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Filling gap

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38 minutes ago, Doug Sundseth said:

 

Cyanoacrylates are very strong in tension but brittle in torsion and shear. Also, by themselves they work best when as thin as possible. The best bonds are in tension between two very flat surfaces with effectively no space in between. ...

 

To get any gap filling, you need to add something to the superglue. Most commonly, this is baking soda, which makes quite a strong bonded aggregate, but there are various substances added to "gel" superglues to give them some gap-filling capability.

 

What he said.  With a caveat.

 

When I use baking soda and cyanocrylate (superglue) as a filler, I fill the gap with baking soda and then add a very small amount of cyano by "dropping" or "easing" it on the baking soda.  It will penetrate the volume of the baking soda.  As soon as the glue hits the baking soda, there is a chemical reaction which will produce heat and the mix will set rock hard instantly.  It is particularly effective filling gaps and holes in resin.

 

Then sanding and/or filling the rest of the now much smaller gap with something else.

 

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Pure baking soda (Natrium bicarbonate, here in Norway sold as 'Natron') or 'baking powder'(Natrium bicarbonate, Natrium diphosphate and MonoCalsiumphosphate)? 

 

Have you seen the Glue Looper?

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It's made to 'tease' glue into the correct spot.

 

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4 hours ago, Gadgetman! said:

Have you seen the Glue Looper?

c50c6591d2be260217928b59d3fb56aa_original.png?w=680&fit=max&v=1489090989&auto=format&lossless=true&s=408422686ec3d3de036621fdc1edc8a3

It's made to 'tease' glue into the correct spot.

 

Years and years ago I made the same thing, an AC glue applicator, by pushing a large needle into the end of a paint brush handle, and filing the end of the needle until the eye just barely opened into a fork.

 

Not something I would recommend now, but I used to clean it by burning off the dried glue in a candle flame.

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I'll also apply the superglue with the tip of the paper clip. I'm fiddling with opening the superglue from the crimp of the tube, so that the stuff doesn't keep drying out!

 

Once I have a bond, for gap filling, I'll just use Vallejo Plastic Putty. No kneading, although the stuff may shrink. Mostly use it for plastic, though.

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The key to mixing epoxy properly is:

 

step 1: once you're absolutely certain you've fully mixed the two components... Keep mixing. 

 

Then when you're done that, see step 1.  :)

 

I like epoxy for pinning too, never having had any real luck with CA glues, and I use Jester's old spit-and-poster-tack method to locate the second hole so it lines up perfectly with the first.  There's a tutorial on CMON somewhere but I haven't been there in ages, I'm sure everything has been helpfully reorganized over there by now in order to make it impossible to find... 

 

Kazmania7 posted above advising gluing first then drilling all the way through from one side and installing the pin that way and puttying over the hole, OMG that's genius!  Why did I never think of that over the years?!?

 

Kang

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