Metal inside plywood (between layers)

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Forum topic by hackery posted 10-25-2016 09:10 PM 941 views 0 times favorited 9 replies Add to Favorites Watch
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49 posts in 911 days

10-25-2016 09:10 PM

Topic tags/keywords: metal embedded in plywood faulty flawed flaw

Hi All

I am fairly new to woodworking been doing it for last 3 years or so but in that time I went through a considerable amount of plywood for the home gamer.

I was ripping up a 8ft x 4ft sheet that I got from a local supplier and was the 6th sheet from the same delivery batch and suddenly sparks started to fly so I knew I had hit metal somehow and thought either there was something wrong with the saw or the blade so I quickly backed of the cut and turned the table saw off.

On inspecting the plywood there is actually some mild steel about 1mm thick sandwiched between the layers of the plywood not a lot in terms of length about 50mm or so and don’t know how wide it goes as I am unwilling to put the piece back on the saw as I have just spend $50 on a new Freud blade only two days ago.

I am assuming this is a rarity was just wondering if this has even happened to any of you more experienced guys? At a shot in the dark guess it’s maybe been part of a blade from the machine that made the ply or some other part of the machine and more than likely coming from China quality control has been non existent. Although the ply wasn’t what I would call cheap at around $30 US Dollars per sheet but it was the cheapest I could get locally.

Anyways just wondering if its ever happened to anyone else?



-- Notice woodworker and now metal worker - Belfast, Northern Ireland, UK

9 replies so far

View splintergroup's profile


2425 posts in 1422 days

#1 posted 10-25-2016 09:13 PM


Never seen that but I think you are on the right track, some part of the machinery.

View Kazooman's profile


1237 posts in 2152 days

#2 posted 10-25-2016 09:23 PM

You could get some idea of the dimensions of the piece using a cheap metal detector. Harbor Freight has one and can find a coupon it will be even less. You could then cut around the piece to salvage the rest of the sheet of plywood. You might also want to take a quick scan of any other sheets from that batch to check them for metal. Once you have isolated the problem area it would be interesting to pry the layers of ply apart to see what the metal looks like. Also try a strong magnet to see if you could use that to identify the borders of the metal. That would depend on the type of metal involved.

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 2149 days

#3 posted 10-25-2016 09:44 PM

I’ve seen it before, but so small I didn’t notice it until I had hit it with a router bit(slot cutter). probably the best I have seen was the butter knife in a piece of shaft wall. for those who don’t know shaft wall is, its 1” thick drywall like 20”x10’

View Tony_S's profile


955 posts in 3283 days

#4 posted 10-25-2016 10:54 PM

I’d take the sheet of ply and the saw blade back to the vendor and ask(tell) them to replace both.

-- It is the mark of an educated mind to be able to entertain a thought without accepting it. Aristotle

View hackery's profile


49 posts in 911 days

#5 posted 10-25-2016 10:58 PM

Thanks for the replies guys. Good idea about the metal detector I have a multi detector (stud) so might run that over it to see if it picks it up which it should given it’s steel but also have some really and I mean really strong neodyNium magnets that should give me a good idea of the overall size of the metal piece.

I was wondering why my previous blade had lost a carbide tooth or two when it had only seen fairly light use but now thinK I have been hitting this metal the other day when making a jig with my sled and didn’t see the sparks because of the back fence of the sled and the plywood base where as today I was using it with no sled so must be quite a big bit running through this sheet of plywood so I reckon it’s quite long but not wide otherwise I would have hit it quite a lot.

Would have been really p1ssed off if it had of wrecked my brand new blade but can’t really blame the lumber yard has they would have no way of knowing…. never ceased to be amazed by how much Chinese factories go out of their way to wreck the products they make but never thought plywood would be one.

Will get a photo tomorrow when back in the shop so you can all see what I mean.

An interesting experience none the less.



-- Notice woodworker and now metal worker - Belfast, Northern Ireland, UK

View TheFridge's profile


10718 posts in 1686 days

#6 posted 10-26-2016 01:47 AM

Stuff rolls downhill. Your lumberyard replaces it and China gives them a credit. I’d get a new blade thrown in.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View GR8HUNTER's profile


5121 posts in 913 days

#7 posted 10-26-2016 02:20 PM

I d take the sheet of ply and the saw blade back to the vendor and ask(tell) them to replace both.

- Tony_S

DITTO ^^^^^^ SAME ^^^^^^^^
IM guessing will never happen again in your lifetime

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

View hackery's profile


49 posts in 911 days

#8 posted 10-26-2016 02:49 PM

Hi Guys

Well took a magnet to the mystery steel to trace around it within the wood and cut it out with a stanley knife (box cutter). Turns out it’s a craft / utility knife or at least looks like one with the scores on the blade to snap of blunt parts but also looks like it had a pivot point for folding see the hole on one of the pieces. No surprise there is Chinese characters on part of the blade.

Strange I would be surprised if parts of the ply sandwich were cut my hand but then again it is China (can you tell I love Chinese manufacturing practices).

I know what you are saying about taking the ply and saw blade back to the supplier to complain but I know it will turn into a massive argument very quickly as I know the type of place it is and I will end up losing my temper and doing something I will regret and I could pursue it through small claims court (petty sessions) but to be honest the blade it wrecked was worth about $20 and it’s just not worth wasting my time over…. would be different if they had of known about it or deliberately done it for some reason in which case they would soon find one very p1ssed off ex Royal Marine (me) at their door but the older I get the more I realize it’s just not worth my energy.

I took my brand new Freud Pro blade of the saw and inspected each tooth and it all looks fine and to be honest I love my new blade much better than the cheaper blade the metal embedded ply wrecked so sort of done me a favor even if forced into the issue.

Anyways here are the photos of what was found…

-- Notice woodworker and now metal worker - Belfast, Northern Ireland, UK

View muleskinner's profile


916 posts in 2637 days

#9 posted 10-26-2016 04:52 PM

Interesting. I assume it is a piece of knife that broke off during the pealing process. Would have thought they’d have noticed that pretty quickly.

-- Visualize whirled peas

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