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AuthorTopic: What's the material of the A1200's case ?  (Read 191 times)

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Offline Jose

What's the material of the A1200's case ?
« on: November 10, 2019, 04:39:18 PM »
I accidentally got a small chunk off a corner near the floppy drive. Nowadays it's possible to find specialty glues for many types of materials, so I was wondering if anyone knows what specific plastic the A1200's case is made of.
Maybe there were various materials depending on the factory...

By the way, I've been out of here for a few years (was only checking AWorld from time to time) and it's nice to see some familiar nicknames back again.

Cheers
\\"We made Amiga, they {bleep}ed it up\\"
 

Offline TribbleSmasher

Re: What's the material of the A1200's case ?
« Reply #1 on: November 10, 2019, 04:48:33 PM »
It is plastic, noone knows the specifics.

You can try to 'melt' it back onto the case with acetone, but be careful and try it somewhere on the inside beforehand to be sure it works.
 

Offline Jose

Re: What's the material of the A1200's case ?
« Reply #2 on: November 10, 2019, 04:55:28 PM »
I tried a cyanoacrylate based super glue and it fell off right away when it was subject to some pressure (it's on a point of contact with the other half of the case). I took care to let it set in for more than a day...
Acetone, I rather not make experiences at this point, I'm sure I'm gonna ruin it... It's surface is probably already altered because of the cyanoacrylate...
\\"We made Amiga, they {bleep}ed it up\\"
 

Offline pyrre

Re: What's the material of the A1200's case ?
« Reply #3 on: November 10, 2019, 06:21:05 PM »
I have had success with loctite superglue on computer plastic parts....
have never, though tried on amiga parts...

I have also used soldering iron and plastic filament from 3d printer/pen... does not look pretty. but it seals the plastic off....
Just don't do that to the outside....
I fixed a "bruder" tractor my todler has as his favorite toy. tossed it away and broke some parts. used superglue (loctite) and soldering iron and filament.
Still works nice....
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Offline TribbleSmasher

Re: What's the material of the A1200's case ?
« Reply #4 on: November 10, 2019, 07:03:22 PM »
@Jose
If you find the right glue you can glue a small plate onto the inside of the case holding the broken off part in place without showing the gap to much by adding glue to it.
Melting would come to mind again, if the afore mentioned plate is of metal.
 

Offline Jose

Re: What's the material of the A1200's case ?
« Reply #5 on: November 10, 2019, 07:33:05 PM »
Found it, it's made of ABS.
https://www.amiga-shop.net/Amiga-Hardware/Amiga-Cases/Brand-new-Amiga-1200-cases::857.html?language=en
Also, if you look a the bottom of the case from the inside it says ABS.

So now I got to get the patience to find a strong ABS glue, hopefully the acrylate residue won't screw things up...
\\"We made Amiga, they {bleep}ed it up\\"
 

Offline TribbleSmasher

Re: What's the material of the A1200's case ?
« Reply #6 on: November 10, 2019, 07:45:00 PM »
Nooo!

These are new cases, without the bromide included to the composition of the plastic in the past that causes yellowing and crumbling of those old cases nowadays.

It might still be some kind of ABS, but certainly not the same as the original ones.
 

Offline Jose

Re: What's the material of the A1200's case ?
« Reply #7 on: November 10, 2019, 08:55:40 PM »
"...
This new case is the perfect solution to make your Amiga 1200 bright and shine again and while being made of ASA Plastic (instead of ABS on the original cases). It will no suffer any yellowing."

I don't know if the original was pure ABS though, but seems to have been mostly made of it, at least judging by the yellowing of some old ones..
Then again, there's probably many other things that also yellow....
\\"We made Amiga, they {bleep}ed it up\\"
 

Offline rkidd7952

Re: What's the material of the A1200's case ?
« Reply #8 on: November 11, 2019, 02:30:22 PM »
Solvent welding using acetone is the best technique I've found for repairing ABS.  I've done it successfully on several computer cases and car parts.  I've even been able to salvage hopeless looking screw holes that shattered into three or four pieces.  Don't worry about the verbs melt or weld - it's really not any harder than applying CA glue.

I'd practice on a piece of junk ABS first.  I use a q-tip (aka cotton swab, cotton bud - a little piece of cotton on a stick) to apply a thin coat of acetone to each side of the broken piece, then press them together.  If it's a piece that will be visible, try to bias the acetone toward the inside corner, leaving the outside corner dry.  The pieces still stick together within 10 seconds, then just let it sit to evaporate.  After the acetone evaporates, I usually go back and add another coat or two to the inside face of the crack to get the plastic to flow into the crack a little more.

Acetone will immediately change the appearance of the surface, so be careful to keep it toward the inside face.

I agree that the CA residue may interfere with the weld.  If there's room to affix a plate on the inside, as suggested earlier, I would try to weld a plate cut from some junk ABS. 

You might be able to sand back the glued surface to reveal clean ABS, bevelling the wall toward the inside of the case and leaving the outer face untouched.  After applying acetone, add some bits of pulverized ABS to fill the gap.  I haven't tried this technique.  It might be tricky to get a bevel on the thin wall section, and it would leave a thin point on the outside face that may be easier for acetone to leak through and make a visible mark.

In my experience, the most common things to break on plastic parts are tabs and clips that hold pieces together.  They tend to break right where they flex.  Due to the need to flex, those will probably always be a marginal repair.  Every time I've tried to repair a tab with CA, it breaks as it flexes on reassembly.  Solvent welded tabs will usually go back together at least once.

Super glues also seem to be a one-shot deal in my experience.  The first repair is reasonably strong, but subsequent repairs fail quickly.  Since you're not adding foreign material to the joint, solvent welding works about as well on later repairs as on the first.

Robert
 

Offline rkidd7952

Re: What's the material of the A1200's case ?
« Reply #9 on: November 11, 2019, 02:43:50 PM »
Here are a couple pictures of solvent-welded repairs.  The first is on a Sun case.  The bottom edge of the front panel clips into the bottom plate.  You have to rotate the top case forward to disengage the clips, which wants to twist and break the thin section under the 5.25" bay.  Using the technique I described earlier, you end up with just a hairline crack visible in the outside face.

The second is a generic CD-ROM enclosure.  This shows what acetone welding looks like on the welded surface.  The tab bends inward and cracked in the outer face.  I don't really care about the cosmetics on this case, so I applied acetone to the outside face without being too careful.  The repair is strong enough to survive flexing during reassembly.

Robert
 
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