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I am planning on making frame and panel door with a panel of ½ MDF veneered with a walnut burl. Normally I use the traditional method of “floating’ the panel the frame, but is this necessary if the panel is MDF? Is it reasonable to simply glue the panel into the frame?<!—-><!—->
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Neil<!—-> <!—->
Replies
I think MDF still swells with humidity.
Maybe just a little glue on the panel corners if you're trying to keep the panel from rattling.
Why would you want to glue the panel and risk getting glue on the burl?
Neil,
My shop produces these quite often. It's totally uneccessary and just adds clean-up work to glue the panel into the frame. We make the panel 1 mm undersize (in width and height) because there's practically no expansion issues in either direction. Just let it float as usual.
DR
Good thing that I asked…<!----><!----><!---->
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About the only comment is that if I use ½ “MDF in a ¾" frame, the reveal will be only 1/8 on each side (actually less because of the veneer thickness).<!----><!---->
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Are your panels ½", or do you use a thinner base material? <!----><!---->
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Neil<!----><!---->
In most cases we use 3/8" MDF, which after veneering comes to about 10.5 mm thickness. We make the joints of the frame pieces with a groove 5/16" (8 mm) wide x 1/2" deep. The panels therefore get a rabbet on the "back" side, 2.5 mm deep, and 1/2" wide. These joint measurements are beefier than most common router-made joints, but I much prefer their strength. On the shaper I'm not limited to making "standard" joints. But the principle remains the same for your application - make a rabbet on the back side of the panel to allow it to exactly fit your (I assume 1/4") groove. Keep the 1/4" setback on the face of the door; the rear will effectively be flush.
DR
The frame expands & contracts, too. It is the differential expansion that does the damage. Don't glue the panels!
Cadiddlehopper
But the stiles don't expand toward or away from the panel.
Hal
http://www.rivercitywoodworks.com
I believe the stiles will move rails & rails will move stiles. Panels can still expand or contract. It is still differential movement no matter how small. No?Cadiddlehopper
Cadiddlehopper,
Well, it seems to me that the stiles are stuck on the ends of the rails. The rails won't expand or contract lengthwise, unless they are built of cedar. So the inside of the rails should be in a stable position unless the joints between the stiles and rails are not secure, and the outside of the stiles is stuck in a position where they cannot move. But this could only cause the joint between the stile & rail to break. It couldn't crush in toward the panel because of the compression strength of the upper and lower (and possibly intermediate) rails.
It's all academic at this point though, since the joint between the stiles and rails is usually sturdy and it is uncommon to attach the outer edges of the stiles to anything that is unmovable.
An inner cabinet could perceivably break the joints in end panels though, if it wasn't built correctly and restricted the expansion and contraction of end panel stiles & rails. It would be more important the wider the stiles of the end panel are made.
Wow, did this ever get to be so much more complicated than I ever intended when I started to reply!
Sorry about the big breath you needed to take just to read this. If it doesn't make sense to you, I totally understand. I personally hate it when people post things a bit too technical just for the sake of winning the argument. That is not my intention whatsoever. I just hope I explained it so it makes sense. If you don't understand you are welcome to come to my shop tomorrow and I will show you what I mean. JK!
Hal
http://www.rivercitywoodworks.com
" The rails won't expand or contract lengthwise,"Where do you get wood that does not contract lengthwise? All that I have been able to buy does. One should never ignore differential expansion even when edge gluing different species. Even then the two woods should change at near the same rate.Cadiddlehopper
I think that the change in length is generally negligible in hardwood furniture building.
The only wood that I have seen shrink lengthwise is western red cedar, which is generally not used for furniture building other than outdoor furniture. Once dry though, it is a great wood. There may be other similar species that do the same.
To answer your question though, I buy most of my lumber from industrial suppliers, then check to make sure it is around 8 to 10% moisture content.
Most retail hardwood seller's wood is like this too, I think.
Hal
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