callmerob
starting to spend too much on rocks
I really like a dirt road
Member since September 2019
Posts: 143
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Post by callmerob on Jun 10, 2021 16:31:53 GMT -5
My smallest sphere… This little rock is my souvenir from the Royston turquoise mine, Tonopah, NV. It is a very badly sawn preform, lopsided and uneven because I had trouble holding a rock this small. Trying some diamond segment discs to grind it…   These discs looked good, but were really slow grinding because of such little area and grit contacting the rock. So I made some grinding cups with water bottle caps, velcro discs, SiC grit, super glue. 1/4 teaspoon of grit. Made the cup shape by smushing a dent with the spoon into the loose grit, then dripped water-thin super glue. About 30 drops of super glue each, so it dried overnight. Photo thru a 4X eye loop…  36 grit SiC thru a 40X microscope…  This puts a lot of grit on the rock, more than the diamond segments. Grit got worn after a few hours so I mixed grit, gel hand soap, and a few drops of water into a paste and let it chew on the rock…   Finally got it roundish, rounder, not perfect but good enough for now…  Water bottle caps with grits 36, 120, 500, 1000 pre-polish, polish…  Pre-polish and polish pads are 1” Dremel felt buffing wheels, cut with a razor blade to ~1/16” thick…  Polishing…  Sphere measures 1.25”,  Woohoo! I made a marble! Hope you like it.  |
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Post by miket on Jun 10, 2021 16:53:17 GMT -5
Very cool! I like how you used the bottle caps to solve a problem...
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Post by jasoninsd on Jun 10, 2021 19:35:24 GMT -5
Way to go Rob! That is awesome! I love the "redneck engineering" with the bottle caps! |
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Brian
fully equipped rock polisher
Member since July 2020
Posts: 1,512
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Post by Brian on Jun 10, 2021 20:18:37 GMT -5
Great work, Rob! I love the solution you came up with for your small grinding cups! That was an excellent idea and it looks like it worked rather well. I wonder how much more efficient a custom cup would be compared to a typical sphere grinding cup.
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callmerob
starting to spend too much on rocks
I really like a dirt road
Member since September 2019
Posts: 143
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Post by callmerob on Jun 10, 2021 22:07:11 GMT -5
Thank you all for the supportive responses.
The water bottle caps are just the right size for a marble. Water-thin super glue wicks right into the coarser grits, but needs a few drops of alcohol to reduce surface tension on the 500 SiC grit. It probably interferes somewhat with glue polymerization, resulting in a weaker bond, but still good enough. Got a few little pieces crumbling out, but mostly good cups. I thought to recover the SiC hockey puck from the first coarse batch and toss it in the coarse tumbler. Put a 2x4 on the patio and smacked it hard 6 or 7 times with a claw hammer, but could not break it or knock it out of the cup.
Pre-polish and polish is just a wet smear on the felt pads, pushed into the cups, no glue. Works great.
Velcro 1" discs peel & stick to the bottle caps just fine.
The cups work much better at capturing the ball compared to flat abrasive discs. I can adjust more grinding pressure on the ball. Overall, I'm very pleased.
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Post by jasoninsd on Jun 10, 2021 22:20:05 GMT -5
Thank you all for the supportive responses. The water bottle caps are just the right size for a marble. Water-thin super glue wicks right into the coarser grits, but needs a few drops of alcohol to reduce surface tension on the 500 SiC grit. It probably interferes somewhat with glue polymerization, resulting in a weaker bond, but still good enough. Got a few little pieces crumbling out, but mostly good cups. I thought to recover the SiC hockey puck from the first coarse batch and toss it in the coarse tumbler. Put a 2x4 on the patio and smacked it hard 6 or 7 times with a claw hammer, but could not break it or knock it out of the cup. Pre-polish and polish is just a wet smear on the felt pads, pushed into the cups, no glue. Works great. Velcro 1" discs peel & stick to the bottle caps just fine. The cups work much better at capturing the ball compared to flat abrasive discs. I can adjust more grinding pressure on the ball. Overall, I'm very pleased. Rather than alcohol, would a silicon spray do the same to reduce surface tension? It's used on felt pads when using diamond paste... |
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callmerob
starting to spend too much on rocks
I really like a dirt road
Member since September 2019
Posts: 143
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Post by callmerob on Jun 10, 2021 22:54:41 GMT -5
jasoninsd, I'm pretty sure paint doesn't like to stick to silicone, but don't know about glue. I was trying to get the glue into 500 grit SiC, but it just beaded up and rolled down into the crater. Tried alcohol first, just to see if it would make the grit/glue "wetter", and it worked. |
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Post by Peruano on Jun 13, 2021 6:23:18 GMT -5
Thanks for the details. I'm sure you have taught or stimulated to try a new trick or technique to a lots of us.
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callmerob
starting to spend too much on rocks
I really like a dirt road
Member since September 2019
Posts: 143
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Post by callmerob on Jun 15, 2021 18:57:01 GMT -5
This is the water-thin super glue I use. It is a lot wetter than liquid super glue. Sold on Amazon by Pen Kit Mall for those who make ink pens from exotic hardwoods. It saturates the wood and plasticizes it.  Oops. Don't know what happened to that image. Let's try that again...  Oops again. Better picture, but photo of the thick version. Amazon link below is to the right glue. Duh, Robbie. Amazon link... www.amazon.com/gp/product/B009356B92/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 |
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Post by Rockindad on Jun 18, 2021 7:49:57 GMT -5
Late to the party but just wanted to say I love the ingenuity and appreciate you posting this. It’s got my wheels turning (pun not intended, though it’s not bad).
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callmerob
starting to spend too much on rocks
I really like a dirt road
Member since September 2019
Posts: 143
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Post by callmerob on Jun 18, 2021 15:11:20 GMT -5
On another thread I think someone mentioned that their kids were eager to make marbles from rocks. Whoever mentioned that got my wheels turning too, so I got a small rock and started messing around. Thanks to them for the inspiration! I don't remember much about the 4th Grade, but I remember playing marbles in the dirt. Over by the swings, where the grounds crew had added extra soft dirt before school started that year. The girls would swing, and the boys would shoot some serious marbles. For keeps. Always for keeps. Always had my shooters in my pocket. EDIT - Oh! And I forgot that the girls played Jacks - a game that is a lot harder than it looks, and still mystifies me. |
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Post by paulshiroma on Jun 24, 2021 10:55:51 GMT -5
This is really slick, Rob, nice job. Thanks for taking the time to post and "take us along"!
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Sabre52
Cave Dweller 
Me and my gal, Rosie
Member since August 2005
Posts: 20,490
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Post by Sabre52 on Jul 7, 2021 15:49:38 GMT -5
Nice! I lie small spheres. I ran into a guy on a rockhound trip one time that kept his rock collection in a pouch in his pocket. He had him one of those marble machines I guess, and would make a marble from the best example of a particular material he could find. Basically a small sphere collection. I thought that was pretty cool.
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callmerob
starting to spend too much on rocks
I really like a dirt road
Member since September 2019
Posts: 143
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Post by callmerob on Jul 13, 2021 0:29:35 GMT -5
Nice! I lie small spheres. I ran into a guy on a rockhound trip one time that kept his rock collection in a pouch in his pocket. He had him one of those marble machines I guess, and would make a marble from the best example of a particular material he could find. Basically a small sphere collection. I thought that was pretty cool. Sorry about the late reply. I'm liking the smaller sphere/marble. It certainly saves on material. On the fee dig at Otteson's Royston turquoise mine, I was looking (like everybody was) for high-grade turquoise nuggets suitable for jewelry. I don't really do jewelry, and I didn't yet have any rock cutting equipment, so that oddball piece was just my souvenir from the trip. Now I am really looking at smaller rocks to see their potential for spheres/marbles. Everything doesn't have to be as big as a baseball. Thanks for your comment. Really like the idea of a rock collection of marbles in my pocket. |
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Post by jasoninsd on Jul 13, 2021 9:06:52 GMT -5
Nice! I lie small spheres. I ran into a guy on a rockhound trip one time that kept his rock collection in a pouch in his pocket. He had him one of those marble machines I guess, and would make a marble from the best example of a particular material he could find. Basically a small sphere collection. I thought that was pretty cool. Sorry about the late reply. I'm liking the smaller sphere/marble. It certainly saves on material. On the fee dig at Otteson's Royston turquoise mine, I was looking (like everybody was) for high-grade turquoise nuggets suitable for jewelry. I don't really do jewelry, and I didn't yet have any rock cutting equipment, so that oddball piece was just my souvenir from the trip. Now I am really looking at smaller rocks to see their potential for spheres/marbles. Everything doesn't have to be as big as a baseball. Thanks for your comment. Really like the idea of a rock collection of marbles in my pocket. I would just lose them...well...I guess some people think I already have.  |
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