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overall vertical movement in frame and panel construction?

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Forum topic by martin007 posted 02-24-2010 03:17 PM 949 views 0 times favorited 6 replies Add to Favorites Watch
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martin007

141 posts in 2441 days


02-24-2010 03:17 PM

Hi all

Need some advise here.

I will build a frame and panel back for a dovetailed carcase cabinet. The frame and panel back will be glued into the carcase rabbet. The stiles will run the full height of the frame. to minimize stress on the carcase, I need to consider the overall seasonal movement of the f&p.

To minimise the overall F&P movement in width, I will use QS stiles no larger than 2 inch. That should keep the movement below 3/64 for maple.

Where I get puzzled, is for the vertical movement. Will there be any?. Since the stiles will run full height of the frame and I will use mortise and tenon joinery with no allowance for movement. Since there is no movement length wise for the stiles, I suspect that the joint with keep the vertical movement to nil.

The width of the rails will be about 2” for the top and 3 1/2 for the bottom Rail.

thanks for comments

Martin

-- Martin, Gatineau, Québec


6 replies so far

View Sawkerf's profile

Sawkerf

1730 posts in 1734 days


#1 posted 02-24-2010 05:39 PM

Virtually all expansion/contraction in wood is across the grain, so vertical movement will mostly be in the pieces with the grain running horizontally.

-- Adversity doesn't build character...................it reveals it.

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martin007

141 posts in 2441 days


#2 posted 02-24-2010 05:44 PM

sawkerf,

Yes I get that, but since the rails are joined to the stiles, wouldn’t that prevent any vertical movement in the frame

-- Martin, Gatineau, Québec

View CaptainSkully's profile

CaptainSkully

1190 posts in 2224 days


#3 posted 02-24-2010 05:58 PM

If I’m understanding the question, you’ll get no measurable movement along the length of the wood, along the grain, so you can glue that up with no problem. The width will move considerably, depending on your seasonal weather, as a function of board width. My old dining table in Texas moved over 1/4” across 36”’ which caused my breadboard ends to only be flush for a few months out of the year. Very frustrating. The narrow stiles won’t move noticeably in either direction, so you should be good to go.

With frame and panel, I would recommend pre-finishing the panels, then letting them float in the frame with snug dadoes deep enough to handle any expansion (an extra 1/8” deep), so don’t glue the panels into the frame. Spaceballs might be useful. Then glue up the frame around the pre-finished panels. The frame will hardly move in comparison. Tape off the panels and finish the frame. Pre-finishing removes the danger of the panel contracting and exposing unfinished wood that would be very unsightly.

Hope this helps. My dresser sides have large panels, and the matching night stands have smaller ones. I’ve seen no evidence of wood movement because of the pre-finishing technique. On my new dining table, I made the breadboard ends long on purpose to handle the table top width moving.

-- You can't control the wind, but you can trim your sails

View Sawkerf's profile

Sawkerf

1730 posts in 1734 days


#4 posted 02-24-2010 06:28 PM

Martin -
The joint will reduce movement, but not eliminate it. Part of your M&T joint is just a simple butt which isn’t very strong. The glue bond in the butt areas will eventually give due to the stresses of repeated expansion/contraction leaving only the M&T part of the joint to keep things together. There will be some vertical movement (probably very slight) in the boards with horizontal grain.

-- Adversity doesn't build character...................it reveals it.

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martin007

141 posts in 2441 days


#5 posted 02-24-2010 06:38 PM

thanks sawkerf

That makes sense. So since there will be negligible vertical movement in my F&P. That means that I will be able to use wider flat saw rails .

-- Martin, Gatineau, Québec

View oluf's profile

oluf

256 posts in 1705 days


#6 posted 02-25-2010 07:21 AM

I don;t think you can glue the stiles into the rabbits in the sides of the carcase. You would have grains at right angles, and the glue joint would surley fail. If your dovetails are not running up the front corners of the carcase tham I am wrong in what I have stated above.

-- Nils, So. Central MI. Wood is honest.Take the effort to understand what it has to tell you before you try to change it.

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