

while I'm not using it. There's no easy place to install a switch.

Paul

d

ed.

d

re

I measured some ordinary NiMH cells' self-discharge, 1,600mAH, @ 1.6mA IIRC. The high-capacity rechargeables are wickedly worse. I've got one set that won't hold a charge much over two weeks, no kidding, even brand-new. Self-discharge current on the order of 5-7mA.

There are low-self-discharge NiMH that hold a charge much longer, sometimes up to a year. Highly recommended. Ray-O-Vac Hybrids, Sanyo Eneloop, and Duracell has some too.

-- Cheers, James Arthur

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

I'd not go by Wikipedia,I'd go by the actual WD-40 MSDS. if you read the MSDS -for each ingredient- listed for WD-40 on the WD-

40 MSDS(like I did),you'll see that it's mostly kerosene.

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