Bonding Plastic/Large Resin Parts

[Tiger331]

I've just embarked on an Airfix Nimrod project, utilising the A2Zee engine/intake conversion parts. These resin components are quite sizeable and heavy and I am concerned that 'normal' CA glue will not be strong enough to hold them in the longer term. I have seen a recent build article for the Nimrod/resin combo on this forum with what appears to be a glue that sets clear holding the various parts together. What I need is something strong that does not need a considerable amount of sanding afterwards.

I have seen some discussion about resin epoxy glues (such as Araldite) but they are a real problem to sand afterwards.

Any ideas/suggestions gratefully received.

Tiger331

[TonyT]

I used the ZAP medium superglue on all my resin models, does it not last??

[kev67]

I use araldite as it does not dry to quick so allows you to position the part more easily, but this is only for larger areas I also add some metal pins to give it some strength and helps the pieces bond better, as Araldite is not that good at sanding back, I don't put that much on and if any does blead over I usually just wipe it clean

[Mike]

Like Kev, I think 2-part epoxy is a good idea. I use the Devcon Epoxy Resin with a 5 minute initial cure time. I've also got a pair of tubes of their 30 minute product that has something silly like a 10-tonne shear strength when cured. Should be enough for most applications

One thing that super glue isn't good at is shear strength. That's where the pressure is along the line of adhesion. Pulling perpendicular to the seam it's hard as nails, but along the line it's relatively weak. That's why I use epoxy for larger joins. Just rough up the mating surfaces with a sanding stick before you apply the glue - it'll also help remove any mould residue, which also won't help adhesion

[little-cars]

The devcon instant and 5minute epoxy are good.

Like CA glue they are much harder than plastic/resin when they have cured.

You can use padding like micro balloons and similar products to make it easier to sand.

The shear strength problem can also happen when plastic in the kit flexing, this can cause problem with CA and pieces .

You can try flexible (rubber impregnated ) CA much better in that situation.

[TonyT]

For normal plastic I use 100% neat MEK...

I can get loads of Devcon so may try that.

[pigsty]

Why worry about sanding the adhesive afterwards? When I use epoxy, I make sure the little blobs of glue are well away from the edges of the mating areas, and if any does squidge out as I close the gap, I wait just a little while and remove it before it hardens. This leaves only small traces to be eliminated later. Very small mating areas are a bit of a challenge but this generally works OK.