sfgems
off to a rocking start
Member since November 2011
Posts: 6
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Post by sfgems on Nov 2, 2011 1:05:05 GMT -5
Okay here is whats going on... in 2009 my business trip to Pakistan from San Diego i acquired a real large quantities ( few thousand pounds each of Lapis , peridot and black tourmaline ). Our Lapis has been a fast seller but the other two were really slow to move as rough even at dirt cheap prices. This year i have been here in Pakistan again and have some time to my hand ( thanks to no bars and clubs aghh ) so i decided to start a tumble project in little larger scale for Peridot and black tourmaline. Well there is no concept of tumbling rocks by tumbler in local market. To my astonishment they do it by hand ... so for last one month i have been doing some research and made one small rotary tumbler ( 7" internal dia and 2 feet long ) it can carry 20 pound lapis . While doing some test one this baby i have already ordered comparatively three bigger tumblers ( 1.5' dia and 3 feet long ) to my local machinist by showing them the prototype i made in pieces. I will be receiving them in this week. In meanwhile i have been busy tumbling Lapis as test ... so far i am having problem in final stage of polishing. I believe one problem is that i have been doing my four stage process little quicker ( cant blame me as i didnt realize it would be so exciting so Patience is bit short ..but i am working on patience part. Currently my prototype have been running for almost 18 days of which last 7 days with cerium oxide polish . The stones are nicely rounded by now but cannot get the wet finish i was anticipating.... I added detergent powder with polish and even a few table spoon of cooking oil which helped making making the face of stones more smother but still not sure if i will be able to get a wet looking stones. Any way question is for my under construction comparatively bigger tumbler?? My this prototype is making 15 rounds per minute. I am thinking to make the bigger one atleast 25-30 rpm . Machine i am planning to use will be 0.25hp 1700 rpm 60 HZ. Any input will help and i will post few pictures later to keep you all posted on the projected. Thanks Qazi www.sfgems.com
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Post by Jack ( Yorkshire) on Nov 2, 2011 4:19:56 GMT -5
Qazi A warm welcome to RTH,from a cold damp Uk
Yes the speed should be around 50 RPM for a 7"barrel (from the Victors Book )
at 15RPM it is nearly 4 X to slow the rocks are Traveling only a 1/4 of the tumbling road at that speed you will have to put them on for 4 weeks instead of 1 week
Also the stones inside the barrle wont be "Cascading" properley (rolling ) and you could end up with flat er stones ,
I will leave this to the proffesional as regards a "wet " polish look as I myself find Lapis quite difficult to polish
Jack Yorkshire uk
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Nov 2, 2011 13:20:56 GMT -5
The things I would consider -- first make sure that you're actually getting tumbling action instead of just sliding action. Homemade barrels are usually have round sides, which store bought larger barrels have flat sides - hex shape. With the slow speed and probabily round side you may not be getting enouhg action. -- next make sure that there is no contamination when you move from one stage to the next. -- third is the time issue that you've already identified. One way to make sure that your batch is ready for polish is to pull out a test piece and put it on a polish wheel. If you can polish it without making use of sanding wheels, you should be ready to go.
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bushkraft
having dreams about rocks
Public nuisance Number 1
Member since July 2011
Posts: 65
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Post by bushkraft on Nov 2, 2011 17:30:10 GMT -5
I have been involved with the commercial side of the lapidary business for many years and have travelled to India and the rest of the subcontinent several times, teaching those guys in Pakistan how to tumble will only result in the market being swamped with cheap tumbled stones.... essentially putting to the sword those of us in the West who rely on technology to keep level with those nations that rely on the use of cheap labour, the combination of cheap labour and new technology will see the lapidary business in the US and down here in Australia go the same way as the textile and motor industries.
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sfgems
off to a rocking start
Member since November 2011
Posts: 6
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Post by sfgems on Nov 3, 2011 5:19:20 GMT -5
Jack and steve, Thanks for the input.. cold in UK is good excuse to get some brandy.
Today i will see if i can speed up the rpm to 50 from 15 .. four time larger pully at the machine should do it. What do you think the speed rpm should be for 18 inch tumbler ..rough guess??
Steve, as BushKraft from Australia mentioned labor is comparatively cheap so the 7" round tumbler is hexagonal tin plate which i had it lined inside with used car tiers. I believe increasing speed as suggested by Jack may help.
Now Mr. Bush, at present in Peshawar the Afghan craftsmen are doing most of the tumbling by hand. They use sand paper of different size. It is more philosophical discussion about cheap labor in east and expensive cost of doing things in west. 15 years ago when i first selling in States there was lot of discussion about this especially custom facetors versus commercial facetors. Today i think we have way past that discussion. If you come to any local show in America let alone Big ones, most of the vendors there are selling gems prepared by Billion people force from China. India and especially Pakistan has lot to do catching up. Issue is not cheaper inferior quality work as i am sure in next fifteen years quality will increase . I believe issue is treatments which are not disclosed. I have yet to see Lapis bead in these shows which are not dyed or at least disclosed.
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sfgems
off to a rocking start
Member since November 2011
Posts: 6
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Post by sfgems on Nov 3, 2011 10:55:29 GMT -5
increased the size of the pulley to 4" at the machine and now it is running 30 rpm ( previous 15 rmp ). Will check the progress tomorrow and may increase it to 6" at my proto type after I get my three big ones from machine shop. Have any one of you tumbled black tourmaline, Kashmir Peridot or tangerine garnets?? any suggestions / tips about the grits and polish for them based on experience . I will let you know complete progress with you tube video for someone else experience.
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Post by Jack ( Yorkshire) on Nov 4, 2011 2:12:30 GMT -5
Hi Sfgems
In the victors book they give the RPM for a 24" barrell as 27 RPM
Worked out by the following Formular
Critical speed (in RPM ) is calculated by dividing 54.19 by the square root of the radius of the mill in Feet,
24" barrell The Radius is on foot.The square root of one is one so 54.19 divided by one is 54.19 the "Critical speed "in RPM is 50% of this or 27RPM as a operating speed
Hope this helps you to calculate your own needs
Jack Yorkshire uk
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Nov 4, 2011 4:40:36 GMT -5
Greetings "Sfgems", firstly may i welcome you as the 2nd from the other side of the pond, i have a comercial Lortone C300 rotary tumbler with a 1400rpm 0.25kw (0.33 hp) 220V / 50hz motor, with 2x 6lb & 2x 12lb hex rubber barrels, which rotates around 30rpm regardless whether 1x 6lb barrel or a whole set. My 16.32kg (36lb) 2x (12lb) 2x (6lb) Lortone C300 runs 32.65kg (72lb) & is quite capable of running 12x (12lb) or 24x (6lb) & double the weight if extended with 130.63kg (288lb) max load Lortone's specification, from a single 0.25kw (1/3hp) motor, but will probally run 2x of that 24x (12lb) or 48x (6lb) 261.26kg (576lb). I often run a 6lb barrel on my 3lb Beach tumber with a gross weight of 6.5kg (14.33lb) which runs at 20rpm, the 3lb round rubber barrel runs between 45-48rpm. Garnet = Chrome Oxide, Zam or Tin oxide. Lapis Lazuli = Aluminium oxide or Tin oxide. Peridot = Peridot is a fussy stone, but All major polishes work, if not try another. Tourmaline = Aluminium oxide or Tin oxide. -- I hail from (The Barony of Seabegs) Bonnybridge, Stirlingshire, U.K, where aliens (15mb) sometimes come for a visit & about 4 miles west from this monstrosity! Sticky's: their contents are resource information 1#: Vendors worldwide (2mb), 2#: How to use the forum, 3#: How to identify rocks & minerals, 4#: Save money on expensive grits & polishes!
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Post by connrock on Nov 4, 2011 9:52:29 GMT -5
Qazi,,,, Although you have got some very good information here already I would like to say that all of this will only give you a starting point.
The tumblers you are building are "one of a kind" so comparing their size to other tumblers and trying to calculate the RPM's from a mathematical formula will get you close but I don't think it's the final answer for you.
The RPM's of commercial tumblers is calculated very precisely for the specific size and shape of a specific tumbler barrel.
The "tumbling" "action" in a barrel is VERY important and without the correct RPM's you will just waste time and money.
The "recipe" of grit/rocks/water/soap,etc,etc also enter into the total equation for the correct "tumbling action" as well.
The correct tumbling action of ALL rock tumblers looks exactly like a wave "cresting" on the shore of the ocean. If you can picture in you mind,,,a person on a surf board who is right on top of the crest of a wave as he/she surfs toward shore,,,then this is the action that MUST be in a rock tumbling barrel for it to work correctly.
If the speed is too slow the rocks will only slide up the inside of the barrel and will not "crest" as the wave does. If the speed is too fast the rocks will crash down as does that wave cresting and crashing down on the sea shore. What you want is to have that "crest" roll down onto itself and NOT crash down.
The only way I can suggest for you to get that exact action in each of your tumblers is to put a Plexiglass cover on each of them and adjust you RPM's accordingly.
Each of your rock tumbles is unique because they are home made and each will act differently.
The only other way to get the action close to what it must be would be by trial and error of tumbling load after load.
Hope this helps.
connrock
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sfgems
off to a rocking start
Member since November 2011
Posts: 6
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Post by sfgems on Nov 5, 2011 8:56:14 GMT -5
Thanks you all for your help and time... increasing the speed did help a lot and now one ingredient along with Aluminum Oxide polish( this i was missing and was added today and that is plastic media, not beads but actual media which is a by product of petroleum and is used to make plastic product.. the pieces are 1-2 mm oval like rounded pieces one one side and the kinda flat on the other ) I will check the load tomorrow when it has run at least 24 hours to see any improvement. I will keep you posted and will take some pictures of final product and see ...Let see if i get this Lapis to Polish ... if not then my best way out will be hire a help for a day and buff the pieces with polishing soap which is usually what local worker use to bring the wet look.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,352
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Post by quartz on Nov 5, 2011 22:20:30 GMT -5
One thing not yet mentioned here is the sound of the process. If you are running too slow, you will hear a sliding sound, too fast and the rocks ride up on the barrel walls then crash down; you will hear this. Important to us in setting the speed of our three homebuilts was the obtaining a uniform rolling and tumbling sound. It took some fiddling, but we got it worked out, get compliments on our tumbling quality from people with much more experience than we have.
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sfgems
off to a rocking start
Member since November 2011
Posts: 6
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Post by sfgems on Jan 25, 2012 13:25:52 GMT -5
Well here i am to report my new tumbling operation . I made a video before i left for United States. Thank you all for your help..sorry for amature tumbling video.
My current production is around 110 pounds a week and several thousand pounds of rough to process. Not sure what i will do once all is tumbled . I was thinking to drill holes in the stone and make them all as pendants.
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Intheswamp
Cave Dweller
Member since September 2015
Posts: 1,910
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Post by Intheswamp on Jan 1, 2016 10:01:43 GMT -5
Wow, quiet the operation. I'm curious as to where your market is/will be...?
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Post by captbob on Jan 1, 2016 17:33:32 GMT -5
Ed, if you click on the OP's name you will see he hasn't been logged in here since Feb. 2012
Hope you are not holding your breath for a response.
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Intheswamp
Cave Dweller
Member since September 2015
Posts: 1,910
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Post by Intheswamp on Jan 1, 2016 18:00:42 GMT -5
Shoot, if I'd looked a the post I replied to I'd of seen it was old. They say it gets worse the older you get....
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