A heavy door can put a lot of faith in a couple of hinges. Put those hinges too close together, and you may be asking them to work a lot harder than they need to.
Proper hinge spacing helps manage the forces created by the weight of the door. Giving the hinges more distance can reduce the force they need to resist. And when that distance isn't available, the hinge itself may need to do some heavier lifting.
Of course, your product design may have other ideas about where those hinges can go. When mounting space gets tight, the hinge design has to pick up the slack.
So, how much space should you give them?
Hinges may only take up a small part of the design, but where you put them can change how much work they have to do. Move them too close together, and the forces going through the hardware can increase.
That can affect:
There isn’t one hinge spacing measurement that works for every application. How the door or lid moves changes what those hinges are being asked to handle.
On a left- or right-swinging door, gravity is constantly pulling down at the door’s center of gravity. Because that weight sits away from the hinges, it creates a moment that the hinges have to resist.
The farther apart the hinges are vertically, the less force they need to resist that moment. As the door pulls down:
When the design allows, we like to see the hinges spaced farther apart vertically than the door is wide. That gives the door better support without asking as much of the hardware.
If the hinges have to sit closer together, the design can still work. It may just require a more robust hinge with larger pivot pins or stronger bushings to handle the added force.
In other words, sometimes a few extra inches of hinge spacing can save you from needing a lot more hinge.
With an up-and-down lid, wider hinge spacing still helps, but now stability becomes a bigger part of the conversation. Ideally, the hinges sit as far apart as the design reasonably allows.
Every hinge has some clearance around its pivot. On its own, a few thousandths of an inch may not sound like much. Put the hinges close together on a wide lid, though, and that small amount of movement can become much more noticeable at the outer edges.
Our engineers gave an illustrative comparison using just 0.003 inches of pivot clearance. With hinges 2 feet apart, the lid can feel fairly solid. Move those hinges to only 6 inches apart on a 3-foot-wide lid, and the movement at the end can feel closer to 1/8 inch.
With hinges close together, lifting one side of the lid can cause that side to move before the other catches up. Nothing necessarily failed. The lid simply has enough play to feel loose.
Moving the hinges farther apart helps reduce that effect. The lid responds more immediately when lifted and requires less torsional rigidity to maintain that solid feel.
Sometimes, a tiny bit of play just needs a little too much room to show off.
Ideal hinge placement looks great on a drawing. Then the rest of the product gets involved.
The available mounting structure may limit where the hinges can sit. On an insulated cabinet, there may be only certain areas where the hardware can mount securely. Appearance can influence hinge placement, too.
When the preferred spacing isn’t possible, the hinge design may need to adapt.
|
Design Constraint |
How the Hinge Design Can Adapt |
|
Hinges can’t be moved farther apart |
Use a more robust hinge |
|
Higher forces at each hinge |
Increase pivot pin size or use stronger bushings |
|
Two hinges don’t provide enough support |
Add a third or fourth hinge |
|
Mounting locations are restricted |
Pair hinges or reconsider the mounting structure |
|
Insulation limits mounting space |
Adjust the cabinet design or insulation around the mounting area |
These constraints are why we want to think about heavy-duty hinge installation early in the design process. If the proposed hinge placement creates higher forces than we’d like, we can look at the hinge itself or talk through changes to the mounting area before the design gets too far along.
There’s no universal measurement for hinge spacing. The right distance depends on how the application moves and the room the design gives you to work with. Getting those details figured out early leaves more options for the hinge instead of asking the hardware to make up for them later.
A few extra inches between hinges may seem like a small design choice on paper. Once gravity gets involved, those inches can make a pretty convincing argument for themselves.
Hinge spacing is one piece of a much larger motion control puzzle. Our Intro to Motion Control e-book covers the basics behind designing controlled movement into your application.
Download your free copy to get started.