1960s-1970s Telephone Repair

J. B. Wood prodded the keyboard with:

You could always try a steel pin heated hot enough to sink into the plastic, a bit like a staple, or cross drill it and press a staple in the holes.

Glue the broken parts back together but do NOT reinstall them in the phone. Instead, find someone with a 3D digitizer and 3D printer who can make a reproduction of the original. I'm not familiar with SC phones, but the equivalent part in a Western Electric wall phone is a flat plate with two rectangular holes. That can probably be machined out of plastic. I couldn't find a photo with Google Images.

Are you sure about the model number? The SC number was SC-554 while the WE number was 2554.

SC-554:

WE 2554:

There is a line of products of which Plastic-Weld is one that I have used w ith much success over the years for similar types of problems. This is a s olvent based "glue" that actually dissolves the plastic a bit and reforms i t. The joint essentially disappears. Caution though, don't press together too much or you will deform the plastic. Only apply enough pressure to be sure that the two parts meet firmly.

Dan

Thanks for the response, Jeff. The number stamped on the back of the instrument is S-C 2554BPM. Perhaps the "2" designated a DTMF type dial? Sincerely,

Thanks for the follow-up, Dan. Are you referring to one of the products from

If so, is there a specific one from this company that you can recommend? Thanks. Sincerely,

Mpfffff... take out the part. Put it back together with JB Weld - available everywhere. Be sloppy with the material, but make sure that you do not glu e the part to anything else. I will on occasion tie such a part together wi th fine thread (if there are holes through it, even better) and suspend it during the curing process. Then with files, X-Acto and sandpaper, reshape t he part to its correct size, removing flash and sprue, so to write. Re-dril l any filled holes and you are done. JB Weld will be harder and stronger th an the OEM plastic by a considerable margin.

Peter Wieck Melrose Park, PA

I have had good luck with some plastic parts using Gorilla super glue.

In most cases, I would suggest super glue - Gorilla or otherwise. But many

to be one of the materials used to deliver super-glue as it does not stick to Delrin. I am not stating that this particular part is Delrin - but a gre at many friction and contactor parts are made from that material because of its self-lubricating and excellent insulating properties. Further to this, it naturally repels metallic dust and powder, such as could build up and a rc.

JB Weld *does* stick to Delrin reasonably well, and has enough self-integri ty to bridge and fill.

Peter Wieck Melrose Park, PA

The product I am referencing is NOT JB-Weld. The product is made by Plastruct and is called Plastic Weld. It is a clear liquid not an epoxy that actually dissolves the plastic and allows for reformation. It is considered a plastic solvent and cement.

Dan

Dan:

If that part *is* Delrin, it will be entirely impervious to Plastic Weld. As will be many high density, self-lubricating plastics.

The material you suggest is useful on the polystyrene/acrylic based materials, not so much on others.

Peter Wieck Melrose Park, PA

Ah, that's a better number. There's one for sale on eBay if you need parts:

It's impossible to get into a discussion on adhesives without everyone recommending their favorite potions, concoctions, and methods. I'll just make things worse.

My guess(tm) is that the plastic in the phone is probably ABS (acrylic butyl styrene) which will weld nicely with acetone solvent. There are overpriced potions available that are mostly acetone, but might include other solvents (MEK, toluene, etc).

Superglue (cyanoacrylate) is too brittle and mutilates acrylics.

Urethane adhesives, such as Gorilla Glue, don't do well with many plastics because they do NOT contain any solvents. Fortunately, the phone switch insulator (or whatever it's called) sees force in only one direction, so marginal adhesives will probably work, for a while.

Just to muddy the waters, I've been learning plastic welding using some home made brass nozzles attached to my SMT desoldering station hot air gun. When it works, it works great. When I do something wrong, it destroys the part. Plastic welding works best for me on large plastic parts, and not so good on small plastic parts.

I'm also a fan of hot melt glue, but that's not appropriate for this job. However, if you do decide to try hot melt glue, be sure to get the correct type of adhesive stick:

Good luck.

A URL is amazingly helpful: The MSDS at: says that it's: Methylene Chloride (Dichloromethane) 80-90% Methyl Ethyl Ketone (MEK) 5-15% Yep, that will certainly work for ABS, PVC, and various styrene plastics.

However, methyl chloride is rather dangerous. The EU banned the stuff in 2011. It was commonly used for furniture stripper before it was recognized as hazardous: Suggestion: Use the stuff outdoors and wear the usual protection (breather, glasses, gloves, etc).

Plastruct video: (1:23)

I don't know what kind of plastic your part is but there is a two part plastic cement that bonds well to many of the plastics that are hard to glue. I don't remember the name but I think it is made by Loctite which has lots of epoxies and the like at hardware stores. Anyway, the stuff is made specifically for plastic repair, not general repair jobs like JB Weld (which is pretty good stuff) and 5 minute epoxy and the like. I have used the stuff and it worked very well. Smelled bad when curing but no smell once cured. I even used it in a test repair. The radiator in our Toyota Camry developed a crack in the upper plastic part of the radiator. I ordered a new radiator and while waiting for it tried this plastic repair stuff. I cleaned and roughed up the plastic, slathered on the glue, then I laid a piece of cloth which was saturated with the glue on top. After it set the car was driven for a couple weeks before I replaced the radiator. The patch never gave up and the radiator got hotter than the recommended highest temperature for the glue. I don't know how long the patch would have lasted but since it was on the car I installed the new radiator. Eric

Methyl chloride (CH3Cl) != methylene chloride (CH3Cl2). The stuff with the shorter name is pretty evil, but the longer stuff you can practically drink. (Just joking, kids. Don't drink paint remover.)

Cheers

Phil Hobbs

CH2Cl2.

Cyanoacrylate resin and MEK as "activator". Works quickly and great for most plastics. However, the MEK tends to dry out prematurely in the bottle. Have some extra MEK handy if you're going to use it. Also, make sure everything is free of grease or it won't stick.

Oops. Thanks for the correction. I thought they were the same stuff.

Grumble... Jeff L.

Greetings Jeff, The stuff I'm talking about is not a cyanoacrylate resin and activator system. It is two parts that must be mixed and then applied. This is the stuff. I think. See the link:

Eric

ABS=Acrylonitrile butadiene styrene.