keeta
off to a rocking start
Member since August 2014
Posts: 3
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Post by keeta on Aug 19, 2014 0:14:29 GMT -5
I am an elementary Montessori teacher, ages 6-9. In our classroom we are studying geology and erosion right now and I would like to provide a manual rock tumbling experience for my students. The idea would be that they could go work on it when they want a break from their work, as a "practical life" activity. I have been looking for plans or materials for a completely manual tumbler, but have been unable to find one. I could have sworn I'd seen a project idea for something like it when I was a kid. I'd love it to be transparent to a degree as well, so they could see what they are doing. Is this possible or am I simply dreaming?
Thanks for your help!
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Post by gingerkid on Aug 19, 2014 0:36:04 GMT -5
Hi, keeta, and welcome to the forum! Are you wanting a hand crank tumbler? I googled to see if I could find one, and couldn't. Found this, which does not require a motor. Maybe you could use a container and lid that the students could see through so they may see the process? I'm sure other members will share some information and their expertise with you. Sounds like fun for your students, and I hope you'll share their experiences with us.
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Post by gingerkid on Aug 19, 2014 0:37:38 GMT -5
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Post by glennz01 on Aug 19, 2014 1:03:44 GMT -5
I would not to hand crank a tumbler for 1 week non stop for 1 rough tumble
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Post by gingerkid on Aug 19, 2014 1:08:58 GMT -5
I would not to hand crank a tumbler for 1 week non stop for 1 rough tumble ROFL, glennz01!
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Post by Peruano on Aug 19, 2014 6:50:59 GMT -5
I realize a vibe is not a hand crank device, but it could be a wonderrful visual experience in that those with clear plastic lids can allow the movement of the rocks (mesmerizing if I do say so) to be watched (and in fact the Raytech vibe 5 can be run without the lid. The transformation of rocks from plain to wonderfully smooth in a few hours and permanently smooth in a few days could be a wonderful experience (tactile, visual, auditory, and scientific). If the tumbler is run without the lid just protect from occasional splashes, and monitor water so that it does not run dry and lock up. Just thinking. Tom
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keeta
off to a rocking start
Member since August 2014
Posts: 3
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Post by keeta on Aug 19, 2014 7:55:05 GMT -5
I would not to hand crank a tumbler for 1 week non stop for 1 rough tumble Well this would be a slow process and I want them to see that, as erosion in nature is (generally) a slow process. It would be one tumbler shared by the whole class, that they would work on when the mood struck them. So, it might take a couple weeks to see finished results, but that's ok. Practice with patience, perseverance, and interdependence are usually a good thing.
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keeta
off to a rocking start
Member since August 2014
Posts: 3
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Post by keeta on Aug 19, 2014 7:57:03 GMT -5
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Post by Jugglerguy on Aug 19, 2014 8:02:29 GMT -5
It takes me months to produce good rocks with a motorized tumbler running 24/7. I'm 46 and hardly had the patience for this when I started a couple years ago. I can't imagine hand cranking them.
Petoskey stones can't be tumbled to completion, but the first stage or two can be done in a tumbler, then they can be finished by had with wet/dry sand paper. They could also be hand sanded from the beginning. You might want to go with something soft like that instead of tumbling agates or jasper or something hard like that.
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transcendental
spending too much on rocks
Member since June 2014
Posts: 459
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Post by transcendental on Aug 19, 2014 8:23:12 GMT -5
In my understanding of the tumbling process once you start eroding the rocks the material that is ground off mixed with the grit and water basically becomes like cement, the barrel needs to be in constant motion to keep it from hardening. I don't think it's a fast hardening, especially in a sealed container but all the grit etc will settle to the bottom of the barrel and when rotation resumes it may be off balance and some of the stones settled into muck where they wouldn't roll freely around the barrel.
Sounds like a good visual lesson but I think getting a motorized tumbler and modifying the barrel to be clear you'd end up with the desired final stones that shows the power of erosion
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Post by connrock on Aug 19, 2014 8:41:39 GMT -5
There's more to rock tumbling then meets they eye.
For one thing,each specific barrel diameter HAS to rotate at a specific RPM.This wound not be possible if each child took a turn at cranking a handle at different speeds. If the tumbler is left sitting over night, without rotating,the rocks,grit and slurry will settle to the bottom and you will have to mix everything by hand to get it all rolling again.This is not a clean operation. I doubt if you have a place in a classroom suitable for rock tumbling as it can be quite a messy experience especially for someone who has never seen it done or done it his/her self. Rocks and silicon carbide grit are VERY abrasive and would scratch a clear barrel in hours so it is fruitless to have a clear barrel.
If you consider that it takes Mother Nature many,many years to even round off a soft rock with wave action in the sea or a lake,you young children may be parents by the time you see any erosion with a hand cranked tumbler.
In my opinion a hand crank tumbler is a waste of time for you and your students. connrock
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Post by deb193redux on Aug 19, 2014 8:57:10 GMT -5
I do not think this is the most productive time. it would take too long, and grit would obscure the work anyway. the tumbling process is also grinding - not erosion. This is not the gentle force of water moving soils and breaking down embankments.
You might consider a grit plate with a rock that has a flat but rough face on bottom. let students use elbow power to push it around on grit slurry. you might even consider wet/dry 100g paper to avoid gray slurry all over hands.
if the rock was a dolomite (or some rhyolites or epidote) that has a nice pattern to be revealed when sanded, this could be built in visual reward. periodically change grit/sheet and discuss why it wears down. periodically measure the increasing flat/smooth areas. try to measure the deepest spot and discuss how everything has to be worn down to reach the deepest spot.
do not do a MOHS 7 agate or jasper. if it goes well, you can repeat with a smaller agate already face sanded to 3000g, and have them push around on a piece of 50,000g diamond belt or disc. discuss how polishing is related to sanding, only smaller. review size of grits using 30g, 60g, 100g, 180g, 400g, 600g sand paper. give them information on the size of polish (e.g., AO polish is 50,000 to 1000,g)
for this 2nd project maybe you can rig some way to measure how much light the increasingly polished surface reflects onto a light meter or something.
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Post by glennz01 on Aug 19, 2014 10:19:06 GMT -5
Use some material that scratches real easy that none of us would tumble as it would break down to nothing in a few hours.... kaolinite used with a large rock or 2 and sand Trhis might work.. but you won't get a polish i presume
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Post by braders on Aug 19, 2014 13:14:36 GMT -5
Im with all the other folks here I just dont see there being enough time with anything manual that will sit more then it would move .... Best would be to get a tumbler and one with rubber drums so it would not disrupt class while other topics are going . Tumbling stones I think is great for kids and I wouldnt steer away from this great project just because of the manual thing not being very productive in a timely matter I am also very sure you could get a very nice donation of stone from the great people on this site me included for the kids to see turn into beauty with a little patience .. Have a great day
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FLrockhound
spending too much on rocks
Member since July 2014
Posts: 343
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Post by FLrockhound on Aug 20, 2014 6:32:51 GMT -5
I just saw this thread and I have to say for kids 6-9 the "Barney law" needs to be applied here. My suggestion is to use limestone rocks in a tumbler made from a modified exercise bike. Those rocks will be soft enough to show erosion in a timely manner without the need for a complicated operation.
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