I’m building interior, flat-two-panel doors and am debating whether to glue the panels to the rails or not to help with strength. The panels will be plywood so stability in the panel isn’t an issue. If these were cabinet doors, I’d glue the panel to the rail and stiles but not certain here with my three rails being 4 1/4, 6 1/4, and 8 3/4.” Thanks for your thoughts on this.
Jeff
Replies
Always glue plywood panels.
Agree - wood movement is not going to be an issue so glue is the way to go.
In my 40 years of building cabinets and interior/exterior doors I’ve never glued a panel, plywood or solid, to the door rails, nor have I ever heard of it being done. I just don’t see the need to “help with strength”. If it was a solid wood raised panel, for example, would you glue that? No, of course not. Would you worry about it not having enough strength? No. Millions upon millions of frame and panel doors have been made, and they don’t come apart because the panels weren’t glued to the rails. Just my 1 1/2 cents.
Solid wood panels aren't glued because they need to be free to expand and contract. If they were glued, they would Crack.
Plywood doesn't move. There is no need for it to float in the groove. Glue will add strength to the door, and not harm it in any way. All of the commercial doors I've seen with plywood panels have all been glued.
The door can be strong enough without glue on plywood panels. But adding glue definitely makes them stronger, and costs nothing but a few cents worth of glue and one minute of time.
The plywood will move. Not as much as lumber, but any product moves with changes to temperature and humidity. The rails will also move. Long grain may not move as much as cross grain, but it moves. I made interior and entry doors for 30 years and never glued a panel. My stiles and rails for paint grade were stave cored poplar and panels were mdf. No reason to change what works flawlessly.
Completely agree.
Uh uh. First of all, “all of the commercial doors you’ve seen” are almost certainly made from stiles and rails made of engineered veneered materials (often a stranded core) not the one piece solid wood that Jeff is using, and while the plywood panels might not move, the 12-20” combined width of those solid rails will, so gluing them into a solid 6’6” high piece with the ply not moving, but the 3 rails wanting to, could look ugly. I say don’t bother, Jeff.
Speaking of commercial doors, this from one of the biggest, Masonite: “Unlike a slab or flush wood door, stile and rail door construction uses linear strand lumber, which consists of strips of wood glued together. One door requires a dozen or more pieces—stiles, rails, panels, mullions and, in some cases, glass and muntins. They absolutely must be cut precisely so that they fit together perfectly.
Glue and dowel pins create strong joints and a sturdy door. The panels are made from MDF and are “floating” between the stiles and rails. With no glue restricting their natural expansion and contraction, you avoid warping or cracking of the door. In the end, they give the illusion of a single carved piece of wood.”
“[Deleted]”
Great advice, Thank you! I’ll be at the glue up stage next week and will post a picture then.
I agree, there is no reason to glue the panels in place.
Sure there is. There's no reason not to glue them in. It's plywood, and already mostly glue.
Jeff, I suggest you build 2 doors, one John's way and one the right way. Then report back to let us know if those non-plywood solid wood rails expand and contract enough to totally screw up your door. :-) Spoiler alert, they will. The solid wood rails, which *will* expand and contract, at 20-30" total in height, will be up to more than a third of the total height of the door, with no place to go. A recipe for disaster.
Nonsense. If that happened, every door would tear itself apart. Those rails are mortised and tenoned into the stiles, and don't have anywhere to move. Not even a little. Not even a tiny bit.
The ONLY reason panels are left to float is because the PANELS are solid wood, and need to be free to expand and contract. If the panels are made of a material that doesn't expand and contract, they DON'T need to float.
Woodworking is full of useless myths. This is one of them.
I would not glue the panels in. Leaving them to float in the frame is a safe bet as it is the traditional method for frame and panel doors. No reason to risk problems by glueing them in. Wood always moves even plywood and the rails and stiles. Gluing adds an unnecessary risk. Hope this helps, cheers.
Another myth busted-thanks!
Eerily similar to another classic post:
"There seems to be this assumption that you can't make furniture without a jointer. It's on every list of must have tools for new woodworkers.
But they aren't necessary. Not even a tiny bit. You can do anything without one. You can actually do a lot more without one, and save yourself the space and money.
That's all. Woodworking is full of a lot of myths. Needing a power jointer is one of them."
So whatever you do Jeff, when you mill the stile and rails for your doors, DON'T use a jointer- you don't need that. And- don't forget to use lots of glue on those panels.
:-) Priceless!
Oh, and go ahead and delete your snarky reply, just as you did the last three times. It's nice to fling your feces and then delete it, before everyone gets to see a schmuck in action.
Maybe you should take a deep breath John, or better yet a nice walk outside., the only one being nasty here is you. It’s only a woodworking forum, no need to go ballistic over harmless comments.
Harmless? 27B knew exactly what he was doing. He was the one being nasty. And you knew it, by patting him on the back.
In the absence of a block button I'll be happy to ignore him, and you if you like. As soon as he stops replying to me, or digging his spurs in. He's not funny, cute, or witty. He knows exactly what he's doing, and worse, he's trying to cover his own butt the way he's doing it. It doesn't make him any less nasty, just more of a coward.
Let's all chill this out before we have to start deleting or worse, banning people.
A stable panel can absolutely be glued into a 5 piece door. However the science doesn’t work quite as well with doors more than 5 pieces, as intermediate rails can’t have their movement isolated to the exterior edge of the door. Similarly a stable panel can bottom out in a groove of a 5 piece door. Once intermediate rails are introduced even stable panels need to be undercut as appropriate to allow those captured rails to move.
In a 5 piece door, for a cabinet or passage door, I prefer to glue in stable panels. It does not give me issues, nor did it give any of the cabinetmakers I learned from issues in their long careers. The only benefit to this, as far as I understand the wood technology of the equation, is not having to prefinish panels before glue up. I don’t know that it adds to stability or strength. If you don’t glue a stable panel in, it must be prefinished like with a solid panel. If finished after assembly as one piece, seasonal movement of the rails and stiles will reveal unfinished edges of the panel (1/32” or so, not anything glaring but not professional nonetheless).
As a test of this, I made my personal kitchen doors with the MDF panels glued in. I floated the drawers’ panels, glueing up both doors and drawers without prefinishing anything. In the winter, the drawers have a tiny reveal of raw MDF. The doors do not. The doors do, however, isolate all their movement to the reveal side of the rails and stiles. Thus in the winter my 3/32” reveals are a solid 1/8”.
All this to say — everyone has made valid points. But thinking through the science should tell us when and why it’s okay to glue a stable panel. Also, I have gotten way far afield of building interior doors and for that I apologize. To the original questioner — don’t glue the intermediate rail to any panel, its movement will have nowhere to go. The top and bottom rail and the stiles are up to you. If you don’t glue, use space balls or similar to keep from wintertime rattling.
Yes, agreed, don't glue, but if you must for some reason, don't glue into a monolith, let the rails (and the ply, and yes, plywood moves, check the APA site, they even say it does) expand and contract up and down. Speaking of space balls, where were they 30 years ago? :-) We used to shoot a short 18 gauge brad (I don't think they made 23 ga pinners back then) through the back of the frame top and bottom at the center into the panel to keep the panels centered in the frame.
"Speaking of space balls, where were they 30 years ago? :-) We used to shoot a short 18 gauge brad (I don't think they made 23 ga pinners back then) through the back of the frame top and bottom at the center into the panel to keep the panels centered in the frame."
Well said. That has been my experience and procedure as well. Another consideration, a frame; properly milled straight, flat and square will want to stay that way. If the entire assembly is glued up as a "monolith" it will, like a lamination be iron bound when the glue sets, so if something is a bit out while resting in the clamps, it will not be corrected.
Sitting at my mid-century teak dining table I canot help but contemplate the mitered solid wood frame surrounding the 36 X 60 teak veneered plywood top. Similar to the coffee tables in the next room, a large plywood panel with a teak moulding sanded flush with the veneer and jointed at all four corners, some of those pieces have 60 years , not a single open miter or sign of wood movement between the plywood and solid wood. Down in the Mans cave, 18 mahogany doors/drawer fronts with a 1/4 inch plywood panel glued in a solid mahogany frame, again, no cracks, no wood movement whatsoever. Dont glue the panel, it won't move , glue the panel, it won't move.
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