Best adhesive for paxolin

[poppydog]

Can anybody recommend the best adhesive for gluing paxolin please?
I have a circuit board in a 1960s Tesla radio (late fathers day present) that has been very badly damaged in the post and I would like to attempt to repair it.


Regards Poppydog

[crackle]

I use superglue, and use a spare piece of paxolin to bridge over the crack on component side.
Both the surfaces must be thoroughly roughened first.
Avoid breathing any fumes if you have to solder near the joint, the fumes can make your eyes water as well.
But it hasn't killed me yet.
Mike

[poppydog]

Thanks for the reply, I think I will have to put some pics up of the damage to the board. It complicates things having 2 transformers which are quite heavy on/near the break, I don't think there is enough space to bridge the break either.

poppydog

[poppydog]

Here are some pics to show the extent of the damage. Do you think super glue would be man enough for this? The edge of the board that's broke slides into a groove in the cabinet so needs to be strong enough to support the weight of the transformers.

Poppydog

[Goldie99]

As a chemist, I'd hit it with 2- component epoxy, e.g., Araldite or similar (I normally use 5' Araldite). Super glue is fine under tensile stress, but much weaker with any shear / bending stress. Additional pieces of paxolin, or similar, could be added as needed.

Make sure any surface to be glued is roughened, and scrupulously clean, before applying any adhesive. I'd wipe it over with acetone just before applying glue.

Alan

[crackle]

To be blunt I dont think any repair is going to be reliable with that transformer there.
I am assuming the paxolin sheet forms part of the mounting for the transformer and then the paxolin is mounted in the chassis.
It looks like it has broken due to a heavy crash and the weight of the transformer has caused it to shear.
I think I would find an alternative way of securing that end of the board and use insulated stranded wire to make the required connections to replace the lost copper track that was on the missing paxolin.
Mike

[Freya]

I have repaired far worse damage with £ shop epoxy. use selotape to hold everything in place.

[McMurdo]

My old boss used to use epoxy for that sort of thing and I agree. Also good for Bakelite when you drop an AVO off the top of your ladder.

[TowerRadio]

I would say a repair is viable, you can put small bolts with large insulating washers through the transformer rivets to hold everyhing tight.Araldite will do a good job, plus point to point wiring. Les

[Michael Maurice]

Originally Posted by Goldie99

(I normally use 5' Araldite).

Which Araldite is that?

[Radio Wrangler]

I think he means five-minute Araldite, not five-foot
' is sometimes used for angular minutes and " for seconds.

Loctite used to sell an activator spray for their IS-12 superglue. The Aerosol bore the instruction "Spray on both parts, and mate immediately" Always caused a smile when someone new used it.

David

I use Araldite "Precision" for this type of thing, it does take hours to set but sticks like **** to a blanket. There is a quote "Longer is stronger". You could also add a layer of glass fibre tissue too, after the first fix has set again using Arladite.

[Goldie99]

David is of course absolutely correct. 5' Araldite refers to 5 minutes Araldite, correctly called "Araldite Rapid". If it helps at all, I prefer the package with 2 individual tubes, rather than the combined syringe type dispenser - mix 1:1, and you have about 5 minutes to work with it, hence the 5 minutes reference.

Although I normnally prefer to stick to SI units as much as possible, I've used the ' & " notation for minutes and seconds duration since at least my university days, and probably even before that (back to the 60's ?). It's a very useful 'shorthand' when you're trying to take lecture notes, or quickly note reaction & process times.

Alan

[crackle]

I have found Araldite rapid never sets fully hard, you can still make in imprint with a nail after 2 days.
I believe the old fashioned slow araldite sets harder.

Mike

[Goldie99]

Originally Posted by merlinmaxwell

I use Araldite "Precision" for this type of thing, it does take hours to set but sticks like **** to a blanket. There is a quote "Longer is stronger".

I'm inclined to agree, but the difference is probably quite small if the Araldite Rapid is mixed and applied properly (and quickly) - you'll probably also find that if either does subsequently 'fail', it's failed at the adhesive / substrate interface, e.g., the epoxy itself will almost certainly still be intact. The issue there is far more likely to be adhesive failure due to poor surface preparation and cleaning prior to application, or it's an unsuitable substrate for epoxy (Paxolin will be fine).

Originally Posted by merlinmaxwell

You could also add a layer of glass fibre tissue too, after the first fix has set again using Arladite.

Excellent idea - would also be my preference if it indeed has to provide any significant load bearing or structural function.

[Andrewausfa]

I'd go down the Araldite route as well but if you do go down the superglue route on this or anything else then this stuff is pretty good. Same sort of principle as David mention above, superglue and a kicker for an almost instant set. Glue one side, spray then other and then mate as quickly as you can.

Available from your favourite on-line emporiums for around six quid.

https://www.everbuild.co.uk/product/...t-bonding-kit/

Andrew

[Walkmann]

I would go down the superglue route.

I have been using "Hafixs" which is a professional superglue available on their web site. It is about the best one I have found and used and have repaired etc almost every type of material. It bonds solid in about 20 secs and is fully set in about 2 hrs. Just remember this glue is very quick and I would lay the pieces out on a surface that you can peel off after, clingfilm works for me. If you want to use kicker then spray after putting the pieces together, you will find kicker on RC modelling sales web sites

[snowman_al]

I'm not sure adhesive alone will give you the mechanical strength it may need or you would wish.
Why not fashion a 'brace' out of paxolin (or similar) that fits on the copper side. You have the transformer and mounting holes to put screws through to clamp it in place. You can drill holes where the solder pads are so it fits flat.
Then I would use the gel type super glue to repair the original, it gives a little more time to get everything spot on. Repair the tracks with wire links or copper track, make good. Once working then fit the brace.

[Mr 1936]

Hmm, heavy transformer supported only by thin paxolin - not the finest example of mechanical design !

Unlike others, I have often been rather disappointed by the strength of superglue. Maybe OK if you have a very clean break and the glue layer is very thin.

If time is not of the essence and the job can be temporarily braced, I prefer traditional long curing Araldite. As others say, clean and abrade the surfaces where possible. Putting the whole thing in a warm place for a few days also helps it to cure fully. I find that Fibreglass tissue reinforcement, thoroughly stippled with araldite, works very well. Obviously if used on the track side it would be sensible to check out any track repairs before covering them up.

Scraps of Veroboard with the copper removed (hot soldering iron and peel off) are also useful for reinforcement, as the glue wicks up through all the holes and gives a tight bond.

[HamishBoxer]

Talking of Araldite Precision,I have not been able to find it for a long time.Trust it is out there somewhere.