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Araldite Rapid, Cyanoacrylate & PCB material.. does it stick?

flippineck

Sep 8, 2013
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Tried to make a cover for a hole in some unknown soft casing plastic, out of a cutout bit of clear polypropylene sheet (a chinese dinner no
odle tray)

Tried to stick it over the hole with Araldite Rapid which is a 5-min setting 2-part epoxy available in UK.

The epoxy stuck fast to the casing plastic, but once set, the polypropylene just peeled off with zero adhesion.

It left the epoxy surfaces beautifully smooth level and flat, ready for something else to be glued on top if I can only find the right combination of material and glue.

I was thinking of trying to make a new patch out of bog standard PCB / veroboard material, in the hope of getting a good adhesion between that and the hardened epoxy using a dab of superglue.. anyone with experience of what sticks to what, would be great to hear any input..

The holes in veroboard would be useful for a bit of ventilation but it's not strictly neccessary. Blank PCB or blank sheet of some other sort would be ok too as the underlying design does allow for air passages. It's replacement covers for a sealed lead acid battery which ran dry of water, which I refilled and recharged after pulling off the original covers which hid the cell caps. The covers need to be well glued down as they prevent the rubber cell caps rising too far on venting.
 
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Bluejets

Oct 5, 2014
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Use small screws.
Plenty available on Ebay etc.
1.7...2.0....2.2mm...cheap as...
 

flippineck

Sep 8, 2013
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With it being a battery I'm a bit scared of puncturing it any more than I have to.. The old covers were made of a similar plastic to the main battery casing & had been glued on, in their 27mm x 100mm recesses above the banks of 3 cells each, with some kind of glue or other. Was hoping to put it back together as close as possible to the original construction. Unfortunately the old covers didn't come off cleanly so I'm having to come up with something to replace them. The PP sheet I tried to make replacement covers out of, just wouldn't stick down though with the epoxy. Tried a bit of cyanoacrylate on the PP sheet hoping it might be ok to stick the PP to the hardened epoxy which -had- stuck ok to the battery case itself, but no joy - the PP just rejects the superglue 100%
 

Bluejets

Oct 5, 2014
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Some types of plastic require acetone based adhesive.
Otherwise you're trying to sail up the current without a paddle.

You could try plumbers silicon, it sticks to most things.
24 hours to cure though.
 

John Canon

Jun 1, 2022
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... It left the epoxy surfaces beautifully smooth level and flat ...

You forgot to roughen the surfaces with sandpaper. So just roughen the "beautifully smooth" epoxy and also the patch material. Then try again with more epoxy.
 

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flippineck

Sep 8, 2013
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The PP is indeed very smooth and slippery to the touch.. I'll try some fine sandpaper. Sure I've got some silicone too. Couple of plans for tomorrow, thanks..
 

John Canon

Jun 1, 2022
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The PP is indeed very smooth and slippery to the touch.. I'll try some fine sandpaper. Sure I've got some silicone too. Couple of plans for tomorrow, thanks..

Don't use fine sandpaper ... you are not looking for a satin surface, you are looking for a rough surface.
 

ivak245

Jun 11, 2021
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I have only found 1 glue which worked with Polypropylene, It was an epoxy which had "microspheres" in it, and was very expensive. Polypropylene does not like to be glued, and silicon tends to peel off. Besides the expensive epoxy, heat welding with a filler rod works, but only if joining to the same stuff. Can you use aluminium, or another material?
 

flippineck

Sep 8, 2013
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Worried about trying metal because it's conductive and each cover bridges across 3 individual cells. I'm about to try some rough sandpaper on some scrap PP & see how superglue sticks that, & if that's no good I have some veroboard to try, guess I'd have to etch off the copper though if it looked likely to work
 

73's de Edd

Aug 21, 2015
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I'd be dragging a cut off wheel chucked in a Dremel tool . . . . . and dragging it from side to side , instead of the linear in line motion that you would normally use, that then really roughs up the surface and leaves no gloss, therefore, a better adhesion performance.
 
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