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Reply to Tishatang:
Hi Tish,
That would certainly be an acceptable variation if you simply want to heat just the room where the device is located. If you want to replace an oil burning hot air furnace that heats several rooms through ducting, that's a different story. With ducting, you would want all of the generated heat to go into a collector box placed above the friction device, and the collector would be attached to your ductwork. In any case, the problem with modern disc brake rotors is that they are made thin to reduce weight. If you try this method, use a rotor from a car built prior to 1975, when the CAFE standards were introduced, as the prior years will have much thicker rotors. Look for a junked car with less than 40,000 miles on it, otherwise the rotors may have been machined already and made thinner. Modern rotors don't usually have enough thickness on them to be resurfaced more than once, if at all. An even better bet than an old car rotor would be a heavy duty truck rotor, if you can find one.
Yes, a horizontally mounted brake rotor will allow the wood to be pressed full face against it from the very start, and this could be advantageous. On the other hand, though, if you use a 10 pound weight to force the wood against the rotor (as Lloyd's setup does) then we have to consider that the 10 pounds of pressure is distributed over a 16 square inch area of the wood 4 x 4, and that equals 0.625 pounds per square inch. With a curved rotor, you would have less area of the wood exposed (until it conforms to the rotor), but with the same 10 pound force applied - say to a 2 square inch area of wood, you would have 5 pounds per square inch pressure. Thus, the actual heat generated may be nearly the same. With less surface area of wood exposed, you would simply be concentrating the heat on a narrower area of the rotor, whether it be a horizontal or vertical one. Lloyd's newer horizontal roller does have quite an advantage, in that multiple pieces of wood can be loaded on each side, and each piece can have its own forcing weight. You may not need all that additional heat, though, unless you do decide to go for the steam output to provide for both heat and electric generation.
If you do go with the brake rotor idea, be sure to post some plans and/or photos.
Best wishes,
Rick
Originally posted by Tishatang
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That would certainly be an acceptable variation if you simply want to heat just the room where the device is located. If you want to replace an oil burning hot air furnace that heats several rooms through ducting, that's a different story. With ducting, you would want all of the generated heat to go into a collector box placed above the friction device, and the collector would be attached to your ductwork. In any case, the problem with modern disc brake rotors is that they are made thin to reduce weight. If you try this method, use a rotor from a car built prior to 1975, when the CAFE standards were introduced, as the prior years will have much thicker rotors. Look for a junked car with less than 40,000 miles on it, otherwise the rotors may have been machined already and made thinner. Modern rotors don't usually have enough thickness on them to be resurfaced more than once, if at all. An even better bet than an old car rotor would be a heavy duty truck rotor, if you can find one.
Yes, a horizontally mounted brake rotor will allow the wood to be pressed full face against it from the very start, and this could be advantageous. On the other hand, though, if you use a 10 pound weight to force the wood against the rotor (as Lloyd's setup does) then we have to consider that the 10 pounds of pressure is distributed over a 16 square inch area of the wood 4 x 4, and that equals 0.625 pounds per square inch. With a curved rotor, you would have less area of the wood exposed (until it conforms to the rotor), but with the same 10 pound force applied - say to a 2 square inch area of wood, you would have 5 pounds per square inch pressure. Thus, the actual heat generated may be nearly the same. With less surface area of wood exposed, you would simply be concentrating the heat on a narrower area of the rotor, whether it be a horizontal or vertical one. Lloyd's newer horizontal roller does have quite an advantage, in that multiple pieces of wood can be loaded on each side, and each piece can have its own forcing weight. You may not need all that additional heat, though, unless you do decide to go for the steam output to provide for both heat and electric generation.
If you do go with the brake rotor idea, be sure to post some plans and/or photos.
Best wishes,
Rick
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