# Plywood Joint Question



## MHoffmann (Sep 21, 2011)

I am building a leaning bookshelf. The attached picture of the joint is what I am trying to accomplish. I am planning on using glue in all surface to surface contact. 

The vertical 2x4's are the primary support that runs vertically at about a 80 degrees off the 

Will this work? What is the rule of thumb for pilot holes, so that its not to smalle or to large? What type of glue should I use? Do you guys have any better ideas?


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## cabinetman (Jul 5, 2007)

From what your drawing shows, IMO, the 1x3 Poplar is unnecessary. If the 3/4" plywood sits in a good fitting dado with glue, it will be more secure than being screwed and glued to the 1x3. 












 







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## MHoffmann (Sep 21, 2011)

It actually has 4 more shelves I was at work and didn't want to spend to much more time on it. It is also going to be primed and painted. But would you suggest besides poplar? It seems to be one of the cheapest next to pine. But I've read on here that pine isn't the best for furniture.


Are you talking about doing a 3/4" Dado into the 1x3? How much lip do I need on the bottom to ensure that it is secure?

Also what type of Glue would you suggest?

Thanks,

Michael


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## cabinetman (Jul 5, 2007)

MHoffmann said:


> Are you talking about doing a 3/4" Dado into the 1x3? How much lip do I need on the bottom to ensure that it is secure? Also what type of Glue would you suggest?


I corrected a typo in my reply. Eliminate the 1x3. I meant to dado the 2x4, and glue in the 3/4" plywood. The dado depth can be 1/4"...3/8" max. You can use any white or yellow glue...Titebond II or Titebond III work well.












 







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## MHoffmann (Sep 21, 2011)

I can't/don't want to get rid of the 1x3 because it forms a vertical edge around the border of plywood. It adds both stiffness to help support books and its decorative addition my wife wanted. I will try to load pics of the plan I modeled, when I get home latter.

Thanks for the help.

Michael


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## cabinetman (Jul 5, 2007)

MHoffmann said:


> I can't/don't want to get rid of the 1x3 because it forms a vertical edge around the border of plywood. It adds both stiffness to help support books and its decorative addition my wife wanted. I will try to load pics of the plan I modeled, when I get home latter.
> 
> Thanks for the help.
> 
> Michael


The way you have it drawn, the plywood joined by screws (and even glue) is a much weaker joint than having the plywood dadoed into the 2x4.












 







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## firemedic (Dec 26, 2010)

cabinetman said:


> The way you have it drawn, the plywood joined by screws (and even glue) is a much weaker joint than having the plywood dadoed into the 2x4.
> .


+1

I have to say I really don't understand what you are trying to accomplish here however the sketch is showing a weaker joint than a simple dado with glue like C-man suggest. It's not terrible, but it's really overthought and over designed for a negative gain.

~tom ...it's better to remain silent and be thought a fool than to open one's mouth and remove all doubt...


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## jlord (Feb 1, 2010)

Hi Michael,
I have to agree with the others. The way you have the joint drawn does not look like it will hold over time with the weight of books. The 1x3 as drawn does not add much to the strength of the joint. If it is the look your wife wants just change the orientation of your parts. Make the dado the same but run the shelf all the way thru. Then rip your 1x3 to fill in the remainder of the dado on top of the shelf. This way your shelf is fully supported by the dado & you still show the 1x3 on top for the vertical edge around the border of plywood.


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## gfadvm (Jun 23, 2011)

I am hesitant to suggest another site but I posted a leaning shelf unit like you want on Lumberjocks. Just go there and search gfadvm projects. It is a 5 shelf unit for displaying my boxes in a Market booth. I can stand on the shelves so it will certainly hold up books. Hope this helps.


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## Engineer/sawjock (Oct 10, 2011)

Well the pin (#10 screw) is not a good bearing connection. At the very least find a way to get the 1x3 under your shelf. Books weigh about 25-35 lbs/cf and 3/8" of plywood (disregarding the laminating glue) is not going to do it unless the shelving is very short.


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