Epoxy user issues

Sean Yaw

Sean Yaw

Gold Member
Joined
Feb 26, 2019
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417
I have been using G-Flex epoxy to affix micarta slipjoint covers to 410 liners. More often than not, I will have the covers separate from the liners at some point in the processoing afterwards (e.g., during shaping, thinning cover material). I prep everything by doing randomized (figure 8) sanding on 80 grit paper. I then epoxy and clap together with Harbor Freight spring clamps and keep it clamped for about 24 hours. When the material separates, the 410 liners don't seem to have any epoxy on them. I am not sure what I am doing wrong, but I don't think that my post-processing is overly aggressive, so I suspect my issue is with the epoxying step. Perhaps I a clamping too much? Any ideas would be appreciated. Thank you.
 
Clamps are too strong. Use the smallest and lightest clams possible. The tiny HF clamps that are 5 for 41 are perfect. If you clamp hard the epoxy is squeezed out and you create a glue-starved joint. Such a joint will pop apart easily.

Grinding a slight hollow grind in the scales and liners/tang is a great thing. It creates a shallow reservoir of resin ... very strong.
 
Clamping certainly seems to be my issue. I have been using as many 2" clamps as I can fit on it. It seems like it would be easy to go too far the other way (i.e., not enough pressure). Are there any tricks to get this dialed in? Hollow grinding the scale material seems like a good trick, but I am not sure I am able to do that easily with my tools.
 
yaw said:
Clamping certainly seems to be my issue. I have been using as many 2" clamps as I can fit on it. It seems like it would be easy to go too far the other way (i.e., not enough pressure). Are there any tricks to get this dialed in? Hollow grinding the scale material seems like a good trick, but I am not sure I am able to do that easily with my tools.
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How about kissing your inner surfaces with a drill bit?
 
yaw said:
Like little mini indentations?
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Yes, to increase surface area.
I'm thinking .015 to .045" deep.
Spread all over on the tang, and under the scales.

I know some makers rough scratch/grind lines.
But I think pockets would be better

You could blind pin them too

But I'm sure more experienced makers will chime in.
 
Bill DeShivs said:
Why not just pin the handles to the liners? Then you won't need to epoxy them.
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I thought it was "good practice" to reduce the likelihood of water intrusion and such. It seems like it could also compensate for fitting together not dead-flat components without a gap.
 
Make sure after sanding flat everything is completely clean and degreased. Light clamping pressure. I personally use thin CA glue for all liners and have found that it’s strength is more than adequate. I also like to use mechanical fasteners (corby bolts) anytime I’m using liners as well, just as a fail safe.

Edit - just saw the slip joint comment, ignore the part about corby bolts 😬
 
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Holes in the tang ain't just for pins and bolts.

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My first thought would be to thoroughly degrease. I use brake cleaner or alcohol, something that does not leave a residue.

I’d also make sure I’m keeping the steel cool, easy to hear it up do on a thin liner, potentially compromising the adhesion of the epoxy.
 
I use Maxi Cure CA. Prep, wipe clean with acetone, glue up and clamp. Never had an issue. When your making shadow patterns your pinning occurs when you pin the knife together or pin a shield in. Otherwise extra pins just look dumb IMO.

I should add I also use the cheap little HF spring clamps. Hell I usually only let the glue cure 20 minutes or so before I head over to the disk to rough profile the micarta. Hammer them around too much though and they'll separate. Not a lot of flex forgiveness once cured.
 
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Bill DeShivs said:
It's a good practice on fixed blades that use carbon steel.
I see no reason to glue scales to liners-especially if the liners won't rust.
Nothing compensates for ill-fitting components.
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I'm pretty sure most makers who build shadow pattern slip joints would disagree with this advice 100%.
 
Signalprick said:
I use Maxi Cure CA. Prep, wipe clean with acetone, glue up and clamp. Never had an issue. When your making shadow patterns your pinning occurs when you pin the knife together or pin a shield in. Otherwise extra pins just look dumb IMO.

I should add I also use the cheap little HF spring clamps. Hell I usually only let the glue cure 20 minutes or so before I head over to the disk to rough profile the micarta. Hammer them around too much though and they'll separate. Not a lot of flex forgiveness once cured.
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Good to know, Jason. When you glue up multi-part scales (micarta + micarta bolster + g10 liners), do you glue everything together with the steel liners at once, or do you glue the scales together first and then glue them to the steel liners?
 
yaw said:
Good to know, Jason. When you glue up multi-part scales (micarta + micarta bolster + g10 liners), do you glue everything together with the steel liners at once, or do you glue the scales together first and then glue them to the steel liners?
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For instance, on this last knife I just built I used my file guide with both liners clamped in. I glued on the larger bottom pieces to both liners and just clamped while in the guide. Once cured I removed and individually glued on the micarta bolster piece and clamped I also added a clam to both ends to keep the joint secure. If you do a g10 similar divider same principal. Hope that makes sense.
 
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