Looking for adhesive suggestions

Don M

I have a plastic part that is broken and I'd like to glue it back together. It's the swivel mount for the AM ferrite rod antenna on the back of a 70's Pioneer stereo receiver. I'm not sure what type of plastic it is. Seems slippery, shiney and maybe a little waxy. Possibly nylon?

Anyway I first tried super glue. Didn't hold. Then super glue for plastics. That held for a short minute then came apart. Next I tried 2 part epoxy made for plastics. Held a little longer but then broke. I should mention that the parts fit snug together and that I let each one cure for 24 hours plus before applying any pressure. The adhesives I used were all Loctite brand products.

Anyone have any suggestions? Someone told me to try the adhesive you see advertised on TV that you cure with a UV light. I always felt that was a gimmick but have not heard any actual experience with it.

W9GFO

If it is nylon then I don't think there is any glue that will hold well. If it is ABS then you may be able to solvent weld it together using acetone. Generally the most successful repairs I have done with plastic involves super glue (or epoxy) and thread (or unwaxed dental floss) to reinforce. If the geometry allows it, I think that would be the most durable solution.

A picture of the broken part would be helpful.

DigitalBob

I would call loctite and ask one of the chemical engineers what glue would be best for nylon, teflon etc. I doubt it would be teflon because of cost.

potatohead

If you do not mind thickening it a little, you can paint on whatever epoxy did stick a little, then lay fibers in one direction, let it get tacky, re apply epoxy, and let it set firm.

Repeat and put fibers in the other direction.

Repeat that for a few layers. Sewing thread can work great. Use a lot of them, like every half mm or so.

If you wrap those around the part in the direction where that is possible, and make sure the fibers cross the break and engage both parts in the other direction, you will end up with a very strong composite.

You do not need to let it dry completely, but you do want a firm set.

Also important to avoid stress during the process.

Takes a bit to do, but I have been surprised more than once at the outcome.

Phil Pilgrim (PhiPi)

"Slippery, shiny, and maybe a little waxy" describes polyethylene rather well. If it's linear poly, it can be heat-welded back together. Cross-linked poly requires a whole 'nuther process. After a wide search when I cracked a roto-molded c-l poly kayak, I came across this site:

https://epoxyworks.com/index.php/gluing-plastic-with-gflex-epoxy/

By using the recommended G/flex epoxy and following its instructions to the letter, I was able to repair the crack, and it's as strong as the original poly ever was.

-Phil

radciffkaty1

You must try hot glue. According to me, this is the best long-term option.

Mickster

Anyone have experience with Sugru?

Don M

Here's a couple pics. The parts are in order of assembly. The spring is rather strong. When the cap is screwed in on the bottom to tighten spring is when the piece breaks off again.

zappman

Your best bet, for a long term solution to your "broken plastic antenna mount", might be to create a 3D model of the "mount" and have a replacement part 3D printed using black ABS plastic.

jones

zappman wrote: »

Your best bet, for a long term solution to your "broken plastic antenna mount", might be to create a 3D model of the "mount" and have a replacement part 3D printed using black ABS plastic.

If that turns out to be feasible, and if any surrounding structure allows it, you might consider modifying the model. It looks like there might be enough room between the mounting holes for some fairly thick gussets extending from the sides of the ball cup down to the flange, which should add some strength.

Don M

Actually I think I'll just buy one from Ebay. I've spent as much or more already in glues and time.
https://ebay.com/itm/Pioneer-SX-1250-SX-1050-SX-950-SX-1010-Base-Mount-Holder-for-Antenna-W72-092/142935922017?hash=item2147a51561:g:IHwAAOSwEzxYZtbk

Don M

Looks like someone else tried the 3D printer path.
Not very nice looking and in fact is not at all like the original.
https://ebay.com/itm/Pioneer-NEW-AM-Antenna-Mount-Base-SX-950-1050-1250-1010/271677290831?_trkparms=aid%3D333200%26algo%3DCOMP.MBE%26ao%3D1%26asc%3D20170829074220%26meid%3D0b7f6b456f4d4835993a0e358656dc6d%26pid%3D100817%26rk%3D1%26rkt%3D12%26sd%3D142935922017%26itm%3D271677290831&_trksid=p5713.c100817.m4967

Publison

Don M wrote: »

Actually I think I'll just buy one from Ebay. I've spent as much or more already in glues and time.
https://ebay.com/itm/Pioneer-SX-1250-SX-1050-SX-950-SX-1010-Base-Mount-Holder-for-Antenna-W72-092/142935922017?hash=item2147a51561:g:IHwAAOSwEzxYZtbk

I could have sold you an original I have. I would have cost you $1,200 as it's attached to my SX-1250.

Don M

I have a 1250 as well along with a pair of HPM-100's. This 1010 I'm repairing.
Also rebuilding a pair of these...

zappman

Don M wrote: »

I have ..... a pair of HPM-100's. ...

I also own a pair of HPM-100's. They don't build them like the HPM-100's anymore: Tweeter, Super Tweeter, Mid-Range and a real Woofer.

erco

In general, bonding nylon or polyethylene is going to be very difficult. From my experience, your best options are to use a special superglue & primer combination such as https://www.homedepot.com/p/Loctite-2g-Plastics-Bonding-System-681925/100371829 or the primer at https://express.google.com/u/0/product/8336390961989007373_1632106490908152924_7472660 with a good quality superglue.

Don't even bother with cheap superglues. Use Loctite or other proven brands. Clean off any other glues you have tried prior. I like thick CA glue (Great Planes) and accelerator (zip kicker or equivalent).

Finally, per jones' comment, you want to build up MASSIVE material gussets outside. MASSIVE. Rough up the entire outside area for best adhesion with a rough file and/or rotary tool, and build several layers of coating, alternating glue/kicker etc.

MASSIVE. Did I say massive? Assume that the fracture area provides no strength and that 100% of the repair is external.

MASSIVE. Ugly but functional.

Don M

Erco- I did use Loctite products and in particular the exact one you mentioned for plastics. Didn't hold. I ordered and received a replacement from Ebay.

Don M

Regarding the gussets and "build-up" good idea but it would not look original which is important in maintaining its originality.

Mark_T

When I had plastic parts like that that failed, the only thing that worked was wrapping heated wire around
as a splint that slightly melted into the part, and that wasn't easy to get right. Here there is significant
mechanical load, the repair needs to be stronger than the original really, since it failed.

Dremel/machine out a new part from a block of delrin?

Ditto for aluminium, and add an insulating gasket/bushings to maintain electrical isolation?