Plywood Sucks

[Dennis McDonaugh]

I don't use a lot of sheet goods and when I do I try not to end up with a lot left over. Tonite, I needed a piece of 1/4 ply for the back of a cabniet and went to Lowes to buy a 48 X 48" sheet of birch. I needed to cut the piece 31 and 3/8" inches wide and my fence only goes to about 31 inches. So, I subtract 31 and 3/8" from 48" and end up with 16 and 5/8". Set the fence and cut the piece. Its too narrow. Put the pieces back together and they measure 47 and 3/8. Unless I cut a 1/2" kerf with my table saw, the piece was only 47 and 1/2" wide when I started. Just for grins I measured the length and it was only 47 and 7/8" long. First they short us on the thickness and now they are shorting us on the width and length!

[Randy Meijer]

Measure twice..........!!

I feel pretty confident you can blame the 47-7/8 on the manufacturer. The 47-3/8 may be the fault of Lowes. I think the lumber yards buy "full" sheets of plywood and then hire a couple HS kids who haven't passed math to cut the sheets in half. What do ya think???

[Kirk (KC) Constable]

Initial size aside, I think you would've ended up narrow anyway because you didn't factor in the width of the kerf that you lost when you cut it. Cutting off 16-5/8 would've left you a 33-1/4 or so 'waste' piece, using a full kerf blade. I think.

KC

[Bill Arnold]

First they short us on the thickness and now they are shorting us on the width and length!

Hmmm...measure twice, cut once comes to mind...

[Byron Trantham]

Yup, Kirk is right - don't foreget the kerf!

I have had the same experience with the local big box store. I bring my tape measure!

[Dennis McDonaugh]

Kirk, Bill, Bryan

I took the kerf into account when I set the fence. I measured the panel to give me 1/4" overlap on each side of the cabinet. The half inch short made the panel fit exactly inside the cabinet. If it'd only been a quarter or even an eighth short I could have made it work.

I understand the length will be a little short when you cut a full sheet in half because of the kerf, but how do you get the width too short by half an inch? Isn't all 4X8 ply 96 X 48???

[Mac McAtee]

I think the 47 7/8" dimension is from the grade of the plywood you bought. People using plywood to build houses measure things in multiple and divisions of 4' steps. Like 24" centers and 16" centers. Plywood is normally laid with a 1/8" gap between sheets.

If the sheet was a full 48" wide then when you laid 5 sheets across a 20' span the last sheet would have to be cut to fit. Not to mention that as you went across the surface you would loose the rafter or floor joist center as each piece went down. You would be adding 1/8" to the 48" dimenson every sheet you nailed down. By the time you got across the span, the edge of the plywood would no longer be centered on the nailer, and may even miss it. Hence the 47 1/8" dimension sheet.

[Jim Becker]

Mac, you bring up a good point about construction/exterior ply, but this was birch plywood which is typically an interior-only product. In addition to "vendor error", this may also be a byproduct of how the big boxes seem to be buying plywood material from time to time...factory seconds.

[Ted Shrader]

Dennis -

Have you gone back to get another piece yet? When you go, meaure the other ones in the stack. If they are short, talk to the manager and explain what happened. Maybe he will comp you. Worth a try anyway.

Ted

[Dennis McDonaugh]

Mac, I understand that concept. However, the sheet measured 47 1/2 across the grain which I'm assuming is the width. The 47 7/8 measurement was with the grain so I'm assuming that was length. You can account for the short length if Lowes cuts their own half sheets, but not the short width.

I never actually considered how those smaller pieces ended up in the store, but if they "roll their own" so to speak, then you can probably get anything out of those bins.

[Dan Gill]

I can't account for the width difference, but the 47 7/8 probably came from taking a 4 x 8 sheet and cutting 48 inches off of one end. With the kerf, that leaves 47 7/8.

[Donnie Raines]

I dont think this was a manufacture error...but a store error with respect to the size of the sheet. My local big box store is always taking larger sheets goods and ripping them into the 4X4, 4X2 and 2X2 sheets.....you can see the edge is a little less then smooth. Plus, the size will vary a little bit. I needed some 4X2 1/4 ply..and I needed the full lenght. I noticed that a few were a little shorter.....they were almost 3 foot in lenght.

Goes to show you....need to bring the tape with you as was already stated.

[Bill Arnold]

I needed to cut the piece 31 and 3/8" inches wide and my fence only goes to about 31 inches. So, I subtract 31 and 3/8" from 48" and end up with 16 and 5/8".

Dennis,

My earlier response was to make a point we all miss at times. Further to your issue, I've had to perform a similar operation myself. One learns never to assume anything. If I need to make such a cut, I measure (using your figures) 31 & 3/8" from a good edge and make a mark. After making sure the opposing edge is parallel to the first edge, I line up the mark to the blade on the side opposite the fence, then cut away. This way, it doesn't matter what the remaining measurement might be.

Another way to make your cut would, of course, be with a circular saw and a straight-edge. If you wanted a cleaner cut, you could get it close with the circular saw, then clean it up with a router against the straight-edge.

My bet is that the big box guys won't be too sympathetic, unless you know someone who works there really well. I can imagine a response from them like, "the measurements are nominal, just like a 2 by 4." When was the last time you bought a '2 by 4' that measured 2" by 4"? Like others have said, it's best to take your tape measure with you when making this type of purchase.

Regards,