Message:09

Subject: My response to Bob, the new Facetron owner
Date: Mon, 21 Jul 2003 20:48:34 -0500 (Central Daylight Time)
To: <faceters@caprock-spur.com>
From: "jim gray" <jlgray@vci.net>


To: Bob Mestdagh
From: A one-time beginner and full-time learner (jlgray@vci.net)
Date: July 16, 2003
Subj: You have to start cutting to have fun!
 
I read your post on the Lapidary Arts Digest, and for the first time I think I'll weigh in and try to give some thoughts based on my limited experience. I'm normally a lurker, but have benefited greatly from reading the advice and experience of others.  It's my turn.

I got hooked on the idea of cutting 3 years ago for no good reason.  I went to one of those gemstone prospector tourist traps in Gatlinburg and was intrigued about the idea of cutting a pretty gem from something so ordinary looking.  I started checking out info on the internet (there is a ton!), and got really interested.  I bought my Factron because a lapidary in Louisville Ky. was one of the few I actually met and talked to, and he had one and was pretty happy with it.  No regrets, it has been a joy.  He used Dyna Discs for cutting and polishing (cerium and alumina), and so do I.  From recent experience the availability of Dyna Discs is somewhat spotty and you may have to shop around to find them in stock.  They were a great way to get started at a reasonable initial investment, and I have upgraded to a more durable coarse (80-100 mesh) lap and some diamond charged polishing laps (limited success) as my interest and commitment to cutting has warranted.

Since you are just starting, I would recommend skipping the Dyna Disc polishing laps initially and opt for an inexpensive Lucite master lap ($15-20) and use the Ultra Lap cerium and alumina films.  It won't give you as sharp an edge as the Dyna Disc polishing laps and they don't last forever but it is cheaper and more forgiving as you begin your journey.  Also, I have had pretty good luck recharging the film with the cerium and alumina spray you can get for the Dyna Discs. 

For cutting I initially recommend a coarse (80-100), medium (325 or 600) and fine (1200) lap. Also, if you don't have a trim saw, you should.  It will really help you when you buy larger pieces of rough that you want to cut into smaller sizes (more on rough later).  I purchased a used 1/6 HP 1725 rpm electric motor from an appliance dealer, bought a new 6 inch Rock Rascal Model J, and bolted them on to a piece of BD inch plywood.  The motor has a 4 inch pulley and the saw a 2 inch pulley.  I use Pella oil as a lubricant and a ProSlicer blade, all with good results.

If you only buy one book on the topic of faceting, I recommend Faceting for Amateurs (3rd Edition) by Glenn and Martha Vargas.  Lots of good faceting info and diagrams, although some is dated, including a table in the appendix that I used to get the right pulley sizes for my saw and motor speed combination.  Also, get an Optivisor so you can see what you are doing, and the least expensive plastic dial caliper in millimeters you can find.  When choosing a cutting diagram, I recommend a standard round brilliant (SRB) cut for your first couple of stones, and synthetic quartz or LaserGem for your material.  I have had pretty good luck with a 42 degree pavilion and 35 degree crown in these materials.

Regarding dopping the rough, I am an avid glue-guy.  I tried wax a couple of times but some info on the web got me hooked on glue.  Others had most of these ideas, but I'll give you what works for me.  I always start with the pavilion cut, so after I saw a piece of rough pretty close to the size I need I prep the rough by coarse and medium cutting a flat surface that will maximize yield.  In terms of orientation, this means the flat surface you are preparing will be the table of the finished stone.  You have to look at your cutting diagram and estimate the shape of the rough in relation to the design you are cutting.  With practice you'll get better at using the length/width, crown/width and pavilion/width info in the cutting diagrams to make this estimate.  In other words, if you are cutting a round design the narrowest width of the rough on the dop will determine the maximum width of the final stone, assuming it allows adequate depth to complete the design With non-round cuts you need to take extra steps to estimate the length/width you can reasonably retrieve from the rough in order to properly estimate the required depth of the rough.  Sometimes the depth of the rough will be the governing factor, and will drive the decision on length/width Your rough must fit all three parameters - length, width and depth - to successfully cut the stone from a piece of rough.  Be sure to leave 3-4 millimeters of extra depth so you can re-cut the stone a couple of times if necessary (it will be the first few times, trust me).  In heat sensitive rough I recommend even more depth be allowed for the transfer method I will describe below.

After cutting the flat surface with a 325 or 600 lap, clean the rough and dop with alcohol and allow 10-15 minutes for drying.  I use off-the-shelf super glue to attach the flat dop to the center of the rough if it is a symmetrical cut.  If it is a pear or other non-symmetrical cut you will need to glue the dop off-center, and you can use the cutting diagram to estimate the amount of offset - this is when the calipers can really help because you can use the diagram to make your estimate of the best location for the dop. This takes a steady hand and a little practice to get good.  If you screw up (I do, often) then drop the errant dop and rough in a jar of acetone (available at most hardware stores), and try again.  Acetone will release the superglue in about 4-8 hours.

When I cut the pavilion, I almost always cut the steepest angle in the diagram first in order to establish the depth of cut, particularly if adequacy of rough depth is in doubt.  You should not do this with Omni cuts, since the early shallow cuts to a temporary center point are used to establish the girdle (90 degree) cuts.  After cutting and polishing the pavilion, use the transfer jig that comes with the Facetron to glue and transfer for the crown cut.  I use Devcon 5 Minute Epoxy for the cone or vee pavilion dop.  Clean both the pavilion of the cut stone and the dop with alcohol, allow to dry, and mount both dops in the transfer jig for a dry fit

  I personally have had no luck using the keyed notches for anything other than round, square or trillion cuts, and for these I use the round cone dop.  If the cut is not round/square/trillion I use the vee dop and open the jig up and slide both of the dops in past the keyed notches (almost all the way in).  I put the dop with the rough in the base, and the empty dop in the sliding block.  Tighten the base screws and lightly snug the sliding block screws.  I bring them close together carefully, not touching, and with my Optivisor on magnification I use landmarks on the facets to align the empty dop symmetrically with the pavilion, and tighten down the sliding block screws. I then pull the dops apart, mix a small amount of the epoxy with a toothpick on a paper plate, and put a small glob on the inside of the empty dop, then carefully slide them together.  Try not to let them actually touch, since it may cause chipping of the pavilion during curing - mostly on larger ovals, when the epoxy cures and expands.  Using the toothpick I put a very small amount of epoxy on the outside of the joint as well.  When the cut is round,square or trillion I use the cone dop in the keyed slots, and apply the epoxy as described above.  The keyed dops will properly center the stone.

If the rough is heat tolerant (quartz, garnet, topaz, spinel and CZ for example) I put the jig in a 250 degree pre-heated oven for 30 minutes to harden the epoxy and loosen the super glue.  At the end of this time, open the oven door slightly.  After 30 minutes of cooling remove the dops from the transfer jig. Use small channel lock pliers, cushioned with a folded paper towel, to hold the rough and lightly tap the original super-glued dop with a screwdriver shaft  it almost always drops right off. 

If the rough is not heat tolerant (Jewel-lite, CreativeGem, Laser Gem), and you have allowed a little extra depth in the rough like I suggested, you can use your handy trim saw to cut the stone to release the flat dop after the epoxy has hardened.  With a good eye, adequate depth of rough, and a careful hand you can cut off a really thin slice from the "crown" portion of the rough, and skip the whole oven deal.  If you tend to be a little clumsy or are really afraid of sharp things (like diamond saws) then DON'T TRY THIS.  It works for me and I love it!  Rinse both the vee/cone dop and stone, and the flat dop with the thin slice of rough, in a jar of waste alcohol.  Plunk the flat dop into the jar of acetone so the thin slice of rough will be released. Then clean the flat dop with fresh alcohol and it's ready to go again.

I always align my stone when ready to begin cutting the crown, even when I use the keyed slots for the transfer.  To do this, mount the transferred dop& stone and set it to 90 degrees.  Put the index wheel on a setting for one of the 90 degree/girdle cuts you made on the pavilion, and eyeball the girdle cut to as close to perpendicular to the lap as you can.  Lower the stone and lightly touch it to the polishing lap, and adjust the mast until the needle is centered.  Now put the stone on the lap for a second, lift it, and use the polished portion to guide you in adjusting the cheater wheel until the polished portion is in line (horizontal) with the pavilion girdle line. 

Once aligned I usually advance the index wheel to the next girdle cut setting and repeat the process to confirm alignment.  Then cut and polish the crown per the diagram.  One tip here  when you are cutting/polishing the crown of a oval or pear, I prefer to open the screw on the 45 degree device and insert the dop almost all the way into the block, past the keyed portion of the shaft of the dop, and eyeball the stone to square it with the block.  This way, as I adjust the height or cheater to get my table cut to align with the meet points I have less lateral variance to deal with. 

Once you have cut and polished the crown you can put the dop and attached stone carefully in a jar with enough Attack solvent in it to cover the stone. It will release the epoxy in a few hours.  Clean the stone and dop in alcohol, and admire your handy work!!

You mount the stone yourself, and if I am really impressed with something I've done I put it in 14K and give it to my wife!  I suggest you purchase the special stone-setting pliers, they really work well. Wow, this has been fun.  I hope you find this story useful, and that it helps you quickly and successfully get started in your new hobby, using your Facetron machine. 

There are so many great cutting diagrams available on line, and so much to learn about different materials and techniques. 

You will have a ball.  Happy Cutting !!