janglepro
off to a rocking start
Member since June 2021
Posts: 10
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Post by janglepro on Jun 19, 2021 19:49:19 GMT -5
Hi, I just made a vibrator prototype. I've never used one before so I'm not sure what to expect. The rocks in the bowl go round and round with some vigor but they don't pour down toward the center and rise up the walls like I've seen on videos. Is this important? How can I redesign the vibe to make it do this? Right now I have a motor with a weight on it screwed to the bottom of the board that the bowl is on. See video. diy rock vibe linkThanks!
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jamesp
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Post by jamesp on Jun 20, 2021 7:02:55 GMT -5
It would be best if there was more 3 dimensional mixing. It appears the smalls have settled to the bottom and the big tumbles have risen to the surface.
I have a Vibrasonic with a long cylindrical hopper that separated the big stuff to the left and the little stuff to the right. Causing problems, the little protective media was no longer protecting the larger tumbles. Solution - built another much shorter fatter hopper with a center divider that way increased the mixing of large with smalls.
Is there any way to alter the counterweight or rotating shaft to another angle to get more mixing ? The only way I know how to describe these situations is 2 dimensional vibration verses 3 dimensional vibration. You may be able to put some baffles in the hopper to force more mixing...
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Post by Rockoonz on Jun 20, 2021 8:41:43 GMT -5
Looks like you have a horizontal cyclone but no vertical cyclone. I think the way my Thumlers create the vertical action is the shape of the bowl, like angel food cake pan. James is definitely the tumbler engineering guy here, I'm more the fix it when it breaks type.
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jamesp
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Post by jamesp on Jun 20, 2021 14:59:38 GMT -5
Looks to be laminar flow instead of turbulent flow. Flow that stays in layers instead of tumbling and turbulent. Modify the hopper to create mixing either with a middle post like an angel cake pan as Lee mentioned or baffles to create mixing. The action looks darn good. May need some slurry added.
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janglepro
off to a rocking start
Member since June 2021
Posts: 10
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Post by janglepro on Jun 20, 2021 15:58:47 GMT -5
Looks to be laminar flow instead of turbulent flow. Flow that stays in layers instead of tumbling and turbulent. Modify the hopper to create mixing either with a middle post like an angel cake pan as Lee mentioned or baffles to create mixing. The action looks darn good. May need some slurry added. Thanks all. I do have an upside down funnel in there. I'll try flipping the motor around so they weight is hanging down instead of up. Also, my bowl hangs from rubber bands. Is it possible that the bands allow too much movement? Would springs be better? Do I need a heavier weight? More rpms? Last night the motor jangled itself lose and thrashed around the floor all night. I'll bolt it back on with bigger bolts and try some different configurations.
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jamesp
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Member since October 2012
Posts: 36,555
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Post by jamesp on Jun 22, 2021 8:01:06 GMT -5
Vibrating systems all have the same components. spring(s), damping, mass and an external force. Tuning can be done by varying any 4 of the components. And/or varying the geometry of such components. Target for rock tumbling is short vibration travel(amplitude) with enough power and frequency to make the rocks move w/out damaging them. In my experience it is a fine line to achieve optimum conditions for polishing rocks. Few people can do the math to design such a machine on paper. But anyone with a bit of mechanical and fabrication skills can build and alter a machine to do the job with some luck. This is the most basic vibration system using all 4 components.(damping is optional, undamped and damped vibration is common). The force in this example does not change because it is gravity, something is going to have to apply a stimulation force. This is an example of one dimensional vibration. Rock vibes have either 2 or 3 dimensional vibration. Usually 3. Hat's off to you janglepro if you succeed at making a rock vibe that can lay down a polish. It is a big accomplishment.
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janglepro
off to a rocking start
Member since June 2021
Posts: 10
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Post by janglepro on Jun 22, 2021 11:15:52 GMT -5
Thanks again. I didn't realize it was so complicated. I like to tinker so I'll try a few tweaks. Has anyone on this forum made their own successful rock vibe that I could learn from?
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stewdogg
spending too much on rocks
Member since January 2020
Posts: 388
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Post by stewdogg on Jun 22, 2021 11:41:38 GMT -5
Thanks again. I didn't realize it was so complicated. I like to tinker so I'll try a few tweaks. Has anyone on this forum made their own successful rock vibe that I could learn from? Have you checked this page out...? forum.rocktumblinghobby.com/page/diy-projectsThere's a couple vibes under the tumblers.
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Post by Starguy on Jun 22, 2021 13:44:08 GMT -5
Cool project janglepro I can’t wait to see results. I’m a purely rotary guy but I’ve considered vibes for polish. Let us know how it goes. jamesp knows his stuff.
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jamesp
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Member since October 2012
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Post by jamesp on Jun 22, 2021 14:44:28 GMT -5
Thanks again. I didn't realize it was so complicated. I like to tinker so I'll try a few tweaks. Has anyone on this forum made their own successful rock vibe that I could learn from? Have you checked this page out...? forum.rocktumblinghobby.com/page/diy-projectsThere's a couple vibes under the tumblers. quartz is a brilliant fabricator. His vibe is one of the coolest designs (to me anyway). I modified a Vibrasonic It had a long cylinder hopper. The big rocks would work to the left, the small rocks and protective media would work to the right in the 12 inch wide hopper. Useless. Plus it bruised glass no matter the slurry thickness or size of the glass. So, I built a new platform to mount on the deck of the Vibrasonic that held two much narrower Mini-Sonic hoppers to prevent large/small separation issue. This new platform was made intentionally much heavier than the original long hopper because I knew that adding weight(mass) had to 'numb' or 'shorten' the vibration travel(amplitude) so the machine -might- tumble polish sensitive glass. Polish glass it did. Not only did it polish it but it cut polish time by 1/3. AND it was not so sensitive to slurry thickness or type of slurry. IMO it improved it's entire operating range for sensitive tumbles. Best way to say it is that this vibe is now much more user friendly. I considered myself very lucky because it was all about luck except the knowledge that increasing the mss would reduce the vibration amplitude because that is a property of mechanical vibration. But this machine has lots of power and was able to handle the extra mass, another streak of luck. Here is a link to my madness: www.flickr.com/photos/67205364@N06/sets/72157691385722155this has some operational design photos of a Vibrasonic and some photos of a machine I designed to mimic the Vibrasonic. This new machine was way to violent, beat the hell out of the rocks due to excessive vibration travel so I abandoned it and decided to modify the Vibrasonic since engineers developed the Vibrasonic for agates and other hard rocks.(they had it dialed in for rocks) My only need was to make it gentler. www.flickr.com/photos/67205364@N06/sets/72157649367092502
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quartz
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breakin' rocks in the hot sun
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Post by quartz on Jun 22, 2021 23:22:51 GMT -5
jamesp said I'm a "brilliant fabricator", well I appreciate the opinion but prefer "confirmed tinkerer". I got a link to the vibe I built a few years back, go read it if you want, the entire thread is fairly long. forum.rocktumblinghobby.com/thread/73985/vib-tumbler. The one thing I see with your idea is that the bottom outside of the bucket is pretty much square, I think that in itself inhibits the vertical aspect of the tumbling process. All the bowl shaped vibes I've seen are rounded at the bottom, not flat at the outer edge; my UV-18 included. You have a good idea going, now the fiddling to perfect it starts, great challenge. The 10" tumbler is built, has run, and dialing-in process is ongoing, but very slowly. Finding workable springs has proven difficult. My wife has been diagnosed with a condition called Multiple System Atrophy, she has been getting worse for near 4 years now, and I have had to become everything, even have dishwater hands. She did well today, chopped up a bunch of vegetables for salads for upcoming hot days. It's hard taking care of her and doing other things, but I do get to grab an hour or so every day.
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jamesp
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Post by jamesp on Jun 23, 2021 6:27:27 GMT -5
So sorry to hear quartz Larry. Health factors become so much an issue as we age. You guys were romping all over eastern Oregon collecting just a few years ago and had to be in excellent shape. The job of care taker is difficult and often unappreciated. Mom had Alzheimer's for 8 years and wife and I were only ones to care for her, but fortunate to have her in assisted care towards end years. Be sure to look after your own health, spousal care takers often neglect their own health. Thought are with you.
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jamesp
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Post by jamesp on Jun 23, 2021 6:33:50 GMT -5
You mention the 10" tumbler quartz. Didn't you use a section of PVC pipe ? Can you refresh my memory ? Remember I used a 9" to 10" long section of thin wall 6 inch steel pipe and simply mounted it on the Vibrasonic with good success. I could see making another hopper out of 10" pipe about 9" long too as the Vibrasonic would shake it if counter weight was increased. Probably would hold 30 to 40 pounds.
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jamesp
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Post by jamesp on Jun 23, 2021 6:40:27 GMT -5
Cool project janglepro I can’t wait to see results. I’m a purely rotary guy but I’ve considered vibes for polish. Let us know how it goes. jamesp knows his stuff. Thanks Brent. Ha, I just built a heavier hopper and stuck it on a stock Vibrasonic. I do have some basic knowledge of vibration analysis that assisted in making it run more gentle - make the hopper heavier to smooth the shaking action. A no-brainer. Building a vibe from scratch seems mighty intimidating.
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jamesp
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Post by jamesp on Jun 23, 2021 7:00:39 GMT -5
This is the hopper I built for the Vibrasonic. I later welded a divider in the center to split the 6 inch pipe into 2 shorter sections for doing 2 rocks up to 3.5 pounds each at same time without them banging into each other. It must be about 50% heavier than the stock cast aluminum hopper. But there was another mod, this hopper sits lower and closer to the vibration source. As if bouncing on a diving board in the middle instead of out on the end where the vibration travel is much longer at the same frequency. This was the first hopper. It too is heavier and has most of it's weight at the bottom close to the vibration source. If it was more top heavy and/or taller it would vibrate much more wildly like sitting in a short rocking chair verses a tall rocking chair both rocking at the same frequency. The hoppers were too small to handle 2 pound rocks so I went with the larger hopper above. Now the machine is a pleasure to use because it is difficult to damage a load even with poor slurry management or type. Polish times are short - 3 days in AO 220 and 8 hours in AO polish be it agates or glass. Really like this machine. I saw these later. I don't know if they were fabricated before my design or after. If they are light weight they may not do glass well. They need to be heavy to be gentle for glass IMO. I guess 6 - Mini-Sonics would tumble 24 pounds and the VSV50 must do 50 pounds. Imagine running 50 pounds !!
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jamesp
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Post by jamesp on Jun 23, 2021 7:24:51 GMT -5
Glass in AO 14,000 polish and 8 tablespoons of sugar in each 4 pound compartment. Polish takes 8 hours. Note very little bouncing and rattling. Glass is stuck together constantly for full time rubbing contact.
Rocks in SiC 500 again with sugar after 2 days. Ready to clean out(or add water if running longer). This is the thickest I let slurry get before adding more water. It takes a powerful vibe like a Vibrasonic to vibrate such a thick slurry. And the slurry is very sticky which increases the abrasion/polishing rate yet prevents banging of tumbles against each other.
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jamesp
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Post by jamesp on Jun 23, 2021 11:41:20 GMT -5
A note on rocks in a vibe bouncing and rattling - the time it takes for the rocks to hit is a short period of time compared to the time it takes for the rock to bounce away and come back to make contact again. Like a basketball being dribbled only spends a short time contacting the floor. Granted it is bouncing much further but if you add a the 'away' time on the short bounce distances it adds up to a lot of the tumbling time. The rocks are not abrading when they are not in contact.
Same situation in a rotary, if the rocks are tumbling down the hill in the barrel there is not much abrasion time. If they are stuck together and sliding on each other due to a tacky slurry they are in constant contact as the move down the hill.
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quartz
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breakin' rocks in the hot sun
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Post by quartz on Jun 23, 2021 12:13:15 GMT -5
jamesp, here's the "refresher" you asked for. The barrel is 10" PVC a foot long with a piece of 6" fitted to it for an opening. It has so far liked to run with a loaded weight of ~60lb. Problem to solve is the load rotated very slowly, way too slowly. oregon helped out after I posted the treadmill experiment last fall by sending a link to a motor controller build for the treadmill motor which I saved, variable speed instead of constantly fiddling w/pullies. He also got me in touch with a friend in this general area who is looking into springs in his stock of stuff. It will work out, giving up is hard to do. The frame is in pieces now, I'll get more of it on here when things come together better.
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Post by oregon on Jun 23, 2021 17:58:09 GMT -5
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reeniebeany
starting to spend too much on rocks
Rotary Only
Member since January 2020
Posts: 125
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Post by reeniebeany on Jun 23, 2021 18:14:10 GMT -5
Looks to be laminar flow instead of turbulent flow. Flow that stays in layers instead of tumbling and turbulent. Modify the hopper to create mixing either with a middle post like an angel cake pan as Lee mentioned or baffles to create mixing. The action looks darn good. May need some slurry added. Thanks all. I do have an upside down funnel in there. I'll try flipping the motor around so they weight is hanging down instead of up. Also, my bowl hangs from rubber bands. Is it possible that the bands allow too much movement? Would springs be better? Do I need a heavier weight? More rpms? Last night the motor jangled itself lose and thrashed around the floor all night. I'll bolt it back on with bigger bolts and try some different configurations. Bundt cake pans seem like an option - They are heavier than Angel Food cake pans, they usually have the rounded bottom and tapering cone in the middle. They are often lobed, so no idea what that would do to your flow...Thrift stores usually have them
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