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Last Updated: , Created: Monday, December 22nd, 2003

Getting trim to stick to the edge of panels.

There are quite a variety of techniques and tricks to getting trim to stay put on the edge of a particle board or plywood panel. Many plastic and metal trims come in a 'T' shape. This requires you to cut a groove down the centre of the panel edge, just the right width and well centred to receive the trim. The standard tool for this would be a wing cutter on a router. Small items are best done with a router table, but large panels are best done with the router moving on the panel.

The same slot can be used for a spline joint. That can be as simple as a strip of masonite board glued into a grove on the panel with the same groove cut into a piece of solid wood trim as in the second photo above.

This type of spline joint has been simplified in modern cabinetry with a tool called a biscuit cutter. It cuts oval slots into boards with the same type of wing cutter as used for slots, except that rather than running the length of the joint, you simply push in two or three oval cuts in matching positions on the panel and the trim. Then, special pressboard oval biscuits are glued into place to secure the joint. Once the glue is applied, the biscuits swell to a tight fit.

One of the keys to a successful job with all of these joints is getting the glue to spread evenly on both inside faces of all the slots. That requires a special head on your glue bottle as you can see in the fourth picture. Here is a link to a set of good glue heads from LeeValley Tools.

One other essential gluing technique comes when using either plastic or real wood heat-applied trim tape. When you apply these tapes to the edges of plywood or pressboard, it's essential to have sanded the panel edge quite smooth, which usually means sliding a wood block backed piece of sandpaper "against the grain".  Run your hand back and fourth -- you will see that the saw or router left fibers bent to one side, that will stand up when wet and keep the trim from getting close to the panel.   Even with a smooth edge, the glue tends to flow into the panel and get lost, giving a poor glue joint with all but the best of trim tapes. The simple guarantee of a lasting trim tape job is to prime the sanded edge of the panel with contact cement, solvent or water based, and let it dry overnight. This will saturate the panel edge with glue and then heat fuse with the tape glue when you apply the tape.  The glue on the tape doesn't soak into the board and does stick very well to the contact cement prime coat.


Keywords: Woodworking, Saws, Glues, Trim, Router, Techniques

Article 1852