External laptop hinge ?

Duraluminum

I doubt that the hinges are made of Duralumin alloy. Most of them are cheap zinc, which is why they crack and deform so easily.

If you would kindly disclose the maker and model of your laptop, it might be possible to search eBay for a replacement hinge.

I've had zero luck gluing hinges. The forces involved are just too high. I had one old Thinkpad, that I reinforced with sheet aluminum and epoxy. However, the underlying plastic flexed sufficiently to crack the epoxy. The hinge usually breaks through the mounting holes, making repair problematic.

One method that worked was to tack the broken pieces together with SuperGlue. I then cut a slot along the length of the hinge with a Dremel cutoff grinding tool. Into the slot, I pounded a stiff piece of hard steel and covered it with epoxy. Don't use a flexible nail. That's on an old Thinkpad laptop I use for radio programming and has held together for many years.

Rule of thumb. If it looks bad, it will probably work bad.

It's going to be rather difficult to maintain the center line unless you replace both hinges. Even so, an externally mounted hinge will have a different radius of rotation, and thus require a longer connecting cable. I don't think that's going to work. Just replace the hinge(s) and be done with it.

Now, I'm confused about the question. If you're trying to fix a broken cast metal hinge, here's how I do it. Remove the hinge and take it apart. You don't wanna damage the parts that rotate.

Make a jig that holds the two broken parts in alignment and supports it from underneath so it doesn't sag when you heat it.

Use a low temperature torch. Propane is too hot. Use one of the ones with a butane lighter inside.

You just heat the joint and poke at it with a paper clip. When it melts, you stir it a little to close the joint. A little welding rod helps too, but you gotta hammer it really thin so it melts instantly. I use Welco 52, but it's sold at RV shows as "miracle rod" or aluminum solder...at a MUCH higher price.

Be very careful. The temperature at which this works is about a degree cooler than the temperature that makes a big puddle out of the whole thing.

If you put on too much welding rod, just grind it back to shape. It's pretty easy about the third time you do it.

Are we having fun yet?

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I will try and remember your brazing/welding techique for broken lumpy parts such as hinges. By Duralinium I meant the casing of the laptop. The hinges themselves are not broken but the casing for the display section is fully split/loose in the area of one hinge and susbstantially cracked around the other hinge.

Many laptops have a metal strip up each side of the display that's connected to the hinge. Those don't need any plastic to make it work. Might try emulating that.