UPDATE 3-20-21 Input, opinions, tips for cabbing

[stardiamond]

The stone can with the edge against the wheel ------------------ tilting the stone to cut above the girdle line
or 90 degrees angling the cut above the girdle line.
-g-
-g-
-g-
-g-
-g-
-g-
-g-

I guess I need to take some pictures.

[manofglass]

September 1969


With the cabbing article in it

[USMC15]

Okay, I have not read all 12 pages of this, but I am confused.

You have to have a 30° angle on the edge, then you add another angle to start the dome, or is that 30° the start of the dome?

I need visual aides!

[rockjunquie]

Mar 16, 2021 20:36:06 GMT -5 USMC15 said:

Okay, I have not read all 12 pages of this, but I am confused.

You have to have a 30° angle on the edge, then you add another angle to start the dome, or is that 30° the start of the dome?

I need visual aides!

As far as I see it there are 3 kinds of girdles- a girdle that doesn't "break" from the dome to the table (like this month's cab contest); a girdle that has an approx 3mm thick edge on the side with a 30 degree angle (although that's a ballpark figure, mine are more like 15-20) that stops at the edge of the dome; then there are the rounded over girdles which don't have the sharp edge that the preceding one has- it is softer.

The 30 degrees (or thereabouts) goes up to the edge of the dome. It is about 3mm thick, then you start your dome.

I'll try to find a graphic. I thought it was posted in this thread somewhere.

eta   check out this page- scroll down for a visual.  www.gemsociety.org/article/lapidary-fundamentals-cabochon-cutting/

[USMC15]

Mar 16, 2021 21:09:35 GMT -5 rockjunquie said:

Mar 16, 2021 20:36:06 GMT -5 USMC15 said:

Okay, I have not read all 12 pages of this, but I am confused.

You have to have a 30° angle on the edge, then you add another angle to start the dome, or is that 30° the start of the dome?

I need visual aides!

As far as I see it there are 3 kinds of girdles- a girdle that doesn't "break" from the dome to the table (like this month's cab contest); a girdle that has an approx 3mm thick edge on the side with a 30 degree angle (although that's a ballpark figure, mine are more like 15-20) that stops at the edge of the dome; then there are the rounded over girdles which don't have the sharp edge that the preceding one has- it is softer.

The 30 degrees (or thereabouts) goes up to the edge of the dome. It is about 3mm thick, then you start your dome.

I'll try to find a graphic. I thought it was posted in this thread somewhere.

eta   check out this page- scroll down for a visual.  www.gemsociety.org/article/lapidary-fundamentals-cabochon-cutting/

Thanks! Great read and resource. It was very helpful.

[standles]

So I am only 6 stones into my cab making career but here is what (I think) I have figured out to this point.

1. I am learning is use your fingers to "feel" the symmetry of the dome. I find it gives better feedback that visual.
2. I also hold the stone on the dop up with good light and a graph paper background then spin it slowly in each direction looking for the symmetry.
3. Use more water than you think you need. I am balancing it between seeing a slurry n the edge of rock and taking a bath in overspray
4. Wipe and inspect the stone regularly. I keep a damp microfiber cloth in lap and look at wiped stone wet and dry
5. Finally, I was feeling pretty proud of my accomplishments but picked up a jewelers loupe. When looking at my finished stone that had been polished up to 50K grit I saw old scratch marks and where the girdle wiggles. I also saw pits that were unseen and fracture lines that I thought were solid as little canyons. The stone looked great but seeing those help me to know what to look for for the next stones.

[hummingbirdstones]

Mar 19, 2021 8:53:19 GMT -5 standles said:

So I am only 6 stones into my cab making career but here is what (I think) I have figured out to this point.

1. I am learning is use your fingers to "feel" the symmetry of the dome. I find it gives better feedback that visual.
2. I also hold the stone on the dop up with good light and a graph paper background then spin it slowly in each direction looking for the symmetry.
3. Use more water than you think you need. I am balancing it between seeing a slurry n the edge of rock and taking a bath in overspray
4. Wipe and inspect the stone regularly. I keep a damp microfiber cloth in lap and look at wiped stone wet and dry
5. Finally, I was feeling pretty proud of my accomplishments but picked up a jewelers loupe. When looking at my finished stone that had been polished up to 50K grit I saw old scratch marks and where the girdle wiggles. I also saw pits that were unseen and fracture lines that I thought were solid as little canyons. The stone looked great but seeing those help me to know what to look for for the next stones.

Good on you for discovering using your fingers to "feel" the dome.  We do that all the time to feel for flat spots and to make sure the dome is even.  You really don't need a damp cloth to wipe your stone.  It's nice to see it wet and shiny, but inspecting it dry is the only way to see any scratches or imperfections that you need to remove. 

Regarding the water, you don't need to take a bath in it.  Keeping the wheels wet is your objective because grinding on diamond wheels dry will ruin them.  The water keeps the rock dust down and the stone cool, too, but there's no reason I know of to use more than necessary to just keep the wheels wet and the stone cool.

A loupe is a great tool, but if you don't have one already, I would recommend picking up an Optivisor to use while you're cabbing.  Since you can just flip the magnifying part up and down, it's more convenient for inspecting your stone while cutting it.

[stardiamond]

More water = faster cutting. Rub a pencil on the face and top edge to see defects. My girdles got better when I started to work circular where the face meets the edge and with the face vertical to the wheel to square the girdles. I rock the edges with the face facing up to balance the edges. The bottom can match the lines on the bottom but that doesn't mean the top is even.

[rockjunquie]

The first edition of the digest of this thread ends here. New posts will be collected into an update when needed.

See first post for the link to the digest.  forum.rocktumblinghobby.com/post/1048326/thread

[Rockindad]

Thanks standles, printing this off and saving on the computer for future reference.

Al

[geoyeti]

Thank you for these tips everyone. A huge help!

[bfield]

I don't know about the rest of you but there are 3 things that have helped me tremendously in making my cabs.
1. The book by John Sinkankas "Gem Cutting - A Lapidary Manual". It has explanations for just about EVERYTHING to do with the art of lapidary. Pricey but worth it!!!
2. I joined my local mineral society (not sure where yours is? google AFMS minerals and use the drop down menus to find your local area/clubs - AFMS stands for the national association American Federation of Mineralogical Societies). Mine happens to be in Sacramento, CA. Most clubs (these are non-profit clubs so CHEAP!) have an introduction to cabbing. Ours has a video you must watch that explains everything about making the cab and the equipment used.
3. Other members in the club and our shop foreman. Our club shares information so easily and I've been in other clubs (bay area) that are exactly the same with instructions, helpful members, tools, machines, rocks, etc., etc., etc. My knowledge base as grown diabolically (hee hee) since joining my first club!
Take care and ROCK ON!

[chompa]

Dop pots, and the lack thereof.

I’m looking for a dop setup. After scouring the web for a kit or something, I could only find a few options. The old alcohol flame, Covington’s pot, Rio/Kingsley/Amazon pot and a three compartment dental wax melter. None of which have great reviews, and none of them come with everything you need to get doppin. I feel like there’s an opportunity for someone to make a nice one and come to market. That all being said, does anybody have any suggestions?? Thanks in advance for any help on this issue.

[hummingbirdstones]

Sept 25, 2021 10:17:50 GMT -5 chompa said:

Dop pots, and the lack thereof.

I’m looking for a dop setup. After scouring the web for a kit or something, I could only find a few options. The old alcohol flame, Covington’s pot, Rio/Kingsley/Amazon pot and a three compartment dental wax melter. None of which have great reviews, and none of them come with everything you need to get doppin. I feel like there’s an opportunity for someone to make a nice one and come to market. That all being said, does anybody have any suggestions?? Thanks in advance for any help on this issue.

Here's an old Raytech dop pot on Ebay. 

Kingsley North has their brand.  Ron's Rocks on Ebay sells the Kingsley North ones and has sold a lot of them.  Never used this one.

Vince uses an old Rock Rascal Model D dop pot.  I use the alcohol lamp -- it's what I learned with and I kind of like it.

The Raytech's aren't made anymore and they're pretty hard to find.  The lapidary instructor at our local college loved them.

I have never seen a dop "kit" being sold.  Dop wax is relatively inexpensive and lasts a long time and you can make your own dop sticks by using wood dowels and cutting them down to length, or nails or whatever you want.  Ron's Rocks has some dop pots with the wax but he's way expensive on that IMHO.

[rockjunquie]

I have an Inland Dop Station. I have to say, I really like mine. It has been perfectly reliable. The rim is nice and wide to place stones on and that rim is some kind of nonstick material. But, I still use acetone to clean it up.

I have never seen a kit.

Beware of cheap dop wax. It's from overseas and NOT good. I had to pitch mine.

I did like hummingbirdstones said and cut up varying sizes of dowel rods to my personal perfect length.

[knave]

Jul 12, 2021 13:55:01 GMT -5 bfield said:

I don't know about the rest of you but there are 3 things that have helped me tremendously in making my cabs.
1. The book by John Sinkankas "Gem Cutting - A Lapidary Manual". It has explanations for just about EVERYTHING to do with the art of lapidary. Pricey but worth it!!!
2. I joined my local mineral society (not sure where yours is? google AFMS minerals and use the drop down menus to find your local area/clubs - AFMS stands for the national association American Federation of Mineralogical Societies). Mine happens to be in Sacramento, CA. Most clubs (these are non-profit clubs so CHEAP!) have an introduction to cabbing. Ours has a video you must watch that explains everything about making the cab and the equipment used.
3. Other members in the club and our shop foreman. Our club shares information so easily and I've been in other clubs (bay area) that are exactly the same with instructions, helpful members, tools, machines, rocks, etc., etc., etc. My knowledge base as grown diabolically (hee hee) since joining my first club!
Take care and ROCK ON!

Which edition of gem cutting do you own.

[knave]

[hummingbirdstones]

Sept 28, 2021 17:31:59 GMT -5 knave said:

Gotta love the Captain.  Everything he has ever written is worth owning and reading.

[knave]

Just saying Abe Books has hardcover ones for a good price

[knave]

Posting this gem from a different thread, for posterity.

Sept 29, 2021 2:13:53 GMT -5 holajonathan said:

knave

Here is my current setup / process. I think it's a winner in terms of speed and results:

Step 1: Cut preform on trim saw and shape preform on 8" flat lap with 60 or 80 grit diamond disc. Flat lap grinds faster than wheels. Discs are cheap, so I work them hard.

Step 2: Fine tune preform shape and cut dome on 8" Covington grinder with 80 grit and 220 grit sintered wheels from Kingsley North. This machine gets me through the hard wheels twice as fast as grinding on the Genie. The Kingsley sintered wheels are great. They work as well as Inland wheels costing more than twice as much. (I have an Inland sintered wheel, so my comparison is justified.) And the diamond layer is 6mm thick, unlike 3mm for the Inland. I lightly dress the sintered wheels often because I'd rather them grind fast for a few years than grind slowly for the next 30 years. I have no patience for spending a half hour on the 80 grit wheel.



Step 3: My Genie is setup with resin wheels only with these grits:

Left arbor
140
280
600

Right arbor:
1200
3000
8000

140 resin quickly removes scratches from the 220 hard wheel and smoothes out the dome. Even though 140>220, the 140 resin is less aggressive and scratches much less than the 220 hard.

On the Genie, most of my time is spent on the 140 and 280 resin wheels. If I do things right, I can't feel scratches with my fingernail after the 280 resin wheel, at which point I run through the last 4 resin wheels quickly.

With resin wheels only on the Genie, I can cab all day without cleaning out the pans -- only adding some water once in a while.

Step 4: I do a final polish on a flat lap with 0.3 micron AO on rawhide. Or I throw a cab or two in the Lot-O tumbler with ceramic media and the same AO polish. Sometimes I do both.

This sounds like a lot of machines and steps to make a cab, but adding more steps / wheels / machines has cut in half the time it takes me to make a cab. Most importantly, I never get bored using this process, and I am happy with the results.