Saturday, March 17, 2012

Re: [papercreters] Re: MIXERS;



Jay, you won't get any argument from me about the torque output of a series wound DC motor. The problem with using this in an off grid situation is providing the power to run it. These motors take a lot of current to operate and therein lies the problem. To provide the power to run these motors would require a solar panel array and battery bank of such size that the cost to purchase said panels and batteries would be terribly cost prohibitive. And you are somwhat confused on the torque output of diesel engines. One of their strong points, at least in a small truck, is that they deliver a lot of torque at a low rpm. My Dodge 4X4 3/4 ton pickup runs at 1700 rpms at 65 miles per hour. And, true, a diesel engine puts out zero torque at zero rpm, but so too does the electric motor. If the motor isn't turning it can't put out any torque. My tow mixer is on the small side, 160 gallon tank and let me tell you takes a lot more than "measly" power to operate it. Even a tow/stationary mixer made from a 55 gallon barrel would require a large motor to operate it and that large motor is going to require a lot of DC current to run on.


--- On Sat, 3/17/12, JayH <slurryguy@yahoo.com> wrote:

From: JayH <slurryguy@yahoo.com>
Subject: [papercreters] Re: MIXERS;
To: papercreters@yahoogroups.com
Date: Saturday, March 17, 2012, 12:23 PM

 
It looks like we are going to disagree.

That doesn't mean I do not respect and appreciate your experience. Obviously you have a system you are happy with and works well for you. That's great. I find nothing wrong with that. The "best" system is the system each individual thinks is best for themselves.

You may find it amusing, but many of the reasons you cite in support of a tow mixer are the same reaons I suggest using something else.

You talk about how much power it takes to pull a mixer, but the examples you cited perfectly illustrate how low end torque, not power, is so critical to the operation of a mixer. Internal Combustion engines are notorious for being very weak and inefficent at supplying power at low rpms and high torque. This also happens to be where a Series Wound DC Electric motor shines. These motors can supply enormous torque. For those unfamiliar with what torque is, it's how hard of a push something can offer in a turning motion. This is exactly why the biggest modern freight train locomotives are diesel electric. The diesel engine is used at higher rpm all the time where it is most efficient to generate electricity to power the high torque electric motors that actually power the train wheels.

At zero RPM, internal combustion engines supply zero torque. At zero RPM, a Series Wound DC Electric Forklift motor can supply. John Wayland used two of this class of electric motors I suggest. He uses them to power his electric drag racer. He consistently beats the best internal combustion engine cars at the drag strip. He gets 538 Electric Horses, and a WHOPPING 1250 ft/lbs of torque... AT ZERO RPM. Dude can go from zero to 60 in 1.7 seconds! He doesn't even use a transmission. He directly couples the electric motors to the drive shaft of his car. Here comes the hilarious part. It's an old Datsun economy car. He can blow the doors of most macho muscle cars that come to the drag strip on a trailer, and John's ugly Datsun is still street legal and can drive to the race and back home in his race car. No street legal gas car has a chance to compete against John Wayland's hole shot.
http://www.youtube.com/watch?v=fNT-dnrzqKk
http://www.youtube.com/watch?v=RESC54vHr40

A measly mixer doesn't need that kind of power or torque. That would be insane. John uses two motors. I suggest using one would still be overkill. John advances the timing on his twin motors and over volts them beyond their specs. I suggest staying within the design specs of the motor and going with 36 to 48 volts, just like a typical electric fork lift. There will still be plenty of torque and power to mix papercrete with room to spare.

If your Polaris ATV were converted to electric drive, it could easily tow your mixer at low speeds as long as it had good tire to ground traction. That would be the big problem with using an Electric ATV. Traction.

These motors are not for wimps.

--- In papercreters@yahoogroups.com, Donald Miller <donald1miller@...> wrote:
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> Well the mixer debates continues............Anyone who has done any serious volume of block making/slipforming of papercrete will tell you that it takes a LOT of slurry to do a building of any size. The tow mixer fills the bill wonderfully and there a lot of plans, pictures and design on this forum. Jay, I totally disagree with you on the amount of energy used to tow the mixer with a vehicle. It takes a LOT of power to cut up paper or cardboard.A LOT OF POWER! An AC or DC motor of any size would still be very slow and would take a long time to make any useful amount of slurry. A great deal of the energy used to tow the mixer is actually used to mix the slurry. I tried to pull my 160 gallon tow mixer with a large Polaris ATV and it put such a strain on it to get the mixer moving that I had to go back to the diesel pickup. Once the paper/cardboard starts to shred it takes less power but I have a Dodge 12 valve diesel 3/4 ton pickup and it makes it grunt
> till the mix gets cut up some. I am cutting heavy cardboard and I load the soaked board til it comes to top of the tank then fill it with water and take off. It would probably take less power if I added the cardboard more slowly but that is hard to as I work by myself and it would slow the process down considerably.
> I live totally off grid and have solar panels and a small wind generator to charge my batteries. I run a 22 cu. ft. refrigertor, a microwave, coffee maker, satellite tv, computers, lights and in the summer months a couple of swamp coolers and fans. (I live in SW Arizona) For my money the wind genny is basically worthless as it takes a really big blow to generate any really useful power, but that's off topic I guess. Any kind of electric motor, whether DC or AC through an inverter is going to require a humongous array of solar panels and an even more humongous battery bank. I just bought 12 new 230 ah 6 volt heavy duty batteries to the tune of $1300.00 and they will run my system but not any big motors for any length of time. My old battery bank is getting weak so the new ones will be held in reserve. One has to factor this cost into the Solar equation. The power required to mix papercrete in any kind of volume would not be practical with a solar/battery
> system. I run my pickup on used cooking oil so my cost for fuel is minimal. I also have a 5 cylinder Mercedes diesel engine that I plan to make a stationary generator with. I can run it on used cooking oil as well.
> Another thing to factor in is the amount of water it takes to soak the paper/cardboard and to mix it. It takes a lot of power to pump water. I run a gas generator to pump water for my papercrete mixing and household needs. So to say that a motor powered mixer would be practical for an off grid setup is misleading from my experience. Another thing to factor into the equation is the fact that solar is not cheap and the reason that many people are attracted to PC in the first place is that they do not have a lot of money.
> So,to all the newbies that are looking for advice, be forewarned that it takes a lot of manual labor to do much volume and it will not be an instant gratification type of situation. But if you can be patient and are not adverse to a little sweat you can end up with an excellent building with a minimal cash requirement. And think of all the money you will save by not having to pay a "health" club to get some excercise!-- On Fri, 3/16/12, JayH <slurryguy@...> wrote
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