breaking plastic, breaking RF shield flaps

[lost_lemming]

Ok this is my last thread for a while (honest)

Basically, what I want to say is, it breaks my heart when another bit of plastic breaks... I'm talking the screw thread holes here, not only because it's making the amiga a bit less secure, but this happens to be my amiga500 from my childhood. Also, constant flipping the RF flaps back and forth and caused them to fall off (I only have 1 left intact )
This is all the bottom case, I know this isn't electronic techy thread - but it's still hardware related. What does one do when things like this happen. poor amiga I hate seeing it break slowly because it's 20 year old plastic/metal.

Can I some how put the flaps back on, and how do I think of a way to get the broken bits of plastic back on the screw holes? ... or am I wasting my time?

PS. last thread from me I promise I've gone new-thread mad today and it's probably p%$£S you lot off!

[Photon]

Hehe, np. But that's caring about the wrong thing imo. Real caring is putting your nice mobo in a flawless case/shield instead. You can keep the top half if you want something familiar around the keys...

Usually everything digital electronics can be fixed, it's mechanical stuff that are the real 'killers'. Like broken floppy eject button, how to find one that fits? Or those little pesky plastic tabs on the A600, no way to close the case properly.


Me, I don't care about the hardware at all as proven by misc hardware shots :P Well... maybe a little.

As a tip for future shieldtabbenders: I usually leave'em pointing straight up and never touch'em. Except the ones that are in the way when closing the case.

[Secret Vampire]

broken screw holes/posts can be repaired by sticking them back together with superglue, a suitable plastic cement or epoxy resin, and then building up the area around the breakage with car body filler or more epoxy (But epoxy tends to run when used in large quantities) to strengthen it. I've had good success with this technique reattaching broken screw posts to the front panel of an A2000 that had apparently been thrown in a skip, and repairing old headphones where the casing had broken around the point where the cans attach to the headband. if the screw posts are beyond saving then you could remove the remains and install plastic threaded spacers of the correct length, or any suitable plastic tubing using the same method.

Where plastic threads have been stripped, and the plastic around the screw hole is intact, a drop of glue, not enough to fill the hole, but just enough to coat the inside edges and allowed to set properly (Will probably take weeks to fully go off for most UHU/Bostik type things, polystyrene cement might be a bit quicker and will probably be more secure in the long term) should give the screw something to bite into provided you're not a barbarian with the screwdriver, try to avoid the temptation to use oversized screws.

Replacement shield tabs could be manufactured by cutting them from a spare piece of shielding with a large base, something like this:

   / \
  _| |_
 |_____|

and soldering the base to the original shielding using one of those handy disposable lighter powered gas torches that maplin sell for about £5 (Do remove the shielding from the motherboard, protective plastic undersheet, and case before attempting this). Pretty much all my Amigas live without top shielding though with no ill effect...

other tricks? cracked plastics can be glued together but will not be as strong as they originally were, cut a flat piece from the outside of an old floppy disk and glue it behind the repair for added strength (This probably won't work if the area is subject to bending stresses).
Model engineers can probably fabricate much stronger replacements for broken bits which can somehow be installed with no visible change to the outside of the casing, people with normal levels of tools will have to be content with what they can achieve with a dremel or similar, which is quite a lot if you use your imagination and bits of wood to make jigs and holders.

Injection moulding is not practical in a home setting, but there are now a variety of pourable plastics that can be used to 'cast' short production run plastic parts with silicon moulds, you could even use plasticene moulds for a one-shot copy of an existing plastic part, I wonder how tricky a floppy button to retrofit more modern drives would be?

I'm not sure any of this will provide a fix for the A600 tabs though, you could probably make a stick on clone, there's enough space in there, but the reason they broke in the first place is the amount of stress on them, I'm currently performing an experiment with epoxy putty and will report back with pics if it's succesful, right now it looks like I stuck a couple of bits of used chewing gum to my A600

[Secret Vampire]

Success!

The back is a bit untidy, but at least the case top shouldn't flap about once it's put back together.

What I did:

1. Stick some blobs of epoxy putty to completely cover where the original case tabs would be.
2. Eat pizza while the putty cures.
3. Attack blobs with mini drill equipped with cutting disk, drum sander and pointy burr to remove material until I had a shape that would fit the holes in the top case.

I'm quite happy with this as a hack, only time will tell how long the repair lasts.

[lost_lemming]

Secret!!!!!! that is a nice case mod!

your reply before that is amazing and i've saved it to print out later on cause that will be some major help. Because if anything, I want to strenghen my original a500, rather than using spare parts that I never had back-in-the-day, if I did that - then my retro gaming sessions wouldn't 'feel' right.
of course, I'll have to spend some money buying some kit, don't have everything you mentioned but I will have a crack at this once I've go the electronic side of things working 101%! thanks again Secret

[Washac]

Hi All


Would'nt this stuff help us with our enlarged Screw holes and cracked cases etc

http://www.amazon.co.uk/HUMBROL-MODE...6496539&sr=8-6