Strong flexible plastic glue?

[JOEPRO]

I need to quickly glue these heater box knobs back on. Small contact area as they are meant to flex a little in use.



Its 1989 plastic so they snapped off with very little resistance sadly.

Is there a glue I can order from amazon that is strong for plastic and flexible? Or do I use hot melt glue of no other ideas?

Maybe this stuff?

 

[Seadog]

 

[JOEPRO]

View attachment 519664

I should have mentioned I tried a loctite plastic super glue and it was no good for this application. Too thin for a.start and cracked apart easily

 

[tigdlo]

Loctite 380 may work but it is also quite thin, have you got a photo of the job?

 

[Puglet1]

I’ve tried JB weld plastic weld and have had great results with it. It’s a 2 part putty in a tube which reacts when rolled together.
It sets hard after about 25 minutes but is more of a moulded / bulky repair that can be reworked / sanded etc. If it is a straight 2 surface adhesive that you’re looking for, it may not work for you

 

[JOEPRO]

Loctite 380 may work but it is also quite thin, have you got a photo of the job?

Photo didnt attach first time around - now in post #1

 

[Dapph2]

I should have mentioned I tried a loctite plastic super glue and it was no good for this application. Too thin for a.start and cracked apart easily

Looks like a solvent weld that plumbers use for hard non oily plastic pipe joints might work . lightly smear some on both parts , let it start to dissolve the plastic then press both parts together with out moving them for a minute or so

 

[Kram]

If the plastic is ABS, quite likely so, you can rough up both parts and coat in a thin coating of a thickly mixed ABS/acetone slurry (drop some scrap abs parts in a small sealed pot, add small quantity of acetone)
Strength will be somewhat like new plastic, the disadvantage is it will take a while to fully set and slightly soften the surrounding ABS as the acetone escapes, tho it will harden up fully once its gone. In cold weather that can be slow.


Perhaps a better option is the isocyante containng polyurethane permenent rubber glue, as used for wetsuit repairs and I have used for climbing shoes. Its very flexible, strong and sticks to nearly anything. Takes a good 24h to fully cure

 

[dobbslc]

Can you get to the back of it and put a small self tapper through it with some glue?

 

[roofman]

Ct1

 

[steveo3002]

any of the 2 part plastic glues should be fine , they're very good and its not a stupid repair to attempt

always used innotec brand at the bodyshop , doubt that's avail on amazon , and some will need a gun unless you inventive with the mixing

 

[Gareth J]

Whatever you use, you'll need to make the repair stronger than the original as it'll surely break again. Even if the joint doesn't fail, due to the weak design/again plastic the next bit of plastic to it may just crack.

Bulking out the repaired area with a putty type glue or thicker glue might spread the stressed area out enough for it not to fail. Or you could glue it then strategically drill and pin with some thin rod. Even a few bits of 1mm might wire.

 

[steveo3002]

Whatever you use, you'll need to make the repair stronger than the original as it'll surely break again. Even if the joint doesn't fail, due to the weak design/again plastic the next bit of plastic to it may just crack.

Bulking out the repaired area with a putty type glue or thicker glue might spread the stressed area out enough for it not to fail. Or you could glue it then strategically drill and pin with some thin rod. Even a few bits of 1mm might wire.

id trust a decent 2 part glue to fix that for years without any extra reinforcements

 

[Gareth J]

id trust a decent 2 part glue to fix that for years without any extra reinforcements

If the parent material is up to it, yes. But the OP suggests this broke because the original plastic is not so tough as it once was. For a repair to last now, it needs to add more strength the part, not to make it the same. If that makes sense.

 

[steve_s]

This will do the job
https://www.ebay.co.uk/itm/364959277810

 

[dobbslc]

https://giantmonster.tumblr.com%2Fpost%2F160120988798

 

[iNf]

Black Stixall
https://amzn.eu/d/ae6P3gh

 

[Turbo]

View attachment 519664

I have used that on auto plastic before and it is surprisingly strong.

 

[ukracer]

This will do the job
https://www.ebay.co.uk/itm/364959277810

Does that come in clear as well?

 

[JOEPRO]

Thanks all for the replies - this photo may show the items in more context



(Not sure why forum software turned photo 180)

The little tabs are a no longer available part and besides that they are moulded into the heater box assembley so its the whole 1/2 heater box you havw to buy if it was available.

So glue is really the only option. I will sand the parts to give extra surface area then clean them with pure acetone before using the jb weld plastic epoxy to glue whilst not putting too much on so some flex is still possible.

I will report back on the JB weld plastic epoxy performance.