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Let's Rock => Rockhounding Tips, Maps, Trips Etc. => Topic started by: jalapeno333 on April 23, 2020, 11:58:09 AM
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Hi I’m running a 12” Lortone slab saw, and I’ve been slabbing many different materials recently (new to cutting and only been really into for a couple months now).
My question is, what is the ideal thickness to make slabs? I’m sure it’s a matter of preference, but is there a generally agreed upon “standard”? I’m cranking it 4 turns and getting 4.75mm or 5 turns and getting 5.5-6mm
I slabbed some pietersite into some rather thick slabs and then regretted it because if I had gone one less turn I may have squeezed an extra slab out.
Thank you!
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if your slabs are meant for the cabochon guys, then I look for slab cutters who give me room for a proper bezel. 6-8mm minimum.or I pass. I always measure. I have passed on a lot of nice rough slabs for this reason above all others. I cannot do much with a 4.75mm slab.
I am just all that into specimen stones, which these thinner slices I find to be of the best and highest use. These days I find a lot of vendors trying to cut way too many slabs to get the "most" out of their work.
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Thank you! 6-8mm sounds good
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For most cabs 6 mm is plenty. You can cut a low dome cab from a 5 mm slab if the face size isn't huge. It gets pretty flat after that if your girdle is 2.5 to 3 mm.
If you have translucent material for cutting old fashioned high-domes, you might want a 10 mm slab.
I slab most of our rough to at least 6 mm.
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6 mm or more for me. I absolutely despise thin slabs unless they for making doublets.
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It’s interesting to read the comments above because I started out liking thick slabs but now genuinely prefer thinner ones for certain material. For example, I generally associate thinner cut Koroit boulder opal cabs with higher quality because the better artists who obtain the highest polish I’ve seen for that material seem to go for modern cabs with flat tops. There are other materials I prefer thin too. Iris agate must be cut super thin and I had a friend mistakenly cut some ( we didn’t know was Iris) thick for me. I like Madagascar labradorite either super thick for color or relatively thin so I can make a doublet with it. Etc. Etc.Same for rutilated quartz. Either very very thick or quite thin for doublets is preferred.
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“the better artists who obtain the highest polish I’ve seen for that material seem to go for modern cabs with flat tops.”
Modern cabs with flat tops.. hmmm thank you for this input. I find myself making cabs with sharp angles from where the “shoulder” transitions to the dome. As opposed to a smooth gradual rounding from the base of the cab to the middle of the top.. I’m doing Not quite a flat top, but my cabs definitely have a “low” dome.. I wonder if that’s the same thing. I’m thinking of ordering some silver and trying my hand at bezel setting to see what the actual jewelers are facing when working with cabs after they leave our hands.
It makes sense that different material would require different thicknesses. . Great feedback!
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Not the same thing. I've been seeing a lot of low dome cabs for sale lately that are also very thin, get more out of a stone, I guess. This is okay if the stone is hard and not brittle, but doesn't leave much for a bezel. People often use glue these days, but I don't trust it on chalcedonies and quartzes, jade and the like. I do some almost flat tops also like with tiger's eye for example, or other stones that could lose the pattern if too much is taken away from the edge. It's still normal thickness, though. Room for a good bezel. If you acquire a good slab, but want a large cab, dome as necessary. I'll try to post some pictures in a bit.
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Well as a retired jeweler, one of the gripes I had when buying a few cabs, was the thinness. I like fat slabs and I cannot lie. Give me a nice stone to have a good dome on. I do not want the stone that looks good to be over shadowed by my metal work. I have a lot of slabs right now and a trim saw. My birthday present this year is a nice sized slap saw. I will cut 1/2 slabs for my self.
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Think about the finished thickness of cabochons. Also, think about who your market is... I love nice domed tops on cabochons with a finished size of 5mm. I do cut many cabs that are thinner and they just do not sell as well. Thin cabochons are much easier to sell.
BUT: My jewelry making customers on clear stones such as Montana Agate and opal want thinner stones, 3 to 4 mm as a rule. Jasper cabochons up to but not over 5mm as a rule. Plume agates 4 to 5mm also.
I have sold over 1,000 cabochons on Etsy with prices from $20 to $250. Customers are very demanding when you go over the $40 mark and they tell me what they like at all prices. Size preference for 90 percent of my customers is what I listed above.
Customers who want display pieces that will not go into jewelry do tend to buy the larger cabochons. This is a much smaller market but they do want the best and tend to pay more.
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Think about the finished thickness of cabochons. Also, think about who your market is... I love nice domed tops on cabochons with a finished size of 5mm. I do cut many cabs that are thinner and they just do not sell as well. Thin cabochons are much easier to sell.
BUT: My jewelry making customers on clear stones such as Montana Agate and opal want thinner stones, 3 to 4 mm as a rule. Jasper cabochons up to but not over 5mm as a rule. Plume agates 4 to 5mm also.
I have sold over 1,000 cabochons on Etsy with prices from $20 to $250. Customers are very demanding when you go over the $40 mark and they tell me what they like at all prices. Size preference for 90 percent of my customers is what I listed above.
Customers who want display pieces that will not go into jewelry do tend to buy the larger cabochons. This is a much smaller market but they do want the best and tend to pay more.
day to day selling and making jewelry I was asked when it was a thin stone "Why so small, and why so thin? Different markets. Most were set along side high end faceted stones. Part of why I'm learning is to have the thicker stones. Opals are ones I would go on the thin side. Common opal, thick is better. It's just over 40 years of listening to customers that now I tend to agree with them. If they are going to pay the price of my jewelry, they want a nice stone with a higher dome.
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on my slab saw i only use 4 turns, it equals four pennies thick.
I get nice cabs with that thickness
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I cut all of them 1/4" unless I have a specific purpose for the slab.
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I think it depends on your eventual purpose. I make pendants so I tend to cut at a minimum 8mm and sometimes thicker. It all depends on the shape of the pendant. A thicker slab makes it easier to then drill through it for the necklace and then grind evenly towards the holes.
Thicker means more grinding but having the extra material gives you a better chance at accuracy in shape.
Cheers,
Kent
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Sounds like a very interesting topic, but can someone explain to me what it is, about the turns and thickness please? I have a hard time wrapping my head around this one....
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Easy. Slab saws have threaded screws on the stone vise to adjust the thickness of the cut of the stone. When one cuts a slab one selects the depth of cut (or the thickness of the slab) by turning the screw adjuster on the slab saw vise. On some saws 4 turns of the screw gives 1/4 inch of slab thickness, some saws may take more turns for the same thickness slab since it depends on the threads per inch of the screw adjuster on the vise. So "turns" equals "thickness", the more turns the thicker the slab, the less turns the thinner the slab. By the way, I am one who prefers thicker cabs for my jewelry, I like a higher dome, so I cut many of my slabs to 6-8 mm. (6mm equals close to 1/4 inch).
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In a slab saw the blade is in a fixed position and the rough is in a vise on a carriage that can move toward or away from the blade and the vise with the rough is also on a carriage that allows travel across the blade. The amount of turns is on the vise carriage and it determines the thickness of the resultant slab. The threads on the second carriage are largely standard so many saws advance across the blade the same amount with various saws.
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Hi Anita.
It will be easy. There is a "TPI" - threads per inch - number included in bolt sizes and such. A "1/4 - 20" bolt is 1/4" diameter, with 20 threads per inch. In that case, five threads (turns) would equal 1/4" of "travel". 20 threads divided by 4 (quarters of an inch) = 5 turns).
For a saw, you'll have to add an additional part of a turn to account for the width of your saw blade/cut.
Your saw might have a 3/4 - 16 crossfeed size/thread pitch. If so, 4 turns (1/4") plus another 1-1/2 turns or so (for blade thickness) will give you slabs close to 1/4" thick. I turn our drop saw crossfeed 5-3/4 turns.
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Hi Anita.
It will be easy. There is a "TPI" - threads per inch - number included in bolt sizes and such. A "1/4 - 20" bolt is 1/4" diameter, with 20 threads per inch. In that case, five threads (turns) would equal 1/4" of "travel". 20 threads divided by 4 (quarters of an inch) = 5 turns).
For a saw, you'll have to add an additional part of a turn to account for the width of your saw blade/cut.
Your saw might have a 3/4 - 16 crossfeed size/thread pitch. If so, 4 turns (1/4") plus another 1-1/2 turns or so (for blade thickness) will give you slabs close to 1/4" thick. I turn our drop saw crossfeed 5-3/4 turns.
Hey ya Vince! I'll print this out, and give it to my dear hubby. He's got a way of explaining things to me, not that I can't understand but I'll catch on quickly! :icon_thumleft:
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Cool. I was trying to add technical info without making it sound condescending. Glad you were happy with the way it came out.
I've worked with a surprising number of "technical" people who haven't known the second part of a thread size callout is the "TPI".
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Cool. I was trying to add technical info without making it sound condescending. Glad you were happy with the way it came out.
I've worked with a surprising number of "technical" people who haven't known the second part of a thread size callout is the "TPI".
LOL, yeah and If my hubby and I still don't understand, I have a strong pair of lungs to ask questions....