mikew
off to a rocking start
Member since March 2011
Posts: 12
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Post by mikew on Apr 14, 2011 20:40:52 GMT -5
When I first got my Thumblers AR-1 I was surprised to see that the motor was at rated at .5 amps. This translates to 60 watts. Volts X amps = watts. 120 x .5 = 60. That seems like a lot of power to just roll 3 lbs of rocks and water. I did some research, and it turns out that the motor that thumblers and probably Lortone use are whats called shaded pole ac motors. They are the least efficient motor going. They are cheap to make but very reliable. There are no brushes to where out, so keep them oiled and they will almost last forever. I also found out that the speed they turn at is dependent on the frequency of the ac and not as much on the voltage. I have a device called a VARIAC, which has a knob on it that allows you to set it output voltage from 0 to 120 volts. I found that I can run my tumbler down to 80 volts and only have a 2% drop in barrel rpms. 40 rpm at 120, 39 rpm at 80. The current drawn by the motor at 80 volts is .35 amps which brings the wattage to 28, which is less than half. If you live where electric rates are high, you may want to look into getting a VARIAC and do some experimenting.
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Post by johnjsgems on Apr 14, 2011 21:57:09 GMT -5
Most if not all brushless motors will not run long on low voltage. The amount of work the motor does isn't dependent on voltage but what it turns. This is why a 1/4hp motor that turns a load at 5 amps runs the same as amps as a 1/3 or 1/2 hp motor running the same load. Even motors with brushes will run hotter and with decreased power at lower voltage. The only way you can lower the watts used is to decrease weight in the barrel or change pulley ratio. From personal experience you won't notice the tiny watt draw of your tumbler on your electric bill. I tumbled a lot back in the day and saw no increase until I ran a 40 lb. tumbler with a 1/3 hp motor.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,685
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Post by Fossilman on Apr 14, 2011 23:26:31 GMT -5
I noticed the electric rates are double in Oregon than when I lived in North Dakota!
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Apr 15, 2011 9:09:46 GMT -5
3 amp Variac = $50 + shipping on 10lbs
Electricity = 11 cents per kilowatt (here).
mikew did you measure the current draw at the motor or at the input to the Variac? (you have to include the inefficiency of the Variac as it will be in the circuit). Have you tried it with a triac speed control (cheaper)? It chops the AC signal but you may have a start-up issue as these motors don't have hardly any start-up torque to begin with.
And John is correct, you could have a heat issue since the motor isn't fan cooled.
Dr Joe
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Apr 15, 2011 9:11:59 GMT -5
Fossilman, can you reduce the size of your signature, it takes a minute to scroll pasts it everytime ;D ;D
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Post by rocklicker on Apr 15, 2011 11:05:10 GMT -5
I was also wondering if you took your wattage reading before or after the vairac. A variac is basically a transformer so it may be drawing power. If the variac is at all warm then you are losing power through it.
I agree with John. A 3lb tumbler is pretty insignificant. I used to run 5 lortone 3 pounders, and a 6 pounder and still barely noticed any difference in the electricity bill. Once I added a 60 pounder powered by a 1/3 HP motor I saw a difference. Steve
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Post by johnjsgems on Apr 15, 2011 13:20:05 GMT -5
And, the .5 amp is the motor rated load amps, not the amps used. It is probably close on the loaded tumbler but you would need a clamp on amp meter to check actual current use.
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mikew
off to a rocking start
Member since March 2011
Posts: 12
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Post by mikew on Apr 15, 2011 18:54:32 GMT -5
To all repliers, the motor is running much cooler than at full voltage. The motor draws close to .5 amps with not barrel at all. I'm measuring the current with an amp meter at the motor. Yes there are core losses in the VARIAC. Current into the VARIAC is .3 amps bringing the wattage to actual wattage to 36 watts I tried a triac motor speed controller. It didnt work as good as the VARIAC. 60 watts = 1 kilowatt hour every 16.6 hours, which translates to about $7.50 a month where I live. Cutting that down to less than $4.00 isn't going to let me get a new car, but its something.
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Post by johnjsgems on Apr 15, 2011 18:57:20 GMT -5
Tumbler turns same speed? If slower you will have to run longer.
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playin4funami
noticing nice landscape pebbles
Member since March 2011
Posts: 87
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Post by playin4funami on Apr 15, 2011 20:07:32 GMT -5
I would be more worried about frying the motor under a load running it short on juice. It's a good experiment but if it would run right with less motor then the manufacturers would probably see it as cheaper to put a smaller motor in it to start. But hey, if it works for you great!
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Apr 16, 2011 8:22:20 GMT -5
14 months to pay off Variac then the profits roll in .Seriously, I hope you stay around for the long run as I am interested in the long term effects (both bad and good), and if you consider this an experiment a monthly current reading for an extended time period would not go amiss. If you don't mind ..where are you? Just curious about electrical costs (double mine). Still don't understand why people are paranoid about putting in a general location with their name. Anybody with Mod rights can see the IP and " They" (you know who I mean) aren't that interested in us rock crushers Dr Joe .
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mikew
off to a rocking start
Member since March 2011
Posts: 12
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Post by mikew on Apr 16, 2011 16:28:25 GMT -5
Hi Dr Joe, I live on long island and pay the highest electric rates in the country. My variac is a tiny 1.75 amp job I've had forever. I think I paid $1.00 for it a garage sale over 20 years ago. No waiting to see profits for me. The reason I tried this experiment in the first place was from an ad for whats called a motor miser. It lowers the voltage to an ac motor when it detects that it is under a light load. Under loaded motors are very inefficient, which apparently even with a full load of rocks, my thumbler motor seems to be. As I stated before, its running cooler and using less electricity. Its a win win situation.
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Jon
starting to shine!
Member since June 2011
Posts: 41
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Post by Jon on Jul 30, 2011 0:43:52 GMT -5
I just got into tumbling a couple months ago. I've got 3 tumblers, a lortone 3a, a lortone 45c, and an old lortone 66 (probably 25 years old, bought it at a garage sale probably 18 years ago). I also have a handy little device called a kilo-watt meter. You plug it into the wall and you can directly measure the wattage of whatever you plug in. My lortone 66 draws about 60 watts when fully loaded. Motors have large start up currents, and the listed current is likely the peak rating. I doubt it uses that much once its up and running.
All three of my tumblers loaded and running take about 105 Watts, that figures out to about $8.50 a month assuming $0.11 per kilowatt hour for a total tumbling capacity of about 20 pounds. However, I also inherited a really old 6 pound tumbler that Sears made at one point, I plugged that in and tried it out, it was pulling 100 watts all by itself for only 6 pounds and was getting very hot. Didn't want to push my luck and burn down the garage, nor pay the electric bill for such an in-efficient tumbler, so it got retired.
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dkurtz
having dreams about rocks
Tumbling to de-stress from my work. :)
Member since February 2010
Posts: 66
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Post by dkurtz on Jul 30, 2011 19:09:15 GMT -5
My wife has been blaming me and my 5 or so QT-12 tumblers for our electric bill. lol I asked her about why she has the TV on while playing on her iPad and the boys are each on their own computer. So................... I'm adding an 8.8 kW AC (CEC) solar system to my house. 6 years pay back.
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tumblesondown
off to a rocking start
Member since July 2011
Posts: 11
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Post by tumblesondown on Jul 31, 2011 19:16:24 GMT -5
Perhaps a dumb idea, but solar power?
Saw a YouTube video with some guy doing it. (There is a wind power one too.)
Would love to know how hard a solar set up would be.
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tumblesondown
off to a rocking start
Member since July 2011
Posts: 11
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Post by tumblesondown on Jul 31, 2011 21:06:32 GMT -5
Here is the link (re: solar powered tumbler)
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