Raised Panels — Rip and Re-Glue or Not?
Is there any reason not to use the boards as they are? Or should I slice them in half to relieve any pressure and re-glue? Does that serve any purpose if I don't also flip one of the board faces? Lastly, is it generally better (in terms of minimizing cupping or twisting) to keep the panels as thick as possible, with a relief cut around the back edges, vs. making them 9/16" thick and no relief cut?
From contributor D:
There was a thread on here not long ago in the furniture section. A lot of what was said about a table top applies to a door panel, even more so, with a door's extreme exposure and moisture changes.
It was a mixed bag of opinions about alternating grain and so forth. Bottom line is, if this is an exterior door, I personally would rip 10" boards in half and flip them. They are cupped now and will move in a cupped motion again, not simply in width as many say. A fielded panel, 3/4" or 9/16" thick, flat sawn, trapped in a groove where it can't cup, will crack. Yeah, they look better as a single board. It might look better if they weren't split down the center next winter though.
From contributor H:
This argument has been going for years and years. Some say single piece is just fine, some say rip and flip, and others say rip and flip or don't flip - it doesn't matter. Personally I rip and don't give consideration to flipping or not flipping but rather look for good clean appearance on the face side. I've done hundreds and hundreds of door panels this way over the years without any cupping.
However I've also seen 15" wide single piece cherry raised panels that were flat as the day made. In your case maple is a very strong wood and I would err on the side of caution and rip and re-glue.
From the original questioner:
Thanks for the replies. I should have noted these are 3/4" thick interior doors for a mudroom, matching an existing adjacent kitchen.
From contributor S:
Mill the panels and get them into a frame ASAP! I would be cautious at 9% MC, and would likely set those boards aside for something less important. This may not be such a big deal in your climate however. At 8% I would definitely pre-finish. When I bring rough lumber into my shop I allow it to acclimate to the temperature of my shop for about 72 hours.
I start by rough milling my stock for the panels, sticker, set weights on top, and allow them to sit for as long as I can. If I am in a hurry that may be a few days, if I can I like to allow a couple of weeks. I then build my frames, and when they are ready I start working on the panels. I plane the faces and joint fresh edges then glue up. As soon as they come out of the clamps I like to cut to size, raise, sand, and pre-finish immediately.
The panels get dry fit/stored in the frames which really helps at preventing unwanted cupping or twisting. If this isn't an option I sticker them on a flat surface, and set weights on top. I work with allot of wide boards 13"-15" but I only have an 8" jointer. I prefer not to rip/glue unless I have to. Just make sure to allow for plenty of movement. Do the math or use one of the movement calculators. Rule of thumb is not to be trusted.
From Gene Wengert, forum technical advisor:
As discussed in the furniture forum regarding table top movement recently, one key is the curvature of the rings (viewed from the end grain). With flat rings, there is so little tendency to cup that it can be ignored (assuming no knots or other slope of grain issues). As the curvature of the rings increases (usually due to lower grade lumber), the idea of flipping has more merit. The discussion was more extensive; this is a brief summary of the various views; the curvature is also why some people swear that flipping is essential and others, like above, say they never do and never have problems.
It is key to remember that one will not change its size or shape unless the moisture content changes. So, get the wood at the same MC that it will have in use, and you will be safe indeed. As mentioned, 8% MC might be high for an interior door in much of the USA. This MC level is more important and more effective than relief cuts (which do work). The fact that you already have some cup indicates that you are dealing with a cup-prone piece of wood and so extra care must be taken (extra care like correct MC and maybe even rip and flip).
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