2006 - Volume #30, Issue #4, Page #20[ Sample Stories From This Issue | List of All Stories In This Issue | Print this story | Read this issue]
Press Puts Curve Back Into Concave
"I had a couple of badly bent concaves on the floor and studied them till I figured out a way to do the job," recalls the 80-year old craftsman. "Now I can fix most concaves for about $100, including building up the worn bars, instead of the farmer having to pay $400 to $500 for a new one."
Hickman built a steel bench press out of I-beam and channel iron. A moveable top panel with a hydraulic jack on a shelf beneath it serves as the press. A section of box beam a couple of inches above the concave, and mounted to two channel iron arms that pivot from the bench's base, serves as the anvil. It can be swung in an arc to any spot over the concave, while the jack can be moved to any point beneath the concave.
To straighten a concave, Hickman uses aluminum templates patterned from new concaves to identify where the bend has occurred and how far out of round it has become. He then moves the jack to the side he wishes to work on first, swings the anvil over the top of the problem, and applies pressure.
The concave sits on a flat plate with a round roller at one end. The roller lets the concave move as the jack presses against the anvil. One end has to give to take the bend out, notes Hickman.
"By moving the jack and the anvil back and forth, I can take the bend out regardless of where it is," he explains. "Some bend as much as an inch, but even a quarter of an inch can interfere with threshing a crop like bluegrass seed."
Hickman chose a small hand jack to deliver pressure to force the concave against the anvil because it's easy to position.
In addition to bringing concaves back to their true arc, Hickman also builds up worn bars on the concaves. "If they are worn down 3/16 in. or less, they are easy to build up," he says. "If they are worn down too much, it is hard to build them up without burning the wires behind them. My rebuilt concaves show no apparent wear after two years."
Contact: FARM SHOW Followup, Bill Hickman, 2834 W. Conkling Rd., Worley, Idaho 83876 (ph 208 686-1493).
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