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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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best starting point to build a homebrew centrifuge?
i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too expensive. I thought to start with a washing machine, it's a decent volume of spun space, and they are relatively cheap. Anything even better? Willing to spend as long as results/incremental-dollars margin is positive. |
#3
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best starting point to build a homebrew centrifuge?
Keep YerSpam wrote:
wrote: i have in mind a project which would require some medium amount of centrifuging batches of materials. Industrial centrifuges are too expensive. I thought to start with a washing machine, it's a decent volume of spun space, and they are relatively cheap. Anything even better? Willing to spend as long as results/incremental-dollars margin is positive. You might be surprised how cheap a 'real' centrifuge can be had. I bought a couple large ones at a Silicon Valley auction for $20 for the pair. I sold them for more than that, but ebay has all kinds of them for pretty cheap. About what you'd pay to setup a washing machine that won'yt realy spin at a very good speed. http://search.ebay.com/centrifuge That's true. A friend of mine has picked up four for nothing from science labs recently. I think 3 out of the 4 worked okay. They were scary 10,000 rpm machines, too, but only had a fairly small capacity. Chris |
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best starting point to build a homebrew centrifuge?
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#5
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best starting point to build a homebrew centrifuge?
I don't think he was going to use the centerfuge for making beer.
"Homebrew" seems to be used as a synonym for homemade. "Peter Huebner" wrote in message t... In article . com, says... i have in mind a project which would require some medium amount of centrifuging batches of materials. Industrial centrifuges are too expensive. I thought to start with a washing machine, it's a decent volume of spun space, and they are relatively cheap. Anything even better? Willing to spend as long as results/incremental-dollars margin is positive. What on earth do you want a centrifuge for w.r.t. homebrewing? I've done it for years without ever seeing the need, and we have two boutique breweries around, one in the valley and one in the village and neither of them ever owned a centrifuge (nor do the large commercial German breweries I've visited)?!? -P. -- ========================================= firstname dot lastname at gmail fullstop com |
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best starting point to build a homebrew centrifuge?
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#7
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best starting point to build a homebrew centrifuge?
Peter Huebner wrote:
In article , says... I don't think he was going to use the centerfuge for making beer. "Homebrew" seems to be used as a synonym for homemade. Oh dear. A blonde moment ?!? Lol, -Peter I was going to say somthing about how yours must be REALLY good home-brew... ;-) |
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best starting point to build a homebrew centrifuge?
What on earth do you want a centrifuge for w.r.t. homebrewing? I've done it for years without ever seeing the need, and we have two boutique breweries around, one in the valley and one in the village and neither of them ever owned a centrifuge (nor do the large commercial German breweries I've visited)?!? We had two, 100 Hp centrifuges at a brewery that I worked at In Sydney. We used them to spin out most of the yeast before the beer was filtered. It save a significant amount of money in diatomaceous earth filter powder as well as saving on the disposal costs of used filter medium.. They frightened hell out of me. The rotor weighed about 100 Kg and spun at 300 rpm. . They used an eddy current drive to get it up to speed. It took over an hour to get to operating speed from cold start. I did a "back of an envelope' calculation with regard to the stored energy in one of these things,and avoided them like the plague ever since. Tom Miller |
#9
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best starting point to build a homebrew centrifuge?
Tom Miller wrote in message ... What on earth do you want a centrifuge for w.r.t. homebrewing? I've done it for years without ever seeing the need, and we have two boutique breweries around, one in the valley and one in the village and neither of them ever owned a centrifuge (nor do the large commercial German breweries I've visited)?!? We had two, 100 Hp centrifuges at a brewery that I worked at In Sydney. We used them to spin out most of the yeast before the beer was filtered. It save a significant amount of money in diatomaceous earth filter powder as well as saving on the disposal costs of used filter medium.. They frightened hell out of me. The rotor weighed about 100 Kg and spun at 300 rpm. . They used an eddy current drive to get it up to speed. It took over an hour to get to operating speed from cold start. I did a "back of an envelope' calculation with regard to the stored energy in one of these things,and avoided them like the plague ever since. Tom Miller That's a lot less energy than an average IC engine spinning at 6k rpm so I'm not sure what you are so frightened about. -- Dave Baker |
#10
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best starting point to build a homebrew centrifuge?
On Thu, 27 Oct 2005 10:21:22 +0100, with neither quill nor qualm,
"Dave Baker" quickly quoth: Tom Miller wrote in message I did a "back of an envelope' calculation with regard to the stored energy in one of these things,and avoided them like the plague ever since. That's a lot less energy than an average IC engine spinning at 6k rpm so I'm not sure what you are so frightened about. Are you sure, Dave? The forces at such a larger radius and such a larger mass at 300 RPM would seem to have a lot more energy than an average IC engine could put out. (I'd like to see figures on both for S&G. Throw in 1,500hp funny car/dragster engine figs, too, please.) My truck's V-8 engine is spinning at an angle which would not slice and dice me if it blew. (Although the new small cars with transverse engines have their radial mass trajectories (what's the correct term for this?) "aimed" more toward you, they have considerably less mass to throw atcha.) LJ--who doesn't recall hearing the term "centripetal" before this newsgroup and has zero college math under his belt. -- SAVE THE PARROTS! Eschew the use of poly! ---------- http://diversify.com Poly-free Website Development |
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best starting point to build a homebrew centrifuge?
Larry Jaques wrote:
LJ--who doesn't recall hearing the term "centripetal" before this newsgroup and has zero college math under his belt. Aw yes! That is always a good starter for a LOOOOng thread. :-)] Watch you have done Larry. ...lew... |
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best starting point to build a homebrew centrifuge?
radial mass trajectories (what's the correct term
for this?) Tangential |
#13
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best starting point to build a homebrew centrifuge?
"Dave Baker" writes in article dated Thu, 27 Oct 2005 10:21:22 +0100:
Tom Miller wrote in message ... They frightened hell out of me. The rotor weighed about 100 Kg and spun at 300 rpm. . They used an eddy current drive to get it up to speed. It took over an hour to get to operating speed from cold start. I did a "back of an envelope' calculation with regard to the stored energy in one of these things,and avoided them like the plague ever since. Tom Miller That's a lot less energy than an average IC engine spinning at 6k rpm so I'm not sure what you are so frightened about. -- Dave Baker Tom didn't give us enough numbers to calculate energy. The energy of a spinning hollow cylinder is (1/2)*mass*(radius*angular_velocity)^2. What was the radius of the rotor, Tom? The mass of the moving parts in a car engine is much less than 100kg, and the radii are probably also much less -- radius of the crank and cam, and half the stroke length for the pistons, which is a high-ball estimate because the pistons only move at (radius*angular_velocity) in the middle of their stroke. -- spud_demon -at- thundermaker.net The above may not (yet) represent the opinions of my employer. |
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best starting point to build a homebrew centrifuge?
"Dave Baker" wrote in message ... Tom Miller wrote in message ... What on earth do you want a centrifuge for w.r.t. homebrewing? I've done it for years without ever seeing the need, and we have two boutique breweries around, one in the valley and one in the village and neither of them ever owned a centrifuge (nor do the large commercial German breweries I've visited)?!? We had two, 100 Hp centrifuges at a brewery that I worked at In Sydney. We used them to spin out most of the yeast before the beer was filtered. It save a significant amount of money in diatomaceous earth filter powder as well as saving on the disposal costs of used filter medium.. They frightened hell out of me. The rotor weighed about 100 Kg and spun at 300 rpm. . They used an eddy current drive to get it up to speed. It took over an hour to get to operating speed from cold start. I did a "back of an envelope' calculation with regard to the stored energy in one of these things,and avoided them like the plague ever since. Tom Miller That's a lot less energy than an average IC engine spinning at 6k rpm so I'm not sure what you are so frightened about. -- Dave Baker Wouldn't that depend a lot on the rotor diameter? The further out you move that 100Kg from the center the faster it will be moving at 300RPM. It seems to me like we could be talking about a LOT of energy. Especially considering it takes a 100HP motor over an hour to spin it up! Bob |
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best starting point to build a homebrew centrifuge?
Bob wrote:
...we could be talking about a LOT of energy. Especially considering it takes a 100HP motor over an hour to spin it up! 100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-) Nick |
#16
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best starting point to build a homebrew centrifuge?
"Tom Miller" wrote in message ... What on earth do you want a centrifuge for w.r.t. homebrewing? I've done it for years without ever seeing the need, and we have two boutique breweries around, one in the valley and one in the village and neither of them ever owned a centrifuge (nor do the large commercial German breweries I've visited)?!? We had two, 100 Hp centrifuges at a brewery that I worked at In Sydney. We used them to spin out most of the yeast before the beer was filtered. It save a significant amount of money in diatomaceous earth filter powder as well as saving on the disposal costs of used filter medium.. They frightened hell out of me. The rotor weighed about 100 Kg and spun at 300 rpm. . They used an eddy current drive to get it up to speed. It took over an hour to get to operating speed from cold start. I did a "back of an envelope' calculation with regard to the stored energy in one of these things,and avoided them like the plague ever since. Tom Miller Is this RPM right? 220 lbs. at 300 RPM just doesn't seem all that dangerous to me. How much weight was spinning when it was loaded? Garrett Fulton |
#17
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best starting point to build a homebrew centrifuge?
On Thu, 27 Oct 2005 08:55:28 -0400, "gfulton"
wrote: "Tom Miller" wrote in message ... What on earth do you want a centrifuge for w.r.t. homebrewing? I've done it for years without ever seeing the need, and we have two boutique breweries around, one in the valley and one in the village and neither of them ever owned a centrifuge (nor do the large commercial German breweries I've visited)?!? We had two, 100 Hp centrifuges at a brewery that I worked at In Sydney. We used them to spin out most of the yeast before the beer was filtered. It save a significant amount of money in diatomaceous earth filter powder as well as saving on the disposal costs of used filter medium.. They frightened hell out of me. The rotor weighed about 100 Kg and spun at 300 rpm. . They used an eddy current drive to get it up to speed. It took over an hour to get to operating speed from cold start. I did a "back of an envelope' calculation with regard to the stored energy in one of these things,and avoided them like the plague ever since. Tom Miller Is this RPM right? 220 lbs. at 300 RPM just doesn't seem all that dangerous to me. How much weight was spinning when it was loaded? It depends on the size of the 'fuge. With a 10 ft dia 'fuge, tangential velocity at 300 RPM is 157 ft/sec or about 107 mph with about 150 G's on the load -- so the 220 lb mass is straining to leave the bucket with 33,000 lb of force if I did me sums right. I once saw a $20K (1966 dollars) electrostatically-suspended gyro fly thru the 'fuge housing, go about 30 feet and then thru a brick wall. There were no pieces larger than a nickel left. I think that one only went up to 100 G's. |
#18
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best starting point to build a homebrew centrifuge?
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#19
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best starting point to build a homebrew centrifuge?
Depends upon what you expect from the centrifuge.
If you intend to clean up waste vegetable oil with it, you might look for a cream separator as used in a dairy. If you project can be solved by filtration, it might be cheaper and easier to fabricate from available junk. |
#21
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best starting point to build a homebrew centrifuge?
When you get to making ones own stil let me know....
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#22
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best starting point to build a homebrew centrifuge?
i have in mind a project which would require some medium amount of centrifuging batches of materials. Industrial centrifuges are too expensive. I thought to start with a washing machine, it's a decent volume of spun space, and they are relatively cheap. What's wrong with a bucket on a rope? |
#23
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best starting point to build a homebrew centrifuge?
...we could be talking about a LOT of energy. Especially considering
it takes a 100HP motor over an hour to spin it up! 100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-) About 1530 pounds, ie 1.5 kilotons. Nick |
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best starting point to build a homebrew centrifuge?
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#25
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best starting point to build a homebrew centrifuge?
In article et,
Lew Hartswick wrote: wrote: 100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-) About 1530 pounds, ie 1.5 kilotons. ***** Nick Come again Nick ? a ton is 2000 pounds. ...lew... Small kilotons :-) One site says 100 grams of dynamite is 0.43x10^6 joules. Nick |
#26
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best starting point to build a homebrew centrifuge?
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#28
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best starting point to build a homebrew centrifuge?
100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-),
About 1530 pounds, ie 1.5 kilotons Erm, it would doubtless be "killa" if you were standing nearby at the time of an uncontained failure but it isn't "kilo" (1.5 kT = 3 million pounds, said of the blast aspect of nuclear weapons in broad comparison to TNT). I also think the amount of time needed to spin it up is irrelevant to a calculation of how much rotational kinetic energy it has when done (though perhaps highly relevant to how much energy will drain out of you when you get the electric bill!); and that's the key fact for safety. BTW, I think the energy use is 268 MJ, not 3 GJ, if you run a 100 hp (input) motor for an hour. Check my logic... A horsepower is 745 W. A watt is a joule per second, so if you do that for 3600 seconds you get 268,200,000 joules. See for instance http://www.newton.dep.anl.gov/askasc...9/phy99x45.htm and (one of the most eminently bookmarkworthy and explorable sites around) http://hyperphysics.phy-astr.gsu.edu/hbase/rke.html --Joe "Whatever the numbers, centrifuges are built strong, and operated according to safety instructions, for a reason" Chew |
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best starting point to build a homebrew centrifuge?
Ad absurdum per aspera wrote:
100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-), About 1530 pounds, ie 1.5 kilotons Erm, it would doubtless be "killa" if you were standing nearby at the time of an uncontained failure but it isn't "kilo" (1.5 kT = 3 million pounds, said of the blast aspect of nuclear weapons in broad comparison to TNT). I also think the amount of time needed to spin it up is irrelevant to a calculation of how much rotational kinetic energy it has when done (though perhaps highly relevant to how much energy will drain out of you when you get the electric bill!); and that's the key fact for safety. BTW, I think the energy use is 268 MJ, not 3 GJ, if you run a 100 hp (input) motor for an hour. Check my logic... A horsepower is 745 W. A watt is a joule per second, so if you do that for 3600 seconds you get 268,200,000 joules. Assuming you lose nothing to friction during that hour of the giant heavy drum spinning. - Logan |
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best starting point to build a homebrew centrifuge?
Sure enough... that's why I took the liberty of specifying "100 hp
(input"). That may not have answered quite exactly the question asked, but lends itself to doing a finite-envelope model without having to look around in the bottom drawer for another envelope. Accounting for real-world efficiency, the actual power usage curve, and other things you'd want to tease out if you were designing or specifying equipment, rather than just getting a quick calculation onto the right order of magnitude, makes for big equations with a lot of moving parts. Cheers, --Joe |
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