rrod
having dreams about rocks
Member since December 2020
Posts: 72
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Post by rrod on Apr 2, 2021 19:53:37 GMT -5
Thought I'd show how grit moves and evolves over a week or so. Here's a pea-gravel (+ a trio of small, lucky labradorites) tumble with some SiC on Day 1:
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irlcjrohr
starting to spend too much on rocks
If it does not melt, polish it.
Member since April 2020
Posts: 123
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Post by irlcjrohr on Apr 2, 2021 20:59:13 GMT -5
rrod , I really enjoy the slow motion clip.
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stefan
Cave Dweller
Member since January 2005
Posts: 14,095
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Post by stefan on Apr 3, 2021 6:29:04 GMT -5
I did that once! Long ago I made a clear lid for a 3 Lb barrel. Thought it would be so cool to watch the progress and it was for the first few days. you day 4 or 5 the lid had been ground pretty bad and there was nothing but a hazy glimpse of slurry lol. I gave up after 2 weeks and used the lid to repair the lid for my AR-12. NEVER even dreamed of taking a video. Thanks for sharing. Pretty much what I observed except I used rough rock so the action was a little more erratic at times.
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Brian
fully equipped rock polisher
Member since July 2020
Posts: 1,506
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Post by Brian on Apr 3, 2021 9:26:53 GMT -5
Great video, rrod! The slow mo was interesting to watch. After watching that one three times, including once just to try to track individual stones, there were a few interesting things I noticed. First, stones on the outside tend to stay on the outside, particularly the bigger stones. The stones near the middle of the barrel look like they only tumble a short distance with each rotation. Second, it looks like the extra head space is critical for movement. There was more movement of the rocks into the head space than I expected to see. I would guess that even with 5-10% higher fill levels, you would have really decreased the overall movement of the rocks. With even more irregular shaped rocks, I would imagine you would see more far more erratic movement (both in path of motion and more jerky motion) like stefan noted in his experiment. Did you use any of the guar gum in this one? What material did you use for the lid?
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rrod
having dreams about rocks
Member since December 2020
Posts: 72
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Post by rrod on Apr 6, 2021 17:07:44 GMT -5
stefan Yeah at day four the slurry is starting to cover the acrylic enough to prevent seeing the action. Next video I'll show how larger rough moves. brian Makes me wonder if, when tumbling smaller rocks in a larger barrel, if you can fill to a larger % of full, since the effective headspace will still be equivalent to the 75%-filled smaller barrel. No guar in this one: When I tried a guar batch the cover gets coated by grit pretty much immediately. Thinking of doing a video using a magnetic stirrer to show how larger grit (say my 36 SiC) floats better with a thickener.
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Post by Bob on Apr 8, 2021 12:15:27 GMT -5
I predict what we are seeing may not be as representative of the internal cascade face during a week. These videos, which are super fun, show clean rocks, new grit, and clear water such as exists in the first part of a new batch. There is no slurry. Slurry is thicker than water and may greatly affect the cascade face and other rock behavior.
It might be interesting if you want to tackle this. Take a normal batch half-way through the week, after decent slurry has formed, remove the lid, and replace with a clear lid. Then start the tumbler with the camera rolling and before seeing through the lid is blocked by the slurry splashing all over it. Maybe a few seconds of viewing will be possible. Maybe not.
If not, then I think the water could be replaced by something with a similar viscosity to slurry, but transparent.
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