Cracked Hinge on Mac Portable

JDW

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Is this portion of the chassis removable - a subframe?

Yes.

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BOTTOM
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JDW

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is this a common problem? I’ve not heard of it before.
One other person in this thread has the same exact problem. And @techknight has a recent video (mentioned earlier in this thread) showing a Portable with the same cracked hinge holder too. That means there are likely others out there.

Sadly, many Portable owners seem to be hibernating, Stephen. For example, I have tried REALLY hard to get a peep out of the folks in the Mac Portable FaceBook group, but it's like pulling teeth.

Gone are the days of DanTheAppleMacMan on EBAY who often sold Portables. Those guys were really knowledgable and would provide quick answers and feedback, but I never owned a Portable back in those days.

Seems like most Portable Owners these days never use the machines and simply have them in a closet.

Well, I've been working on a video about my Mac Portable for more than a month now, and once that video goes out, I suspect there will be renewed interest. And when people see my crack (ha ha), some may chime in after checking out their own machines.

What I can tell you is that hinge takes a lot of pressure when you close the LCD. A lot! The crack closes when I fully open the LCD. But if I put my thumb and all my might on top of that cracked hinge, hoping to keep it pushed closed while I close the lid... well... that's utterly impossible. So yeah. The lid puts THAT much force on the hinge! It's pretty crazy Apple chose to make it out of something other than metal. Even Portables with that hinge holder intact are ticking time bombs, in my opinion.

Also, when I first got my portable, there were other tiny parts that had broken off that subframe. None were critical. They were just tiny tabs. I was able to get them back on with superglue and they continue to be attached today.

It's because there is so much stress on that HINGE HOLDER that I have taken huge pains and a lot of time trying to figure out how best to CHEMICALLY WELD it back together. But tiny air bubbles compromise the strength of the bond a bit. DCM is better than superglue, by far, but not as strong as the original unbroken part.
 

Stephen

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The broken hinge cannot be repaired with glue, it will continue to break. I suspect that the existing structure can be reinforced economically (such as metal 3D printing).

I’ve been very busy recently but the direction I would explore is a custom 3D printed reinforcement bracket which is screwed into the existing sub chassis. Mounting points should reflect the force direction so that the new holes reinforce the brittle plastic - not weaken it.

FDM may be impractical if there’s limited space available. The metal option is becoming very affordable and would be my first choice.

Maybe it’s time for an old dog to learn new tricks (3D Modeling)? @JDW
 

Paolo B

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The broken hinge cannot be repaired with glue, it will continue to break. I suspect that the existing structure can be reinforced economically (such as metal 3D printing).
Agree: without proper reinforcement it will never work for regular use. 3D printing something out of metal seems to be an interesting proposition, but I am afraid it would just offset the bonding issue somewhere else. Maybe waiting for a chassis to pop up on eBay is the most reasonable proposition, unfortunately many Portables are failing due to the LCD…
 

Stephen

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Agree: without proper reinforcement it will never work for regular use. 3D printing something out of metal seems to be an interesting proposition, but I am afraid it would just offset the bonding issue somewhere else. Maybe waiting for a chassis to pop up on eBay is the most reasonable proposition, unfortunately many Portables are failing due to the LCD…
I am envisioning a perfectly form fitting bracket which is both epoxied and bolted into place — ideally, this will spread the load over the entire upper chassis rather than just the upper segment of the hinge mounth.
 
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joevt

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There appears to be some voids on the underside of the subframe assembly (shown in this image on the left side) that could be filled in with putty to add reinforcement?

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Stephen

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There appears to be some voids on the underside of the subframe assembly (shown in this image on the left side) that could be filled in with putty to add reinforcement?

1764117867312-png.24936
Definitely! This could be a great place to add more support for a bolted on reinforcement bracket - or just plain old reinforcement!

mod anyone tries it, I recommend a two part epoxy. I’m suspicious that this alone won’t eliminate the risk of cracking (could maybe even make it worse?) but it will definitely be stronger.
 

JDW

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What I’m trying to do is avoid a situation that leads to a permanent gluing (via 2-part epoxy like JB Weld 24-hour cure) of the right side cylindrical hinge into its hinge holder. And it is the hinge holder that cracks, not the cylindrical hinge.


Again, if you scroll back through this thread and find the most recent video from @techknight, in that video (I’m on my iPhone now and I’m not going to go hunting for it), he uses some kind of two party epoxy to fix only the crack initially, but then he finds his fully cured epoxy cracked, and then he proceeded to epoxy everything, including the cylindrical hinge that fits inside that cracked hinge holder, making it permanent and impossible to remove the right side hinge ever again. But that wasn’t his machine and he shipped it off to the owner and there’s no way to know whether it has cracked again or not.



I always have to roll my eyes whenever I give disclaimers like I’m going to do right now, because it’s never my intent to say anything that would tear down anybody or hurt their feelings, but I’ll just give this disclaimer anyway: I’m not criticizing anybody for doing anything. I am merely somebody who observes facts and considers what I myself should do in any particular situation. Disclaimer done.



I don’t want to make any fix to disallow removing of the cylindrical hinge because those hinges are lubricated inside and at some distant point in the future may need it again. It also makes removal of the LCD more fiddly.


Look, I’m a very busy person, and I get stressed out when overworked, and to be honest, if somebody sold a subframe assembly that wasn’t cracked on the right side, I’d probably buy it just to eliminate this massive repair headache. I’ve invested so many hours in it already that I’m ready to scream. But my guess is that all hinge holders on the right side are susceptible to cracking in the same way, so swapping out the subframe assembly may not be the most permanent solution, especially if you want to open and close your LCD more than a few times. And anyone who is going to use the machine will open and close it many times. If you don’t, it means you just closeted the machine and that would a real waste!


So it would be wonderful to see an excellent solution that not only can repair existing cracks but also reinforce unit units that haven’t yet cracked.


I’ve also spent hours with ChatGPT and while I know it’s not always accurate, I’m not getting a whole lot of super detailed feedback on this crack issue from real people who have the problem, so I really had no other choice. ChatGPT is adamant that I shouldn’t attempt drilling and screwing anything into the area of the cracked plastics and attempt to fix it because, according to ChatGPT, that may end up fracturing these aging plastics. But the greater problem is, you don’t have a lot of plastic thickness on that hinge holder anyway. Drill or screw more than a couple millimeters towards that cylindrical hinge and you’ll end up drilling or screwing into the cylindrical hinge!