That is a lot of sag, but I don't see any mention that it interferes with the operation of the drawers.
If it's not hurting anything, I'd leave it alone. It took many years to develop, it will take many years to flatten without using lots of force and risking cracking and placing other components under stress. If anybody else even notices it, call it "character" and explain to them how it proves originality and enhances value. It's OLD, it's supposed to be wrinkled.
Reshaping, only, is not always temporary, if the over correction is sufficient to maintain a flattened result.
I'd agree that extra support would assure further stability. A narrow metal angle iron type bracing, under neath, would help.
I think someone mentioned placing a cross piece/divider inside the drawers, to function similarly. A divider is a good idea, also, and probably wouldn't look unsightly, either.
Sonny
On 04/11/2016 8:59 AM, dpb wrote: ...
BTW, presuming the bottom is still solid but just bowed, you can do the divider trick w/o actually attaching it directly to the front so the modification evidence is minimal if taken out. The bottom is constrained by the groove at the edge and held in place by the brads at the rear plus you can go thru the rear side so when the bottom is brought up to the bottom of the divider it (the divider) can't go anywhere; the bottom has to come up to it. That's for front-to-back; side to side you've got grooves both ends.
For the one I recall specifically did for wife's shop I actually took the bottom out, used a hand router plane and cut a stopped dado for the divider in the front inside and pinned it to add some extra rigidity. It was even wider than yours, though, 42" iirc...was a buffet-like piece, not a dresser.
Wait! You mean that all those jillions of frame and panel doors are useless??? :)
Quite true if the construction was such that bending could occur. If you glue a 1/4 x 36 x 18 piece of ply across a couple of 2x4s then clamp down the 2x4s and stand on the ply, do you think the ply will bend? I don't.
Also true but it doesn't take years, just a few days. Maybe even less in the winter with the heated house resulting in much lower humidity.
I'm in the process of building an entry door. The glued up panels are 7/8" thick. They were built 3-4 weeks ago during a rather warm, humid spell. It turned cool again and I noticed a couple of days ago that the 26" wide panels had bowed, probably 1/4" - 3/8" belly. No big deal, if they haven't flattened themselves out when I get to assembling stuff I'll just dampen the concave side.
Note that the panels would not have warped if the edges had been constrained; split, maybe, but not warped.
Maybe so but whatever you do won't last unless you correct whatever caused them to warp in the first place. If it were me, I'd just do the best I could and forget it. A bit of belly in a dresser drawer isn't gong to hurt anything; maybe even help if one keeps one's marble collection in it :)
On 04/11/2016 6:09 PM, dadiOH wrote: ...
Huh?
DerbyDad03 wrote in news:1df6083d-1b73-47c2-993a- snipped-for-privacy@googlegroups.com:
OK, think I mis-read your prior post to say you were measuring up from the underside of the drawer.
I am surprised, with 1/2" of sag, that the bottom hasn't pulled out of the grooves in the sides. If that bottom is solid wood, which way does the grain run? Is it possible the wood has expanded due to humidity, and can't fit without bowing?
John
On 04/11/2016 6:13 PM, dadiOH wrote: ...
Of _course_ it will; it doesn't have an infinite modulus of elasticity; if it were 1/4" steel plate it would still bend; just not quite so much...
Let's see...from FPL Wood Handbook, for plywood
E --> 1.10-1.24x10E5 lb/sq-in
and for a rectangular solid beam the moment of inertia is bh^3/12 where b=width, h=height so for the drawer that's
I=18*(1/4)^3/12 --> 18/(12*4*4*4) --> 3/(2*4*4*4) = 3/128 =0.02344 in^4
For a constrained beam at both ends, max deflection at midpoint is
ymax=Wl^3/192EI
For a 200 lb load that's
ymax=200*36^3/(192*1.1E6*0.023) = 1.88"
For comparison, E for steel ~27E6 so the deflection would be about 0.07" instead.
...
If you build a panel door that is fully and tightly constrained on all sides with no expansion room, it'll fail sooner rather than later. Door panels in exterior doors are _not_ fixed; they float.
I wasn't going to mention the fact that dadiOH wants me to secure the bottom on 3 sides. Aside from all the other reasons that fix won't work, securing the panel on 3 sides is probably a bad idea too.
Gee, I learn something new every day.
You're welcome... :)
OTOH, I don't know why you're now getting snippy; just responded to your comments implying trying to keep a panel flat by constricting the edges...
But, suit yourself.
I wasn't trying to be snippy. If I was trying to be snippy, I would have asked, "Float in what?" or "So I can't glue in a plywood bottom?". :)
And I don't think restraining the edges keeps a panel flat. Restraining the top and bottom of the FACES at the edges, yes; edges themselves, no.
On 04/11/2016 6:50 PM, dpb wrote: ...
...
BTW, just for comparison, if the ends were free instead of constrained from rotation as was postulated, the maximum deflection is
ymax=Wl^3/48EI
Same form, just the constant turns out different. The deflection would be 4X that of the constrained case (192/48-->4).
When you have solid board core and a layer on both side that is pretty it is PLY. Takes 2 to Ply.
Your requirements of this or that or orientation doesn't hold water.
Apple ply is not the same as a fur or pine ply.
Having a solid core is strong. The ply's on the outside is dressing.
You are making commercial product and saying PLY has requirements to be ply.
I've used Plywood since 51 or 52. They made it in the back shop of the hardware store. They bought vernier sheets and made their own using their waterproof glue for all uses.
Martin
That is very often lumber core, not plywood.
Actually I think it does.
Apple ply is an American version of Baltic birch plywood. Hard wood veneers through out and each is running 90 degrees to the next.
I'd call that "veneer", not "plywood".
"In 1797 Samuel Bentham applied for patents covering several machines to produce veneers. In his patent applications, he described the concept of laminating several layers of veneer with glue to form a thicker piece ? the first description of what we now call plywood.[1] Samuel Bentham was a British naval engineer with many shipbuilding inventions to his credit. Veneers at the time of Bentham were flat sawn, rift sawn or quarter sawn; i.e. cut along or across the log manually in different angles to the grain and thus limited in width and length."
Yes, lumber core plywood. All sorts of plywood, lumber core, MDF core, Particle board core, veneer core, combination core etc. etc.
It might based on some old patents for making plywood, but the term plywood today seems just a generic term for laminated wood, which has been around forever, (3000 BC?)and the requirements pretty much seems to be 2 or more pieces of wood glued together. You can fight all day over definitions, but ply and wood used together indicates laminated wood, thus Martin got it right, "takes two to ply"... I'm thinking like tissue paper vs kleenx
I bought some oak veneer "plywood" once at Allegheny Plywood that had a core of some unrecognizable stuff that looked like plaster. Still, it was 2 sheets of wood glued to some non-wood product, and they called it, and sold it, as "plywood".
You'd be wrong, veneer is not plywood. Veneer becomes plywood when two or more sheets of it are glued together, then it is called plywood, and if 3 or more sheets of veneer are glued together, it is called veneer core plywood, as opposed to lumber core plywood, for example.
Jack wrote in news:nelnng$teo$ snipped-for-privacy@dont-email.me:
No. It becomes plywood if the veneers are glued cross-grain. That's fundamental to the definition of plywood. If you don't beleive that, go ask the APA.
John
Agreed and IIRC. Plywood always has an odd number of ply's.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.