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Post by 1dave on Feb 6, 2021 10:33:18 GMT -5
I just saw this thread, looked at the photos, skimmed the beginning text, but didn't read everything. Still I might have some comments that could help. I have been tumbling rocks like this and larger for several years. That rock isn't a good one in my opinion. It's highly fractured. One of the skills that I'm so thankful to have developed, but it took years, is to more or less judge a rock that is fractured and how much and whether to throw it away. In the beginning I took rocks like this and would just keep grinding away for months. There was hope that the fractures didn't go in too far and I would eventually get to solid fracture free material. And, sometimes, it actually happened. But, when a rock looks like that one, I've learned it's a goner. When I see fractures with shattering patterns, and deep cracks too, and especially when I see fractures on all sides, it usually means the rock is fractured all the way through apparently via some crushing blow in the past. I give it a week, or 2, and sometimes 3, to be able to inspect it clearly when dry NOT when wet. Often a rock like this, when given a blow with a 3lb sledge, will shatter into many pieces, some of which will be keepers if they are solid. If my comments are of base because the thread isn't necessarily about the topic I just addressed, please ignore them and I apologize for blurting all that out. Excellent advice about life!
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Post by 1dave on Feb 6, 2021 10:47:06 GMT -5
I just saw this thread, looked at the photos, skimmed the beginning text, but didn't read everything. Still I might have some comments that could help. I have been tumbling rocks like this and larger for several years. That rock isn't a good one in my opinion. It's highly fractured. One of the skills that I'm so thankful to have developed, but it took years, is to more or less judge a rock that is fractured and how much and whether to throw it away. In the beginning I took rocks like this and would just keep grinding away for months. There was hope that the fractures didn't go in too far and I would eventually get to solid fracture free material. And, sometimes, it actually happened. But, when a rock looks like that one, I've learned it's a goner. When I see fractures with shattering patterns, and deep cracks too, and especially when I see fractures on all sides, it usually means the rock is fractured all the way through apparently via some crushing blow in the past. I give it a week, or 2, and sometimes 3, to be able to inspect it clearly when dry NOT when wet. Often a rock like this, when given a blow with a 3lb sledge, will shatter into many pieces, some of which will be keepers if they are solid. If my comments are of base because the thread isn't necessarily about the topic I just addressed, please ignore them and I apologize for blurting all that out. Yea, I'm still in this learning curve, even though I have a handful of these under my belt. Some are solid, some seem solid at first but end up being super porous or fractured. It's frustrating sometimes because hopes are high initially, but if I cant rotary grind through a bad spot in a "reasonable" time, I end up truncating the coarse grind and sending it through to polish. One of the 12lb barrels is going to open back up next week, and I've been pondering what I want to put in it. Part of the idea is to, this time, actually pull out the angle grinder with the diamond wheel and go at it. Y'know, trying to put the best foot forward with a low-barrier-to-entry tool. The first big one, Giant Quartz Experiment, 1dave said, "I think it best to start with desired outcome" and that's been rattling around in my head every time I do one of these and didn't have a way to shape it prior to tumbling. The rivers are churning up material like crazy right now and I'm picking jaspers up left and right. Big-ish, small, with agate bands, red, yellow, brown... just tons of it. Really finding one that's super solid is even more rare, to heck if it's a decent size. So tumbling even that stuff now presents its own challenge. It's absolutely beautifully colored, but it is probably going to come out with chips. So, to that end with this stone, I will push it through the process, and whatever chips and gouges it has will come with it. It wont be perfect but it will still be pretty. I'll put it on my shelf as a testament to "lessons learned" so I remember where I've come from on this big rock tumbling journey. I just did cleanouts, so I'll follow this post with those updates, and it's in coarse for another week. I may swap out the material that's grinding with it for my well-rounded sacrificial quartz next week, and see if I can sort of gently smooth out what's rough and try to minimize chipping. I think I need to have a sit-down with my big rock rough and have a heart-to-heart, and just... get to know them a little better before I toss them in the barrel. My "thang" is "How did this rock come to be? Who were it's ancestors?" This rocks mixture of red and yellow iron (hematite and limonite) are reminiscent of welded ash flow tuff - Holt Canyon material. Perhaps it had that kind of birth before its relentless trip down stream?
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Post by Bob on Feb 6, 2021 22:32:17 GMT -5
Those look very much like some material I find near Ludlow in the desert.
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Benathema
has rocks in the head
God chased me down and made sure I knew He was real June 20, 2022. I've been on a Divine Mission.
Member since November 2019
Posts: 703
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Post by Benathema on Feb 14, 2021 0:09:17 GMT -5
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Benathema
has rocks in the head
God chased me down and made sure I knew He was real June 20, 2022. I've been on a Divine Mission.
Member since November 2019
Posts: 703
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Post by Benathema on Feb 20, 2021 16:51:16 GMT -5
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Post by Pat on Feb 20, 2021 17:43:35 GMT -5
I swear.... tumblers are the most patient people!!!
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Benathema
has rocks in the head
God chased me down and made sure I knew He was real June 20, 2022. I've been on a Divine Mission.
Member since November 2019
Posts: 703
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Post by Benathema on Feb 20, 2021 20:36:19 GMT -5
Ohhh I'm getting to the point of wanting to double my capacity just to increase throughput.
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Post by stephan on Feb 20, 2021 23:42:32 GMT -5
I swear.... tumblers are the most patient people!!! Certainly more patient than I am.
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Benathema
has rocks in the head
God chased me down and made sure I knew He was real June 20, 2022. I've been on a Divine Mission.
Member since November 2019
Posts: 703
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Post by Benathema on Mar 1, 2021 15:59:00 GMT -5
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Benathema
has rocks in the head
God chased me down and made sure I knew He was real June 20, 2022. I've been on a Divine Mission.
Member since November 2019
Posts: 703
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Post by Benathema on Mar 6, 2021 4:14:42 GMT -5
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Benathema
has rocks in the head
God chased me down and made sure I knew He was real June 20, 2022. I've been on a Divine Mission.
Member since November 2019
Posts: 703
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Post by Benathema on Mar 13, 2021 3:36:40 GMT -5
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Post by greig on Mar 13, 2021 11:44:50 GMT -5
I was thinking you took it out of coarse too soon, but my goodness it is looking great in pre polish. It is going to be a wonderful surprise when polished. Personally, I think I would leave it in polish for 2+ weeks and perhaps longer. This is too much fun.
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Post by Bob on Mar 18, 2021 15:00:23 GMT -5
Benathema, one thing to mention even though I trashed your rock due to fracture issues...
In your 12th photo the Hertzian cones are obvious, especially in the lower left. These are often not visible until the first week of rough grind to get the weather rind off, but sometimes they are obvious when you pick up a stream rock. These shallow conical surface fractures are associated with quality and usually desirable tumbling material of Mohs 7 or higher, so watch for them. They do take a while to grind out. Some will be only 1mm deep but sometimes 3mm and rarely more. Some of my fav polished rocks were located by actually purposefully watching for Hertzian cones.
I was in a stream bed recently in Missouri, and most of the rocks were nothing but lousy soft tan/beige chert like is used in driveways in this part of the country. There were a few pieces of quality grey chert in there too. I found one orange size almost black rock covered with Hertzian cones and got excited because I know it means this rock was hard enough to survive many impacts and only suffered the cones and didn't fracture. It might be pet wood--I don't know yet because it's not in process.
Oddly, in 7 years of field collecting, I have found almost no quality true black rocks. I get excited because I have found many black rocks, but for some reason it seems almost all black rocks that I find are fractured with fine lines that sometimes aren't even visible until several weeks along in tumbling. So true black rocks are really lacking in my polished rock bowls, though I do have a few pieces of pure black jasper.
The more spherical the rock--if it also has Hertzian cones--the more I want you to get excited about what you find. Round rocks resist fracturing the best upon impact with other rocks.
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stefan
Cave Dweller
Member since January 2005
Posts: 14,095
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Post by stefan on Mar 19, 2021 10:40:31 GMT -5
Hertzian cones! Thank you as I always wondered what the technical name was (but never even tried to Google it).
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Benathema
has rocks in the head
God chased me down and made sure I knew He was real June 20, 2022. I've been on a Divine Mission.
Member since November 2019
Posts: 703
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Post by Benathema on Mar 19, 2021 23:38:28 GMT -5
Week 11: Polish AO. 1607g. Running total mass loss: 11.3% It's doooonnnneee! And it took quite the shine. And a video to go with it. It's shiny for sure. For anyone wondering, my lamp that I take most of my photos under is a circular ring of LEDs with a big magnifying glass in the middle of it. And the plot of mass loss over time. Big Tiger's-Eye number 2 on its way next!
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Brian
fully equipped rock polisher
Member since July 2020
Posts: 1,506
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Post by Brian on Mar 20, 2021 7:23:11 GMT -5
That shined up well! It was fun seeing the shape of the reflection of the light change in the video. The circular light really helps getting a sense of the curves of the rock.
This one was a fun one to watch and I’m already looking forward to seeing the progress of the next one!
Edit: I just noticed how the 120/220 followed a similar slope for the reduction in weight. I would have guessed the reduction would not have been as much, but then again, it is still a fairly aggressive grit compared to the AO.
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Post by jasoninsd on Mar 20, 2021 21:31:06 GMT -5
Way to get this one out of the way so you're ready for the next one! Great final result on this big bad boy!
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Post by hummingbirdstones on Mar 20, 2021 21:35:37 GMT -5
That one turned out great and it is shiny!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Mar 21, 2021 0:40:51 GMT -5
The elusive big rock polish - Tame that monster ! One big rock and the rest small rocks seems to be the ticket.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Mar 21, 2021 8:28:06 GMT -5
I came to the conclusion that a small 6 pound barrel did just as well as a 15 pound barrel when tumbling large rocks. Instead of having 12 pounds of smalls and a 2-3 pound rock I used a 6-7 pound barrel with 3-4 pounds of smalls and a 2-3 pond rock. Replaced the 15 pound barrel with several small barrels with a large rock in each barrel. And used way less abrasives if the large rock was the only target.
Pre-polish and polish steps were faster to achieve and had a higher shine when using (in my case) small pre-polished quartz pea gravel.
With only one large rock in the barrel bruises became near impossible and the step 1 speeds could be doubled and almost tripled if someone was interested in speeding the shaping.
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