"Downdraft" Cutting Table

"Downdraft" Cutting Table FARM SHOP Tools 27-4-39 After Brad Noth bought a Hypertherm 1000 plasma cutter, he decided he needed a better cutting table and ventilation system. "The plasma cutter is an excellent machine but it produces a lot of heavy smoke," he says. So he built a portable downdraft cutting table equipped with its own fan exhaust. Smoke is pulled down through the table, which is partially open on top. From there it goes through a pair of curved 8-in. dia. pipes to a couple of squirrel cage fans mounted on one side of the table. The fans are belt-driven by a 1 hp 1,725 rpm electric motor. The 3-ft. high table measures 4 by 5 ft. and has drop-in grates made from 3/16-in. thick, 1 1/2-in. wide flat stock. A hopper under the table funnels sparks and slag down into a removable catch pan. A pair of 8-in. dia. holes were cut halfway up on opposite sides of the hopper. Elbows and some short lengths of stove pipe connect the holes to the fans. An extension cord is attached to a switch that he mounted on the table. Whenever Noth wants to use his plasma cutter, he pushes the table next to an overhead garage door and raises the door a foot or two so he can blow the fan exhaust outside. "I was surprised at how well it works, especially because I had never seen a downdraft system like this before," says Noth. "It works much better than a hood system and is also much cleaner and healthier. The fans are two 1/3 hp 1,000 cfm single-inlet radial blowers that I found at a local repair shop. Since the fans are symetrical, I had to reconstruct one fan wheel so that I could run both fans back-to-back on a single shaft with a pulley in between them." Noth estimates his total cost to build the table at about $500. Contact: FARM SHOW Followup, Brad Noth, 9018 Enterprise Road, Tomah, Wis. 54660 (ph 608 372-3191).

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