Editors note from Bob Keller: Jack Lahr passed away in December 2005 due to complications from surgery. He was from Mt. Vernon, Ohio were he served as President, Show Chairman and Newsletter Editor for the Licking County Gem and Mineral Club. Jack demonstrated his hand powered Lap-Lap faceter actively at Ohio gem and mineral shows and served as a public ambassador for the faceting community at large. The following article by Bob Jones describes Jack's Lap-Lap faceter, which is about as basic as a faceting device can get. To the best of my knowledge the Lap-Lap is no longer in production or available for sale through other sources.

Faceting By Hand
Jack Lahr's Lap-Lap Relies On Primitive Power
by Bob Jones, Senior Editor Rock&Gem Magazine

After attending the Columbus, Ohio, show in late March, I was regretting that I did not buy one of Jack Lahr's lap-lap faceters during my flight home. It wasn't until then that I realized why he calls the thing a "lap-lap": You can hold it in your lap, no power needed, and lap stones to your heart's content. Imagine the kinds of conversations that would trigger on a plane. The airline hostesses would surely want to know what the heck you were doing with this little mechanical gadget, rubbing it back and forth, back and forth while you read, while watching the in-flight movie, or just staring out at the clouds.

Jack was doing just that one day while flying cross-country when he realized two pilots and an engineer were watching intently and asking questions. Jack's question for them was, "Who's flying the plane?" It seems they were on auto-pilot!

The Lahr faceter is a nifty little device. I've seen Jack demonstrate it at the Columbus show for several years now without realizing what a neat little device he had developed. I finally came to my senses and I decided to get his permission to tell you all about it.

You can actually facet stones on the thing since it uses all the conventional devices such as a diamond-charged lap, dops, a dopping transfer angle, a protractor, an indexer and more. You can either supply your own lap (Jack gets used ones when he can) or get his "deluxe" setup, which includes two copper laps. Even if you go first-class for one it costs just under $100.

I couldn't help but marvel at the flexibility of the lap-lap. Instead of being trapped at a workbench, you can sit and watch TV, or carry it in your car so when you're stuck in traffic you can haul it out and lap away!

The obvious drawback is, of course, time. It takes maybe 10 times longer to facet something using this little mechanical marvel. At the same time, you can use it almost anywhere, so time is not necessarily lost. I've been to some mineral club meetings where this device would have come in handy!

The lap-lap depends on the same geometry as a machine-driven faceter. Everything has to relate to a level surface, since all angles reference it. Jack uses a sheet of glass and puts his diamond-charge lap on that.

The device is a tripod arrangement which holds the index, dop, etc. Jack realized that a tripod would provide the necessary stability and accuracy, both of which are critical to any faceting work. He built his lap on what he calls the "third leg principle." He developed a tripod frame to hold his dop. It is welded, then coated with plastic by fusing the plastic to the metal. This makes for a pleasing appearance while it is a little easier on the hands: It is the tripod frame that you grip to rock the preform back and forth to facet it.

On the tripod frame is an adjustable bolt used as a stop to indicate when a facet is done. You set this when you measure your angle with the protractor and index as you work.

The index is critical, and he machines that so the index barrel will have either 64 or 96 indexes or degrees of setting. The finer the indexing is, the more accurate you can get your facet angles. Accurate geometry is absolutely necessary for any faceting operation. After all, the flash of a gem depends on the facets being at the correct angle to refract and reflect incoming light. The index is attached to a faceter body and the dop slides through these with the gem waxed to it.

Being an engineer, Jack decided to try to develop something like this about 20 years ago. He first begged for used laps from friends, simply recharging them as needed. Then he began using copper roof flashing from the hardware store. Pure copper is soft enough to accept a charge of diamond dust if properly applied. He did this by using the outside flat bearing race of a ball-bearing assembly to roll the diamond into the copper. (Remember: Bearing races are hardened steel so the diamond paste can be pushed right into the softer copper.)

In faceting, getting the gem properly dopped or glued to the end of the dopping stick may seem easy. If, however, this preform gem is not properly dopped and comes loose during the operation, you've got a real problem.

Jack uses a metal dop with the end just slightly concave to hold the gem better. The trick here is to mount the rough gem to the dop so it stays and always sits at the same angle. Jack's solution is simple: a piece of metal bent lengthwise at a right angle. In the middle of this bend he cuts a rectangular opening or window. This provides a space where you can insert the preform gem for attaching. The dopping rod has a concave tip, which is placed into the angle of the metal that he refers to as a transfer angle. Fittingly, the concave end of the dop is close to the middle of the opening.

From the opposite side, Jack places a second rod that looks like a dop but has a flat tip. This is pushed against the preform gem and the entire business is held tightly by rubber bands. This enables you to wax or dop the stone tightly to the dopping rod with little chance of a mistake. Once dopped, the preform gem is ready to be faceted.

Using the protractor, Jack sets the proper starting angle for the frame, runs the dopping rod through the index, sets that at the angle he wants and he's about ready to facet something. You might wonder what the proper angle is for starting to facet a stone. Each is different, but there are references you can get which will give you all the necessary faceting-angle data.

If you are just starting out, Jack recommends you start with something really simple and inexpensive, such as round glass beads, or even a small marble. As your confidence grows, you can risk a few dollars and switch to inexpensive gem material, slowly building on your ability while getting used to the machine and the techniques of faceting.

Jack also recommends you use a good handbook for faceting. He prefers Soupak's Cutter's Handbook, but you may have another preference.

The machine, once you get familiar with it, can be used for other things. Jack sharpens engraving tools on it, since he can set the angle he wants and give it the old back and forth treatment until it's sharp. He has also used it to get an absolutely flat end on rods. This is particularly useful if you are welding two thin rods together, such as fiber optic rods.

Of course, the Lahr lap-lap hand faceter is not intended to replace the fancy, very expensive, commercially manufactured faceters. Instead, it provides anyone, even kids, with a way to learn the basics of faceting for very little cost. It is also a way to make better use of time.

My mother used to crochet or knit whenever she sat to listen to the radio or just relax. If she had had one of Jack's faceters, maybe I would have had a drawer full of faceted gems now instead of a closet full of crocheted table cloths!


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