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Post by orrum on Sept 1, 2015 22:18:08 GMT -5
Could be a hoax. However I once had a coil spring on the rear of a car move over and it rubbed the tire until the spring was worn thru but the tire was only scuffed up... Who kjows.
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Post by Jugglerguy on Sept 6, 2015 9:43:04 GMT -5
I'm starting to think that this is possible. I reran the last batch that I messed up starting at 220 in the rotary, followed by 500. At that point, they didn't look as good as they did the first time, so I probably should have taken them back to 80 grit. I was eager to try dry tumbling, so I just used them as they were. I filled my Lot-O with corn cob from The Rock Shed so that It was about 80% full. Then I added five Petoskey stones and a tablespoon of AO polish. I checked on them after several hours and they seemed to be already starting to polish. I let them run for two days, checking occasionally. I think they were improving slowly for most of that time. They definitely shined up. They don't have the shine that I can get with a flat lap followed by Zam, but they're not bad. They are speckled with tiny holes filled with polish, but that's from the stages before the dry polish. If I can improve that, I think they'll be pretty good. I haven't tried using Zam on these finished rocks yet. [/url] I'm going to rerun some Petoskeys from 80 grit and try this again. I'm also debating about doing the 500 stage with dry corn cob.
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Post by orrum on Sept 6, 2015 17:12:15 GMT -5
I wonder if a little Zam dust and threads from the hood on a Muslim bench polisher wit corn cob in the loto would work?
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Post by Jugglerguy on Sept 6, 2015 17:39:21 GMT -5
I actually think the polish was just fine the way it was. Those pores were there before the polish stage. Give me a couple weeks and I'll have another batch done. I'm pretty excited about this. My dilemma now is whether to do 500 in the rotary or in the vibratory with corncob. I've got Petoskeys running in 80 grit now. I think I'll go 2 days and then 220 for a couple more days, and then I have to make a decision. I'll probably try it both ways, but which one first?
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mibeachrocks
starting to spend too much on rocks
Member since September 2013
Posts: 198
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Post by mibeachrocks on Sept 9, 2015 13:14:43 GMT -5
Thanks for the update Jugglerguy (Rob). I am in agreement. I think that it might be possible to polish petoskey stones with a tumbler. I am still waiting on the final product, which is a few days away. In the meantime, here is where i stand. I took a small batch of petoskey stones that my son found this summer and started them out in 60/90 SiC for days followed by 120/220 SiC for 3 days. This was followed by 500 AO for 3 days. Below is a picture of the batch when dry after the 500. This is the control group that will receive no additional treatment This is the group that went in for an additional 3 days in 12/20 walnut shell (from the Rock Shed) with 6 Tablespoons of 1,000 grit AO. All dry. The barrel was loaded 80% to 85% full. The other two groups will get a treatment with ZAM (the traditional method of polish after 500 grit) and run wet with 1,000 AO. These are the results of the stones after the 1,000 AO dry with walnut shell. Please note that all stones are dry. I washed them after their run. Also, the one stone on the top is not a petoskey stone. It is some other type of fossil. A few observations at this point. The 1,000 grit did work; however, I did not put that many stones in the barrel either. I had done this in the past and ended up with too many fractures. Also, can can see that results vary by stone. Stones with darker eyes and more fossilization came out looking better than stones with clear eyes or those with more voids. here are some close up pics For comparison, here are some of the control group stones that did NOT get the 1,000 AO treatment. I will be sure to keep you posted as the others are finished.
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Post by Jugglerguy on Sept 9, 2015 14:30:47 GMT -5
Thanks for the update, Jason. I'm interested to see how those do with the dry polish. They look good so far. I don't think you have a close up of the stones that got a wet 1000 run. Did they come out worse than the dry run in 1000? That's what I would expect.
Did you do these in a rotary or vibratory?
I'm using corn cob, so I'm glad you're using walnut. The more stuff we try, the more likely we'll figure it out. I feel like Thomas Edison experimenting with different lightbulb filaments.
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mibeachrocks
starting to spend too much on rocks
Member since September 2013
Posts: 198
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Post by mibeachrocks on Sept 10, 2015 8:34:47 GMT -5
As long as neither of us are Tesla in this situation ;-)
I have not run the 1,000 AO wet yet nor the Zam batch. I will be sure to do that very soon.
The worst variable in the equation is the fact that there is so much variability in the Petoskey stones.
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Post by Jugglerguy on Sept 10, 2015 11:41:26 GMT -5
They're variable, but it's usually pretty easy to tell if it's going to polish or not. There are a lot of Petoskeys with horrible patterns on them that will polish up just fine. They end up being ugly shiny rocks, but they do get shiny. If you want to test the polish, it's pretty easy to polish a test spot with the last couple steps on a flat lap to see if it gets any better.
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mibeachrocks
starting to spend too much on rocks
Member since September 2013
Posts: 198
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Post by mibeachrocks on Sept 14, 2015 9:32:55 GMT -5
Looks like it worked. I ran the 1,000 AO grit dry through polish (dry) for three days. I only have a few complaints. 1. I did get some minor bruising on two of the stones. 2. I have polish stuck in some of the voids. I will be running it in an ultrasonic cleaner. 3. I am not sure of the time savings yet. I am not sure if it easier to run through 500 AO wet and then use a dremel and Zam or to go through all of this. One aspect that is easier is that small stones can easily be polished. Those can be the hardest to polish by hand. I still have two other groups to run (wet and Zam) for comparison. I will have results soon.
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mibeachrocks
starting to spend too much on rocks
Member since September 2013
Posts: 198
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Post by mibeachrocks on Sept 14, 2015 9:43:52 GMT -5
Comparison of one stone After 500 AO (wet) After 3 days of 1,000 AO grit (dry) After 3 days in AO Polish (dry)
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Post by Jugglerguy on Sept 14, 2015 14:31:51 GMT -5
Aaaarrrggghh! The last picture is missing! It's a cliffhanger!
In the last series of pictures (the single stone), did you set your camera different? The color is almost purple in the second picture. I know they get darker but something looks strange there.
For me, the point isn't just speed, but the challenge of doing it in a tumbler. If I could get them to the point where I could polish them with Zam, that would be great, but to accomplish the impossible (or so I've been told) is just fun. I'm going to move some to 500 dry in corn cob tonight. We will see how that goes.
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mibeachrocks
starting to spend too much on rocks
Member since September 2013
Posts: 198
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Post by mibeachrocks on Sept 15, 2015 7:19:50 GMT -5
Good point. It is about being able to do something that many said cannot be done. I fixed the pic. I need to start using a better camera.
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Post by Jugglerguy on Sept 19, 2015 19:37:02 GMT -5
Ok, here's my latest Petoskey Tumble. This is the best one yet. In fact, I think it's about as good as I can expect. This one still has some holes filled with polish. I'm blaming the rock. This is my favorite. This one's good too. These rocks are just as shiny as the ones I do on a flat lap. They have texture to them, but I don't think it takes away from the look. My wife didn't agree. She prefers the rocks done on the flat lap. Here's my method: Rotary tumbler: 80 grit - check every three days and remove when done. Use extra water and less grit that usual. I used a full cup of water and one tablespoon of 80 grit in a 3 lb. barrel. No plastic or other cushioning material. 220 grit - Add plastic pellets and fill barrel to 80%. Use 1 tablespoon of 220 and 1/2 cup water. Tumble three days. Lot-O vibe tumbler: From here on, everything is done with dry corn cob media in a vibratory tumbler. 500 grit - I only moved six rocks to the vibe. I might be able to do a lot more, but I started small. I added the rocks one at a time as I filled with corn cob media so the rocks were not touching each other. 1 tablespoon of 500 aluminum oxide grit, no water. Tumble three days. The rocks looked slightly shiny after three days. Polish - I changed barrels to my polish barrel and used fresh corn cob. 1 tablespoon aluminum oxide polish, no water, tumble 2 days.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on Sept 19, 2015 20:54:18 GMT -5
Broke the sound barrier on the Petosky's Rob. Dry tumble eh ? Congrats and well done, they look fantastic. I see amber, fluorite, calacite in your future. I got some oyster shells fossilized in calcium carbonate to tumble. Gotta get the corn cob stuff and giver a go.
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Post by Drummond Island Rocks on Sept 19, 2015 20:55:21 GMT -5
Looks pretty darn good Rob. I had a few people ask me if those could be tumbled today.
Chuck
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Post by Jugglerguy on Sept 19, 2015 21:36:08 GMT -5
What'd you tell them, Chuck? jamesp, Petoskey stones are limestone, which I believe is mainly calcite, so that's done. Amber seems a bit expensive, so I don't have an interest in that. Flourite is definitely on my list. I also have some Kona dolomite in the rotary tumbler now. It's up next in the Lot-O. I'm pretty excited about this.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on Sept 19, 2015 23:32:02 GMT -5
You sent me some of the dolomite, worth effort to get a polish on it.
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Intheswamp
Cave Dweller
Member since September 2015
Posts: 1,910
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Post by Intheswamp on Sept 19, 2015 23:51:22 GMT -5
Rob, it sounds like you've done something that few have done....kinda like "...to go where no man has gone before." Congratulations!!! I like the patterns, can't say I've ever seen rocks like those.
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Post by Jugglerguy on Sept 20, 2015 6:13:09 GMT -5
Intheswamp, it's fossilized coral, Michigan's state stone.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on Sept 20, 2015 7:19:52 GMT -5
Rob, it sounds like you've done something that few have done....kinda like "...to go where no man has gone before." Congratulations!!! I like the patterns, can't say I've ever seen rocks like those. Been waiting on Rob to carve the path to dry tumbling Intheswamp. Hoping he did not use polyurethane...
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