doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Jun 19, 2017 8:59:31 GMT -5
Thanks James for confirming.
This is the first time I had this issue. I believe you use round barrels? My understanding is that round barrels give a significantly faster and rougher tumble versus hex barrels that the Thumler's use.
Should be able to create a gentler tumble by adding more smalls and adding more water. To cliff's question, thicker slurry should also make the tumble gentler.
The variables for tumble gentleness seem to be
-fullness of barrel -thickness of slurry -amount of water -size of rocks -amount of smalls / filler used -speed of barrel -size of barrel -hex versus round barrel
Also seems that the rougher the tumble, obviously the faster the material removal, but also the more efficient your grit becomes (more rock removal per unit of grit used)
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Jun 19, 2017 8:16:35 GMT -5
I've recently noticed some some small crescent shaped bruises on a few of my polished tumbles. First time I had this issue, and the bruises are very small and only noticeable if you look closely and are only visible on clear rock.
This is the first time I had this issue and I believe this is the result of tumbling a large 3 pound agate using a high speed 15 pound Thumler. Likely the big rock is just causing some small impact damage to everything else in the barrel.
I know some others have tried tumbling big rocks, and I'm wondering if anyone is familiar with this issue?
Going forward I will probably not tumble any high end material with big rocks..
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Jun 8, 2017 20:04:43 GMT -5
I usually end up removing 40 to 50% of the material to get it to a nice shape that I'm happy with. But you should experiment and do what you like.
Its good to mix small material with large. The small material will wear down a bit faster.
I have the same tumbler, and don't use any ceramics. Never had any issues with bruising on 7 hardness material.
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on May 21, 2017 22:27:04 GMT -5
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on May 15, 2017 8:25:07 GMT -5
doublet, I use the sequence of machines for productivity. The bull wheel is very fast, particularly when sanding a ground slab. I get a super polish on the big flat lap, which I like to have because selling the rocks is my business. The vibrating lap is capable of a nice polish, but it requires a lot of babysitting and is not suitable for production work. Ah ok sounds like its mostly for speed. I just leave the vibrating lap on the original card board box that it came in when its running, which seems to stop it from moving around or making a mess.
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on May 14, 2017 22:27:57 GMT -5
woodman, your machine looks like a Bob Strayer machine (he has passed- Joe Cota knew him well). I also have one like that, not made by Bob but by a fabricator in central Oregon. I cannot understand why these machines are not more popular. Sounds like we process our stuff the same way; grinding lap, bull wheel, flat polishing lap. You machine was designed by Bob to be a grinding lap. Grit range used on the lap from people I know that use them is 120-220. Some of you who may have noticed the counter-rotating top platter is not centered over the bottom plate. This was by design, to help avoid wearing the plate in one place. The centerlines of the top shaft and plate are the same- the oscillating motion is achieved by making the angle iron arms on the top platter different lengths. This moves the rocks 2-3 inches back and forth across the plate. My machine has an upgrade over Bob's original design- I had the plate fabricated from AR (abrasion resistant) steel. I actually do not need to turn on the upper motor at all. The upper rotating system is only to move the specimens back and forth across the plate, not to reduce grind time. I run my pieces the same amount of time either way. My next grinder will not use the upper motor assembly at all. The nice thing about this machine is how much quicker the bull wheel sanding goes when you start with a flat specimen. I do not waste time trying to remove scratches or grooves on the bull wheel. After a few seconds on the bull wheel with 100 grit, I can tell if the sanding process is going to be too much work- if so, back to the grinder it goes. It also makes apparent how sharp and well-aligned your saw blade is. Next to my polisher, this lap was the best lapidary $ I've spent. When I think of the hours I've spent on vibrating laps trying to get them working, keep them from marching around my shop smashing up everything in sight, cleaning the splatter off everything within ten feet, these laps are a dream. I can grind on this machine in one hour what took eight hours on the vibrator. Polishing is even faster- it takes about 30 minutes to polish whhat took eight hours on the vibrating lap. I can final polish 100 pieces a day easy on the polisher. If you intend to stay in lapidary or just want to ramp up your production I cannot recommend these machines too highly. They are quiet and reliable. Don't say you don't have space- nix your dining room table, and just throw a sheet of plywood over the machine when you have company. You wife can hang pots and kitchen doodads from the top part. Yes, I am married. Can I ask you guys why you use this 3 machine process to face polish a specimen (grinder, bull wheel, flat polishing lap)? I recently purchased a covington vibrating flat lap, and using 150 grit, 500 grit, and AO polish, I've used solely this machine to polish the specimen, and although the polish is okay, it is not a mirror polish. Hoping to get some advise on why you use a bull wheel for the middle of the process, and what kind of machine you are referring to for the polishing lap? Thanks..
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Mar 27, 2017 22:22:02 GMT -5
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Mar 19, 2017 23:12:25 GMT -5
My guess is that these rocks are just too soft to take a shine. While cross contamination may be an issue, it won't result in your polish stage producing rocks less shiny than the pre-polish stage. From my experience, even with some cross contamination, you should still get some shine unless your rocks are just not suitable for polishing.
I would recommend buying some easy to tumble rocks such as agates from an online vendor and tumbling those. I wouldn't start with self collected rocks unless you have more experience and know what will take a polish.
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Mar 14, 2017 17:12:38 GMT -5
I'm trying to tumble a 3 pound rock in my 15 lb thumlers. It is quite slow. Maybe 1/3 to 1/2 the speed of tumbling a 1 pound rock. Let me know how your 10 lb rock works out!
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Mar 13, 2017 16:49:26 GMT -5
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Mar 7, 2017 10:01:06 GMT -5
For the frugal tumbler, buying grit 50 points at a time is not enough, haha.
I've always wondered about the tumbling costs of a large scale commercial guy. For myself, I estimate it costs about $4 to produce a finished pound of tumbles, not including my labor and material costs.
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 26, 2017 14:51:59 GMT -5
aDave
Rock Shed Botswana agate
A couple random handfuls from Rocktumbler.com
I'll have some comparison tumbles from the new material in a few months, maybe sooner since some are already rounded.
Nics bots. The bots I got from rockshed were probably not has good as yours. Just part of the variance when you buy online sight unseen. $7 / pound seems a decent price. I haven't really found them cheaper than that online or on ebay. I keep an eye on ebay for them since they are among my favorite materials as well.
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 26, 2017 11:39:14 GMT -5
Those are nice. What did the blue colors look like before treatment?
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 25, 2017 18:37:31 GMT -5
I agree that some of these Madagascar agates are quite attractive and look like a well banded laker. I'll try to buy a cheap one and cut it up to see what it looks like natural. I am also curious. (edit..actually if the heat treatment goes all the way thru the stone cutting it up won't reveal anything different, does the heat treatment affect the entire stone?)
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 21, 2017 17:26:43 GMT -5
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 21, 2017 16:52:37 GMT -5
Very interesting. Some of those madagascar agates look impressive. Although I hate artificially altered stones, I'll probably buy some just to see how they look in person. Strange to buy a stone mined in Africa, shipped to China, and then back to the US. Went over some of stonemaster499's old posts. Seems like he uses 350lb capacity rotary tumblers which he seems to suggest is significantly faster and more efficient. Having a tumbler that large must be nice for tumbling large stones as well. Maybe one of these days haha..
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 21, 2017 10:04:59 GMT -5
Thanks for showing your process!
Seems like a lot of heat treated rocks turn darker red or brown. Also seems to me the color gets a little blotchy. Its helpful seeing more of these to know what an altered rock looks like (I hate buying the unnatural ones by accident).
I wonder if something like this (http://www.ebay.com/itm/Precious-94g-Banded-agate-Madagascar-xlarge-tumbled-beautiful-patterns-/322425598351?hash=item4b1210318f:g:T8QAAOSwx6pYpeyJ) has been heat treated, dyed, or chemically altered?
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 18, 2017 10:40:42 GMT -5
Tony/catmandew on here let's the huge barrel he has roll for months and got a straight to polish in a vibe. They r very nice when he finishes. I let mine roll at least 2 months, sometimes I wonder if they grind themselves down once the grit is gone. I am like Capt/Bob in that slow and steady goes a long ways without brea king a sweat! LOL I was curious about what would happen without grit and ran a barrel with just rocks and water for three weeks weighing them every week and did observe consistent weight loss. It was substantially slower than the barrels with grit. How much was the rate of weight loss without any grit compared to the coarse grit? Like 10 or 20%? Interesting that you found that the rocks can basically shape themselves slowly in the tumbler without grit.
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 14, 2017 18:32:21 GMT -5
Thanks for the response. Even pre-polish is not okay? I didn't think there'd be much rock snot or dust from the pre-polish stage.
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doublet83
starting to spend too much on rocks
Member since March 2016
Posts: 118
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Post by doublet83 on Feb 14, 2017 14:52:42 GMT -5
It is okay to wash off stones finishing up the prepolish stage with 500 AO and let the stuff go down the drain? I know letting slurry go down the drain is a big no-no, and will clog the drain quickly. However, I figured the prepolish stage would be okay, but I'm not sure after years or decades of doing this, whether this will create a clog. Thoughts?
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