agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Post by agatewhisperer on Jan 10, 2021 18:12:58 GMT -5
It's been a while but finally got down to cut a rock or two. Here's a piece of larvikite. I've been trying do get a lower dome since I want to leave space for a groove around the sides. Whats the trick to getting a nice low dome but also getting the scratches out of the middle? Probably a noob question but hey, that's me lol! Also, it seems like with this stone, under magnification, you can see little pieces that look like they flaked off on me leaving an uneven surface in some places. Thoughts? Hard to photograph the flash but looks pretty cool in person   |
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Post by Pat on Jan 10, 2021 21:01:40 GMT -5
I've always liked Larvikite; like the big crystals and color combination. Good looking cab! I don't see any problems.
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Post by rmf on Jan 10, 2021 23:06:01 GMT -5
The simple answer is diamond. If you are using diamond make sure you use light pressure. Diamond with too much pressure on a soft stone cuts groves too deep.
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Post by pauls on Jan 11, 2021 0:59:53 GMT -5
Your flaking problem could possibly just be the stone. Feldspar has a very pronounced cleavage that can result in flakes falling off.
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agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Post by agatewhisperer on Jan 11, 2021 14:45:26 GMT -5
Your flaking problem could possibly just be the stone. Feldspar has a very pronounced cleavage that can result in flakes falling off. Yeah that makes sense from what I can see on the surface. Are there any techniques to deal with that? or is what it is for this kind of rock... |
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Post by jasoninsd on Jan 11, 2021 20:54:08 GMT -5
Don't feel all alone. I struggle with too much pressure on the softer stones... darnit! I love the looks of the larvikite. Beautiful stone!  |
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Feb 13, 2021 12:14:05 GMT -5
The only problem I see with that cab is the cleavage line right coming in from the left, right below the tip of the teardrop. That is almost guaranteed to fail. Personally, I’d fix that, unless it’s purely for display as is. If it’s meant for jewelry, pop it and regrind, or risk an unhappy customer. Feldspars are definitely a love- hate relationship for the lapidary!
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Post by hummingbirdstones2 on Feb 13, 2021 13:20:41 GMT -5
Hi there! Larvikite can definitely be turned into eye-catching cabs. Have you ever seen photos of the huge pieces they pull out of the ground?
For your doming/scratching problem, check to make sure the profile of your dome has consistent curvature all the way across. If the curve flattens out anywhere going across from edge to edge it will be more difficult to work the scratches out of the center.
Less pressure has already been suggested. Along with that, slow the movement of the cab so the wheel has more time to do it's job. Slow smooth passes all the way across the surface, then back, with a light touch can make a big difference on softer stones.
Same for spinning the dop - slow it down and keep the pressure light and consistent. Sometimes for chippy stones the standard rock-n-roll rhythm just doesn't cut it.
If your wheels or laps are still relatively new and aggressive small chips are almost impossible to avoid with some rough. Hope some of this helps.
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agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Larvikite
Feb 13, 2021 13:42:21 GMT -5
via mobile
Post by agatewhisperer on Feb 13, 2021 13:42:21 GMT -5
The only problem I see with that cab is the cleavage line right coming in from the left, right below the tip of the teardrop. That is almost guaranteed to fail. Personally, I’d fix that, unless it’s purely for display as is. If it’s meant for jewelry, pop it and regrind, or risk an unhappy customer. Feldspars are definitely a love- hate relationship for the lapidary! Oh! Thanks for pointing that out. I'll need to go back and take a look at that. I've been focusing so much on trying to shape and learn how to polish that I admittedly miss seeing some of the cracks that might cause some problems. |
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agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
|
Post by agatewhisperer on Feb 13, 2021 13:46:09 GMT -5
Hi there! Larvikite can definitely be turned into eye-catching cabs. Have you ever seen photos of the huge pieces they pull out of the ground?
For your doming/scratching problem, check to make sure the profile of your dome has consistent curvature all the way across. If the curve flattens out anywhere going across from edge to edge it will be more difficult to work the scratches out of the center.
Less pressure has already been suggested. Along with that, slow the movement of the cab so the wheel has more time to do it's job. Slow smooth passes all the way across the surface, then back, with a light touch can make a big difference on softer stones.
Same for spinning the dop - slow it down and keep the pressure light and consistent. Sometimes for chippy stones the standard rock-n-roll rhythm just doesn't cut it.
If your wheels or laps are still relatively new and aggressive small chips are almost impossible to avoid with some rough. Hope some of this helps.
I haven't seen any pictures of huge pieces but now need to go look! That's some good advice on the speed of rocking etc. Sometimes I start going on autopilot and then realize I'm either pressing too hard or going quickly. I will try to focus on that for the next round. I don't have a rock club or rock buddies in my area so this advice helps a lot. Thanks! |
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