UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Cabinet and Chassis Restoration and Refinishing

Notices

Cabinet and Chassis Restoration and Refinishing For help with cabinet or chassis restoration (non-electrical), please leave a message here.

Reply
 
Thread Tools
Old 3rd Oct 2020, 6:57 pm   #1
John Mann
Triode
 
Join Date: Nov 2009
Location: Banbury, Oxfordshire, UK.
Posts: 42
Question Glue for plastic

Hi All, I am restoring an RGD R130 transistor radio. Internally, the PCB support pillars have all broken off. I was thinking of gluing with epoxy resin and then adding a reinforcing fillet. But the epoxy glue says "not suitable for polyethylene or polypropylene".

I don't have much knowledge of plastic types but I think the case may possibly be one of the above. Any recommendations for a suitable glue? Obviously it has to take the weight of the PCB so needs to be a good strength.

Thanks, John.
John Mann is offline   Reply With Quote
Old 3rd Oct 2020, 7:17 pm   #2
Bazz4CQJ
Dekatron
 
Bazz4CQJ's Avatar
 
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 3,126
Default Re: Glue for plastic

Might be worth taking a look at (say) Loctite's website. I cannot recall ever having dealt with this particular problem myself.

B
__________________
Data beats opinions most times... that's my opinion, though I have no data on that.
Bazz4CQJ is offline   Reply With Quote
Old 3rd Oct 2020, 7:35 pm   #3
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 9,451
Default Re: Glue for plastic

I'd suggest perhaps using a small amount of any glue you intend to use, to bond the head of a flathead screw to some not-normally-visible part of the inside of the plastic case. Leave it for a few days then see how easy it is to remove the screw.

That way you'll at least get to see if the glue bonds successfully, or whether it turns the plastic into a quivering, slimy gelatinous mess.
G6Tanuki is online now   Reply With Quote
Old 3rd Oct 2020, 7:36 pm   #4
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 17,456
Default Re: Glue for plastic

Polyethene needs a solvent adhesive, such as that sold for solvent welding polythene waste pipes.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 3rd Oct 2020, 7:44 pm   #5
Boulevardier
Heptode
 
Join Date: Sep 2017
Location: Bristol, UK.
Posts: 770
Default Re: Glue for plastic

I'm about to embark on the same repair of mounting pillars on a 1980s Soviet radio (discussed on another current thread). Knowing exactly what formulation of plastic you're working with is pretty well impossible. I'm about to try "Araldite Standard" two-part epoxy (which gives the same warning as yours). I will let you know how it goes. If you get to try G6Tanuki's test before I do, please do let us know the result

Mike

Last edited by Boulevardier; 3rd Oct 2020 at 7:56 pm.
Boulevardier is offline   Reply With Quote
Old 3rd Oct 2020, 8:12 pm   #6
Bazz4CQJ
Dekatron
 
Bazz4CQJ's Avatar
 
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 3,126
Default Re: Glue for plastic

Quote:
Originally Posted by Station X View Post
Polyethene needs a solvent adhesive, such as that sold for solvent welding polythene waste pipes.
I'm not 100% sure, but I think the pipes you can join using solvent welding are PVC and ABS. I think those adhesive are based on acetone and basically liquefy the surface for a while. Acetone doesn't react with polyethylene.

B
__________________
Data beats opinions most times... that's my opinion, though I have no data on that.
Bazz4CQJ is offline   Reply With Quote
Old 3rd Oct 2020, 8:22 pm   #7
wave solder
Hexode
 
wave solder's Avatar
 
Join Date: Feb 2007
Location: Chesterfield, Derbyshire, UK.
Posts: 280
Default Re: Glue for plastic

The Pipe adhesive that I use is MEK based and very good it is too.
wave solder is online now   Reply With Quote
Old 3rd Oct 2020, 8:55 pm   #8
Bazz4CQJ
Dekatron
 
Bazz4CQJ's Avatar
 
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 3,126
Default Re: Glue for plastic

I'm pretty sure that, like acetone, MEK doesn't dissolve PE or PP
__________________
Data beats opinions most times... that's my opinion, though I have no data on that.
Bazz4CQJ is offline   Reply With Quote
Old 3rd Oct 2020, 8:56 pm   #9
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 15,009
Default Re: Glue for plastic

I'd be surprised if a radio case were polythene or polypropylene. They're usually something more brittle polystyrene perhaps or ABS.
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is online now   Reply With Quote
Old 3rd Oct 2020, 9:18 pm   #10
Bazz4CQJ
Dekatron
 
Bazz4CQJ's Avatar
 
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 3,126
Default Re: Glue for plastic

Ah, well spotted that man.
B
__________________
Data beats opinions most times... that's my opinion, though I have no data on that.
Bazz4CQJ is offline   Reply With Quote
Old 3rd Oct 2020, 10:11 pm   #11
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 4,033
Default Re: Glue for plastic

My recollection is that polythene/polyethylene and polypropylene have a soapy feel and by their nature cannot be glued or bonded. Something to do with the molecular structure. I think that plastics of these types were used in some of my children's toys, and when they broke I had to mend them using mechanical fastenings such as wire, small rivets or screws as nothing would stick to them. Possibly the radio case would be ABS or Polystyrene in that era, which can be mended using solvents or epoxy adhesives. I remember that the Polyclens paint brush cleaner that was around circa 1960 could be used for assembling Airfix kits as it dissolved polystyrene. Where a pillar needs some extra support, or part of it is missing, I use Plastic Padding. Plastic Padding seems hard to come by these days, so I use Ronson wood filler, which seems to be much the same product.

Edit: crossed with Herald!

Last edited by emeritus; 3rd Oct 2020 at 10:20 pm.
emeritus is online now   Reply With Quote
Old 3rd Oct 2020, 10:29 pm   #12
Boulevardier
Heptode
 
Join Date: Sep 2017
Location: Bristol, UK.
Posts: 770
Default Re: Glue for plastic

Quote:
Originally Posted by emeritus View Post
Where a pillar needs some extra support, or part of it is missing, I use Plastic Padding. Plastic Padding seems hard to come by these days, so I use Ronson wood filler, which seems to be much the same product.
I haven't tried it, but have picked up the impression that two-part epoxy can be used for replacing small mouldings and for filling gaps in broken parts (though a rather expensive way of doing it). Am I misinformed?

Mike
Boulevardier is offline   Reply With Quote
Old 3rd Oct 2020, 10:53 pm   #13
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 16,436
Default Re: Glue for plastic

two part epoxy can, also the resin and hardener for glassfibre work is a cheaper alternative available in larger quantities.

If beefing up or repairing a pillar of a moulding, you can get a big boost in strength by including threads or a wrapping of threads in the wet stuff before it sets.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now   Reply With Quote
Old 4th Oct 2020, 12:00 am   #14
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 4,033
Default Re: Glue for plastic

Plastic Padding sets quickly ( often too quickly) , which can be useful. It is also stiff and will stay in place better than epoxy adhesives like Araldite. For runny epoxy, strategically-placed pieces of masking tape can be used to stop the epoxy running away from where it is needed.

I have mended things like plastic knobs for D-shaped shafts where the boss with the D-shaped socket is cracked, by winding stainless steel wire around the boss and then embedding the wire in Araldite. When "Proops" was stlll in Tottenham Court Road, they once had a consignment of government surplus medical wire. I bought some coils of s/s dental wire in various gauges and hardnesses, and some brass ligature wire, all of which have been useful for making various repairs. The fine stainless steel wire is very flexible and I have mended broken unglueable plastic parts by sewing them together with the wire, first drilling rows of small holes in both parts and threading the wire through the holes using a sewing needle , thereby pulling the broken parts into engagement.
emeritus is online now   Reply With Quote
Old 4th Oct 2020, 8:32 am   #15
Ambientnoise
Heptode
 
Join Date: Feb 2006
Location: Marlborough, Wiltshire, UK.
Posts: 680
Default Re: Glue for plastic

I have successfully used “plastic weld” on such pillars. Available from model shops etc, it produces a solvent welded joint. I think it is MEK. If bits are missing, then epoxy can be used to build it up but mechanical reinforcement such as binding wire, metal pegs etc are useful.
Ambientnoise is online now   Reply With Quote
Old 4th Oct 2020, 8:57 am   #16
mark_in_manc
Octode
 
Join Date: Nov 2011
Location: Manchester, UK.
Posts: 1,372
Default Re: Glue for plastic

Emeritus's suggestion of using wire is a good one. Steel guitar strings are a good source of wire in controlled diameter. And for something-like-Araldite-but-a-bit-thicker-so-it-doesn't-run-away - try a methacrylate glue like Plexus (expensive) or scigrip (cheaper). But watch out - it goes off in about 2 mins.
__________________
"The best dBs, come in 3s" - Woody Brown
mark_in_manc is offline   Reply With Quote
Old 4th Oct 2020, 9:45 am   #17
John Mann
Triode
 
Join Date: Nov 2009
Location: Banbury, Oxfordshire, UK.
Posts: 42
Default Re: Glue for plastic

Thanks for all replies. I'm currently trying the test glueing suggestion and so far no disasters!
John Mann is offline   Reply With Quote
Old 4th Oct 2020, 9:49 am   #18
John Mann
Triode
 
Join Date: Nov 2009
Location: Banbury, Oxfordshire, UK.
Posts: 42
Default Re: Glue for plastic

Quote:
Originally Posted by Herald1360 View Post
I'd be surprised if a radio case were polythene or polypropylene. They're usually something more brittle polystyrene perhaps or ABS.
Thanks Chris, it's certainly a hard plastic which will break with a big enough impact or stress, but I don't have the knowledge to say what it is.

Hope you are keeping well these days, I take it you are not working at OMT these days?

John.
John Mann is offline   Reply With Quote
Old 4th Oct 2020, 9:51 am   #19
John Mann
Triode
 
Join Date: Nov 2009
Location: Banbury, Oxfordshire, UK.
Posts: 42
Default Re: Glue for plastic

Quote:
Originally Posted by emeritus View Post
I remember that the Polyclens paint brush cleaner that was around circa 1960 could be used for assembling Airfix kits as it dissolved polystyrene.
I remember Polyclens. I was using it as a brush cleaner back in 1973 and had it in a margarine tub or similar. I left it while I went out, on return the tub had dissolved away!
John Mann is offline   Reply With Quote
Old 4th Oct 2020, 10:48 am   #20
Humber888
Heptode
 
Humber888's Avatar
 
Join Date: Jul 2012
Location: Bromley, London, UK.
Posts: 647
Default Re: Glue for plastic

Loctite 'All Plastics' superglue is specifically designed to bond 'soapy' plastics such as polypropylene, polystyrene, polyethylene, PTFE, etc. It's a two part glue with an 'activator' and also glues china, rubber, metal and wood. I have used it to successfully repair all sorts of cracked plastic, including the gears on an HP8640B. Don't use it if you just want to surround a weak point with something that will harden off and provide some additional support. Expect to pay at least 5 for a small tube and buy it only when needed as it does not have a particularly long shelf life and tends to bung up the nozzle.
Humber888 is online now   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 4:15 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.