I’ve designed a specialty table and need to attach a hinged lid/tabletop. I’m not sure kind of hinge will accommodate my design wishes.
The table has raised trim around the edges and the hinged top needs to rest flush within (and below) the trim when closed. The top will only be 1/4 inch thick and made of honeycomb polypropylene, a very rigid plastic. I would prefer that the hinge be internal and not visible when closed. There is an inner panel that the lid will rest on top of when closed. The hinge can be attached to the flat inner panel or the edges of the trim (3/8 inch height).
If necessary, I can attach the hinges to the inner frame BEFORE attaching the inner panel. This would require a slight change to the panel design, but that would be okay if required. The inner frame would allow a hinge width of up to 1.5 inches, but would be further inset and would need to avoid movement issues where the hinged edge of the lid meets the frame/trim. Any ideas or suggestions for hinge types (or slight changes to design) to accommodate my needs would be appreciated.
I think you need pivot pins in the sides of the table top. Some small portion of the top would rotate into the frame. The pins would be mounted in a couple of blocks of solid material under the tabletop and you will fence off the portion of the interior where the top rotates down into it. The top of the fence acts as the support for the top at that side and the fence limits the rotation range of the top. This won’t work if the top has to rotate much more than 90 degrees. Just got called, will try to find an example later.
I’m not clear on what exactly you are trying to accomplish with this, even though you show the basic layout of the parts. knowing your goal might help refine what to do.
The first thing I notice, is that in your basic drawing, the lid either can NOT be completely flush inside the outer trim all the way around, or you will have to consider a redesign of the concept.
Solutions I would consider:
make the rear trim part of the lid, and attach hinges to the underside of the table top. The entire rear edge would open, and the plastic lid would be mounted into the trim at a 90 degree angle.
sneaky trick: don’t use a hinge at all. instead, rabbit out a channel in the rear trim, and make the lid slightly larger than the space it is supposed to cover. The “extra” lid would slide into the rabbited area on the rear trim, and the rabbit would be shaped so that when the lid is closed, it would APPEAR to be flush all the way around.
I can’t draw pictures here, so I hope you can visualize what I mean.
If you need the lid to open and then stay open by itself, you could make the rabbit wide enough such that you could add a rail mounted away from the rear trim, the same width as the top cover is thick, that would sit under the lid in the rear. When the lid was raised to full open, the back edge of the lid would rest against the rail. Gravity would keep everything where it belongs.
By the way, the rabbit would be shaped like quarter round, flat at the top, and an arc curving down. I wish I could draw it.
Yeah, I agree, it’s physically impossible for the lid to fit flush to all four sides of the rim and still be able to tilt upward. If you can accept a small gap on one side, then there are a variety of hinges that would work. If not, then you’ll have to pull some tricks like igor frankensteen suggests.
Nitpick: “rabbet”, not “rabbit”. Although I’d really like to see a drawing of a rabbit shaped like a quarter round.
Maybe he uses a cloth hinge, or similar ? This might reduce production cost. The hinge doesnt have to bear weight, as the top sits on substantial frame/panel…
Of course, the cabinet hinges can’t be fixed directly into the thin material of the table top, so don’t attempt to do that - fix an additional piece of timber under the back edge of the tabletop - this piece of material carries the hinges, the table top just attaches to it.
If the lid is flush to the rim, the only possible movement is straight up, perpendicular to the plane of the lid. Any tilting before it clears the rim would cause it to jam between the rims. I suppose it’s possible to construct some kind of complicated hinge mechanism that moves the lid in this way, perfectly perpendicular to the door plane for a short distance, then starts tilting, but I’ve never seen one.
A possible solution would be to put the hinge on top of the lid, contrary to the OP’s preference, and bevel the underside of the opposite edge of the lid so it clears the rim when it tilts up.
My suggestion is a hybrid of TriPolar and igor frankensteen’s.
Use pins at each end going into the frame as the hinge, these are in the ends of a length of wood that runs the full width of the lid (and so rotates on the pins) and attached to the lid underneath. In order to make this work appropriate rabbeting will be needed in the rear frame element to allow the edge of the lid to clear. Done carefully this rabetting will be invisible when the lid is down. Minimally you will need a simple gap to allow the square edge of the lid to rotate into the frame, or as igor notes, you can actually make the lid deeper and rabbet a deeper trench into the back of the frame to make room, which may afford better options for how the lid can be allowed to stay open, and also avoid over-rotating the lid (and hence tearing it off the hinge).
6mm honeycomb is pretty thin. Is that with the facing? Obviously your only feasible mechanism for attaching the hinge is adhesives.
That’s what inset kitchen cabinet hinges actually do - per this image
(for certain tolerances of ‘flush’ - there’s usually a 0.5mm gap between the inset door and the frame - the hinge has a trapezium-shaped lever mechanism so that when you pull on the handle side, the hinge side moves forward before it turns.)
Click the ‘which mounting option?’ tab - the problem of inset doors is actually the same as the problem of half overlay - it has to open out at the start of the movement.
The OP’s table is exactly this engineering challenge, just in a different plane.
I’ve built a lot of cabinets with those types of hinges, and in my experience, that’s not what they do. I just checked several of my cabinets to make sure. They don’t move the door in a straight line and then start tilting – they tilt from the initiation of movement. The reason they work on inset doors is because there is typically a 1/16" or so of space between the door and the cabinet wall, which allows the door to tilt without the rear corner of the door hitting the cabinet. That’s why I said that if a small gap is acceptable to the OP, then there are many hinges that will work. But if he really wants the lid perfectly flush to the rim as in his drawing, that’s a different situation. Granted, for a door that’s only 1/4" thick, the necessary gap will be very small.
Specifically, assuming the movement is perfectly hinged at the top corner of the lid, the gap would need to be sqrt(L[sup]2[/sup] + 1/16) - L, where L is the width of the lid from the hinge side to the other side. For a 12 inch lid width, the gap would only need to be about 3 thousandths of an inch.
It depends entirely on the type. Some of them really do pull out (almost) flat, then start to turn.
A tiny bit of clearance will be necessary regardless.
We’re talking about pretty much the same thing. The ends of the top can be beveled for a tight fit. The frame just needs matching rabbets. The hinged end of the top is moving down so it catches in the angle below the frame. The angle on the other end is undercut to hit the frame. These cuts are a little tricky.
Also, the edges of the top will need some reinforcement. Fill the exposed cells with reinforced epoxy, and I’d suggest additional framing underneath around the perimeter.
