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46  The Gathering / Introductions / Re: Help!! Need to Re-Polish Agate Geode Slab on: January 01, 2016, 04:43:27 pm
Generally cerium oxide is used to polish agate.
Bob
47  Lapidary Shop / Moderator, Catmandewe ( Tony ) / Cabbing And Grooving Machines.. Projects / New and Used Reviews / Re: Need advice about how to remove bearings from my Lortone Lap Combo LU-6X arbor.. on: December 29, 2015, 08:43:18 pm
The best penetrating fluid is PB Blaster, found at most auto parts suppliers.
Bob
48  The Gathering / Introductions / Re: New from N California on: December 29, 2015, 09:32:56 am
There are two clubs near you that might be able to help you.
Nevada County Gem and Mineral Society
El Dorado County Mineral and Gem Society
Bob
49  The Gathering / Introductions / Re: Help!! Need to Re-Polish Agate Geode Slab on: December 29, 2015, 09:25:36 am
I use carpet scraps for my wheels. You probably can get it from your local carpet store. It is an office carpet that is 1/4" thick, probably nylon or some such material. Cut out a disk and glue it to one of those rubber disk attachments.
Bob
50  The Gathering / Introductions / Re: Help!! Need to Re-Polish Agate Geode Slab on: December 28, 2015, 06:48:50 pm
The light colored mark appears to be a left over saw mark that wasn't fully sanded out of the slab. To get it removed you have to go back to the coarse sanding step and sand the whole surface down below the saw mark and then go to the finer grits, sanding and polishing, etc. Polishing on the saw mark only probably won't make it look polished but will make it more evident. I use a piece of window glass and various tumbling grits with water to "flat lap" smaller pieces when I'm making doublets and triplets but this won't work for polishing. Maybe you could use a piece of carpet on your hand drill to polish it. All of this work on the surface could result in going below the penetration depth of the blue dye and the color will be less blue.
Bob
51  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Mineral Specimens / Re: Cady Mountian Agate on: December 24, 2015, 04:30:35 pm
I have used the dry sanding method on slabs, the back and front of my large cabs and the backs of most all my smaller cabs. It is very fast. One of my recent monthly columns in Rock and Gem Magazine is about using the dry sanding process. I've been using it for about 40 years.
Bob
52  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Share Our Finished Cabochons and General Cabbing Questions / Tutorials / Brazilian Agate on: December 22, 2015, 01:00:11 pm
This is my rainy day cab. It was raining a lot yesterday (YEA!) so made this one. It is Brazilian that is 3-3/4" across.
Bob
53  The Gathering / Our Place / Re: Polishing stage in tumbler on: December 17, 2015, 12:17:57 pm
I'm a lazy tumbler! I grind with 60 grit for a month, wash the rocks, put them back into the tumbler and add rocks up to 1" of the top, add water and polish  and run it for another month sometimes 5 weeks. Unload and wash the rocks and load a new batch in. This has been my method for the last 25 years. I polish rocks for our wheel of fortune at our show. I run a 40lb and 2- 12lb tumblers 24/7.
Bob
54  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Share Our Finished Cabochons and General Cabbing Questions / Tutorials / Re: Cutting Perfect Circles on: December 16, 2015, 10:31:30 pm
I wrote an article that was in last November's issue of Rock and Gem in my monthly column that addresses this specific situation. I use a circle template as most people do but when I draw the circle from the template I use a black ball point pen so the line is narrow and well defined. When I'm grinding to this line I go slowly and grind up to this line but never beyond it. I always ensure that I'm grinding at a 90 degree angle to this girdle. If you grind past the line you don't have a reference to know how far beyond you have gone. I use the same pen lying on its side to draw a line halfway between the top and the bottom of the preform. As I grind the first pass I'm always looking at that line and again I never grind below it. As I make the first grind depth into the dome I ensure I have ground it the same all around. I continue grinding around the preform keeping it even all the way around. I do this to keep the symmetry balanced. Sanding and polishing after the grinding activity proceeds as usual.
Bob
55  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Share Our Finished Cabochons and General Cabbing Questions / Tutorials / Unknown Druzy on: December 14, 2015, 12:10:02 am
I just finished this one and I'm not sure where the agate is from.
Bob
 
56  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Mineral Specimens / Re: ID help on: December 08, 2015, 01:59:25 pm
My thoughts were banded onyx
Bob
57  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Share Our Finished Cabochons and General Cabbing Questions / Tutorials / Re: Desert on fire on: December 05, 2015, 05:08:35 pm
Looks like Mexican Flame Agate.
Bob
58  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Rough on the bench and slabs off the saw (general minerals board) / Re: Agate slab ID? on: December 04, 2015, 11:56:21 pm
Your particular slab is a piranha due to the bright orange layers as well as the slab shown by Gemfeller. It comes from the state of Parana in Brazil but somehow the name got changed to piranha here in the U.S.
Bob
59  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Rough on the bench and slabs off the saw (general minerals board) / Re: Agate slab ID? on: December 04, 2015, 06:22:58 pm
Classic Brazilian.
Bob
60  Stone Talk / Moderator, Hummingbirdstones ( Robin ) / Share Our Finished Cabochons and General Cabbing Questions / Tutorials / Re: Dealing with undercutting in agate? on: December 03, 2015, 09:48:06 am
I made an 8" walnut wheel that I install on my slow turning polishing unit and I use Rapid Polish on it for the difficult-to-polish material like nephrite, lapis and most anything else that tries to undercut. I could get a fair polish on some golden picture jasper with my normal method but it took this wood wheel to finish it up. The picture jasper wasn't highly silicified so it didn't really want to polish.
Bob
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