# A new door hinge doesn't lay flat

I'm replacing the door hinge (with a spring hinge so that it closes by itself) then a new hinge doesn't fully "lay flat". Sorry it's hard to describe but see in the following pics that the hinge on the right hand side is not fully touching the wood surface. With this I can't really screw the hinge.

I'm guessing the two other hinges above and below (the hinge in question is the middle) have the knuckles with smaller diameter but the width of the hinge is bigger, hence the spacing between the door and the wall is too tight for the new spring hinge.

(Top is the current (all 3 hinges on this door seem to use the same model?), bottom is the new spring hinge)

What are the appropriate solutions? I'm inclined to just replace the two other hinges with the same/similar size of knuckle and the hinge plate, which is kind of costly but ok to me.

• @tetsujin might be right, but my gut says you won’t be able to align the pivot points both when the door is open and when the door is closed. The simplest solution by far is matching all hinges. Dec 22, 2021 at 20:52
• @AloysiusDefenestrate - it's fairly elementary math/trig. As the centre planes of each hinge pass directly through the fulcrum on both hinge types [by design], then aligning correctly in 2D space as seen from either end, you basically have concentric circles, nothing more, nothing less. Your variation is in the mortice depth, in that the absolute centre of any hinge/fulcrum plane is the centreline of the plane's thickness, not any face. Even with 'fat' & 'skinny' hinges, that's probably <0.5mm variance. Most people can't mortice that accurately anyway ;) Dec 23, 2021 at 18:54

## 3 Answers

Edit. I'd initially ignored the fact that you haven't yet cut the new mortices, I'd assumed that was a given.
Yes you need to cut mortices, but you also need to shift the fulcrum inward by the difference in radius of your old hinge knuckle & new. Otherwise as you try to open the door the new more distant fulcrum will try to push the door into a bow-shape.
The reason they won't yet open to press flat against both door & jamb is because the knuckle is hitting the door edge already, yet its fulcrum is still beyond where it must be to operate correctly. You need to cut this further in. Just offered up this way, your fulcrum is too far out.

Because the standard way to install hinges is with the knuckle as tight to the door as possible, you now have one hinge where the fulcrum would naturally fall further out because the knuckle is twice as wide.
You have three choices, of varying cussedness…

1. Chop more out of the door & jamb for your third hinge to sit in tighter, so the fulcra line up vertically through all 3.

2. Relax the other two outwards, to the same end result. This might require chamfering the opposite face so it clears the frame.

3. Replace all three hinges. This might also require the chamfer.

Poorly-scribbled illustration…

Because the distance A is larger than with your original hinges, you need to cut the mortices to make the distance of A the same as the old hinges, by cutting in deeper, in the direction of the green arrows, than it looks when just offered up. This will require chamfering out a small section of the door 'corner' to accommodate the knuckle.

The mortices aren't deep enough for the thicker hinge leaves. Spring hinges impart force and need more strength, so they're heavier. This creates an angular problem.

Predrill and screw the hinge lightly in place, then trace the leaves. Deepen the mortise to at lease the leaf thickness. All should be well.

A good way to do this is to trace the leaf with a very sharp utility knife, especially where the trace crosses the wood grain. Be careful not to slip and scar your door. Then use a sharp chisel and light taps with a hammer to slice parallel to the grain.

• This isn't really the issue. If the OP mortices as offered up in the pictures, the opened door will be under tension [possibly enough to split something] because of the shifted fulcrum. Dec 22, 2021 at 16:19
• & btw, I don't mean to come over as argumentative, honestly. This is just one of those times where if the OP does it the 'regular' way, they'll end up doing it twice. Dec 22, 2021 at 16:36

I wouldn’t worry about it. Your old hinges opened beyond a 90 degree your new open to exactly that. You should take the door down, put new hinges on, and then rehang your door. That is how you install new hinges. Never really seen hinges replaced while door is still hanging. But if you insist on changing your hinges as so I would firmly screw hinge to door and almost snug hinge to jamb, tightening down once all 3 hinges are on. The door won’t open as far as it did with old hinges but that comes with the type of new hinge you are installing

• I get it.not required to pull door 1st when installing hinges. But when you are installing hinges that are a different size than the ones being replaced smart move is to pull door first. This way there’s no restriction from other attached hinges if need to move door off center of old hinges & in not driving screws into old holes that may not line up square with new hinges. Actually to many mishap elements to replacing different size and model hinges while door is hanging that’ll require at end to pull door and do twice n more the work. smarter to spend10min n pull and rehang door Jan 4, 2022 at 20:17