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Thread: Engineered Raised Panels?

  1. #1
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    Engineered Raised Panels?

    Door makers:
    Should a raised panel that'll be about 3' wide be engineered with an MDF core to prevent extreme expansion and contraction/warping? This is going to be a "solid" Sapele door, but I will be making engineered stiles probably with a ply or pine core and 1/4" veneers.
    Obviously I'm not saving any time on labor, but this door is going to be a massive 4'x9', so I want to make sure I don't run into any warping/ twisting issues with it.
    Jack

  2. #2
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    How are you going to raise the panel without cutting into the mdf core?

  3. #3
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    Wrap a stable panel with mitered solid edgebands wide enough for the panel raise, veneer over that, then machine the edge. If it is an exterior door, use an appropriate core material.

  4. #4
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    The goal was to just use a 1/4 mdf core and solid veneers 7/8 thick on either side. Would the mdf be helpful at that point?

  5. #5
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    7/8" thick is not veneer. Keep the face thickness under 1/8" or you may have surface checks develop over time.

    Opinions vary on facing thickness for doors. You can find people who have success using thicker faces on stable cores (check out David Sochar's posts on Woodweb for example) but I prefer to be conservative. I will put thicker faces on stave core blanks as they will move together, in fact I just finished two 2 1/4" exterior doors with 7/16" recycled barnboard over 1 3/8" pine stave cores. On cores with negligible movement (mdf, plywood, lvl), thinner faces are safer in my opinion.
    Last edited by Kevin Jenness; 06-21-2019 at 12:17 AM.

  6. #6
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    I'm assuming you don't want the look of a center stile even though it would add a lot of strength to the door? Is the top rail beefy enough to handle the weight or the door and the mdf? Most of the joint stress comes on the top and the center stile transfers some of that across the frame. Dave

  7. #7
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    Quote Originally Posted by Kevin Jenness View Post
    7/8" thick is not veneer. Keep the face thickness under 1/8" or you may have surface checks develop over time.
    That makes sense. I was wondering if the variation of movement of the laminated materials would cause checking on the surface. Just curious, why would a thinner veneer (say 1/8") be less prone to checking? The reason why I was going to try to sandwich just a 1/4" of MDF was so I could avoid having to edge band the panel, but if thats the best way to go then I guess I'll just do it. On that same note: On the top and bottom edge of the panel, should your the grain of your edge banding run vertically if the door is to be stained? Otherwise you'll have a very clear glue-line where the grain changes from vertical to horizontal.

    Also, does anyone have any experience with making raised panels out of solid exterior treated MDF? I worked at a shop for a year that cranked out a large order of exterior raised panel doors with that stuff and I was kind of skeptical (plus the dust made from raising the panels was ridiculous). It definitely wouldn't move as much as solid wood, but does it hold up in the elements?

    Thanks for all of the help
    Jack

  8. #8
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    Dave,
    The customer specified no center stile, but I am beginning to think I should strongly recommend it. I'm just guessing that this door is going to weigh over 350 pounds due to the size, thickness, and material.

  9. #9
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    The thicker the veneer and the farther away the surface is from the glueline fixing it to the substrate, the more power it has to expand and contract and the more potential for checking. For the same reason, it would be unwise to put an edge-grain edgeband on the panel ends- it is almost guaranteed to check, especially with exterior exposure. Long-grain edgebanding wrapped around the panel perimeter is far more stable. If the joint between the band and face veneer is located in the step between the field and bevel of the panel no-one will notice it.

    I would urge you to do further research on basic wood technology and door construction before you commit to a project like this; it's not something you want to do over. David Sochar has many posts on Woodweb and Joe Calhoon both there and on this site which are well worth reading. Unfortunately I don't know of any good contemporary books on door building, but the Victorian era Modern Practical Joinery is still available.

    Extira is an exterior grade mdf that some people use for your purpose http://packardforestproducts.com/pro...posites/110-2/. I have no direct experience with it myself. If your project is painted it may be the best option.
    Last edited by Kevin Jenness; 06-21-2019 at 2:10 PM.

  10. #10
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    Kevin,
    Thanks for the input, I ordered the book. I definitely need to do my research which is why I started here. I have done far more windows than doors, so I am just thoroughly planning it out before I go ahead and accept this job. In the shop I used to work at, all of the thinking was already done for you, you just had to make the door/windows to specs... no biggie. That one thing I've learned after going on my own is that not only do you have to do that physical woodworking itself, but also all of the planning, preparation, and designing of what you're making. It feels much more rewarding at the end of the day!
    Jack

  11. #11
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    Here are some pages from the AWI quality standards that might be helpful. They say no solid wood panels over 13 3/4” wide and only rim mitered veneered panels allowed in premium work.
    In my own work our market is big on plank panels and we have workarounds to do solid wood wide plank panels. I know of one shop that has had good luck using thick 1/8” + veneer on a Tricoya core for raised panels.

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  12. #12
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    Joe,

    Would you care to elaborate on your "workarounds to do solid wood wide plank panels"?

    The two doors I recently built to client specs had 22" and 26" wide panels 3/4" thick with 1/8" recycled pine and hemlock edge-glued with Titebond 2 and laid up with epoxy on 1/2" closed cell foam cores. Comments?

    The initial post in this thread referred to "engineered" panels. The term seems to cover a lot of ground including "laminated" and "incorporating materials other than solid wood". I try to incorporate tradition, personal experience, book learning and techniques gleaned from colleagues and forums such as this one in my work. Obviously there are considerable data on wood as an engineering material, but they appear subject to a wide variety of interpretation by door builders. Are you acquainted with any actual engineers in the trade?

  13. #13
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    Hi Kevin,
    my workaround is pretty simple on plank panels. For wide panels of this type I do true planks with T&G and don’t glue the joints. The panel is not captured so I can lay it in the door and attach each individual piece. Usually back to back panels with foam between. Have also done a lot of glued back to back up to 24” wide. Pushing the envelope for sure. I think not having a thin raised panel edge helps on splitting. Any edge joints on exterior work are reinforced with glue joints of some kind. I know a well machined glue joint is stronger than the wood but for exterior I like a little extra. And still using TB3 daily as we have for many years with no issues.
    The rules in the AWI book will keep you out of trouble but I find in my market dealing with designers, odd and specialty material I have to break the rules a lot. Exterior doors are a risky business, unprotected and high exposure locations are risky and maintenance of the finish are the burden of the homeowner. I try to explain all this to the customer.

    Your 1/8” recycled material glued to foam I have no experience with. Epoxy is a very rigid glue. I know some shops gluing 1/8 veneer to Sing cores with epoxy were having some failure. The other shop that glues thick veneer to Trycoya claims TB3 is best for this because it is flexible. I would think the foam would have some give. I plan to start experimenting with thick veneers but I think location, climate and many other factors come into play to make a successful product. Shipping to another climate is always risky with solid wood.

    When I questioned suppliers of solid wood and thick veneer laminated panels at Fensterbau last year about glue types some were using rigid glues and some PVAs. They all said they did not recommend the panels in high exposure areas or areas that get a lot of sun.

    Here are some panels I saw in a French door shop. Solid wood glued to foam. It came in outsourced sheets with the solid wood and the shop cut it and raised the panels. No idea what type of glue was used from the supplier.

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    Last edited by Joe Calhoon; 06-24-2019 at 1:04 AM.

  14. #14
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    Quote Originally Posted by Kevin Jenness View Post
    Joe
    The initial post in this thread referred to "engineered" panels. The term seems to cover a lot of ground including "laminated" and "incorporating materials other than solid wood". I try to incorporate tradition, personal experience, book learning and techniques gleaned from colleagues and forums such as this one in my work. Obviously there are considerable data on wood as an engineering material, but they appear subject to a wide variety of interpretation by door builders. Are you acquainted with any actual engineers in the trade?
    The definition of “engineered” is very vague. I take it to mean a manipulation of various materials to try to make a better more stable product. There is engineered flooring also. Myself, I am primarily a solid wood guy but will use “engineered” or laminations when the need arises with certain materials and sizes.

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