KG1960
has rocks in the head
Member since August 2008
Posts: 512
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Post by KG1960 on Nov 12, 2005 17:56:21 GMT -5
This is my first post. I have just discovered this forum and it looks interesting! I have a question about tumblers and was searching the web and eventually came here.
For many years I have been using a Lortone 3A and have been very pleased with it. Unfortunately it finally wore out, and without going into details, I ended up fabricating my own drive mechanism.
My question is, what is a good RPM for the 3A barrel? Right now the barrel turns at 65 RPM. I know it is faster than the original and I can change it if needed.
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Post by rockds on Nov 12, 2005 19:37:33 GMT -5
welcome kg1960, wish i could help you there but have no idea. I just plug mine in and let 'em go. I'm sure others here will be able to answer your ?s.
robert
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Post by Cher on Nov 12, 2005 22:28:42 GMT -5
Welcome to the forum!!
I was just reading in my Lortone booklet the other night and saw a paragraph on the rpms. Your's is doing just about right, the larger the barrel, the slower they go.
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Post by joe on Nov 12, 2005 22:56:10 GMT -5
Hi. I've clocked my Lortone 33b at 64 RPM right after cleaning, belt replacement, and lube. Then it slows down to around 50 RPM as the belt wears down.
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Post by Jack ( Yorkshire) on Nov 13, 2005 2:20:38 GMT -5
Hi Kg Welcome to the forum hope you get the Information & help and have a happy time tumbling RPMI make my own Tumblers and try to get them in the area of 33 to 70 RPM my tumblers run at 42 rpm I have found that @faster speeds some stones shatter ( eg Amythysist & Rose Quartze) How to check ! Put a paint mark on the tumbler or chalk and use your watch !! remember if its going slower - remember to extend the time.(its all to do with RPM ! ) If you want more information or a book get "Gem Tumbling and Baroque Jewelery Making by the Victors" a old book but still in print with a wealth of information I think the Rockshed sell it ? Another Tumbler maker www.agatehouse.co.uk/Thanks for your post .  Yours Jack Yorkshire UK |
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Post by LCARS on Nov 13, 2005 3:04:27 GMT -5
I read somewhere (could have been here?) that RPM should be between 40-70 for the 3lb barrels... None of the Lortones I have seen have a variable drive so I guess you're stuck with what you got unless you devised a variable speed system into your new drive. Ine way to do it is to have different sized drive pinions for slower or faster RPM's I gave some thought to fabricating another drive pinion for my 33a to optimize it for my polishing barrel. If I still had access to the machine shop at my old work I would have done it by now.  |
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MichiganRocks
starting to spend too much on rocks
"I wasn't born to follow."
Member since April 2007
Posts: 154
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Post by MichiganRocks on Nov 13, 2005 8:25:57 GMT -5
This is an old subject that I've talked about at length before, but here are a couple of tips again: - You can increase the RPM of your barrel by increasing the diameter of the roller that your barrel runs on on the drive shaft. Simply wrapping a little tape will yield sifnificant increase.
- You can decrease the RPM of your barrel by wrapping something like foam weather stripping around the outside of your barrel where it runs on the rollers.
- Another option in to replace the rollers on you drive shaft with a smaller diameter ones. Be careful it doesn't take much to make a big difference. As a last resort, just run the drive shaft without a barrel and apply some sandpaper to wear down the roller a little.
Ron |
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earthdog
Cave Dweller 
Don't eat yellow snow
Member since June 2006
Posts: 2,731
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Post by earthdog on Nov 13, 2005 9:07:20 GMT -5
All I did and always do when I get a new tumbler is go to the hardware store and get a rope pulley, for the price of $1.99, take the wheel out of it and solder it to the motor shaft. The c.e. tumblers always ran at about 25/30 rpm, with the bigger pulley, they are running at 55/60. Even all my lortones ran slow untill I soldered a bigger pulley on. My dual #6 and #12 are running at 40/50 rpm now.
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KG1960
has rocks in the head
Member since August 2008
Posts: 512
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Post by KG1960 on Nov 13, 2005 9:47:41 GMT -5
Thanks for all the replies. So it looks like I'm not too bad off - on the high end of the recommended range. Yes, Jack, I see that a higher RPM may increase the risk of the rocks breaking. I did mark the barrel and used a stop watch to time how long 50 revolutions took. 46.3 sec for 50 revs equals 64.6 RPM. Cher said she looked in the Lortone booklet - I didn't think of that, duh! After a bit of a search I found my booklet and in it was the sales receipt for the 3A. I bought it in 1989. Good service I'd say.
It wouldn't too hard for me to change the RPM simply by using different pulley diameters, but I used what I already had on hand to minimize what I might have to buy new.
Thanks again! Wayne
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Post by alwaysbigatmikes on Nov 25, 2017 7:30:29 GMT -5
I wanted to thank everyone here about the rpm speeds.
As you can see my user name....you will start to understand.....
I bought a small 3 lb tumbler at the flea market 10 bucks....
I've plugged it in once to find rpm speed....it was 50 rpm...a harbor freight model....
But just being myself...I built my own tumbler....it is....big....I made my drums out of 4 gallon buckets....with 3/8 rubber matting liner....made end wheels .....I get about 40 pounds of rocks per drum....I am currently running 5 drums...with room to grow....
Through my 3 step refinement....speeds changed...was spinning 90 rpm....kinda scary....60 lbs drums.....
Dropped the rpm down to 50 rpm....but now have a different vibration from the weight of the rocks....(fist size and smaller)
I have to admit....the faster rpm really did a good and fast rough tumble....
Once I figure out the site I will post pics and videos...
Mike
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Post by youp50 on Nov 25, 2017 8:31:57 GMT -5
I believe that RPM a tumbler works best at is dependent on barrel diameter. A small barrel needs to turn faster than a large barrel. It's really about the speed of the barrel, not measured in revolutions but distance per time.
As stated in this resurrected post, high speeds can get rocks fractured. As you have discovered it will get things done fast.
Welcome to this board.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,602
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Post by jamesp on Nov 25, 2017 10:17:55 GMT -5
For a conservative surface speed I use 30 RPM for a 6 inch barrel.
For fast roughing I use 55 RPM for a 6 inch barrel.
But the surface speed is more important. But for large barrels(over 10 inches in diameter) other factors come into play.
For 6" diameter barrel:
3.14 X 6" x 30 RPM = 565 inches per minute (conservative, great for polish steps)
3.14 X 6" X 55 RPM = 1036 inches per minute (liberal, OK for harder rocks and fast grinding)
Small 4 inch diameter barrel:
3.14 X 4" X 64 RPM = 803 inches per minute (quite conservative for a small barrel with not much weight in it)
For a large 12 inch diameter barrel
3.14 X 12" X 20 RPM = 753 inche per minute (about as fast as a big 12" barrel with lots of weight should run)
Based on my experience.
Welcome to forum.
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Post by alwaysbigatmikes on Nov 26, 2017 6:27:24 GMT -5
And to think it was cranking at 90 rpm with a 12" drum....
Was cutting great....but the polish drum wasn't working correctly...
2 days on slower speed....going to open a couple ...
Thanks for the great info...I was literally taking a shot in the dark
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,602
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Post by jamesp on Nov 26, 2017 10:57:21 GMT -5
And to think it was cranking at 90 rpm with a 12" drum.... Was cutting great....but the polish drum wasn't working correctly... 2 days on slower speed....going to open a couple ... Thanks for the great info...I was literally taking a shot in the dark You can run that size at such speeds if you fill the barrel to 85%, run very hard agates, use a dialed in slurry thickener. But by filling the barrel to 85 to 90% you are just dampening the overly fast speed and wrestling with a lot of temperamental factors. Why not cruise quietly and slowly at 20 RPM with a 75% full barrel and enjoy a user friendly speed that accepts a wide range of slurry thicknesses and rock hardness. 20 RPM 12 inch barrel will flat grind some rocks. |
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Post by alwaysbigatmikes on Nov 26, 2017 13:48:53 GMT -5
One thing I learned while building different things....always make it so you can tweek it.....I left extra long shaft ends and can even run different speeds on the 2 different sets of rollers
I opened the drums today....
First off....I'm running geodes....Michigan agate and also Pennsylvania quartz as my smalls
The polish isn't working..at these speeds anyway....so I'm thinking I'm going to slow one set down.....
I also tried a couple different setups.....
I rough tumbled with 50 silica
Then ran 70 aluminum oxide
I have 2 drums from straight 70 aluminum oxide....
And I still can't figure out how to load a picture.....
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Post by youp50 on Nov 27, 2017 7:24:48 GMT -5
Posting pictures, go to the board related technical help section at the top section of the main menu and find the tutorial.
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Post by alwaysbigatmikes on Nov 27, 2017 14:50:42 GMT -5
Ok....got one side down to 28 rpm on 15" wheels....really sounds like its doing much more than the higher speeds...
I posted a video on YouTube
Search
Homemade boulder tumbler
I guess I'm going to have to make a jack shaft so that I can adjust both sets of rollers...
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