Floatin' free?

[Malcolm Wheeler]

I am building a bed head board with poplar frames and MDF panels, all painted with primer and then latex white paint. If the MDF is indeed dimensionally stable as the advertisements state, can I glue the panels in hard, or should I make them float with foam plugs? Also, should I cut the MDF to exactly the same size as the gap between the frames or should I use a dado to support a sllightly small mdf panel??

[John Keeton]

Not sure that I totally understand the second part of your question. As to the mdf, it should be stable, but the poplar may move. Depending on the width of the poplar frame, and its dryness, it could shrink enough to break a paint seal with the panel. I would lean toward finishing the panel before assembly and glue in place. I would want to use a shellac based primer on the mdf to avoid swelling issues with a waterbased product.

On the second question, need more info. Not sure what you are thinking. How did you plan to install the panel if not in a dado?

[Joe Chritz]

If you are asking if you should cut the panel with no space then I wouldn't do that. As long as the frame closes on the panel it is fine but trying to match the size exactly is a bit tricky. Even a very small cutting error would show on the joints.

Generally I leave a gap of 1/16th for sheet stock panels. If my rail is 12" total length I would cut my panel 11 15/16" wide.

As mentioned you can glue MDF or plywood panels into frame and panel construction. I usually just stick a little in a few spots and call it good.

Joe

[Danny Thompson]

Glue hard and dado.

The poplar will expand and contract away from the MDF not along the glue joint, so movement shouldn't be an issue.

Use a dado because it provides more gluing surface and hides minor cutting errors as Joe said.