Rock Slabbing Fail - ideas?

[NevadaBill]

So, having no experience slabbing at all, I had some rough, and got some help from a local who cut some slabs for me yesterday.  While these are only 3 to 6 inches wide, I learned a great deal about slabbing.  Mostly, what not to do.



Unfortunately, some of my best brecciated Jasper chunks were used for experimentation.  And even though I am almost ecstatic to see some of it slabbed, the general thickness (and width uniformity) in which the local cut them, will not allow me to use much of it for the larger cabs I had hoped.  I just won't get much of a dome.



In some cases, the stone slab are only 1/16 of an inch on one side, and 1/4 of an inch on the other side of the same slab.  I am still scratching my head on some kind of creative application for a slab of such varying thickness.

Q)  Does anyone have an idea of something creative that can be done with a thin sliver of slab?  If there is none, then I understand.



I looked this up, but get various answers.  I swear there is a legit question here.

Q)  Does someone know what is the standard width for a slab, with which you would like to have yield that standard sized cabochon (oval) from?  I am speaking in general.  The most common oval cab which you see on necklaces.

I just want to try to create some cabs, by sticking to standards right away.  Marking real girdles, making real angle cuts, and ending up with properly domed cabs.  Sorry if this sounds vague.

Q)  How about cabs that are smaller (such as 1/2 or 3/4 of an inch ovals)?  Is there a standard width you like to cut these at?  For less domed, or perhaps smaller pieces.

I am not at the point where I feel comfortable running the larger slab machines yet.  And next time I will have a different "expert" at the wheel to assist me.

Sorry for so many questions at once.  Also if there is a link which would save time, I would love to read from it.  Especially if it talks about setting up a saw to make an exact thickness cut (not winging it so much).

Thank you!

[Drummond Island Rocks]

Industry standard slab thickness is 1/4". On some high end materials the slabs are cut 3/16" thick to yield more slabs per rock. I only cut 1/4" and I generally do not purchase slabs less then 3/16" thick. I am wondering how you ended up with uneven slabs? If the rock was clamped in the slab saw each cut should be parallel to the last.

Not sure what you consider larger cabs. 30mm x 40mm (1.25" x 1.5") oval was a standard oval size in the past and I would say a large percentage of cabs being made now fit within that envelope.

Chuck

[Rockoonz]

What Chuck said...
If I'm buying slabs I want 5mm to 7mm
1/4" is 6.35mm. When I cut I only cut thinner than 1/4 for things other than regular cabs. I very rarely cut thicker, usually with soft, less stable stuff or carving blanks.
If my slabs weren't uniform thickness I wouldn't be claiming to be able to cut a rock.

[victor1941]

NevadaBill, I would first mark around all the fracture points to see what is useable. My last group of cabs included a piece of hard and unfractured petrified wood similar to what you have in uneven thickness. I shaped it into a long triangle with the thin edge at the top and think the same approach would also work for rectangles or freeforms.

[aDave]

While I don't slab, and that could be the issue here, but I'm a bit confused. How did you end up with multiple thickness measurements on the same slab? Are you speaking to using end cuts, or did the local guy remove the rock from the vice and then replace it for the next cut? No cross-feed available?

[stardiamond]

My biggest problem with slab thickness was figuring out the cross feed adjustment and the kerf and I learned to err on the side of too thick.

I'm looking at some Hornitos slabs I bought that are very uneven 1/4 inch to almost a knife edge. Miscutting seems to be common.

[rockjunquie]

I would try to use the thicker end for cabs and preform the thin ones to tumble and drill.

[70karmann]

Cutting to 1/4 inch works great for me.

[70karmann]

Cutting to 1/4 inch works great for me.

[quartz]

I agree with victor1941, there's a lot can be done with your material, but the idea of standard textbook ovals might have to wait for better cuts. That is nice material you have, would make good freeforms.

[NevadaBill]

Jun 7, 2019 14:02:00 GMT -5 Drummond Island Rocks said:

Industry standard slab thickness is 1/4". On some high end materials the slabs are cut 3/16" thick to yield more slabs per rock. I only cut 1/4" and I generally do not purchase slabs less then 3/16" thick. I am wondering how you ended up with uneven slabs? If the rock was clamped in the slab saw each cut should be parallel to the last.

Not sure what you consider larger cabs. 30mm x 40mm (1.25" x 1.5") oval was a standard oval size in the past and I would say a large percentage of cabs being made now fit within that envelope.

Chuck

Thanks Chuck.  Noted.  

Uneven slabs (one most, due to him taking the rock out of the vise, and then clamping it back in.  Also due to the rock falling out of the vice on 2 occasions, and having to put the rock back in, and maybe guessing really badly.  It was not pretty. 

I think I consider 30mm x 40mm oval to be the kind of cabs that I am shooting for.  I just realized that I am an idiot.  I looked at my templates (plastic ones) and just realized that the sizes are printed below each of the shapes.     I should have looked before posting.  I hadn't noticed that before.  Sorry.

[NevadaBill]

Jun 7, 2019 14:37:28 GMT -5 Rockoonz said:

What Chuck said...
If I'm buying slabs I want 5mm to 7mm
1/4" is 6.35mm. When I cut I only cut thinner than 1/4 for things other than regular cabs. I very rarely cut thicker, usually with soft, less stable stuff or carving blanks.
If my slabs weren't uniform thickness I wouldn't be claiming to be able to cut a rock.

Thank you very much for your advice.  Notes taken.

I am going to do the research and watch videos on setting up the rock in the slab saw, and using mechanical feeds, and how to position a rock properly in a vice, so that multiple cuts can be made on one slab, using uniform widths.  

I need to put this in my hands and be responsible myself.  No one to blame but myself though.

[NevadaBill]

Jun 7, 2019 14:48:49 GMT -5 victor1941 said:

NevadaBill, I would first mark around all the fracture points to see what is useable. My last group of cabs included a piece of hard and unfractured petrified wood similar to what you have in uneven thickness. I shaped it into a long triangle with the thin edge at the top and think the same approach would also work for rectangles or freeforms.

victor1941 - Victor, thank you very much for giving me an idea on something that I can make with some of the uneven pieces.  Thin edge at the top, and thicker at the bottom.  I can imagine this.  Perfect.  Even a teardrop might work like this too.

[NevadaBill]

Jun 7, 2019 15:14:53 GMT -5 aDave said:

While I don't slab, and that could be the issue here, but I'm a bit confused. How did you end up with multiple thickness measurements on the same slab? Are you speaking to using end cuts, or did the local guy remove the rock from the vice and then replace it for the next cut? No cross-feed available?

The latter aDave.  Only speaking to the slabs that were not end cuts.  The rock fell out of the vise on two occations.  And on one occation it was pulled out of the vise, and then put back in.  

Having not attended one single slab cutting session ever before, I really didn't know what to expect, or how this would work.  So I just watched.  At least I learned some though.  Chalk it up to experience.

[NevadaBill]

Jun 7, 2019 16:10:42 GMT -5 stardiamond said:

My biggest problem with slab thickness was figuring out the cross feed adjustment and the kerf and I learned to err on the side of too thick.

I'm looking at some Hornitos slabs I bought that are very uneven 1/4 inch to almost a knife edge. Miscutting seems to be common.

Miscutting very well could be fairly common I guess.

There was a veteran cutter in the shop later and I watched him for a while too.  He made clean, even cuts on a slab 10" thick or so.  But when I looked at some of his preforms he showed me (beautiful material), I noted that many of them were not exactly EVEN, one side to the other.  And many were far more than 1/4 inch. 

But, every person has his own application.  They had been marked with a indelible pen, using standard template shapes such as circles, ovals, and squarish (shields) geometric shapes.  But I didn't ask.

It's just that when I see slabs in person, they all look even and uniform in width. 

How does that saying go?  When given lemons, make lemon marangue pie!  Or something like that.

[NevadaBill]

Jun 7, 2019 16:19:44 GMT -5 rockjunquie said:

I would try to use the thicker end for cabs and preform the thin ones to tumble and drill.

Hi Tela (@rockunquie).  "and preform the thin ones to tumble and drill"? 

Like, maybe (preform) cut some shapes out of the thin ones and put them in the tumbler?  And polish them up?

And Drill a hole in them, so they can be used like a necklace?  Or something?

Sorry, I hope I understood the application you had in mind for the uneven cuts.  If so, then thank you!  If not, please correct me so I can picture this.  Or maybe you have a link to something of yours maybe like this?  That would be cool. 

[rockjunquie]

Jun 8, 2019 20:01:37 GMT -5 NevadaBill said:

Jun 7, 2019 16:19:44 GMT -5 rockjunquie said:

I would try to use the thicker end for cabs and preform the thin ones to tumble and drill.

Hi Tela (@rockunquie).  "and preform the thin ones to tumble and drill"? 

Like, maybe (preform) cut some shapes out of the thin ones and put them in the tumbler?  And polish them up?

And Drill a hole in them, so they can be used like a necklace?  Or something?

Sorry, I hope I understood the application you had in mind for the uneven cuts.  If so, then thank you!  If not, please correct me so I can picture this.  Or maybe you have a link to something of yours maybe like this?  That would be cool. 

I think you got it- sorta. Take the thin end and cut it into shapes. Once you have the shape you want. Drill a hole at the top for a jumpring or leather strip- whatever and then tumble polish. I'm doing that with some preforms right now. Also, thin cuts make good earring cuts because they are lighter. Shape into small matching shapes and drill a small hole for a jumpring to attach to an earhook. Then tumble polish and assemble.

[NevadaBill]

That is a fantastic idea! Earring pieces. Thank you Tela, I would not have thought about that at all. But these ultra-thin slices could be perfect for that.

If they can take the tumbler, that is. I might have to run them with plastic pellets so that they don't bang in to other larger rocks and break. I haven't tumbled any kinds of cabochons or preforms or freeforms yet.

But, as you mentioned earlier that video Rob posted (the one with reindeer, crosses, and bears preforms) should have some good hints in there. He also has a lot of experience using DRY tumbling, and corn cob media. Diamond Pacific also sells dry media. I had some a few months back, but gave it away to someone else that could put it to immediate use. You can re-use the stuff too.

Thank you all, for the great ideas on how I can practically use ultra-thin slabs!

[Fossilman]

Vise that material, grab it and pull, if its tight - should be no movement … Cut away.. Never touch the material in the vise again, till finished..
I cut 1/4 slabs, unless it's a custom order... Good luck..
As for all material, there is a use for everything...

[arghvark]

I'd be disappointed too. I'm a rank beginner. Until a couple weeks ago I was using an old 10" Frantom trim saw that I mounted a Lortone vise on to cut smaller slabs. No precise thickness control, but always could get 2-4 parallel-sided slabs before I moved the rock.

Now with my new toy, an old LS-18, I'm feeling pretty spoiled. Exactly 6 turns on the crossfeed yields slabs exactly 1/4" thick. Pretty much idiot proof.

Can't stress the comments others have made about vise tightness enough. Shouldn't be able to move the rock at all in the vise before starting cutting. I'm soooo paranoid about what a rock coming loose could do to the blade that I really reef 'em down tight.

If for whatever reason a rock gets moved and you want more slabs, you can try to replace the rock in the vise by moving the carriage way back so that you are placing the sawn face of the rock up against the blade before tightening it down in the vise. Almost impossible to get perfect but might be better than what it sounds like you got. Due to limitations in carriage travel this might only get you a few more slabs. You could also just bite the bullet and place the rock for maximum slabs and count on the first one being a throwaway.

Argh