If you do renovation, restoration or any carpentry that involves dubious materials and would prefer to discover lurking foreign bodies in advance instead of with your sawblade, Wizard Industries’ battery-powered metal detectors can help. The company offers several styles; I tried the small and medium-size models. It took me a few tries to figure out how to use the detectors: Detection was improved (a lot) when I held the scanner at a slight angle and used it in the factory-recommended circular pattern, perhaps allowing the scanner to pick up more of the length of a nail rather than just the head.
Even with familiarity, using the Little Wizard is a deliberate affair. The sensor head is only about 3 in. wide, so thorough scanning requires multiple passes. In practice, you might need five minutes to check an 8-ft. wide board. The detector was noticeably more effective in identifying larger potential shrapnel such as embedded 10d nails or drywall screws, although I did find all the little nails, eventually.
Although the model tested has been discontinued, an updated version of the Little Wizard is available.
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