best glue for plastic

prkaye · #1 02-25-2011, 06:40 AM

I need to attach two plastic pieces together (two different GPS mounting parts). There's no room for a mechanical fastener. I tried LePage Extreme Repair, but it wasn't strong enough (after two days of curing I was able to pull the piece off with a little bit of leverage). I'm wondering what the strongest glue would be for this purpose?
I was thinking I would use West Systems Epoxy with 406 Adhessive filler, becuase I've found this to be pretty strong in the past, but is there a better choice that you guys would recommend?

ColoCardinal · #2 02-25-2011, 07:09 AM

What type of plastic is it? I have found that chemical or mechanical melting most plastics together creats the strongest bond. Some plastics do not lend themselves to that or you may not want to do that for some other reason. In that case you will likely need an adhesive. Here's an excellent primer on the use of adhesives on plastics: http://machinedesign.com/article/gui...ding-plastics: http://machinedesign.com/article/gui...-plastics-0615
Whichever method you chose, careful preparation is the key.

prkaye · #3 02-25-2011, 07:32 AM

I'm not sure how to identify what "type" of plastic it is... but it's the hard black plastic that GPS mounts are made of.

I don't want to melt the plastic because one of the pieces to be boded has electrical connections encased inside it.

The bond should be strong enough to hold a Garmin GPS and for the normal strength required to swivel the GPS on the mount, so it doesn't need to be strong enough to hold an elephant.

I'll read that primer, thanks!

flyboy1963 · #4 02-25-2011, 10:31 AM

Yes, always tough to glue unkown materials.
In the past, I've usually elected to add an aluminum 'patch' or gusset along the side of the break, and as much 40-grit mechanical roughening of the surface as possible.
don't ignore the automotive store, they have a lot of cyan0-acrylate based krazy-glues for ABS and urethane bumpers that are thickened, and may just do the trick. Model airplane guys are also glue experts.

Repairing a split golf club head shaft once, I mixed up a batch of WEst epoxy and wrapped a zillion strands of fibreglas around the break.....got the idea from Rutan's landing gear axle on the Catbird or Grizzly; to make the right angle attachment, just did the same on a grand scale!

lorne green · #5 02-25-2011, 10:46 AM

Assuming that you have enough mass at the contact points, let me suggest a 1mm layer of premium clear silicone. Some two-sided tapes may work,
but due to higher cockpit temps in the summer, there may be some movement there.
Regards.

prkaye · #6 02-25-2011, 11:15 AM

What about west systems 406 structural adhesive filler? I have lots left over - is it not as strong as i believe it to be?

woodmanrog · #7 02-25-2011, 11:29 AM

I had two parts to bond together on the inside of a battery operated dtill. They were very small and need to be held rigidly. I used ast curing JB Weld and it worked great. I had to put a little on the exterior of the joint but it is still holding up after a year.
Woodman

David_Nelson · #8 02-25-2011, 11:30 AM

... proseal.

David Paule · #9 02-25-2011, 11:31 AM

Quote:

Originally Posted by prkaye

What about west systems 406 structural adhesive filler? I have lots left over - is it not as strong as i believe it to be?

Probably plenty strong, if you can get it to stick. And there's the rub.

Dave

prkaye · #10 02-25-2011, 11:41 AM

JB-Weld... now there's an interesting option. I've never used that stuff.
Based on my reading of their website material, it appears to be an epoxy, so in the same family as West Systems I guess. Maybe a better bet than the 406 with epoxy resin?