Gluing solid wood to MDF

[Alan Tolchinsky]

I'm still making veneered table tops and getting there but I was wondering. Do you have to use biscuits or splines to attach solid wood moldings to the top? Why not just glue them to the MDF? I'm getting a mismatch between the top and solid wood "frame" around the table top and thought gluing without biscuits or splines might make it easier but would it be strong enough? Alan in Md.

[Chris Padilla]

Alan,

Go for it. IMO, biscuits and splines aid in alignment and not necessarily strength. Some folks have trouble with pieces slipping or want to maintain a specific placement and that is where biscuits and splines are invaluable. For example, I often laminate large pieces of plywood together. I like to put two biscuits 90 degrees to each other to keep the two piece from slipping around--especially if the alignment needs to be 'on.' Otherwise, plain old yellow glue (PVA) or poly will be plenty strong in a butt joint.

Biscuits are easy to cut in the wrong spot if you aren't careful with where the fence registers...pull the piece off your workbench a couple inches and then cut the biscuit. This prevents the biscuit cutter from riding on your bench top and cause possible misalignments.

Adjust the cutting depth of your biscuit cutter. Cut a #20 (for example) in some scrap. Insert a biscuit to max depth and draw a line on it where it meets the scrap. Pull out the biscuit and flip and reinsert..draw another line. Pull out the biscuit and observe the distance of the two lines. Should be ~1/16" apart. You need room for glue to flow so adjust the cutting depth as such. Too much space is better than too tight.

Next, presort your biscuits. On that same scrap, insert a bunch of biscuits. You'l find snug ones, loose ones, and "just right" ones. Always presort before you glue up. Snug ones can be thinned in a vise. Skinny ones, well, not sure about those but save 'em! :)