Pre-Form Layout Problem / Carol M's Brazilian Agate

[Carol M]

If you want to keep your 1st layout ideas...here's an area you might have over looked.

Thanks Don, Actually it's all cut up into the preforms and I was grinding, and sanding [but making the two main surfaces flat] and I got up to the 600 grit disc, when I got the word that that's a 'no-no' so now I've gotta go back to tweaking the angles.

Actually, it's interesting that when I was doing the flat version at the 600 grit when you're starting to see a lovely shine, the center of one of my flat cabs wasn't polishing and so I think it was lower there than around the center, so ....a lesson learned.

I'm not sure how far back I have to go to get the shape I need.
I basic full kit came with -
180 Mesh Metal Bond Diamond Disc, hydraulically pressed to a backing plate
325 Mesh Diamond Sanding Disc
600 Mesh Diamond Sanding Disc
1200 Mesh Diamond Sanding Disc
White Polish pad with 14,000 mesh diamond compound

I also added,
100 Mesh Metal Bond Diamond Disc, hydraulically pressed to a backing plate [which is a real 'peach'.  It trims the preform really well.]
and at Krystee's suggestion I ordered two additional backing plates and a
220 mesh and a
3000 mesh Diamond Sanding discs.

My guess is that I shouldn't go back to the grinding discs because I'm afraid it'd be toooo aggressive when the flat cab is so thin [originally 4-5mm thick]
My hunch though is that I might try [on one of the cabs that I like least] to go back to the 325 mesh and see if that forms the angle without eating the stone up.
If that's too strong, I'll move milder and if that's too mild I'll go grittier but at least that way I won't destroy the few I actually like.
Oddly enough, "E" that everyone seemed to think was the best, doesn't really 'turn my crank' much.
The dark lines seem to be paler now and so it's not that wowie.
The one I'm liking the most is "A" which looked so dark but is getting quite nice.

So....on it goes.
Back to the grind....[giggle] ......or should I say 'sandbox' 

[sealdaddy]

I like A, B, C and F, myself
What were you saying about a no-no?

[Carol M]

I like A, B, C and F, myself
What were you saying about a no-no?

Re the 'no-no' - I was saying that the slab is relatively thin and very translucent like stained glass, and I thought I'd make both sides visible and let light shine through by running a bezel around the edge but not putting a solid [or even perforated] back.
To do this, because there's not much material thickness, I was going to make both the front and back flat and was wondering if there was some 'lapidary law' against flat and was told not to go flat.
Since I don't think I can dome much even on one side, if I want to have any bezel left at all, I'm going to just dome the front and leave the back relatively flat.  I'll just dome it enough to be able to polish the center.
I was getting a 'dull spot' in the centre of one of the cabs indicating that it was a tad lower than the surrounding area.

So that's what I was saying was a 'no-no'.

Re your comments, about liking A, B, C and F - one interesting thing I'm discovering about this process, is how much the stone material changes as you polish it. 
Colors that were not visible before, show up, and sometimes colors that were there, disappear.
It's kind of exciting to see it evolve, but I'm sure it could also be very disappointing if one you really like, disappears. 

[lithicbeads]

 With certain stones the polish basically ruins them, it makes them bland . People here are a little too concerned with a high polish finish in my opinion . Matte and high matte finishes can maintain color and interest in cabs that look washed out with a high polish . The crucial thing in my book is that the polish whatever it is , be uniform and suit the stone.

[Carol M]

With certain stones the polish basically ruins them, it makes them bland . People here are a little too concerned with a high polish finish in my opinion . Matte and high matte finishes can maintain color and interest in cabs that look washed out with a high polish . The crucial thing in my book is that the polish whatever it is , be uniform and suit the stone.

Well, I have to say, I LOVE THAT KRYSTEE SHINE.

This is not to say that other finishes matte and high matte are not good too, but I'm a sucker for that 'wet look'.

With some stones, like Indian Paint Stone, I think that the matte finish is fabulous, but with many agates, I do love that high gloss finish if you can get it......or at least you can TRY to get it.

[lithicbeads]

 Those finishes are done perfectly in a vibe tumbler as are polished finishes.

[Carol M]

Those finishes are done perfectly in a vibe tumbler as are polished finishes.

"So many toys....and so little time"

[jakesrocks]

OK Carol. If you haven't already cut it, here you go.
1st cut -- A straight cut between C & D, stopping just short of E.
2nd cut -- Between D & E, meeting your 1st cut.
3rd cut -- Along opposite side of E, stopping just shy of F.
4th cut -- Along the long side of F, to just past the end. This will produce a diamond shaped cutout from between E & F, which can also be cabbed.
5th cut --  Across the bottom of F, meeting the previous cut.
6th cut -- The long left side of A, stopping just beyond the point.
7th cut --  Along opposite side of A, meeting previous cut.
8th cut --  Between B & C, to just beyond the end of C.
9th cut --  Along opposite side of B, meeting the previous cut.
10th cut --  short cut at bottom  C, to remove it from the remaining center piece.

This will leave you much of the center to also cab.

[jakesrocks]

OOPS, my bad. I see that you've already cut the piece.

Anyway, since the slab is thin, you could try just rounding the edges. Flat polish both faces, and if you have a grooving tool you could try groove wrapping them.

[Carol M]

OOPS, my bad. I see that you've already cut the piece.

Anyway, since the slab is thin, you could try just rounding the edges. Flat polish both faces, and if you have a grooving tool you could try groove wrapping them.

No worries, and thank you for the kind consideration of all those directions on cutting.  I'll review 'the principle' of cutting it that way so I can learn for future slabs.

Thanks again

[Carol M]

I'm thinking of suicide!!!!

Since I had some SuperGlue from my Arbor Dust Collector project and bought some large nails with, I decided to dop my little cab-wantabees.  The SuperGlue works wonderfully and makes it way easier for me to hang onto the little suckers.   

After getting my knuckles rapped for proposing a flat front and flat exposed back on my Brazilian Agate, I went back to my 180 grit grinding disc and put some lovely multi-bevels in all of them.   I didn't think they were thick enough but they'll be fine.
That's not the frustration.

So, I proceeded through my various grits perfecting my shape but trying not to make the whole thing too thin so I didn't go nutz on the middle of the top thinking I'd leave some material to remove with the various finer grits. [big mistake]  So far so good and things were going well. 
I'm now at the Blue [1200 grit] and trying like mad to smooth the &^%$ top that I left 'only lightly touched' during each grit level.
At 1200 grit, it's taking forever to try to get those tiny middles smooth, so now I'm poised with my Hari-Kari knife pointed at my stomach trying to avoid suicide [ERGH!!!!]

I decided to stop and make supper and go back at it tomorrow, when I'm going to back way-the-heck up to some grit that will remove material.
I have 6 small cabs and each has only a tiny amount of flat in the middle [like 1mm x 2 mm or so] but I want it to be done right.

How far back should I go to smooth this last little bit??  Should I go all the way back to the grinding disc [180 grit] or should I just go as far as my 220 roughest sanding disc, or what??   

"Tortured in Toronto"

[Carol M]

Another question 'for all you Doppers out there'  [don't I sound like "The Big Bopper" ??]

Anyway, if you dop the cab and go through the grits, how do you deal with the back??  If you want it nice and smooth and polished??

Do you do the whole front all the way to completion and then remove the dop and go back through the whole back with all the grits???

[jakesrocks]

Carol, you might try working from the center out to the edge, or at least until you blend the flat spot in. Always keep the stone in motion, turning it and rocking from side to side. If you let the stone sit still even for a second or two, you'll start to form a new flat spot. Start with the 325 mesh disc.

[lithicbeads]

I like to do the back first freehand .

This requires cutting and coarse sanding of the bevel shape at the same time.
Getting out the flat spot is doable with your coarse sand pad but it beats it up a bit .If you 180 hard disc is pretty unworn that can be very aggressive and remove more material than you like especially with your thin rough .
Thinking outside the box a bit here you could go to the hardware store and get a few sheets of silicon carbide wet -dry paper. It comes in rectangles or squares. You cut a hole in the center so you can mount it above one of your sanding pads,  preferably your coarsest.You cut it round  before you lay it on the mounted disc. It may be smaller than the disc but that is fine just work away from the outer edge a bit.You need to use a washer if possible to spread the force of the nut that holds the disc and the sic sheet down . The force of the disc spinning will flatten the sic disc adequately . Watch the edge as it can be sharp . This can be used wet or dry .
Dry the dust is a health issue but it sands amazingly quickly and will remove your flat if it is of reasonable size. As heat is an issue you just touch roll and lift. It should work just fine wet and even better if you restrict the water a bit . Sic sands very quickly if you use 100 grit saving much abuse to your diamond pads.

[helens]

I took a cabbing class for my first effort, at the local rock shop... I figure I should learn how to do it the 'right' way before I ran off to figure out how to do it 'my' way (every shortcut I could think of)... and it paid off pretty well:). First because I learned exactly the right equipment that pros use, and how to use it... and also the actual technical stuff (templating, cabbing to spec-forgot the right term already, pencil drawing the bevel, coloring the entire top with marker to make sure no spots are missed, then going through each and every grit, and recoloring each grit with marker again to ensure that there were no missing spots).

So to answer your question from what I learned, and not my 'winging' it method of no markers, no templates, and tumbler to polish, you should color your whole rock from the bevel point up with marker, and start at the lowest level grit for the tops again. I was told to NEVER go back to a higher grit from a lower grit without washing the cab, to avoid contamination.

For reference, this is the first cab I ever made - which happened to be the first cab I actually even noticed before I took the class (all I paid attention to before that were faceted gemstones, carvings and opals/fire agates) - ok, I did not use a template, I didn't want a 'standard' shape, and the instructor humored me after I insisted I could hand free-form any shape fast, hand free-forming molten glass nearly every day for years - even with that background, cabbing was a unique experience:


This is the side (I did not get the left bevel a perfect match with the right bevel... but I wanted that dome up top to be a bit bigger, because to me, it was a better balance, as a partial teardrop where the top is fat and the bottom tapered):


Like you... I ended up having to go back a few wheels several times when I got impatient... so this little cab took me 3 hours. But those were an invaluable 3 hours that taught me the basis I could launch my own creativity from.

This was my 3rd cab ever, I bought a cabking 1 wheel machine after I made my 2nd cab:


My 4th cab with my own machine (6th cab ever):


I'm showing these off to empathize about wanting to do unique weird shapes that fit into no templates:P.

I'm also showing them off to point out that it might be a good idea to take a class at your local rock shop, because before you can depart on your own, you should have a base to depart from:).