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Old 26th Dec 2018, 1:00 pm   #1
stevekendal
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Default Plastic cabinet (drastic) repair

Santa sent me a nice red plastic Murphy U572, but failed to pack it adequately before sending via courier. The right hand side is a bit of a jigsaw, but I will make it look half decent eventually. Your suggestions please re glues and filling etc? Its a fragile piece to start with.
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Old 26th Dec 2018, 1:44 pm   #2
Boater Sam
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Default Re: Plastic cabinet (drastic) repair

Edge stick it all together getting the best close fit for every piece with good quality superglue.
Brace it inside with plastic or thin wood and epoxy resin.
Let it set for 2 days then rub it down with fine wet and dry with superglue sparingly in the cracks so the dust fills them up. Polish to finish
I usually achieve an almost invisible repair this way but if all else fails its a paint job.
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Old 26th Dec 2018, 2:08 pm   #3
merlinmaxwell
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Default Re: Plastic cabinet (drastic) repair

If it is made of polystyrene or similar I would go with a solvent weld type of glue, available from model shops. It leaves the plastic the same, no differing material in the joints.
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Old 26th Dec 2018, 2:28 pm   #4
David G4EBT
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Default Re: Plastic cabinet (drastic) repair

According to the article at the link below, the cabinet isn't plastic - it's brown Bakelite sprayed red, later also available in beige. If that is indeed so, an invisible repair is much easier as the whole cabinet once repairs, can be primed with high build primer, then resprayed the desired colour of red. There's such a wide variety of shades of red auto aerosols that an exact match should be achievable.

It will have been well towards the end of the valve radio era, having a printed circuit board:

http://www.classicwireless.co.uk/Murphy_U572.htm

Good luck with it.
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Old 26th Dec 2018, 3:30 pm   #5
stevekendal
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Default Re: Plastic cabinet (drastic) repair

It isn't bakelite, its red plastic and is reponding well to poly cement. Like making an Airfix kit really. Will just need strengthening later.
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Old 26th Dec 2018, 3:45 pm   #6
merlinmaxwell
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Default Re: Plastic cabinet (drastic) repair

It looks thin enough to be polystyrene or a close relative, when gluing with poly cement (it can be had in very usable dispenser types, better than tubes) ignore the bits squeezed out of the joints for at least a week, then rub down and polish. You can hand assemble the bits one by one, leaving a few minutes twixt operations, the glue remains slightly flexible for a while allowing one to do the whole job bit by bit and leaving a twiddle factor for final alignment. Practice on a broken CD case or the like. The "solvent only" glues are not very good for this job.
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Last edited by merlinmaxwell; 26th Dec 2018 at 3:45 pm. Reason: clarification of bits squeezed out
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Old 26th Dec 2018, 5:47 pm   #7
G6Tanuki
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Default Re: Plastic cabinet (drastic) repair

When I've had to rebuild [small] things made out of this sort of material I've drilled 1.5mm holes into the edges of the broken parts and used Superglue to embed short hard stainless-steel pins into one edge, then - with matching holes in the other edge - Superglued the two faces together. The pins provide the real mechanical fix and stop the join from parting when faced with temperature-cycling.

#1 advice - leave it for a week after glueing. Superglue may seem 'hard' after half an hour but it gets a lot better after a few days!
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Old 26th Dec 2018, 8:01 pm   #8
TonyDuell
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Default Re: Plastic cabinet (drastic) repair

If you can find a solvent for the plastic (dichloromethane, sold as 'plastic weld' is a good one to try first) then what I do is :

Put the pieces together

Run a brush dipped in the solvent along each of the cracks. The solvent is drawn in by capillary action and will cause the plastic to weld along the cracks. DO NOT push the pieces together hard when doing this you do not want to squeeze out the softened plastic. Use a natural bristle brush, some of the synthetic bristles disolve in said solvent with unpleasant results.

Now take a piece of cotton fabic and cut it to cover the back of the repair area. An old cotton dress shirt will be fine, or a good sewing shop will have something (maybe an offcut, which iwll be cheap). Put that over the back of the repair area and 'paint' it with the solvent. When the plastic has softened, force the fabric into the softened area.
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Old 27th Dec 2018, 1:50 pm   #9
valveaudio
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Default Re: Plastic cabinet (drastic) repair

For adhesive try PLASTI-ZAP This is the best I have ever used.

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