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Forum topic by RCWoodworks posted 03-15-2019 03:25 PM 380 views 0 times favorited 21 replies Add to Favorites Watch
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RCWoodworks

7 posts in 4 days


03-15-2019 03:25 PM

Topic tags/keywords: ash

Hey, beginner here. I just glued up my 1×6x6 ash wood tabletop and the entire thing cupped on me the next day. Do I need to go ahead and install the tabletop to the apron and legs or what?


21 replies so far

View BFamous's profile

BFamous

299 posts in 418 days


#1 posted 03-15-2019 05:33 PM

Attaching a cupped tabletop to the table apron will not remove the cup. More so, the top should be attached in a way to allow for the natural wood movement of the top.
You’re going to need to get the cup out before moving forward.

Post some pics, and you can get a lot of good advice from this forum

-- Brian Famous :: Charlotte, NC :: http://www.FamousArtisan.com

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Rich

4149 posts in 886 days


#2 posted 03-15-2019 05:38 PM

Depending on the amount of cupping, you might be able to pull it down with Z-clips. They will also allow for movement.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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Snipes

367 posts in 2542 days


#3 posted 03-15-2019 05:38 PM

Yep pictures. Did you set it flat on something?

-- if it is to be it is up to me

View RCWoodworks's profile

RCWoodworks

7 posts in 4 days


#4 posted 03-15-2019 07:20 PM

Thank y’all for the replies. I am using table top fasteners. It is set on a flat workbench . Trying to figure out how to insert photos

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RCWoodworks

7 posts in 4 days


#5 posted 03-15-2019 07:28 PM

View Woodknack's profile

Woodknack

12634 posts in 2677 days


#6 posted 03-15-2019 07:38 PM

Never leave panels flat on a bench, floor, or anywhere else; it cuts off airflow and allows unequal moisture loss or gain which results in cupping. And your pic proves what I’ve been saying for years, alternating growth rings is a myth. I would stand it in the sun, convex side facing out.

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

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RCWoodworks

7 posts in 4 days


#7 posted 03-15-2019 07:49 PM

Excellent info. Thank you very much. Now I’m mad I alternated the panels because I didn’t really like the look. So set on saw horses in the sun?

View CWWoodworking's profile

CWWoodworking

306 posts in 476 days


#8 posted 03-15-2019 07:51 PM

Was it flat when you glued it? If so, flip it over and wait a day. Then suck it flat with z-clips.

View RCWoodworks's profile

RCWoodworks

7 posts in 4 days


#9 posted 03-15-2019 07:55 PM

It was flat after glue up. Ok will do. Thank you

View Aj2's profile

Aj2

2054 posts in 2095 days


#10 posted 03-15-2019 11:41 PM

Sometimes glued up panels can can cup the next day out of the clamps because too much clamp pressure trying to close up gaps.
Esp if the edges were not square to the face. I had this problem before I had a long bed jointer.
I also agree good air flow around work that sits over night. I always wait at least a couple days before I start planing the show side flat.
You might find the panel will relax a bit once you start removing the hump.
You boards you picked for the top are wild with cathedral grain.
That’s also not a good idea if you want a flat table top.
Ash is a excellent wood for a table. I do like working with ash is not available on a regular basis around here because of some beetles eating the trees or something.
Stay away from a oil finish if your going natural. Unless yellow is your favorite color. :)
Good luck

-- Aj

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ibewjon

234 posts in 3090 days


#11 posted 03-15-2019 11:55 PM

Asian Ash borer beetles in the Midwest. Small, metallic green. The larvae bore wandering tunnels under the bark cutting off the food supply to the tree. Lost all my Ash trees to them. Only affects the outer layer. The internal lumber is not damaged if you can find logs to get sawn. Nothing to do with the cupping, just a note about the beetles from China destroying our trees. I have had many logs cut and have a lifetime supply of great Ash lumber.

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Rich

4149 posts in 886 days


#12 posted 03-15-2019 11:56 PM


And your pic proves what I ve been saying for years, alternating growth rings is a myth.

- Woodknack

You beat me to it :) I’m going to save that photo for the next time it comes up. Whatcha want to bet it won’t be long.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View Snipes's profile

Snipes

367 posts in 2542 days


#13 posted 03-16-2019 01:44 PM

The sun definitely works especially if you lay the other side flat on concrete or something moist.

-- if it is to be it is up to me

View SMP's profile

SMP

449 posts in 202 days


#14 posted 03-16-2019 02:40 PM


Never leave panels flat on a bench, floor, or anywhere else; it cuts off airflow and allows unequal moisture loss or gain which results in cupping. And your pic proves what I ve been saying for years, alternating growth rings is a myth. I would stand it in the sun, convex side facing out.

- Woodknack

Yeah its funny, almost everything else i have ever read said to alternate growth rings, FWW, popular woodworking, various internet sites and youtube. Then I read Paul Sellers say not to worry about it and just layout how it looks best or easier to plane. I was kind of skeptical even though I know what he’s talking about. https://paulsellers.com/2016/12/questions-answered-alternating-panel-sections-using-biscuitsdowels/

View Woodknack's profile

Woodknack

12634 posts in 2677 days


#15 posted 03-16-2019 08:29 PM

Never leave panels flat on a bench, floor, or anywhere else; it cuts off airflow and allows unequal moisture loss or gain which results in cupping. And your pic proves what I ve been saying for years, alternating growth rings is a myth. I would stand it in the sun, convex side facing out.

- Woodknack

Yeah its funny, almost everything else i have ever read said to alternate growth rings, FWW, popular woodworking, various internet sites and youtube. Then I read Paul Sellers say not to worry about it and just layout how it looks best or easier to plane. I was kind of skeptical even though I know what he’s talking about. https://paulsellers.com/2016/12/questions-answered-alternating-panel-sections-using-biscuitsdowels/

- SMP

The idea seems to have been popularized by American mid (20th) century Industrial Arts textbooks and just never went away then Canadian Woodworking wrote that article everyone cites and it was suddenly gospel. Apparently someone from PWW has endorsed the idea in recent years? Which is odd since most all of the writers they’ve had are highly skilled in traditional woodworking. All the writings and woodworkers I learned from taught to arrange boards for best appearance, that would have been the Tage Frid, Frank Klausz, and others of that generation.

I wonder if the alternating growth ring thing was a misinterpretation by mid-century Industrial Arts academics for a manufacturing strategy that was called, “rip and flip,” meaning to rip a board into narrow pieces and rotate it 90 degree to create a quartersawn panel. This allowed manufacturers to be less picky about their lumber choice and create more stable panels, the straight grain of quartersawn wood is also more homogeneous. It’s a win-win for manufacturing. I have also found references in 19th century literature to building card tables by ripping the wood into narrow strips and alternating the pieces to create a tabletop that would maintain flatness, so it wasn’t just a 20th century technique.

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

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