# When to reduce board thickness



## aaron52 (Dec 5, 2011)

I'm doing a panel glue up involving a couple of 5" width by 3/4" thick boards 36" long. 
The 3/4 " stock must eventually be reduced to 1/2" thickness.

Question: When do I run the boards through the thickness planer? Do I glue up the 3/4" boards first and plane to 1/2" or plane to 1/2" and then glue up?


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## epicfail48 (Mar 27, 2014)

Depends on your planer really. A smaller, lunchbox style planer is going to have a harder time planing 1 12 inch wide panel over 3 4 inch wide planks. If you have a big old 3hp 20 inch planer though, it doesn't really matter.

Personally, I'd do it in 2 steps. Before the glueup, take the individual planks down to 5/8 or so, then do the glueup and take the finished panel down to 1/2. That way you have a little breathing room to take out any misalignment in the joint


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## d_slat (Apr 10, 2012)

Also depends on the wood you are using. Even a small lunchbox planer can eat a 12" wide soft pine panel down pretty quickly without overworking. If you're working with a hardwood, it's gonna work harder and you won't be able to take as much off per pass.


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## Develin (Oct 1, 2012)

Always thickness your material to its FIN sizes before you glue up panels. Standard practice.


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## croaker (Aug 11, 2012)

I normally run them through the planer after glue up.


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## michaelpugh (Dec 31, 2013)

I would agree with epic. Run them down close, glue them up then take them down to the thickness you want them.


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## hwebb99 (Nov 27, 2012)

I'd plane them down some before the glue up and finish up after its glued. If you are a good gluer( doubt that's a real word) you could plane them down to about 9/16. I'd probably go with 5/8 to be on the safe side.


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## TimPa (Jan 27, 2010)

the reason for not planing them to finished size now, is that during the glue up there is certainly going to be some mis-alignment of the surfaces. leaving some extra thickness allows you to plane the surface smooth and even.


I like to clean up both faces before glue-up, so I can match the wood grains and color better for the finished panel.​


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## aaron52 (Dec 5, 2011)

Thanks folks. Your suggestions were helpful.
Much appreciated.
fb


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## GeorgeC (Jul 30, 2008)

Develin said:


> Always thickness your material to its FIN sizes before you glue up panels. Standard practice.


Whose standard practice? Certainly not the people posting on here.

George


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## d_slat (Apr 10, 2012)

Develin said:


> Always thickness your material to its FIN sizes before you glue up panels. Standard practice.


I would disagree with this statement. Common practice is to plane after glue up unless you don't have a planer big enough to plane the finished panel size. And even then common practice is to glue up several smaller panels that will fit in your planer and then plane them down to final thickness, leaving you the least amount of joints to fuss with at once.


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## Develin (Oct 1, 2012)

When I say standard practice what I mean is that when I was an apprentice it was industry standard to thickness first with the motto in mind that a jointer was not a solution for a sloppy glue up, or that's what my college teacher used to say! 

But I was obviously wrong if you guys do things differently that's fine I wasn't trying to imply all other approaches are wrong I just think it's more efficient to get it right first time because that's the way I was shown and it's all that I know but I'm always happy to learn something new and I'll try your approach next time before I knock it!

Thanks


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## amboy49 (Mar 22, 2016)

Re: a similar but different question - I need a nominal thickness of 3/8" for a top/bottom of a small protest I'm building. I'll be starting with a 3/4" board. If I glue up a panel with the boards at 3/4" will they retain adhesion when planed down to only 3/8" ? There will be no need for strength - just that the joint doesn't separate.

I'm concerned the two surfaces won't have enough glue to keep the boards from separating - even from normal expansion/contraction due to temperature and humidity changes.


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## Tony B (Jul 30, 2008)

If they were glued properly, they should not separate.


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## sawdust703 (Jun 27, 2014)

Amboy, to answer your question, first of all, joint the edges if possible. This way both edges are square, & your glue up will have clean, square surfaces to glue to. Next, fully cover the surface to be glued w/glue, & clamp. This way you'll get a touch of squeeze out on both sides, & a guarantee that you have glue thru each joint. Then when you plane, you should have no problem w/adhesion.


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## firehawkmph (Apr 26, 2008)

When I glue up boards that are going to be too wide to fit through my planer, I leave them slightly heavy, 1/16"+. After glue up, which I use cauls and plenty of clamps to keep things aligned as close as I can, I scrape off any dried up glue, then send it through the Jet open end drum sander. Works well to even any mismatches. Finish up with a random orbital sander just to get rid of the sanding marks from the drum sander. Just did this one the other day for a board to attach a Cavatelli maker to. It's 24" X 24".
Mike Hawkins


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