LumberJocks

Resawn lumber bookmatch glue ups cupping problem

  • Advertise with us

« back to Wood & Lumber forum

Forum topic by DavidG95 posted 01-19-2020 03:23 PM 822 views 0 times favorited 14 replies Add to Favorites Watch
View DavidG95's profile

DavidG95

7 posts in 250 days


01-19-2020 03:23 PM

I used my bandsaw to resaw 8” wide QS White Oak so that I could bookmatch it and use it for the panels of my cabinet doors. I did about 14 of them earlier in the summer, and they came out really nice. Everything glued up nearly perfect, and I used my Supermax 19-38 to bring them down to about .55 inches rough sanded to about 100. All perfectly flat and square.

Now over the summer and into the winter they sat in the house waiting to be used, piled up in a stack. When I took them out to the shop, I was upset to discover that some of them had taken a cup across the entire width. Most of them not too terrible but two of them are awful. I know that some wood movement is unavoidable but I hadn’t really planned for this.

My plan had been to finish sand them and bring them down a bit more from .55, and rabbet the edges down to 1/4” for the grooves in the door frame.

So a couple of questions on this and need a bit of advice. First, any thoughts as to why? Just the dryness of the air? Perhaps I waited too long to apply finish to them after putting them together?

I have options here. I could, bring them down again to flat, probably .40 or so for most of them, maybe .35 hard to say. I could take them all down to .25 which defeats the purpose of trying to make the doors feel less “flimsy”. I could also take them down to .25 and then instead of a rabbet, glue a piece of QS White Oak Veneer plywood (I have a few sheets of it) to the back of each one to provide some additional stability against further movement.

Thanks!


14 replies so far

View Lazyman's profile

Lazyman

5816 posts in 2239 days


#1 posted 01-19-2020 04:10 PM

Sometimes that can happen when they are stacked on top of each other without uniform airflow between them. After milling them, you probably should have stickered them just like you would when milling fresh lumber. Even just laying a board or panel on top of a workbench overnight can cause this.

You can try laying them cup side down on some concrete with a heat lamp or just some bright hot lights shining on them to see if they will “cup” back the other direction. If it weren’t winter, one thing people sometimes do is lay them in the sun on the ground cup side down for a few hours. Moisture from the ground will enter the cupped side and the heat from the sun will dry the other, basically equalizing the moisture on both sides, to flatten them out. YMMV.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View wildwoodbybrianjohns's profile

wildwoodbybrianjohns

1990 posts in 399 days


#2 posted 01-19-2020 05:22 PM

If you go the veneer route, you should do both sides.

-- Wildwood by Brian Johns: The Big Bang: Nothing - exploded into Everything. Thanks to Nothing.

View Jeremymcon's profile

Jeremymcon

415 posts in 1532 days


#3 posted 01-19-2020 06:20 PM

Why? Because they’re only 1/2” thick and there’s nothing holding them flat! Thin wood is going to cup. Nice thing is that if you’re putting them into a frame for a door it’s not going to matter. The door rails will take that little bit of cup out without you doing anything at all, other than flexing the panels a bit to get them into the groove.

I bet you can flex the cup out of even the worst of them with one finger, right? If so I’d move ahead and not worry about it.

View DavidG95's profile

DavidG95

7 posts in 250 days


#4 posted 01-19-2020 07:10 PM



you probably should have stickered them just like you would when milling fresh lumber.

Yeah, they were stickered for months but when I moved them inside I took out the stickers…. should have kept them in. Live and learn.


The door rails will take that little bit of cup out without you doing anything at all, other than flexing the panels a bit to get them into the groove.

I bet you can flex the cup out of even the worst of them with one finger, right? If so I’d move ahead and not worry about it.

An excellent point I hadn’t even really thought ahead that far. They flex just fine with a little pressure, getting them into position will work out easily. Sometimes you look at the problem, don’t think about how the end assembly will be and go into “panic mode” trying to solve a problem which won’t exist in the end! :)

Thanks all.

View Jeremymcon's profile

Jeremymcon

415 posts in 1532 days


#5 posted 01-19-2020 07:36 PM

Yea that’s the great thing about frame and panel construction! I do a lot of work by hand, so things don’t always come out perfectly flat or perfectly square. In frame and panel only the frame really needs to be flat and square – the panel can be out of square a little as long as all the edges are within the groove, and flat enough to flex into the groove, but perfectly dead flat isn’t necessary.

View therealSteveN's profile

therealSteveN

6264 posts in 1426 days


#6 posted 01-19-2020 07:44 PM

Depends how big the panel is in relationship to the frame.

-- Think safe, be safe

View DavidG95's profile

DavidG95

7 posts in 250 days


#7 posted 01-19-2020 08:00 PM



Yea that s the great thing about frame and panel construction! I do a lot of work by hand, so things don t always come out perfectly flat or perfectly square. In frame and panel only the frame really needs to be flat and square – the panel can be out of square a little as long as all the edges are within the groove, and flat enough to flex into the groove, but perfectly dead flat isn t necessary.

- Jeremymcon

Yep. Everything else is precise cut and dead flat so I think it’ll go together well.

View Andybb's profile

Andybb

2834 posts in 1455 days


#8 posted 01-19-2020 10:30 PM

“Mill ‘em and use ‘em” . If I’m not using it the day I mill it I still leave it a little thick and sticker them with wrapping or shrink wrap tape around the stickers on the ends. Had good luck putting that package in a sealed garbage bag filled with sawdust. I know that turners do that with green bowls to reduce movement so it seemed like a good idea at the time. Seems to work great the few times I’ve tried it.

-- Andy - Seattle USA

View RobS888's profile

RobS888

2829 posts in 2697 days


#9 posted 01-19-2020 11:17 PM

Try stacking the 2 to make the largest gap between them then put a sticker at each end a few clamps along the middle. Clamp down to touching. Leave for a few weeks. I’ve done this with 4 inch wide by 1 inch rough cut boards.

-- I always knew gun nuts where afraid of something, just never thought popcorn was on the list.

View Manitario's profile

Manitario

2816 posts in 3735 days


#10 posted 01-20-2020 01:13 AM

I find that wood cupping after resawing is a roll of the dice. Sometimes it works out fine, other times I can do the exact same thing and I get serious cupping. As others have mentioned, esp. with thin wood, I try to leave it a bit thicker and do the final dimensioning just before I use it.

-- Sometimes the creative process requires foul language. -- Charles Neil

View therealSteveN's profile

therealSteveN

6264 posts in 1426 days


#11 posted 01-20-2020 03:35 AM



I find that wood cupping after resawing is a roll of the dice. Sometimes it works out fine, other times I can do the exact same thing and I get serious cupping. As others have mentioned, esp. with thin wood, I try to leave it a bit thicker and do the final dimensioning just before I use it.

- Manitario

A lot of time looking at end grain on those that behave well, and those that don’t is quite educational. Generally vertical is good, circling the drain is bad. Width adds to the potential.

-- Think safe, be safe

View Robert's profile

Robert

3946 posts in 2332 days


#12 posted 01-20-2020 03:04 PM

They cupped because you didn’t handle the wood properly after resawning. Resawing results in two surfaces with disparate moisture contents.

For this reason, resawn planks should always be stickered and either clamped as a stack for several days or up to a week in order for the wood to acclimate. Even doing this, you may be a misbehaving board that will cup due to stress, not moisture.

Glueing to a piece of ply would be a bad idea because it violates the principles of wood movement.

BTW, applying finish will NOT prevent movement. A comment misconception.

All said and done, you may be able to flex the boards and use them as is for frame and panel.

Before resorting to resurfacing the wood, you should see if they will correct. Wet the concave side of each board, sticker alternating cups & clamp the whole stack between two thick, flat boards. Let them sit for a week in a location out of sunlight or air movement. You may get lucky.

All said and done, with that amount of cup, you should be able to flex the boards and use them.

-- Everything is a prototype thats why its one of a kind!!

View paridgerunner's profile

paridgerunner

43 posts in 632 days


#13 posted 01-21-2020 12:13 PM

I have had good luck getting the cup out of resawn boards by wetting the cupped face and putting it down on a flat surface with weight on it for a couple days.

View Woodknack's profile

Woodknack

13474 posts in 3232 days


#14 posted 01-21-2020 10:56 PM



... over the summer and into the winter they sat in the house waiting to be used, piled up in a stack.
- DavidG95

You have solutions but in the future mill stock no more than 24 hours before you need it. Everything will warp eventually.

-- Rick M, http://thewoodknack.blogspot.com/

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com