Do I need to account for wood movement for this?

[Alan Lightstone]

The LOML has another project. An old, pine rolling taboret cabinet needs a larger top, and it needs to match other dark furniture. So I built a walnut new top for it, and need to attach that to the present pine cabinet top.

The new top is 36"L x 18"W. The old top is 20"L x 13"W, so there's not a huge difference in width of the two pieces, but they are two different wood species.

Can I just glue the new top onto the old one, or do I need to account for wood movement? Do two different wood species expand/contract at different rates (or different enough to cause cracking)? I've never tried gluing two different species of that size on top of each other.

The tougher job will be refinishing the present cabinet to match the new top once a dark stain is put on it, but that's a whole other issue.

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[Jim Becker]

To be safe around wood movement, use mechanical fasteners up through the existing top. Pick one side for "fixed" holes and do elongated holes in the existing top on the other side If you do three rows of fasteners, do the middle fixed and the two outer rows elongated. Use pan-head screws with washers from below to do the deed.

[Don Stephan]

Understanding Wood by R Bruce Hoadley is an excellent reference and education book for any woodworker. It includes extensive discussion of wood and moisture, and wood movement. There is also a table showing tangential and radial shrinkage for many common North American hardwoods and softwoods, and some exotics.

[Alan Lightstone]

To be safe around wood movement, use mechanical fasteners up through the existing top. Pick one side for "fixed" holes and do elongated holes in the existing top on the other side If you do three rows of fasteners, do the middle fixed and the two outer rows elongated. Use pan-head screws with washers from below to do the deed.

I was thinking the same thing, Jim, but was wondering if it would even be necessary. Clearly if the pine and walnut moved at different rates, it absolutely does.

[Bill Dufour]

I do not think it will work for your pine because it is too dark but. I have stained pine with iodine to match old yellowed pine.
Bil lD

[Andrew Seemann]

The grain pattern is different enough between the old top and the new top to worry about movement. Add on the fact that they are different species and it is quite likely they will move at different rates. Even if the top and bottom were both walnut or both pine, you likely would have issues due to the top piece being mostly flat grained and the bottom being mostly quartered or rift grained.

Look at it this way:

-If you fasten it mechanically allowing for movement and it moves, you are OK.

-If you fasten it mechanically allowing for movement and it doesn't move, you are OK.

-If you glue it and it doesn't move, you are OK.

-If you glue it and it moves, it will warp and or crack; not OK.

Basically there is no downside to allowing for movement, but risk of failure if you don't allow for movement.

[Mike Henderson]

I doubt if you can stain pine to get it as dark as finished walnut, especially if you stain the walnut. I'd paint the pine the color you want.

Mike

[Alan Lightstone]

I doubt if you can stain pine to get it as dark as finished walnut, especially if you stain the walnut. I'd paint the pine the color you want.

Mike

I've worried about this too. I'm going to start with a very dark stain, and see where it goes. I may then spray several coats of a toner to go darker still.

I'm not fond of that dark color, but SWMBO's studio has a lot a furniture / floating shelves / tables in it now, so I'm somewhat forced to head in that direction.

An even stranger issue I'm facing is that the finish on the pine appears via testing to be a single, extremely thin coat of poly. You cannot see any film finish at all. I've ruled out lacquer, shellac, and oil via testing. This is on a commercial piece she bought about 30 years ago. Not sure why they would have chosen an extremely light coat of poly on pine. Over 30 years, it's turned pretty orange. Not a good color IMHO. She also doesn't like the painted look.

[Alan Lightstone]

The grain pattern is different enough between the old top and the new top to worry about movement. Add on the fact that they are different species and it is quite likely they will move at different rates. Even if the top and bottom were both walnut or both pine, you likely would have issues due to the top piece being mostly flat grained and the bottom being mostly quartered or rift grained.

Look at it this way:


-If you fasten it mechanically allowing for movement and it moves, you are OK.

-If you fasten it mechanically allowing for movement and it doesn't move, you are OK.

-If you glue it and it doesn't move, you are OK.

-If you glue it and it moves, it will warp and or crack; not OK.

Basically there is downside to allowing for movement, but risk of failure if you don't allow for movement.

Thanks, Andrew. Very logical.

I thought I'd be heading down this road (which really, with this piece, is quite easy to do with mechanical fasteners, so that will be my approach.

I have never tried gluing two large boards together of difference species (and different grain orientations to boot), so was curious if I was making too much of this.

[Prashun Patel]

Why not just screw it in from the bottom? A row down the middle, and then a row or elongated holes in the pine along each edge. Easier than gluing imho because you don’t have to clamp.

Are you married to that base? Why try to salvage it when coloring and finish matching appear to be difficult and not fun? Make a simple different base out of walnut. Use the pine base in your shop....

Are those drawer fronts false? Could you just swap those out? You could paint the side panels black and clear coat the walnut parts.

[Alan Lightstone]

Why not just screw it in from the bottom? A row down the middle, and then a row or elongated holes in the pine along each edge. Easier than gluing imho because you don’t have to clamp.

Are you married to that base? Why try to salvage it when coloring and finish matching appear to be difficult and not fun? Make a simple different base out of walnut. Use the pine base in your shop....

The plan is to screw it in from the base.

I'm going to try to do the color match, mostly for the challenge. She has had the base for a very long time, and likes it, but I agree, not a fun task ahead of me. If it looks awful, I'll just build another one. Tons of drawers, though :(

Wouldn't use the base in the shop. Man that color is ugly.

[roger wiegand]

I quite like these figure 8 fasteners for tabletops. I use a forstner bit to make a little mortise in the table rail so the top lies flat, the fasteners rotate a bit to accommodate movement without the hassle of making slots for screws to move in.

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[Andrew Seemann]

I'm going to try to do the color match, mostly for the challenge. She has had the base for a very long time, and likes it, but I agree, not a fun task ahead of me. If it looks awful, I'll just build another one. Tons of drawers, though :(



Yeah, I hate kluges like that. I'd rather rebuild it. I've gotten where I would rather rebuild a piece of furniture that refinish it. Sometimes (usually, actually) it is easier to just start from scratch than redo existing.

[John McKissick]

I quite like these figure 8 fasteners for tabletops. I use a forstner bit to make a little mortise in the table rail so the top lies flat, the fasteners rotate a bit to accommodate movement without the hassle of making slots for screws to move in.

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Appreciate a link where you source those fasteners please

[Prashun Patel]

Lee Valley has them.

[mark mcfarlane]

Appreciate a link where you source those fasteners please

Rockler and Woodcraft should have them also.