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Clamping out the cup/bow of a board?

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Forum topic by Damian Penney posted 03-27-2008 03:57 PM 7038 views 0 times favorited 7 replies Add to Favorites Watch
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Damian Penney

1141 posts in 4387 days


03-27-2008 03:57 PM

Topic tags/keywords: clamps jointing bow cup

So I’m in the process of gluing all the pieces of the top for my workbench, and some of the ripped pieces have subsequently developed some bow. I don’t want to just joint them flat because I’d lose so much stock so is it feasible to just get the faces smooth and then clamp the bow out of it as I glue it up? What would be the best process for smoothing the faces if this is indeed a legitimate approach?

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso


7 replies so far

View CharlieM1958's profile

CharlieM1958

16283 posts in 4614 days


#1 posted 03-27-2008 04:18 PM

I’m not an expert in this area, but it seems like kind of a catch 22. If the faces are not flat, I don’t see how you can flatten a bowed board without losing a lot of stock.

On the other hand, are the faces in question really in need of jointing, or are they already flat enough to get a clean joint if you just clamp the bow out?

-- Charlie M. "Woodworking - patience = firewood"

View GaryK's profile

GaryK

10262 posts in 4384 days


#2 posted 03-27-2008 07:03 PM

Just start with flat ones glued up first as a reference and then glue bowed ones to it. 2 or 3 straight
one are not going to be bent by one bowed one.

Also glue 2 bowed ones to each other with their bows opposite each other at the same time you glue them to your straight ones. They will counter each other and being glued at the same time to straight ones
will keep them straight.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View Lee A. Jesberger's profile

Lee A. Jesberger

6866 posts in 4375 days


#3 posted 03-27-2008 08:21 PM

Gary, ONCE AGAIN, beat me to the punch!

I’m going to have to quit my job to be of any help around here. LOL

Gluing two opposing bows together will result in a straight stable piece.

It’s basic math: two negatives = straight. (that’s the new math)

Lee

-- by Lee A. Jesberger http://www.prowoodworkingtips.com http://www.ezee-feed.com

View Bob #2's profile

Bob #2

3810 posts in 4417 days


#4 posted 03-27-2008 08:25 PM

Lee, they call that plywood. (gd+& r)
—except in China!
Bob

-- A mind, like a home, is furnished by its owner

View Damian Penney's profile

Damian Penney

1141 posts in 4387 days


#5 posted 03-27-2008 08:32 PM

So what would be a good strategy to smooth the faces of the bowed boards so that when they come together there aren’t any gaps?

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

View GaryK's profile

GaryK

10262 posts in 4384 days


#6 posted 03-27-2008 08:41 PM

Joint the bowed face since you can’t do the other. Only put pressure on the infeed table to follow the bow.
Make sure that you joint an edge first so that you will have a square face to hold against the fence.

Then glue two of them together jointed faces together. Clamp them to a straight surface while they are
drying so that you will have at least one straight surface. Then joint that surface after they are dry. Then
finally plane the assembly with the jointed surface down.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

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Damian Penney

1141 posts in 4387 days


#7 posted 03-27-2008 08:53 PM

Genius! Thanks Gary.

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

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