Best adhesive for gluing hardwood to draftboard?

I have a product I’m working on that uses some walnut glued to a draftboard base. The elements are about 3/4" wide and several inches long. I’ve tried several different types of glue, but none really hold it together well - they all kind of snap apart without much force necessary. Dropping it would shatter it into individual pieces.
So far I’ve tried Gorilla wood glue as well as some CA rapid-set glue, several varieties. None seem to hold. I’ve applied weight as well as wait (sometimes for 24 hours), but the joins are all apparently fragile.
Has anyone found a strong glue/adhesive to bond draftboard to hardwood?

Standard wood glue is stronger than most woods. Is the Walnut finished? There may be a coating that is preventing the glue from adhering. (PG Draftboard is not finished)

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How are you gluing it together? Is it just flat, side on side? Or are you gluing the edge of one to the other?

My thought is, draftboard is slick, maybe you can scuff it up with some sandpaper prior to gluing? If that would work for what you’re doing.

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Yes, it’s Finished Walnut Hardwood in the Glowforge shop.

Flat to flat, not edgewise.

You may get better results by lightly sanding the side that will be glued.

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If the boards are not perfectly flat, you may not be getting full contact. CA glue comes in various thicknesses; you may want to find a thick or jel version that can fill some gaps. I use 2P10, but I believe starbond has an equivalent.

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It sounds like there’s some sanding in my future to test this.
Which glue would you use, wood glue or CA?

I have started using both and I am getting good results. Gorilla wood glue evenly applied across most of the surface but leaving a couple small bare spots. Then drop in some Medium Starbond CA glue. CA glue sets quickly so the part doesn’t slip while drying, and for small parts it holds the pieces together while the wood glue dries. I learned this approach on a couple wood working sites.

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Draftboard gluing will never be super strong as in the end, it is just a good grade of MDF. If everything is getting painted or finished I’d try something other than draftboard. Perhaps some Baltic Birch ply? Of the glues you can use, yellow wood glue (tightbond) tends to be among the strongest but you might also want to try a two part epoxy from Aircraft Spruce or a marine supply store.

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Lifetime unbreakable bond with plain old white wood glue…BUT…you have to sand it to break up the finish and smooth surface first, and clamp it. I know no-one likes sanding…sometimes it’s necessary.

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Why not use the walnut veneer? It comes with an adhesive backer - so just peel and stick to your draftboard.

If you need to glue, then you have to sand off the finish. Gluing to a finish is unlikely to ever provide a good join. At that point I’d save some money, add some strength and glue it to Baltic Birch as markevans36301 suggested. Yellow wood glue would be perfect here.

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Hadn’t thought of using veneer, but I was trying to get a quality hardwood product, so I’m not sure if the veneer would wear off over time and look cheesy.

The reason I’m using draftboard is to try to keep costs down; using some ply would increase the materials a fair amount, bumping up my COGS to an uncomfortable level.

So, based on the comments here, I’m gonna try sanding one side of the finished walnut hardwood and see if that helps it bond to the draftboard. I like the idea of using mostly wood glue but with a spot of CA to help immobilize the piece in the jig while it dries. If that doesn’t work, I’ll see if basswood ply as a base instead of draftboard will work better. And if THAT doesn’t work, maybe veneer (which is counter-intuitively more expensive for my project).

Thanks for all the comments and suggestions!

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Without seeing the product, you’re gluing a 1/8" strip of walnut to a 1/8" strip of MDF. Technically you are making a thick veneer. The proofgrade finish is pretty tough and the veneer thickness is pretty good. It is actually too thick for some applications. Veneer can go high quality, or it can go cheap. There is a lot of cheap out there and that is where it gets the bad rep. But if it is cost prohibitive then it is a moot point.

You should be able to source Baltic Birch for less than draftboard. A sheet of draftboard is 240 square inches and costs $4. A sheet of 5’x5’ Baltic Birch is 3600 square inches so break even is $60 (less cutting down and transport). You can also source walnut hardwood for less than proofgrade. Of course you have to weigh the cost of finishing the walnut versus the labor of sanding off the finish from one side. Sanding may be the better route until your quantities climb.

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Revolution Plywood is both less expensive than Draftboard and has the advantage of being actual wood, Walnut is available in a wide range of thicknesses that a “veneer” can be whatever thickness you choose.

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Regular wood glue.

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OK, after testing with the suggestions, here are my results:

  • Sanding the draftboard and hardwood definitely improved the adhesion
  • Some of the bonds were very strong, a couple of others were not - either I didn’t sand them enough, or there was dust in the way
  • Used Gorilla wood glue
  • I’ve priced out Baltic birch ply and will get some to try to laser it out, instead of draftboard

Thanks everyone for the suggestions - this is the right track.

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