IBM 5153 Plastic Repair

[Flamin Joe]

Hi,

I was wondering if anyone here knows what type of plastic is used in the IBM 51xx series CRT's? I have a 5153 of which the plastic has become quite brittle and as a result during transit all four corner mounts which attach the CRT tube to the front have cleanly snapped off so I'm looking to re-glue it. The thing is, taking into account the brittleness of the plastic and the amount of stress these four points have in holding the CRT tube in place I'm trying to devise the best way to fix it using the best possible plastic glue/adhesive, which is why I need to know the type, eg PVC, PET, ABS etc..etc.

The idea I have so far is to glue a 4mm wide dowel in each of the places where the plastic is cracked (taking into account they will need to be shorter for the part where the CRT tube mounts) as well as of course gluing along the crack. Then I plan to use either an epoxy filler or hot glue to go over not only the crack line but also any gaps going right down. My thoughts on this is to try and create a strong base to reinforce the already brittle plastic.



My thinking too into the type of glue to use is that I'm hoping to be able to use a plastic cement glue which breaks down or "melts" the plastic and fuses back together when it dries. In that case I was considering using plastic dowels instead of metal which would fuse to the plastic inside creating what I think would be a nice strong bond. I've had mixed results in the past using other glues so I'm quite liking this idea. Thoughts?

 

[Chuck(G)]

You (technically) don't want "glue"--you want a solvent cement. I believe that the 5153 case is ABS and MEK (methyl ethyl ketone) when used sparingly, will do the job and the "weld" will be as strong as the original. You can also use methylene chloride (dicloromethane), which is somewhat more aggressive in its action. You can also get specific formulations from plastics supply places, such as TAP Plastics.

Needless to mention, don't put the stuff where you don't want it.

 

[MissArgent]

If you're in a fix, cyanoacrylate-based glues also seem to do the trick but don't look the most natural. Mine recently had an accident lately and it did the job in terms of helping assemble my new IBM jigsaw puzzle.

 

[mediasponge]

You (technically) don't want "glue"--you want a solvent cement. I believe that the 5153 case is ABS and MEK (methyl ethyl ketone) when used sparingly, will do the job and the "weld" will be as strong as the original. You can also use methylene chloride (dicloromethane), which is somewhat more aggressive in its action. You can also get specific formulations from plastics supply places, such as TAP Plastics.

Needless to mention, don't put the stuff where you don't want it.

Please take care, folks. MEK and Methylene chloride are extremely hazardous chemicals. Wear a mask that has filtering for organic compounds. If you can smell it wearing the mask, it's not the right kind of mask. The right masks are readily available. Use one, and wear gloves.

 

[Chuck(G)]

In the quantities (drops) needed for plastic solvent repair, it's likely not to be hazardous even to those (such as myself) operating without the benefit of gloves or mask. There's a quart can of the stuff sitting on my workbench this very moment--you can purchase it at most hardware, big-box or paint stores. Dichloromethane is a bit more hazardous, but still unlikely to hurt you in sub-milliliter quantities.

I'll bet you're one of those who uses a mask and fan when soldering with lead-based solders...

Gasoline is one of the more hazardous (both in terms of carcinogenicity and toxicity) substances around--and we let little old ladies pump their own. Grecian Formula 16 hair dye contains lead acetate.

Quite honestly, I don't trust the safety of municipal drinking water (ammonia, chlorine, choramine, etc. added--none of which is particularly healthy).

 

[mediasponge]

In the quantities (drops) needed for plastic solvent repair, it's likely not to be hazardous even to those (such as myself) operating without the benefit of gloves or mask. There's a quart can of the stuff sitting on my workbench this very moment--you can purchase it at most hardware, big-box or paint stores. Dichloromethane is a bit more hazardous, but still unlikely to hurt you in sub-milliliter quantities.

I'll bet you're one of those who uses a mask and fan when soldering with lead-based solders...

Gasoline is one of the more hazardous (both in terms of carcinogenicity and toxicity) substances around--and we let little old ladies pump their own. Grecian Formula 16 hair dye contains lead acetate.

Quite honestly, I don't trust the safety of municipal drinking water (ammonia, chlorine, choramine, etc. added--none of which is particularly healthy).

No need to get personal. As a matter of fact, I use lead based solder fixing old radios and test equipment. Washing up with soap and water is all I do after that. If you actually read the label on a can of MEK, I'm only echoing similar warnings. At least open a window, OK?

 

[Chuck(G)]

Sorry, but it just seems that the world has slipped off the edge of sanity when it comes to ordinary substances.

Drop a thimblefull of mercury in a school classroom and the hazmat team gets called out. That sort of thing.

Life is dangerous by nature--and yet people put benzene-laded rubber tires on their vehicles and lived with tetraethyl lead in their gas tanks and asbestos in brake linings.

I do use ventilation when using carburetor cleaner--it makes me woozy otherwise.

 

[mediasponge]

Sorry, but it just seems that the world has slipped off the edge of sanity when it comes to ordinary substances.

Drop a thimblefull of mercury in a school classroom and the hazmat team gets called out. That sort of thing.

Life is dangerous by nature--and yet people put benzene-laded rubber tires on their vehicles and lived with tetraethyl lead in their gas tanks and asbestos in brake linings.

I do use ventilation when using carburetor cleaner--it makes me woozy otherwise.

I used to work in a semiconductor fab. We didn't have chemicals that gave you cancer 30 years later, we had chemicals where you were dead before you hit the floor...

 

[lowen]

Like the fun chlorine trifluoride? The stuff that can burn sand?

 

[MissArgent]

Safety's a bit of a "better to have it and not need it than to need it and not have it" kind of thing in my book. Granted, there's a difference between short-term exposure and long-term exposure, but at the end of the day I figure being overly cautious and losing a bit of time's better than debilitating injury or illness.

 

[fatwizard]

Even if you melt the plastic back together, won't it still be brittle? I would think it would be no stronger than it was before it broke. I like the plastic dowel idea, but I would be tempted to use epoxy. Something like Gorilla brand epoxy. It mixes easily and cures harder than any plastic I know of. I use it to mend laptop cases and it's amazing.

Not long ago I spent hours desoldering chips from an old motherboard I was trying to repair, so lots of smoke from the flux. I had put it up for the night when I began to feel very unwell . I felt like I was going to be sick so I headed for the bathroom. I came to lying on the floor just outside the bathroom door. I have been careful about ventilation ever since.

 

[Hugo Holden]

Hi,

I have been through this with a 5153 monitor. I got an excellent result, stronger or as strong than before by using 2 part expoxy resin, 24 hour Araldite here in AU (called JB weld in a USA I believe) . It sets very hard and gives a great bond. (don't use the 5 min variety). I also built up the bond with an additional layer of glue. On a pair of the broken areas with flat adjacent surfaces I also deployed a small brass plate (about 0.7 mm thick and about 1cm x 2cm size) with some tapped 2mm metric ISO screws to stabilize strengthen the fracture as well as the glue under and over the plate. Much like plating an orthopedic fracture, but in miniature. I doubt if I could break these off again if I tried. When finished the surface can be painted matt black and the repair is nearly invisible except for thickening in the area from the glue and it is super strong.

This old brittle plastic is not suited to attempt to dissolve it back together with solvents. I would not consider attempting to "fuse" it back together like this and get some sort of imaginary molecular bond, it will be too weak. Cyanoacrylate is too brittle when dry and too runny when wet (though the gel version is better) and often not as strong as its cracked up to be.

 

[MissArgent]

Even if you melt the plastic back together, won't it still be brittle? I would think it would be no stronger than it was before it broke. I like the plastic dowel idea, but I would be tempted to use epoxy. Something like Gorilla brand epoxy. It mixes easily and cures harder than any plastic I know of. I use it to mend laptop cases and it's amazing.

Not long ago I spent hours desoldering chips from an old motherboard I was trying to repair, so lots of smoke from the flux. I had put it up for the night when I began to feel very unwell . I felt like I was going to be sick so I headed for the bathroom. I came to lying on the floor just outside the bathroom door. I have been careful about ventilation ever since.

Texture might be a question, too - the 5153's chassis has a subtle texture to it, similar to the weird spackle paint thing the 5150/5160/5170/etc. have going on with their cases. Fusion might result in textureless gaps depending on how wide your joins are... possibly. Not so sure. Slight scarring's better than a gaping hole, at any rate.

 

[Hugo Holden]

Texture might be a question, too - the 5153's chassis has a subtle texture to it, similar to the weird spackle paint thing the 5150/5160/5170/etc. have going on with their cases. Fusion might result in textureless gaps depending on how wide your joins are... possibly. Not so sure. Slight scarring's better than a gaping hole, at any rate.

Fortunately, these CRT supports crack off inside the housing, so the surface appearance when fixed is not too critical unlike an exterior cabinet crack where that texture issue is difficult to regenerate.

 

[Chuck(G)]

Not long ago I spent hours desoldering chips from an old motherboard I was trying to repair, so lots of smoke from the flux. I had put it up for the night when I began to feel very unwell . I felt like I was going to be sick so I headed for the bathroom. I came to lying on the floor just outside the bathroom door. I have been careful about ventilation ever since.

I do lots of sheet brass soldering with bars of 50-50 solder (more lead than the electronics variety) using acid flux (hugely corrosive; NH[sub]4[/sub]Cl, ZnCl[sub]2[/sub] and HCl) and an acetylene torch for 30 years. I can't ever claim to have been affected (that I can tell) from the fumes. That doesn't even count the "hard" (silver-bearing+copper) soldering that I do--the flux there is really nasty (borax + sodium fluoride).

For electronics, I've often made my own soldering flux from bass rosin (I like Pops) and ethanol. Still hasn't affected me.

I desolder boards using a hot-air gun and a bucket. No effects yet after many sessions.

I can't explain your reaction.

 

[Flamin Joe]

Hi,

I have been through this with a 5153 monitor. I got an excellent result, stronger or as strong than before by using 2 part expoxy resin, 24 hour Araldite here in AU (called JB weld in a USA I believe) . It sets very hard and gives a great bond. (don't use the 5 min variety). I also built up the bond with an additional layer of glue. On a pair of the broken areas with flat adjacent surfaces I also deployed a small brass plate (about 0.7 mm thick and about 1cm x 2cm size) with some tapped 2mm metric ISO screws to stabilize strengthen the fracture as well as the glue under and over the plate. Much like plating an orthopedic fracture, but in miniature. I doubt if I could break these off again if I tried. When finished the surface can be painted matt black and the repair is nearly invisible except for thickening in the area from the glue and it is super strong.

This old brittle plastic is not suited to attempt to dissolve it back together with solvents. I would not consider attempting to "fuse" it back together like this and get some sort of imaginary molecular bond, it will be too weak. Cyanoacrylate is too brittle when dry and too runny when wet (though the gel version is better) and often not as strong as its cracked up to be.

I think your right I'll go with the Araldite which I had actually been looking at the other day but wasn't sure. I assume by the 24 hour you mean the Super Strength? Bunnings just has the "90 seconds", "5 minutes" and "Super Strength" which has an initial bond time of 6-8 hours with maximum strength after 3 days.

I had ideas of reinforcing much like you did but using some strong duct tape and then gluing over it right down to the bottom. I think with how brittle it is it's going to need that reinforcement all the way down or else I can just see it breaking once again just in a different place.

 

[mediasponge]

I think your right I'll go with the Araldite which I had actually been looking at the other day but wasn't sure. I assume by the 24 hour you mean the Super Strength? Bunnings just has the "90 seconds", "5 minutes" and "Super Strength" which has an initial bond time of 6-8 hours with maximum strength after 3 days.

I had ideas of reinforcing much like you did but using some strong duct tape and then gluing over it right down to the bottom. I think with how brittle it is it's going to need that reinforcement all the way down or else I can just see it breaking once again just in a different place.

There's a saying in auto racing, "A layer of epoxy, a layer of duct tape and another layer of epoxy does NOT count as composite construction!" I've had good results using the JB Weld (US) full strength backed up by thin plates of Aluminum. In a non-appearance area, there's nothing wrong with backing up the Epoxy.

 

[mediasponge]

Like the fun chlorine trifluoride? The stuff that can burn sand?

We had HF, which etches glass. I have to shudder anytime I see somebody recommending HF as the answer to something. HF is sneaky, you don't feel it until it's already attacking your bones. We also used Aqua Regia, and the so-called 'Piranha' etch that would take the meat off a chicken leg in 10 seconds. By 'dead before you hit the floor' I refer to Diborane and Arsine. We also had Phosphene, not to be confused with Phosgene, the WWI chemical weapon. Then there was the fun stuff like Silane, which bursts into flame on contact with air (pyrophoric), and dichlorosilane. Needless to say, I worked my way out of the Fab into design work...

 

[Hugo Holden]

Super Strength[/URL]? Bunnings just has the "90 seconds", "5 minutes" and "Super Strength" which has an initial bond time of 6-8 hours with maximum strength after 3 days.

Yes, the super strength variety. This was the initial formulation, but of course people wanted quicker setting resins, but they are softer. The super strength is unbeatable. I once used it to bond three planks of wood for the top of a home made coffee table, it is still perfect more than 25 years later.

 

[fatwizard]

I do lots of sheet brass soldering with bars of 50-50 solder (more lead than the electronics variety) using acid flux (hugely corrosive; NH[sub]4[/sub]Cl, ZnCl[sub]2[/sub] and HCl) and an acetylene torch for 30 years. I can't ever claim to have been affected (that I can tell) from the fumes. That doesn't even count the "hard" (silver-bearing+copper) soldering that I do--the flux there is really nasty (borax + sodium fluoride).

For electronics, I've often made my own soldering flux from bass rosin (I like Pops) and ethanol. Still hasn't affected me.

I desolder boards using a hot-air gun and a bucket. No effects yet after many sessions.

I can't explain your reaction.

I was using a heated solder pump, and because of my bad eyes, I was hunched over a magnifying lamp which was right over the work. My skills at desoldering are marginal at best, so I'm slow. I obsessively worked on this board like that for several hours, basically huffing the smoke the whole time. At my age it certainly could have been caused by other things, but I felt poisoned and the timing seemed to belie coincidence.