Smashed 746 repair & restoration

[andy1702]

One of the things I enjoy most about telephone restoration is repairing old parts rather than fitting new ones. Although there are quite a lot of reproduction parts around (some better than others) for our UK phones, it's always better to fix the originals. So with this in mind, I've now almost perfected all kinds of restoration techniques for ABS plastic cases.

This particular example is a GPO 746 dating from 1974. It came from Sheffield Steam Rally last year, from a stallholder who saw my telephone display and informed me he had one on his stall I might like. So i went over to have a look, but was greeted with a very sorry sight. The case was broken right up the front, below the dial. In addition there were pretty large chunks missing out of both front corners and the whole thing was filthy. The only good point was that the phone was in the relatively rare 'concord blue' colour.

After expressing my disappointment at the damage and explaining it made the value almost nil, the stallholder asked me what I thought it was worth. I said something like "a fiver for spares", so that's what changed hands and I came away with it.

I've done a restoration of a smashed ABS case before, but that one had been damaged in transit so I had all the pieces. With this one I didn't have any of the broken bits so I really did think all I'd be doing would be using it as a source of spares. However I don't like breaking up anything, especially old and historic stuff, so it sat around for a few months. Then, quite by chance, I discovered that the liquid plastic I made by disolving scrap ABS in acetone could also be turned into a lind of plastic putty by letting some of the acetone evaporate off after melting. This gave me something akin to modelling clay, which could be appled to the broken areas of the case and sculpted to shape. To help it stick to the old case I wet the broken edges with neat acetone before applying my 'ABS putty'. Then once the correct shape, I rubbed ober the repaired area with some neat acetone on my finger to blend the soft part to the old case, much the same way as a potter would blend the handle onto the body of the pot.

After a couple of days for the whole thing to dry out, I did the final shaping with 80 grit sandpaper, followed by a wipe with neat acetone to get the surface something like level and flat. The repaired areas still need to be polished up, which I will do with an acetone / methylated spirit mix and then finish with Brasso. I know a lot of people use Novus, but it's expensive, difficult to find over here and (in my opinion) totally unnecessary.

Here are a few pictures of the progress so far.

[LarryInMichigan]

Very nice!  I wish that my repair skills were so good.

Larry

[HarrySmith]

Nice, good work!

[WEBellSystemChristian]

Wow, great work!!

The color matching alone is pretty fantastic, even though you used body pieces to make the putty.

[Hotline]

Great job on the colour matching 

Would this method of using scrap ABS work on repairing small damage on Diakon cases?

[RotarDad]

Thanks for sharing - this this really great stuff!!!  Please continue to document the remainder of your repair process.  I do like that color!

[cihensley@aol.com]

Good restoration.

Chuck

[Nick in Manitou]

Impressive!

[280Parka]

That's a great solution!  Especially for colored plastic parts that need close matching.  I've passed up many phones due to missing cracked pieces in the plastic that, before now, I thought would be impossible to repair.  Could you go into a little more detail of your process of making the "putty" from bits of plactic and acetone?  Where did you get the plastic to use?  From somewhere inside of the phone that you can't see?  Great repair tip!

[andy1702]

That's a great solution!  Especially for colored plastic parts that need close matching.  I've passed up many phones due to missing cracked pieces in the plastic that, before now, I thought would be impossible to repair.  Could you go into a little more detail of your process of making the "putty" from bits of plactic and acetone?  Where did you get the plastic to use?  From somewhere inside of the phone that you can't see?  Great repair tip!

Next time I do this repair I'll document it a bit better so you can see more of the details. The plastic I used was from a spare dial bezel of the same colour, which I sacrificed only to find a broken one a few days later!

To make the putty I used a small glass jar that had previously containde meat paste. I broke up the plastic as small as I could by hand and put a few bits in the bottom of the jar. I then added a little acetone. Just enough to make a small pool in the bottom of the jar. I then replaced the lid and left it. The plastic starts to liquify immediately, but might take a couple of days to completely melt. If you're luck and you've judged it right, you'll have a thick, sticky but smooth mess in the bottom of the jar. Now if you let the acetone evaporate a little the gunge will begin to harden. The trick to make the putty is to scrape it out of the jar (I used an old teaspoon for this) when it's still pliable enough to shape, but it's hard enough not to be sticky to the touch. I used some liquid acetone brushed onto the surface I wanted to stick the putty to. After moilding it into shape I also wiped the whole surface over with liquid acetone to blend it in with the rest of the case. Think of how a potter blends the handle onto a cup or teapot and that's the technique, but using acetone not water. I used my finger and ended up covered in acetone / plastic, but it's not toxic, just a bit messy.

The only problem I've encountered so far was when I did a bit of sanding to the repaired area and found some microscopically small bubbles in the putty. These were not noticable until I started polishing with T-Cut, but the residue got into the tiny indentations and turned white when it dried. It should be possible to solve this by polishing smooth with more neat acetone, but I haven't got around to trying that yet.

Considering the case on this phone has a break under the dial which extended right down to the bottom edge of the case and a big chunk totally missing out of each front corner, I think the repair is pretty good. You can still see the fix if you know where to look (as I say, I need to polish those micro-bubbles out) but it means an original case that was only fit for the bin will now hopefully see many more years of service.

[FABphones]

...The only problem I've encountered so far was when I did a bit of sanding to the repaired area and found some microscopically small bubbles in the putty. These were not noticable until I started polishing with T-Cut, but the residue got into the tiny indentations and turned white when it dried. It should be possible to solve this by polishing smooth with more neat acetone, but I haven't got around to trying that yet...

Did you have any luck solving the 'micro bubble' issue?

[andy1702]

I haven't tried again yet as I ran out of acetone (the pound shop started selling something else as nail varnish remover) and I've only just managed to get a new supply.

I did find a badly damaged grey 746 in the bottom of a box the otehr day though, so I'll have a go at restoring that one and document the process more when I get a minute.

[mentalstampede]

That's a pain; acetone "substitute" is nothing of the sort!

[andy1702]

I've been back to Poundland today and found two types of nail varnish remover on the shelf. there are big bottles, that look the same as the old small acetone bottles but bigger. These are not pure acetone. But there are small bottles, that now have a different label, which says they are 99% acetone.

So basically buy the small black bottles and you should be ok. 

What the other 1% is I have no idea! Maybe colouring as it's a slight pink colour.

[FABphones]

I originally tried 3 or 4 different bottles of 'Acetone Nail Varnish Remover' (from the manicure kit we already had), none of them worked so had to buy a bottle from the DIY store. That one works a treat.