Cracked Hinge on Mac Portable

[techknight]

Thank you, these photos clearly illustrate the hinge assembly.

is this a common problem? I’ve not heard of it before.

Very. I have run into it multiple times, and its because the hinges get stiff. 2 reasons. the hinge plastics shrink a bit, causing the springs to shrink and get hard to move, as well as the lubrication turns to putty.

But also those old polycarb plastics are starting to get brittle in general. That frame needs to be replicated into 3D prints so it can be glued together in halves. somehow.

The fingers of those subframes also break and fall apart ,which hold the motherboard in place. I have seen the rear card support plastic thingy also broken apart and seperated into two.

 

[JDW]

...the hinges get stiff. 2 reasons. the hinge plastics shrink a bit, causing the springs to shrink and get hard to move, as well as the lubrication turns to putty.

I followed your lead and opened my cylindrical hinges, wiped off all visible old grease inside, then dipped one end of a cotton swab in fresh grease and applied that amount. Did you use a lot more grease than that?

I use grease sparingly on my floppy drive lubes, but I'm not sure if that's best for lubing those Mac Portable hinges (the inside part where you see metal).

Before and after I lubed them, I still can't twist them with my bare hands. I need to use my slip-joint pliers to turn them. Is that normal, even after lubing? Or can you turn them with your bare hands after they are properly lubed?

 

[techknight]

I mean, they are supposed to be stiff to hold up the weight and torsional forces of the entire upper display assembly, but they arent supposed to be too stiff. The springs rotate inside the jacket and that is your friction surface.

You can aide in this by removing one of the springs to decrease the torsion resistance in the forward-direction a bit.

There are 6 springs, 3 wound forward, 3 wound backwards. They control the forward and backward tension. You can reduce the forward tension and still maintain the backwards tension, and vice-versa.

 

[JDW]

You can aide in this by removing one of the springs to decrease the torsion resistance in the forward-direction a bit.

Below are photos of mine (before I cleaned out the old grease).
What is your technique to removing one of the springs?
(And are you able to put them back?)

 

[JDW]

I decided to cut a little triangular-shaped piece from my transparent Polycarbonate resin board to solvent weld over one spot that was cracked originally. It didn't crack all the way through there and was the only location where the hinge holder was still holding on. This weld covers more surface area and should be quite strong...



After that cured, I then applied JB-Weld Original 24-hour Cure, and the photos below were taken while it was still wet...





After work, I'll put the machine back together and see how well it holds.


But I'm still curious how to get those "springs" out that @techknight mentioned. It would be nice to ease the stress on the repaired hinge. It's way too stiff now, even though I've re-lubed the hinges. But I have no experience getting them out so if I start tugging on those metal protrusions with needle nose pliers, I'm worried I'll bend or break something, rendering my hinge non-operational.

 

[JDW]

Found photos of another person's broken right-side hinge holder.
Poor guy tried and failed with 3 screws!

If we can eliminate these issues by "spring removal," it would absolutely be worth doing.
I'm just unsure how do it in a way that won't damage the hinges.

 

[Kai Robinson]

At this point it might be an idea to reach out to polymatt on YouTube...

 

[JDW]

At this point it might be an idea to reach out to polymatt on YouTube...

Ah yes, Kai! You mean this brilliant fellow...

But of course, a 3D CAD genius like him would be need for reproducing the entire subframe assembly. But even if it was reproduced, could it easily be printed in polycarbonate (required for strength)? Even if it could, we still need to figure out how to get those extra springs removed, as TechKnight suggested, because it is the sheer stiffness of the hinges that makes the weaker right-side hinge-holder break. Like I said yesterday, it's absolutely impossible to twist either hinge when removed and using my bare hands. I have to use a wrench to turn it.