Good Vibrations
noticing nice landscape pebbles
Overanalysis leads to Paralysis
Member since May 2009
Posts: 91
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Post by Good Vibrations on Aug 6, 2009 3:22:08 GMT -5
I am using a vibratory tumbler, and I am trying to define the qualities that make for good tumbling media. Some factors I have considered:
* Hardness - For example, glass is about Mohs 5.5, so would glass marbles work as tumbling media for a batch of Agates which are Mohs 7?
* Shape - Would rounded media help provide a smoother tumbling action than media with more distinct edges or corners? Also, do you think the shape of the media has any influence on the eventual shapes of the rocks?
* Smoothness - For example, if you are using pebbles that have chips and cracks in them, will that have a negative affect on the rocks? Even if you restrict their use to one particular grit stage, like 120/220? (so they don't carry grit over to the next stage)
I have been using 2 sizes of ceramic pellets, and in the later stages, tile spacers. I recently began adding pebbles bought from a discount store to the mix. they are pretty uniform in size but vary widely in shape (from totally rounded to triangular shaped with sharp edges) Many of the pebbles have chips or cracks in them, so this is what got me thinking about the whole tumbling media thing.
I am also wondering about other possible sources of tumbling media such as beach glass, plastic beads, glass seed beads, marbles, small pieces of ocean worn seashells.....
I am really curious to hear your ideas and input on the subject! Thank you, ~Erica
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Post by LCARS on Aug 7, 2009 11:56:51 GMT -5
I still use small sized feedstock pellet fill in my rotaries as a cushioning and light filler material. One bag of pellet fill seems to last quite a long time in the 3lb barrels, after 3yrs, I have about 1/2 of the original amount left. I HAVE used marbles before as filler material for quartz and other silicates though with good results. I usually end up with cutesie little peewee sized marbles after running them from 120/200 through to polish with a load. ;D I have also added beach glass as a softer filler when I want a thicker slurry faster but I have found gassing to be an issue whenever I use glass in with SiC grits. There must be some sort of reaction going on there because whenever I have glass in a load and I add more grit, I have to burb the barrel almost daily to vent the extra gas production or risk a leaky or bursting barrel lid seal!  Alternatively, I once came across a large pile of small crush alongside a gravel biking trail and couldn't resist "collecting" some to try as small coarse grind filler. It actually worked quite well since the small crush usually disintergrates by the time the load is done in 120/220, especially if i'm tumbling agates or any other "harder than quartz" material. |
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Good Vibrations
noticing nice landscape pebbles
Overanalysis leads to Paralysis
Member since May 2009
Posts: 91
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Post by Good Vibrations on Aug 8, 2009 11:42:35 GMT -5
Hey thanks LCARS! Just the kind of info & experience I'm looking for!
Interesting about your experience using glass & SiC grits together because I had an odd reaction with those two as well. I had used glass media in my 120/220 batch, and when I went to rinse it all, the slurry was two different colors. There was the usual gray color, but there was also a much darker color as well, and the two didn't mix with each other, kind of like oil & water. Weird.
Now I want to go tumble some quartz using marble fillers just to get some cute peewee marbles! ;D
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lparker
fully equipped rock polisher
Still doing too much for being retired!
Member since March 2008
Posts: 1,202
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Post by lparker on Aug 8, 2009 15:28:00 GMT -5
beach glass - has a market of its own...it's already tumbled, just use it to make stuff.
plastic beads - no good in a vibe - mostly floats to the top and stays there.
glass seed beads - too small to be of much use...sell them off to someone with good eyesight. marbles - will work...as LCARS said.
small pieces of ocean worn seashells - probably too soft to be of much use and might gas
I'd stick with ceramic pellets and previously tumbled rocks as filler.
Lee
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Post by tkrueger3 on Aug 8, 2009 15:30:54 GMT -5
Erica, just for self-enlightenment, I'm now running a batch of nothing but beach rocks in my vibratory. I'm doing 500 grit now, and I may recharge it and do 500 for one more day before moving on. I want to see what effects there are by using NO filler with this stuff. I know some of it is hard, probably quartz, and some of it is soft, like a sandstone type rock. We'll see what happens without any filler.
Tom
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MikeS
fully equipped rock polisher
Member since January 2009
Posts: 1,081
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Post by MikeS on Aug 11, 2009 22:47:37 GMT -5
Best filler material I've found to date are those little cross shaped vinyl tile spacers. They are cheap, durable, cushion well and won't scratch your rocks. They work equally well in a rotory or a vibe. If you are using rock or glass as filler, while it is important to look at the hardness of the material IMO it is more important to look at the durability and brittleness of the material. A rock can be high on the hardness scale, but if it is a brittle material, it may chip, fracture or break and scratch up your rocks in the later stages, especially in a vibe. Hardness and toughness are two seperate things that don't necessarily correlate with one other. I like to use nephrite jade as an example of this, it's only 6.5 on the scale, but it is extremely tough and durable. It's nearly impossible to crack or break it. On the other hand, I have worked with quartz, jaspers and agates that are higher on the scale (7-7.5) that fracture and break much more easily. All three of them grind and shape much more quickly and easily on a grinding wheel than jade, even though they are harder. You get the point...  Mike |
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rockdewd
has rocks in the head
Member since October 2007
Posts: 605
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Post by rockdewd on Aug 12, 2009 11:33:02 GMT -5
For a vibe tumbler I use a variety of media. For jaspers and agates and such I use a combination of ceramic media, tempered glass shards, glass marbles, regular glass shards, and those squished marble looking glass things they sell at the hobby store for filling glass vases.
I've been experimenting with vibe tumbling obsidian with just glass but I don't think obsidian likes vibe tumblers because I've yet to have a good batch.
The experiment continues...
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Good Vibrations
noticing nice landscape pebbles
Overanalysis leads to Paralysis
Member since May 2009
Posts: 91
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Post by Good Vibrations on Aug 17, 2009 18:15:35 GMT -5
Rick - Ha ha - the squished marbles, classic! I have been using those too but never knew what to call them. Squished marbles. That's just what they are. There's a discount store by me that sells them and also sells tumbled glass, so I have tried both.
Lee - Right on. Well said. Straight up & to the point. You wanna buy some seed beads?
Tom - Before I ask, I am going to see if you have posted anything about that batch of beach rocks you mentioned above. I am curious about that one.
Mike - I'm sold on the spacers too. They really don't seem to wear out! They might keep turning a darker shade of gray, but they never seem to shrink! Regarding brittleness - I think you just solved one of my big tumbling mysteries. That explains a lot. Good point.
~Erica
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Post by tkrueger3 on Aug 17, 2009 23:14:59 GMT -5
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grant
noticing nice landscape pebbles
Member since March 2007
Posts: 85
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Post by grant on Aug 18, 2009 0:05:30 GMT -5
I just bought a jar of Crosman "softair" plastic BB's, OJ in color and expensive at 8.00 a jar. But, they do NOT float, or at least the ones I have don't. Have two batches of them used so far in an ancient 6lb Loretone, one at 80 and one at 220 and they look good as new and did a good job of cushioning for me.
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RockyBlue
fully equipped rock polisher
Go U.K.
Member since June 2006
Posts: 1,719
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Post by RockyBlue on Aug 18, 2009 8:19:46 GMT -5
When i first started rotary tumbling i went to Lowes and bought me a 25lb.bag of pea gravel for $4.95 and used it for filler.It worked just fine..........Rocky
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Post by 150FromFundy on Aug 18, 2009 11:27:15 GMT -5
As RockyBlue suggested, pea gravel is a cheap source of filler, assuming the pea gravel is hard.
I usually use ceramic media in my rotary and vide, but it is hard to find (must be mail ordered) and it is expensive to begin with. You may want to experiment with "aquarium gravel" from the local pet store. It is a fraction of the price of ceramic media, localluy available, pre-polished and about the right size.
If you try this, buy the natural coloured rock. The blue, red, purple stuff has a coating of paint on it.
Darryl.
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wbrasher
off to a rocking start
Member since August 2009
Posts: 1
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Post by wbrasher on Aug 19, 2009 17:32:41 GMT -5
I have a problem with foam in about half of the batches that I tumble. The bubbles get so stiff, and the canister so full that tumbling action stops. The rocks, grit and everthing in the canister becomes one cushioned blob inwhich there is no movement. Does anyone have a method to avoid this? Or a way to correct a batch that starts to foam excessively?
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Post by Hard Rock Cafe on Aug 19, 2009 21:56:01 GMT -5
I've never had trouble with foam, but I've heard of using Tums, sodium bicarbonate, or other antacids.
What are you tumbling?
Chuck
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