diamond users, important information

D'oh! (I guess the coffee hadn't kicked in)

Don Thompson, Cutler Ridge, Florida

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Overcharging

David Barnett

>A couple things happen when overcharging a lapping substrate. A certain amount of diamond will find its way into the lap. Some will become lodged in the the ditches, channels, pits of the immediate lap surface topography, while other will become seated through pressure when serandipitous pointy alignments occur. What's important to remember is that while the crystal habit of diamond is octahedral, it can fracture into cubic form (and other forms, such as macles). Diamond crystals have few and weaker bonds on their octahedral planes, and are said to have 'perfect' cleavage, a property exploited by diamond cutters.

When diamonds collide with other diamonds (the frequency depending upon density and amount of the diamond lapping medium, how easily the diamonds can embed into the lapping substrate and the degree to which they protrude and offer cleavage planes for further fracturing, as well as the amount of motion to which they're externally subjected), one runs the risk of wearing down the embedded charge and seizing embedding opportunities for these smaller paticles that will prevent the larger particles from serving their purpose.

The obvious strategy is to charge with very little diamond distributed as evenly as possible, embedding with a hard and smooth object under only moderate pressure (avoiding premature fracturing and too-deep embedding). Although oversimplified, this is nonetheless the idea in a nutshell.

A practical way of doing this is to make little circles with a fingertip lightly loaded (very lightly, in fact) with paste, overlapping only a bit (machinist's 'jeweling' with your finger). Then lightly 'set' the grit with a hardened steel roller or a lubricated (olive oil's fine and traditional) stone, such as polished agate, or my favorite, a split boule of synthetic corundum (cheap and plentiful). Lastly, wipe any excess from the lap, and test. Hope this helps.

Wisdom has arrived to save the day

Bill Tindall, E. TN

>I suspected that someone had already discovered and solved this problem. Thanks once again. Will try soon.

It is really amazing how much metal $0.25 of diamond will remove and how quickly it will do it.

PS. the alloy laps can not be cast retangular. From response it is clear that they are spun cast somehow and that is the "secret" to their structure.

We drug, without success

Bill Tindall, E. TN

>We tried dragging across everything in the shop. I was optimistic a plastic would work, but it did not.

Acrylic clarification

Bill Tindall, E. TN

>My lack of success with charging acrylic with small grit was a result of my past being too viscous. I couldn't get the stuff thin enough on the acrylic. I think a water based paste would do fine, or maybe even an oil based if thinned.

Re: Wisdom has arrived to save the day

David Barnett

>Now that's something I sure didn't know, but leave it to Jon to come up with such an exotic process. He's definitely one original thinker and has a pile o' patents to prove it.

Re. the ultrasonics: it'd be a good idea to research the manufacturing literature to determine just what you would require. Some cleaners are heated, ramp through multiple frequencies, and pulse transducers for more thorough effects. The unit I use is large enough to clean a pair of eyeglasses, a handful of gravers, burrs, small tools or gems, but only takes 35 watts, one frequency, and 3 minutes to do its thing. Doesn't look like it's doing much, but set a small glass with an inch of any soft drink in it and look out. It'll knock the bubbles right out.

Re: Wisdom has arrived to save the day

Greg Sloop

>...but set a small glass with an inch of any soft drink in it and look out. It'll knock the bubbles right out.

One summer in college I worked at Tree Top in QA. We used ultrasonic cleaners to remove all the air bubbles from juice samples so we could measure turbidity (cloudiness) and color.

I thought..."Hmm...I wonder about this can of Diet Coke?" Uh...bad plan.

Even an almost instant flick of the switch on and back off produced a volcano - not instantly mind you, but 2-3 seconds later. I thought it was a dud, then Diet Coke spewing out of the top of the can by perhaps as much as 12 inches.

Oops.

Quick run for paper towels to clean up the lab! Anyway - good fun.

Wasn't half as scary as the high molarity HCl I used to boil off Hydrogen from a small bit of Aluminum foil. The reaction got so hot and was so furious I was worried about the heat setting the whole thing off. It didn't and I was duly chastized and didn't try it again. *grin*

Such dumb things we think up eh?

Cheers,

Greg

Re: diamond users, important information

Robert Tarr

>Funny....I was thinking about using the $.15 rubber eraser or the more costly $.75 hard rubber art eraser to rub down the edge and collect particles....might be worth a test and they are easy enough to cut off the "used" portion and expose fresh surface.

Robert

Re: correct statement

Joe Rogers, Northern Virginia

>Just an idle thought but our new car prep department uses clay to remove "rail dust" from the new finish on our cars in inventory. Rail dust is the metallic debris that comes from the transportation of the cars on trains. It is a metallic dust that actually imbeds into the soft uncured finishes of the cars as they are fresh from the factory. The finish will continue to cure for several months and the fresh finish is easily contaminated. Clay will dislodge and capture the iron(and whatever else) that is stuck to the paint. I wonder if it would work for random diamond abrasive particles?JR

Re: Ultrasonic cleaner

Kurt Loup

>Noticed this in a Harbor Freight flyer I received in the mail. It's on sale for $29. Here's the description:

Ultrasonic 42,000 cycle energy wave deep-cleans jewelry and small parts without heat or flammable solvents. Safe, gentle and thorough.

42,000 cycle energy wave cleans without heat

Stainless steel tank with one pint capacity

Quiet operation

Auto shutoff after three minutes

Transparent view lid with interior light

UL, ETV listed

120V, 50 watts; Overall dimensions: 5-1/2''H x 8''L x 5''W; Weight: 2 lbs.

Kurt

Pretty good deal, Kurt

David Barnett

>That's a good price for a good little unit. I have one and paid twenty dollars more from a jewelry supplier. This is a 'miniature' ultrasonic cleaner, more for personal use than jewelry stores or jewelry/dental labs, of course, and is often a giveaway to customers. It won't work like the full-sized machines, but it will work well enough. The unit is rated at 35 watts, so is useful for smaller items such as jewelry, pocket knives, small tools and instruments, gems, loupes and lenses, eyeglasses, clogged drafting or fountain pens, micro-torch heads, gravers, flex shaft carving and stone setting burrs, and so on. It's a real workhorse for 90 percent of my ultrasonic cleaning needs. If you need a small cleaner, you couldn't do better than this for the money. I've seen other small (and more costly) cleaners that simply don't work this well. That said, I'm planning to buy a larger, more powerful unit, but owning this one has let me put that off for awhile.

For Bill's, purposes, I'd suggest a much larger and more powerful system to pack more punch for massive plane blades. And it wouldn't hurt to have multiple frequencies and heated solutions, as well. Although new industrial units are pricey, used and reconditioned ones can be had quite cheaply.

One other thing about ultrasonic cleaners, and this small one is no exception, play with detergents to find what works best with certain target contaminants. I like Simple Green or Basic H (Shaklee) for many degreasing tasks. Also, don't give up after just one 3-minute cycle. I use a rouge that consistently won't release until the fourth cycle. And two caveats: don't use solvents (such as naptha, acetone, and so on), and don't put your fingers in while it's running (you don't want "The Bends" in your knuckles).

Thanks for the info

Kurt Loup, Baton Rouge

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Clay magic *LINK*

Clay C in Miami

>This type of material is mentioned above, here's a source for the stuff I use - it's intended for just this purpose, though removing different grit from different surface. But, it is amazing stuff indeed -- with very little pressure, when lubricated this stuff will 'grab' and pull out particles that are seriously embedded in automobile clearcoat.

When the working surface of the clay gets contaminated, you can just fold-and-knead to get to a 'fresh' working surface. Since here you aren't worried about rogue scratches from the previously-removed particles embedded in the clay (they'll come out in the next step anyway) but only with getting the particles out and making sure that you don't contribute any new ones, this seems like (if it works for this application at all), it may be the simplest/cheapest/fastest solution, certainly faster and easier than ultrasonic. The clay doesn't release any of its particles, once it's got them.

Let us know if this works, and thanks as always for the information!

Clay


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