Warped Plywood

[Travis]

Ok,

I go to a reputable wood dealer buy nice 3/4 plywood. Bring it to the shop, store it flat, cut it up and notice that it is bowed or warped. This happens frequently. Is it something that I have to learn to deal with? Am I doing something wrong? or what?

Thanks

 

[NCPete]

are you laying it over concrete?? that would cause one side to absorb some moisture, and do what you are describing... but I would only expect that to happen to the bottom sheets???

 

[walnutjerry]

Ok,

I go to a reputable wood dealer buy nice 3/4 plywood. Bring it to the shop, store it flat, cut it up and notice that it is bowed or warped. This happens frequently. Is it something that I have to learn to deal with? Am I doing something wrong? or what?

Thanks

Travis----------what grade is the plywood? How many plys are in the thickness? Is it soft wood or hardwood core?

Is it all solid wood plies or does it have a thin ply of pressed wood under the veneer face?

Quite a few things contribute to the behavior of plywood.:eusa_thin

Jerry

 

[Travis]

Travis----------what grade is the plywood? How many plys are in the thickness? Is it soft wood or hardwood core?

Is it all solid wood plies or does it have a thin ply of pressed wood under the veneer face?

Quite a few things contribute to the behavior of plywood.:eusa_thin

Jerry

It is B2 Grade birch. Their are 5 plys in thickness not counting the veneer.

 

[cpowell]

Travis, I have had that happen on several occasions with cheap pine 1/2 ply from the BORG.

I've bought many 3/4 sheets of birch, cherry, red oak without a problem.

I figured the pine ply I got was not completely dry. I could never figure out how to flatten it.

Chuck

 

[taandctran]

I used to work for a place that put the veneer on the plywood. The plywood would warp if the glue was heated to hot or if it wasn't heated hot enough. They are usually sold as shop boards for a cheap price.

 

[Kyle]

B2 grade if using the ANSI standard is an underlayment grade for flooring. I would consider it substandard for fine furniture.

 

[Howard Acheson]

It's difficult to answer your question specifically as there are many variables. First, it a common misconception that plywood is going to always be flat. A lot depends on how the supplier stacked it and what the environment was versas what the environment is in your shop.

"B2" refers to the appearance factor for the face veneers. "B" is a paint grade rating as is "2" for the back face. The best face ratings are "A" and are considered furniture grade best for staining and/or clear coating.

Finally, under most standards, there is no difference in the interior plies for "A" grade and "B" grade plywood.

 

[rhett]

I have found the imported plywood to be the worst as far as warping and delaminating. I routinely use Columbia with little problem warping, an added bonus is that the sheets are 48.5 x96.5.

 

[sapwood]

Thanks Rhett, I never heard of Columbia products :eusa_sile
But I checked them out and the website is pretty cool with lots of excellent info on hardwood ply :icon_thum

Columbia Hardwood Plywood

Roger

 

[McRabbet]

Columbia has a hardwood plywood plant near Marion, just of I-40 Exit 75 (Parker Padgett Rd.) that produces for the Southeast. Catawba Hardwood's main lumber lot and drying kilns are located a few hundred yards down the road and they have some of the best hardwood plywood prices anywhere. See our Region I Wood Suppliers list.

Rob

 

[Travis]

Thanks for the advice. I do lay it flat on the basement floor but I have plastic under it to keep the moisture away. I also buy my lumber at Catawaba Hardwoods, the satelite warehouse of 321 just North of Hickory. Next project which is coming up soon I am going to be sure to inspect the sheet goods very carefully and see if the problem occurs again.

Would you fellows try to work with it or get new stock. I figure with the dados holding the bows semi straight the face frames can hide a little warpage (about 1/4") over 5'.:BangHead:

 

[NCPete]

I think cutting the dado's in a warped sheet of ply would probably be a bad idea inviting kickback, unless of course, you are cutting those dado's with a handheld router?

 

[skysharks]

Travis how bad is your warpage???
I usually dont get up to Raleigh that often, to be able to buy the good stuff. So I find myself buying my ply from Lowes.
Man at 45.oo per sheet for oak 3/4", I'm picky when I select it.
I have had some ply return to flat shape once the shop heated up and I picked it up off of the the floor.
Like others have said there are allot of factors in why ply will warp.
Even the good stuff will warp.

I have found once you cut it down to size, cut and fit it.
Add Some temporary straighteners, glue, clamp and fasten it, allot of warpage will come out while drying.


Good Luck

Hey NCpete where you getting your lumber at??

 

[NCPete]

Hey NCpete where you getting your lumber at??

I made a trip the other day to Klingspor's Woodworking Store in Raleigh to get the stuff I made my Christmas gifts with, but if I can get hold of Eric Feltz, a local sawmill operator, I would like to buy from him, his operation is over in Rockfish. Michael Garner has ordered some wood from Wall Lumber in the past, IIRC, and has been very satisfied with it. Eric's contact info is in the Wood Supplier's list at the top of the page. Another closeby sawmill operation is Turn Bull Lumber in E-town. I will be picking up some of their cypress this spring. They also have some hardwoods, too. Having recently (finally) gotten the tags on my truck really opens up the possibilities. LOML wouldn't have been so excited about stuffing wood in, or on, her Explorer.

 

[Travis Porter]

Personally, I have made it work. Have to use feather boards and such on the table saw or use a hand held router to follow the contours. It is a pain, but once you get it together it seems to hold, just use plenty of glue, nails, and screws.