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Gluing question

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Forum topic by williamhdixon posted 06-19-2018 03:06 AM 436 views 0 times favorited 11 replies Add to Favorites Watch
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williamhdixon

6 posts in 283 days


06-19-2018 03:06 AM

I have a newbie question about gluing.

I’m going to be trimming a plywood edge with a 1×2 strip, attached via tongue & groove. (Tongue on the 1×2, groove in the plywood, if it makes a difference.)

I know that plywood is fairly stable as far as expansion/contraction, but the 1×2 is not. So as I understand the concept, if I apply glue down the entire length it can split over time. I recall seeing somewhere that you should not apply glue from one end to the other, but I don’t remember all the details.

So my question is this. If the strip is 24” long, how much of it should I glue and how much of it should I leave bare? Or is there some other technique I should use?

Thank you to anyone who takes the time to answer this.

Bill


11 replies so far

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JBrow

1365 posts in 973 days


#1 posted 06-19-2018 03:33 AM

williamhdixon,

Solid wood expands minimally along it length. Since plywood likewise expands minimally along its width and length, I foresee no problems gluing the entire length of the solid wood edge banding to the plywood edges.

Perhaps you are already planning to ensure the solid wood edge banding is a little thicker than the plywood and, when glued in place, the edge banding is proud of both faces of the plywood. The edge banding is then routed flush to the plywood faces with a flush trim bit. I find this method reduces the chances of damaging the plywood with a card scraper and/or sand paper when flushing-up the surfaces.

Applying glue along the entire length of a joint of a solid wood panel and a trim strip when the grain direction of the two glued pieces is perpendicular could lead to problems. In this case gluing no more than about 3” near the center (along its length) of the joint would be appropriate. But since your panel is plywood, the cross-grain expansion problem associated with a solid wood panel is absent in this case.

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Bobthewoodbutcher

25 posts in 1162 days


#2 posted 06-19-2018 03:34 AM

I would glue the entire length. Length should be stable. “Breadboard” ends across the width of solid wood needs space to expand/contract.

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waho6o9

8240 posts in 2630 days


#3 posted 06-19-2018 04:19 AM

Put a seal coat on both pieces, like shellac or primer, but not in the glue joint and when it’s dry glue it and clamp it up.

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jerryminer

935 posts in 1494 days


#4 posted 06-19-2018 05:01 AM

Bill, I’ve been gluing solid wood to plywood for decades without a failure. (Common for kitchen cabinet shelves etc.) As JBrow said above, wood movement along the length is negligible. Glue the whole length.

-- Jerry, making sawdust professionally since 1976

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williamhdixon

6 posts in 283 days


#5 posted 06-19-2018 11:23 AM

Thanks all. That makes sense.

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bondogaposis

4830 posts in 2404 days


#6 posted 06-19-2018 01:38 PM

Glue it up the the whole length. Wood doesn’t move in length, just like the plywood. This is a very common practice.

-- Bondo Gaposis

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rwe2156

3000 posts in 1534 days


#7 posted 06-19-2018 01:43 PM

Question answered.

I would add you do not need a T&G.

I’ve had no problems gluing solid wood edging to plywood with butt joints.

-- Everything is a prototype thats why its one of a kind!!

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Gene Howe

10610 posts in 3481 days


#8 posted 06-19-2018 04:16 PM



Question answered.

I would add you do not need a T&G.

I ve had no problems gluing solid wood edging to plywood with butt joints.

- rwe2156


Ditto

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View enazle's profile

enazle

56 posts in 61 days


#9 posted 06-19-2018 04:35 PM

One thing, make sure the plywood is laying flat when you glue the strip on. If it has any warp, bow or curve the band will freeze it like that. If the board has a little bow, force it flat when you glue the band in place and it will stay that way.

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DBDesigns

69 posts in 50 days


#10 posted 06-19-2018 07:35 PM

I agree with most of the opinions above but I would add one suggestion. Plywood will soak up glue at different rates based on the grain direction of different laminations and gaps in the grain edges. By the nature of the product, you have end grain and side grain on the same edge. Consider putting a layer of glue onto the edge and let it soak in before you do your final glue and clamp operation.

-- I remember when Grateful wasn't Dead

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Redoak49

3332 posts in 2042 days


#11 posted 06-19-2018 08:31 PM

I normally only glue a 1/4 -1/2” solid wood strip to plywood. I will use a thin brad nail to help locate the strip and then clamp using blue masking tape. If the edges are smooth, the tape is good enough for clamping.

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