Direct Drive Motor . . . Powdered Mixed Metals . . . Commercially Available Link-Belts . . .
Dear Search Engineer: I am looking for a budget way to control the speed of a 220V ac three-phase delta 3 hp direct drive motor used for a polishing table (yes, I know pulleys would be nice). Exact constant speed is not required. It just needs to be a lot slower than the 3,450 rpm that the table spins at now. Any suggestions?—T.G., DN reader
Dear T.G.: You haven't said if you want constant or variable speed. If the latter, remember that if you change ac motor speeds by whatever electronic means, it affects the available torque dramatically! If you can't use pulleys, try a double cone system or a variable speed gears based reducer, or change the motor to dc—the speed can be modulated electronically without much loss in power. If none of these work for you, check the torque results if you're using an ac power conversion system, then price it out and compare it to the other options. Be prepared for nasty surprises. Don't forget you can simply remove the direct drive coupling, make a parallel shaft, and create a pulley solution. (Is the final shaft strong enough for the increased available torque? Are the bearings sized properly? If you don't need all that torque, why not just change the direct drive motor to a smaller, slower one?) Now, if you don't need variable, I suggest getting a torque motor (with an attached single speed gear reducer system in line).
Dear Search Engineer: I have a massive quantity of powdered mixed metals consisting of iridium, palladium, ruthenium, rhodium, platinum, and gold and inert tailings. I am looking for a solution to separate these with a joint venture partner. Any suggestions?—D.W., DN reader
Dear D.W.: For anything above 90 percent purities, the cost of processing ore tends to go up exponentially. There are methods to accomplish your desired end but they are neither simple nor particularly cheap. Anyone working with you will likely require a "full total disclosure" due to the dubious nature of the product, which produces security issues as well as logistic nightmares. For your protection, all business must be conducted in the most professional manner, with you making sure that everyone's interests are protected under a contract. These metals require special and exact tracking from cradle to grave as many additional issues are involved, such as tax and environmental liabilities. Some refined ores require special permitting just to possess, much less process due to their processes' hazardous nature.
Dear Search Engineer: I'm looking for a commercially available link-belt about 1.2 inches wide, made of stamped metal or molded plastic, to which can be attached individual modular clips for conveying 40 mL glass vials. Any suggestions?—V.Z., DN reader
Dear V.Z.: Try the Flexlink line of conveyors (www.flexlink.com), made with molded plastic chains. Although the small size does not accommodate add-on clips as manufactured, Flexlink does produce a chain that is 3.35 inches wide and designed to allow special tooling to be mounted to the chain. Or the smaller chain can be purchased with cleats, which could be modified further to support custom tooling.
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