Show gadget howls Hoiu ls wizen when near metal tinis thus elimination Elimina eliminating tin ff saw repair bills ASHINGTON A device ifor washington for detecting spikes and other metal objects buried in logs has been developed by the forest service of the united states department of agriculture metal objects in logs are potential causes of costly and sometimes fatal saw smashing accidents the device was developed for use in connection with the northeastern timber salvage administrations new england operations erat ions because an unusually high percentage of blow down timber in some sections hit by the 1938 hurricane was found to conceal old fence nails hammock hooks spikes abandoned sugar sap spouts and even sections of forgotten scythe blades near vermont marble quarries miscellaneous bits of iron and rock apparently blasted into the tree trunks and grown over also have been found as was a jackknife left perhaps by some initial carver of other days howls near metal the detector was designed and built in the forest service radio laboratory at portland ore the machine is easily carried by one man when the exploring coil with which it is equipped is held near a log in which metal is imbedded embedded im bedded the device sets up a howl by moving the coil the operator is able to locate the exact position of the buried metal since the volume of the howl varies with the size of the object and its proximity to the coil armed with this information the sawmill saw mill er then chops out the metal before the log goes to the saw and a possible crack up the detector consists of a box about the size and appearance of a portable radio set to which the flat 10 inch exploring coil is attached by a six foot flexible wire by means of A shoulder strap the operator carries the box upon his hip so that adjustment knobs controlling batteries and circuits rest under one hand the exploring loop or coil is handled with the other headphones are provided so he can better catch the detectors owl howl amid other sawmill noises when the instrument is turned on an audio tone signal is set up in the headphones by twisting the knobs the operator balances out the signal when the exploring coil is brought into the vicinity of any metallic object the balance is bistu disturbed abed and the audio tone signal is heard anew saves much aluch money aloney metal im bedded in logs has been a serious problem to the timber salvage sawmill saw mill operators since the new england operations began having cost thousands of dollars in time lost and repair bills much of the blow down timber comes from picnic grounds playgrounds farm field borders and similar wood patches where spikes and nails are often driven into trees frequently the growth of the tree has so completely covered the metal that no more than a slight bump in the bark marks the spot operators say that sawmill speed and efficiency in many cases has been considerably impaired because of the necessity for workers to watch logs under the saw for discolors eions and other indications of buried metal high speed saws may cut through a small nail with little damage save dulling the teeth but a larger object in the log generally twists the blade tears out a number of teeth and sometimes sends them through the air with bullet speed an im bedded hammock hook was struck by a circular saw in a mill at bellows falls vt recently with the result that the mill was put out of commission for the day it cost to repair the saw |