helsha
off to a rocking start
Member since January 2021
Posts: 7
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Post by helsha on Feb 22, 2021 14:28:25 GMT -5
Hi all, first post but been lurking for months! I just finished tumbling my third batch of rocks and I'm not super happy with the results I've been getting. I've got a Raytech TV-5 vibe because I mostly collect beach stones so I didn't see the need for a rotary tumbler... and also I'm impatient. The problem is that I wind up with a bunch of stones that have a web of very fine cracks on their surface that only appear when the stone dries, when they turn white. The polish on the stones is high and glassy but the cracks prevent you from really "seeing" the stone. At first I thought these were being caused by not enough cushioning in the tumbler. I can't even see these cracks until I get to pre-polish. But I've run the last two batches with a lot of ceramic pellets and still having the issue. Images below with dry on the left and wet on the right. I'm pretty sure my problem is that I just need to give them more time in Stage 1, but it's tough to gauge when to move them on since I can't really see the cracks until after stage 2. But I'm not sure if I just have unrealistic expectations of being able to fully remove (what I presume to be) a weather rind from stones? Or is the 100/120 grit of the stage 1 in a vibe just not aggressive enough to remove them? Thoughts?
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Post by Peruano on Feb 22, 2021 16:44:39 GMT -5
Little imperfections get magnified when white polish gets lodged in and dried in them. Your problem may in part be related to the rocks you are tumbling. Things like quartzite can be polished but they will almost always have a grit texture that will not be as smooth as cryptocrystalline materials like agates, jaspers and their cousins. You may be able to remove some of the highlighting white material by running your stones in soapy water or borax after the polish. You can do it in the vibe just use more water than you would for a typical run. I have a vibe 5 too and often suffer an attrition of stones that don't make the final grade when they are viewed dry. Its not the vibe, its the stones and the time spent. Depressions like those in the last stone pair will not go away in a vibe without a pre-grind step. Luckily beach stones are abundant and the price is right when you are at the beach. More stones!
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helsha
off to a rocking start
Member since January 2021
Posts: 7
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Post by helsha on Feb 23, 2021 2:18:02 GMT -5
So is your opinion that the fine cracks can't be tumbled out of the stones? Or that they need to spend more time in Stage 1?
The cracks show before I use the white polish. But that being said, yes, this is them burnished post-polish. I know the deep pits in the lower stone won't be tumbled out without a coarse grind. I have a dremel to grind out shallower pits or do other rough shaping, but this stone wasn't worth the effort.
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Post by rmf on Feb 23, 2021 9:27:51 GMT -5
Assuming Image 1 left is rough and image 2 left is polished I would recommend tumbling in 220 grit longer. maybe double or tripple to see if the weathering can be ground out. Your finish looks good and so I am thinking the outside is due to previous weathering. Though you may have rocks that are fractured through enough that they will never polish to what you want. We have Garnets in North GA that are base ball size but they are fractured through and will never take a polish.
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helsha
off to a rocking start
Member since January 2021
Posts: 7
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Post by helsha on Feb 23, 2021 18:23:44 GMT -5
Assuming Image 1 left is rough and image 2 left is polished I would recommend tumbling in 220 grit longer. maybe double or tripple to see if the weathering can be ground out. Your finish looks good and so I am thinking the outside is due to previous weathering. Though you may have rocks that are fractured through enough that they will never polish to what you want. We have Garnets in North GA that are base ball size but they are fractured through and will never take a polish. Neither is rough, both are of the stone after it's been polished. But if you think it's rough then you understand my problem! Left is dry, right is wet. I started another batch and tossed both of these back in the mix. So we'll see what happens! Hopefully the fractures aren't so deep they can't be worked out. Still not sure how to determine when to move rocks forward in the process though if I can't see these cracks until later... practice practice practice I guess.
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jcf2112
off to a rocking start
Member since November 2020
Posts: 3
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Post by jcf2112 on Feb 25, 2021 18:11:50 GMT -5
Assuming Image 1 left is rough and image 2 left is polished I would recommend tumbling in 220 grit longer. maybe double or tripple to see if the weathering can be ground out. Your finish looks good and so I am thinking the outside is due to previous weathering. Though you may have rocks that are fractured through enough that they will never polish to what you want. We have Garnets in North GA that are base ball size but they are fractured through and will never take a polish. Curious why the 220 grit? Why not longer in the coarse like 60/90? I'm a newbie so just trying to understand the process and the subtleties of each stage.
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Post by jasoninsd on Feb 25, 2021 18:38:31 GMT -5
Assuming Image 1 left is rough and image 2 left is polished I would recommend tumbling in 220 grit longer. maybe double or tripple to see if the weathering can be ground out. Your finish looks good and so I am thinking the outside is due to previous weathering. Though you may have rocks that are fractured through enough that they will never polish to what you want. We have Garnets in North GA that are base ball size but they are fractured through and will never take a polish. Curious why the 220 grit? Why not longer in the coarse like 60/90? I'm a newbie so just trying to understand the process and the subtleties of each stage. You can't go that coarse of a grit in a vibratory tumbler. The 120/220 is the coarsest grit that should be put in a vibe.
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Post by greig on Feb 26, 2021 9:16:28 GMT -5
I only use a rotary. If those were my rocks, I'd take them back to stage 3 (500 grit) with lots of tumbler media, to see if I can get them to improve. If the cracks are shallow, then that ought to work. If the fractures go all the way through, then no amount of tumbling will help. Kinda like a hole in the drywall. No amount of paint will improve it. ;-)
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Post by rmf on Feb 28, 2021 14:30:57 GMT -5
Assuming Image 1 left is rough and image 2 left is polished I would recommend tumbling in 220 grit longer. maybe double or tripple to see if the weathering can be ground out. Your finish looks good and so I am thinking the outside is due to previous weathering. Though you may have rocks that are fractured through enough that they will never polish to what you want. We have Garnets in North GA that are base ball size but they are fractured through and will never take a polish. Curious why the 220 grit? Why not longer in the coarse like 60/90? I'm a newbie so just trying to understand the process and the subtleties of each stage. I think of coarse (46-120) as for roughing out stones. this is getting the corners rounded and grinding the big stuff off. Once that is done grinding with medium (180- 240) until the scratches and finer cracks are out. This is less wear on the tumbler. This comes under your mileage may vary. You have the rocks you decide based on what you see.
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USMC15
Cave Dweller
I feel like I just came out of the tumbler ...
Member since March 2021
Posts: 273
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Post by USMC15 on Mar 5, 2021 20:58:49 GMT -5
Noobie here, but why not invest in a small rotary for stubborn stones like these?
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