Foreign Material in Sheet Stock

People have found nuts, bolts, wrenches, nail sets, and sheet rock knives embedded in sheets of MDF or plywood. September 3, 2011

Just for grins, and maybe to convince some to wear their safety glasses, I thought I'd ask: What's the strangest or most dangerous foreign object you've found in sheet goods?

The most dangerous thing I have found is a 5" drywall (taping) knife.

Forum Responses
(CNC Forum)
From contributor C:
I saw a crescent wrench embedded perfectly in the bottom of a piece of MDF.

From contributor M:
Sheet goods - bolt, nut and washer complete. Solid wood - many lead bullets, I am guessing from squirrel hunters with 22cal rifles.

From contributor I:
Holy cow, I can't believe this. You mean a wrench was in the panel? How the heck does that happen? Someone dropped it in the press? I guess I can't complain about some stones and bits of metal.

From contributor T:
What size was that wrench, cause I'm missing a 1-1/4" adjustable.

From contributor C:
Not sure of the size. It was close to a 6". I was at a table top company doing some testing on a new tool in the late 90's and when the operator lifted the table top up, you could see the wrench in the bottom of the MDF. If the tool would have hit the wrench, it would have been ugly. The MDF company did confirm later that the tool was either left in the press during maintenance, or somehow dropped in the press.

From contributor K:
I was under the assumption that all MDF scanned through a metal detector.

From contributor C:
I think a lot of it is now. But back then, I don't think so. They actually had metal detectors that ran in front of the CNC that would shut it down if it found something that was in the tool path.

From contributor B:
I was stationed in Germany in the 70's and running some oak through the planer when sparks flew like you wouldn't believe. Turns out it was a big piece of shrapnel from WWII. I dug it out and kept it. The planer knives weren't saved though!

From contributor S:
Many years ago I was ripping a sheet of 3/4" shop maple plywood on the saw, got halfway through and sparks started to fly. Stopped. I had cut into a nail set that was embedded in the sheet of ply. Needless to say, I had to change my shorts after that one.