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Forum topic by Rookie702 posted 10-26-2012 07:04 PM 1293 views 0 times favorited 16 replies Add to Favorites Watch
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Rookie702

42 posts in 972 days


10-26-2012 07:04 PM

I started to sand and plane my first end grain cutting board yesterday, I started small, its something like 9”x 12” more like a cheese board. It’s a simple pattern basic checkerboard, for stock i milled down to 3/4” stock of both maple and walnut.

So after glue up, i stuck the board in my Router Planer jig that i just built for my cutting boards, router it flat (or so i thought), then took my smoothing plane and used that on both sides, then i took something ive used for years to really make something smooth, and that is a glass block 6 or 8 inches long and 4 or 5 inches wide with a piece of 180 and 220 sandpaper glued to the bottom and i sanded the board using circular motions until each side of the board felt like glass, they were both as smooth as as anything you’ve ever touched.

So before i went to bed, i laid the board on my absolute flat 1 1/2” thick granite kitchen counter top, and checked to make sure both sides of the board laid flat on the granite, and both side were perfect, you couldn’t get a piece of paper underneath or even see light, i was very pleased and went to bed.

So i wake up and walk into the kitchen for morning Mtn Dew and just happened to glance at the board and to my surprise the damn thing was bowed like son of bitch, the entire board now is cupped.

Can somebody please explain what the heck happened and how do make sure it doesn’t happen again, because i was planning on making many more cutting boards for x-mas this year.

Thank everyone.


16 replies so far

View CharlesNeil's profile

CharlesNeil

1144 posts in 2566 days


#1 posted 10-26-2012 07:11 PM

the glue dried faster on one side than the other, you laid it flat, menaing the bottom wasnt dryin as fast as the top, next time simply stand it, so the top and bottom get equal air flow, same for glued up panels, however now try laying the convex side up out in the sun a bit, you might be surprised, but keep an eye on it,it can reverse quickly your issue is simply moisture imbalance, dont ask how I know :) let us know how it does

View waho6o9's profile

waho6o9

5112 posts in 1272 days


#2 posted 10-26-2012 07:15 PM

Use bow clamps, (cauls), to pancake the cutting boards.
Underneath the cutting board you can see the bow clamps that
are used to pancake my cutting boards.
Very effective.

http://www.bowclamp.com/

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1854 days


#3 posted 10-26-2012 07:16 PM

The humidity in the shop is different from the humidity of your house. Voila!

A common problem with cutting boards. One day they can be cupped, the next day straight.

You can partly fix it by clamping it the other way, even a bit more the other way to compensate. Wetting it helps. You might not be able to get it perfect, but you’ll get it close. Do this in the house, not the drier shop.

-- jay, www.allaboutastro.com

View Rick  Dennington's profile

Rick Dennington

3480 posts in 1889 days


#4 posted 10-26-2012 07:17 PM

I’ve just got to ask:....How do you know, Charles…..?....I’m the curious type…...LMAO…..!!!!

-- " I started with nothing, and I've still got most of it left".......

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Rookie702

42 posts in 972 days


#5 posted 10-26-2012 07:23 PM

Charles Niel,

Clarification, the glue was completely dry when i begun to sand it, it dried in the clamps, which were upright and open to the air.

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Rookie702

42 posts in 972 days


#6 posted 10-26-2012 07:26 PM

I live in Vegas, there is not any humidity difference between my garage and my house, espiceally this time of year, when i don’t even have the air on inside the house, matte of fact i have the garage fire door open while i’m in the garage working. so conditions are about the same i would think.

View CharlesNeil's profile

CharlesNeil

1144 posts in 2566 days


#7 posted 10-26-2012 07:36 PM

in a cutting board especially an end grain, there is a huge difference in dry and cured, think about how much moisture you provided this wood, it was alot, while the glue had dried, it had not displaced all the moisture, how do I know, Years ago I had glued up a pile of walnut panels, they had been in clamps several days , I unclamped them , stacked them in 3 piles, happened, to have a ceiling fan, left it on, next morning, I could have capped the ends and had canoes, lesson learned, stand them, I learned, the sun with the convex side up, having to refinish tables with cupped leaves, put them in the sun and they will reverse, its simple ,( then put battens on the underside to prevent it happening again ) when wood dries it shrinks, shrinking means it pulls , when it pulls on one side and not the other, it cups, again its a moisture imblalance, doesnt matter how old it is , it will move, there are other factors that will make it cup, but I suspect in this case its the moisture thing,

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CharlesNeil

1144 posts in 2566 days


#8 posted 10-26-2012 07:38 PM

rookie, conditions being the same has nothing to do with it, when you laid it flat you sealed off the bottom from further drying, so the top dried more, thus shrinking more, thus the cup, get it in the sun, convex side up and keep an eye on it,

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1854 days


#9 posted 10-26-2012 08:04 PM

I wouldn’t be so sure about the humidity issue in Las Vegas. Many AC systems put moisture back into the air.

Charles’ advice should always be heeded. It’s a good tip for any glue up and might certainly be the issue here.

Still, there is another possibility, being that if you mill a board today, pieces can still move and expand because of a release in tension tomorrow. This is obvious when you mill a wide board in a planer and then come back the next day only to see it cupped. This is especially true if the boards have spiral or interlocked grain. This is independent of moisture issues.

I would lean more toward Charles’ explanation in this particular case.

-- jay, www.allaboutastro.com

View Rookie702's profile

Rookie702

42 posts in 972 days


#10 posted 10-26-2012 08:30 PM

Ok, so in summary stand the cutting board up after planing flat!!

View CharlesNeil's profile

CharlesNeil

1144 posts in 2566 days


#11 posted 10-26-2012 08:44 PM

just remember you have to keep wood in balance, meaning, what ever happens to one side, has to happen to the other, especially when it comes to moisture, think on this , ever seen some one build a nice deck, using the best treated wood, spend a fortune,then buy the best sealer, and seal the top and do everything correct, give it a winter and summer, and its cupping and twisting all over the place, well what happened is they sealed the top of the deck, but left the bottom bare, and the moisture coming up from the ground underneath is providing moisture to the underside, thus it swells , the top is sealed, so it doesn’t , so it cups, understand the single thing that affects wood is moisture, either the addition of, or the absence, of, the key is to keep it in balance, I will submit to you that those who would tell you to leave the underside of tables, countertops and so forth bare so the wood can breathe, have never made a living doing woodworking, where failure results in them having to redo it and pay for it, now to your question, the short answer is “sorta”, the smart one is , make it thicker than you plan to end up with, then let it sit where the air movement is equal for several days, and then surface it flat, give it room to move and settle in, then dimension it, dry and cured are different, I will often glue up a week in advance where I can, if you are a turner, and you glue up a segmented turning, let it dry over night, turn it, does it move, now you know why,

View RussellAP's profile

RussellAP

2959 posts in 982 days


#12 posted 10-26-2012 08:53 PM

I would leave the clamps on till it’s cured. If it warped when you layed it on the counter, you didn’t wait long enough to unclamp it. Give it three days next time, clamp both sides and make sure a fan can get air flow evenly over the work.

-- A positive attitude will take you much further than positive thinking ever will.

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Rookie702

42 posts in 972 days


#13 posted 10-26-2012 09:00 PM

I really don’t like having to wait on wood to cure or whatever when i want to work on it….but i guess i’m going to have to learn some patience.

So

If i mill some rough sawn lumber to dimension, can i then cut those pieces for the edge attachment of a cutting board.

Allow that glue up to set overnight, then plane flat and cut and glue up end grain, let sit overnight.

Then flatten board, let sit, and then finally dimension to desired size.

View CharlesNeil's profile

CharlesNeil

1144 posts in 2566 days


#14 posted 10-26-2012 09:23 PM

Rookie, cheese board, huh, tell ya what do cut a nice hunk of cheese, ( I like that really sharp cheddar), then simply lay it on the counter, over night and see what happens, then think of the cheese as wood, you will understand

View sandhill's profile

sandhill

2128 posts in 2619 days


#15 posted 10-26-2012 10:05 PM

Could it be an issue with the way it was dried and where? Or acclamation prior to milling

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