Why Mortise An Interior Door Hinge?

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GibsonGM
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Re: Why Mortise An Interior Door Hinge?

Post by GibsonGM »

Yes, you're right, the door stop should cover the hinge leaves when closed, and I was implying the (bigger) gap is what you would see with door closed...but anyway, try it some time...hold up an old common hinge in the door jamb, and get a sense of how it looks if it's not mortised...IMO, it looks like junk. This is with the door open, LOL.

It must be more than just my opinion as most all doors have their hinges mortised, no? *shrug* Yes, it is also stronger.

If I saw a typical "old house door" and they were not mortised, I would think the carpenter didn't know what was going on. Just my 2 cents...

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Re: Why Mortise An Interior Door Hinge?

Post by Casey »

Olson185 wrote:
Mick_VT wrote:
Olson185 wrote:
I think "much stronger" might be hyperbole. I do know a tight mortise will resist some small load of the lateral and downward forces of the door's weight should the screw not be completely tight against the hinge leaf. But we all know a tight mortise isn't vital given how uncommon they can be.


wood in compression on the end grain is remarkably strong, I dint think you are giving it the credit it deserves. You can do a simple experiment with this, try twisting off a door hinge which is not morticed vs one that is - my bet is you will find a substantial difference.

I don't believe this is the only reason for mortising, but I do think it is the primary reason - otherwise I believe the mortise would have died out many years ago, especially in commercial construction


I'm referring to the often uncommon incidence of having the bottom edge of the hinge leaf actually touching the end grain presented by the mortise. If there's a gap between the bottom edge of the hinge leaf and the bottom of the mortise pocket then, obviously, the mortise pocket isn't providing any resistance against the downward force of the weight of the door.

When might this happen? Installing a door using 3" hinges where the previous one had 4" hinges. Would I prefer to reuse the existing holes or drill new holes to make sure the hinge rests on the endgrain? Would I prefer to change the mortise locations on the door or the door frame? What happens if I make the mortises on the door frame 1/8" too low compared to the mortise locations on the door? Do I replace the jamb and try again? The point is, there are many reasons why the hinge might not rest against the end grain. In those cases, does it matter?

Remember, in my original question I was presented with a door frame that had been "mortised-to-death" and, while rare, it begged the question, "Was all that mortising really worth it?". I think it might be a matter of "it's best if...." rather than "it's vitally important that...".

You are literally arguing against wood having end-grain strength under compression, but that is exactly where wood is strongest.
Try another more valid argument.
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Olson185
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Re: Why Mortise An Interior Door Hinge?

Post by Olson185 »

Casey wrote:
Olson185 wrote:
Mick_VT wrote:
wood in compression on the end grain is remarkably strong, I dint think you are giving it the credit it deserves. You can do a simple experiment with this, try twisting off a door hinge which is not morticed vs one that is - my bet is you will find a substantial difference.

I don't believe this is the only reason for mortising, but I do think it is the primary reason - otherwise I believe the mortise would have died out many years ago, especially in commercial construction


I'm referring to the often uncommon incidence of having the bottom edge of the hinge leaf actually touching the end grain presented by the mortise. If there's a gap between the bottom edge of the hinge leaf and the bottom of the mortise pocket then, obviously, the mortise pocket isn't providing any resistance against the downward force of the weight of the door.

When might this happen? Installing a door using 3" hinges where the previous one had 4" hinges. Would I prefer to reuse the existing holes or drill new holes to make sure the hinge rests on the endgrain? Would I prefer to change the mortise locations on the door or the door frame? What happens if I make the mortises on the door frame 1/8" too low compared to the mortise locations on the door? Do I replace the jamb and try again? The point is, there are many reasons why the hinge might not rest against the end grain. In those cases, does it matter?

Remember, in my original question I was presented with a door frame that had been "mortised-to-death" and, while rare, it begged the question, "Was all that mortising really worth it?". I think it might be a matter of "it's best if...." rather than "it's vitally important that...".

You are literally arguing against wood having end-grain strength under compression, but that is exactly where wood is strongest.
Try another more valid argument.
Casey


You are not understanding what I am writing. And I know I am writing it correctly because I get paid for writing things correctly. This is my argument:

"I'm referring to the often uncommon incidence of having the bottom edge of the hinge leaf actually touching the end grain presented by the mortise. If there's a gap between the bottom edge of the hinge leaf and the bottom of the mortise pocket then, obviously, the mortise pocket isn't providing any resistance against the downward force of the weight of the door."

Please, show me I'm not experiencing a Twilight Zone moment and copy and paste the part that leads you to believe I am " literally arguing against wood having end-grain strength under compression".
~James

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Re: Why Mortise An Interior Door Hinge?

Post by phil »

I dont' think it's unfathomable to think that you can have a situation where the pocket is a loose fit and the door is supported by the screws only. It isn't good workmanship but if the screws are into good solid wood it's still pretty strong.

I think some of the newer brass colored screws are pretty weak, they seem to snap easy if I drive them with a modern impact driver.

to make things stronger use longer screws to catch the stud behind, otherwise it is easy to stick a pry bar in the hinged side and pry between the door and the frame. It will then split the door frame near the screws ( it's only 3/4" thick).. and i'll open from the hinged side. I think it is even code here that you use at least one long screw. It' doesn't really matter what lock you put on there if you can open the hinged side this easy.. i'd stick at least one 3" screw in there , like a deck screw not a brass one.. no one notices it. you might not care if it's an interior door of course.

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Re: Why Mortise An Interior Door Hinge?

Post by Mick_VT »

A little bit of research turned up some reasoning in an old carpentry book. The reason given there for mortising is pretty much what we have covered here. It says the prime reason to mortise is to stop the screws suffering shear or torque force. i.e it stops sideways pressure on the screws which may eventually cause them to loosen. Secondary to that is it allows the door gap to be small while using a substantial hinge. Te choice of a third or forth hinge can be personal preference, but allows the carpenter to use less substantial hinges on heavier doors.

Aside: Olson, with due respect I do not think you made your question clear at all. It seemed that you were asking "why are hinges mortised?" not something along the lines of "why do hinges still seem to work with messed up or non-existent mortises?" I have looked through your posts a couple of times and still don't get the latter before you claim that was what you asked
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Re: Why Mortise An Interior Door Hinge?

Post by Olson185 »

phil wrote:I dont' think it's unfathomable to think that you can have a situation where the pocket is a loose fit and the door is supported by the screws only. It isn't good workmanship but if the screws are into good solid wood it's still pretty strong.

I think some of the newer brass colored screws are pretty weak, they seem to snap easy if I drive them with a modern impact driver.

to make things stronger use longer screws to catch the stud behind, otherwise it is easy to stick a pry bar in the hinged side and pry between the door and the frame. It will then split the door frame near the screws ( it's only 3/4" thick).. and i'll open from the hinged side. I think it is even code here that you use at least one long screw. It' doesn't really matter what lock you put on there if you can open the hinged side this easy.. i'd stick at least one 3" screw in there , like a deck screw not a brass one.. no one notices it. you might not care if it's an interior door of course.


Thank you, Phil.

"Workmanship" is the consensus I got from a trusted source. Their explanation is that those who installed flush-frame cabinetry needed mortised hinges to keep cabinet doors as tight as possible (vs bugs, dust, & sometimes air) and this habit was used on doorways even though clearance tolerances were not a factor. The habit stuck and now it's one of those "we've always done it this way" things.

When I asked about shearing the screw, the answer was, "it's much more likely the screw would be pulled out of the wood", something a mortise would have no impact on.
~James

Fourth generation in a family of artists, engineers, architects, woodworkers, and metalworkers. Mine is a family of Viking craftsmen. What we can't create, we pillage, and there's nothing we can't create. But, sometimes, we pillage anyway.

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Re: Why Mortise An Interior Door Hinge?

Post by Mick_VT »

Olson185 wrote:
When I asked about shearing the screw, the answer was, "it's much more likely the screw would be pulled out of the wood", something a mortise would have no impact on.


It would have a lot of impact upon all forces other than those perpendicular to the screw - the mortice holds the hinge to stop the screws taking shear force which can indeed loosen them and pull them from the wood over time. A hinge is constantly under load from the weight of the door, this translates into shear force against the screws (somewhat alleviated by friction) if the hinge is not mortised.

I think all this has been covered multiple times above
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Re: Why Mortise An Interior Door Hinge?

Post by phil »

often people find they can prop doors open by jamming the hinge side and that often causes issues since the door then becomes a big lever essentially, and the forces around the hinge and screws are increased beyond their capability.

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