Sample of what I’m taking about.
How do I repair cupboard seems coming apart?
by
Lyn Davidson
+5
Our cheap cupboard doors corners are splitting where they put them together at. What can be done if anything.
Remove them from the cupboard. You'll need a large pair of F clamps, big enough to span the width of your door. Open the gaps as much as possible without breaking the door and put wood glue in the seam. Clamp the door so the gaps close, wiping off any excess glue that squeezes out. Allow several hours to completely dry, reinstall on cupboard and repeat for any other doors.
I found a video on YouTube that I hope helps...
https://youtu.be/45mME5FEhLU
Are the boards loose? If not, I would add caulk to the seam.
Ditto the answer from Frugal Family Times above with additional tips. I have had good results with Gorilla Glue brand wood glue and their instructions to lightly dampen the wood with water before adding glue and clamps. That technique draws the glue into the wood as the water and glue dries for very strong bond. Also, a set up that I have used when clamps were not long enough...ratchet straps and wood blocks. Place blocks on either side of area you want to hold and use the strap across them to add pressure until tight. Depending on size of your blocks, this also can allow access to the joint for easy clean up of excess glue when the joint closes. Clamps are great if you have them, but big ones can be pricey and then you store them. The ratchet straps are available in many sizes at auto stores, Walmart, Target, etc. They are handy for many tasks and easy to store in in a drawer or your vehicle. Just a thought.
Ratchet clamps, I have those never thought of using them for them purpose, I learn something new everyday day, thanks George.
In a pinch I have used a loop of rope and a wood stick to make what my old timer friends would call a "spanish windlass" when clamps not available.
Bar clamps, strap clamp, rope, whatever you have to clamp. After gluing and clamping I have also pre driiled a hole on the side and nailed with a small finish nail. Countersink the nail and covered with a little drywall patching compound. Glued joints on cabinets can reopen from daily use.
Be careful that you don't twist the joint with the clamps and that it stays flat. You might want to add a V nail fastener or a flat 90º bracket for extra strength