Handle Scale Delamination Issues

A

Aroy87

Gold Member
Joined
Feb 21, 2021
Messages
6
Hello Everyone;

So here are my materials and the order in which they are sandwiched.
-Desert Iron Wood
-G10
-Copper
-G10
-African Blackwood

I'd attempted glue up with G Flex and Gorilla Glue Tough Epoxy and during sawing or finishing the copper has delaminated.
My Process
-Square all surfaces in the mill
-Cut all parts and rough mating surfaces with 60 grit
-Apply epoxy to all surfaces and clamp, let sit for 24 hours minimum
I make one large block and rip it up the middle with the bandsaw, the failure usually comes during that cut but not always. I had a close to finished handle scale let go at the copper mating surface yesterday.
I was assuming the issue was the thermal conductivity of copper so I tried the same process with 416 stainless and went slowly, with very little heat rise the same delamination happened.

Questions;
1) Do most of you typically start with one block and rip the block in half?
2) If not #1 what is your process?
3) Would it be more prudent to just make individual scales to start with instead of ripping a large block?

Comments:
-I seems like I am missing a chapter here, I would prefer not to pin all of the components together as that is an extra step.
-This only occurs with handle scales, when I am doing something very similar with hidden tang handles (Wa specifically) I have had zero issues but I suspect that the lack of bandsaw usage may help
-I am not concerned about matching scale or anything
-A bit of guidance would be appreciated as I have wasted a great deal of wood and copper in the process
 
I’m no expert but I did just finish a knife with copper liners a few weeks ago. My guess is that it’s a thermal issue. How thick is the copper/416 you are using? If it’s very thin that could be problematic as the heat is going to move through it quickly especially when it’s sandwiched between some extremely non conductive materials. You might try one scale at a time and rough profiling it all then gluing it together. I went 1/8“ on mine, glued (G-flex) everything like you did and cut a little at a time while I was rough shaping the scales. I did one scale at a time. For prep I sanded all the surfaces to be glued on the disc with 120 grit then scratched the copper and steel tang with 60 grit and scored the g10 and micarta with a utility knife. I also use a cool mist system when I’m grinding on the 2x72 so that really helps keep the heat at a minimum but I still ground very slowly and dunked in water often. I‘m also in the habit of tapering my pin holes and peening the pins so there is a solid mechanical connection if the epoxy ever experiences an issue on one of my knives.
There is a chance the saw blade is grabbing it and peeling it or possibly weakening the bond through vibration. I‘ve peeled a g10 liner off a scale that way but when I did it I remembered that I forgot to prep the surface before I glued it.
That‘s my 2 cents.
IMG_9619.jpeg
 
It's usually the fact that copper conducts heat exceedingly well. The heat cause the glue to fail.

I have not found a great way to get thin copper "liners" to adhere consistently. I have tried both epoxy and CA glue and the failure rate was too great for me. I no longer use copper for liners on a full tang knives. Spacers in a hidden tang knife, yes however.
 
Are you over clamping, or does the glue need longer to cure? Try leaving them for a week?
I had similar problems with brass and micarta, i just resorted to pinning it. Try some hidden pins a mm or so into the wood?
 
If I try to do another knife with copper I’ll probably dry fit the handle scale components to the tang individually and trace them out so I can have everything essentially to the correct profile before glueing. It took forever to get the scales shaped on the one I did. I was able to control heat buildup with the mist system but it took a while to figure out how long to grind before it started to get warm. I started by grinding and checking for heat every few seconds. Most of the makers that looked at it at the show pretty much echoed what has been said on this thread so far.
 
I've done a few, love copper. Try drilling epoxy bridges in the copper, the more the better, with corresponding hole in the other scale materials. I drill the scales first (not too deep maybe 1/8" and fill them with sanding dust. Then press on the copper and flip the scale, tap out the dust onto the copper and mark it, to get the holes lined up close.

I also only use JB weld for any metal fitups, it's good to 400 degrees. I don't dip or mist in water to cool down though, the expansion / contraction can pop them apart. I hold it in a towel until it's cooled. And certainly as scarfoot said get the profile as close as possible using a scriber, just kissing the scribe line. Then hand sand the rest of the way.
 
Pins connecting all the pieces, within the final diameter of you piece, but as far as reasonably possible from the center, so you'll get less unsupported peeling forces near the edge.
 
I agree with all the above and have made all the mistakes. Heat is a biggie. Most epoxies start breaking down around 200 degrees (the old ball is Hysol that gets stronger).

I'll add one more note to the discussion. Something I learned after my last failure. It seems to be a problem with epoxy/metal bonding:

According to the West Systems documentation you need to "abrade the epoxy into the surface of the metal." Simply smearing it on ain't enough.

As I recall they recommend a wire brush or something. I break a popsicle stick in half and use the rough edge to really work the epoxy into the steel surface. The action is like scrubbing a stubborn stain. Haven't had trouble since.
 
Sando said:
According to the West Systems documentation you need to "abrade the epoxy into the surface of the metal." Simply smearing it on ain't enough.
Click to expand...
arty johnson1.jpg

I wonder if C Cushing H. mentioned that in his mega thread on adhesives from a couple of years back. It was, shall we say, comprehensive ~ and well worth the time. If it was there and I forgot I'll remember next time, Thanks Sando Sando
 
Aroy87 said:
Hello Everyone;

So here are my materials and the order in which they are sandwiched.
-Desert Iron Wood
-G10
-Copper
-G10
-African Blackwood

I'd attempted glue up with G Flex and Gorilla Glue Tough Epoxy and during sawing or finishing the copper has delaminated.
My Process
-Square all surfaces in the mill
-Cut all parts and rough mating surfaces with 60 grit
-Apply epoxy to all surfaces and clamp, let sit for 24 hours minimum
I make one large block and rip it up the middle with the bandsaw, the failure usually comes during that cut but not always. I had a close to finished handle scale let go at the copper mating surface yesterday.
I was assuming the issue was the thermal conductivity of copper so I tried the same process with 416 stainless and went slowly, with very little heat rise the same delamination happened.

Questions;
1) Do most of you typically start with one block and rip the block in half?
2) If not #1 what is your process?
3) Would it be more prudent to just make individual scales to start with instead of ripping a large block?

Comments:
-I seems like I am missing a chapter here, I would prefer not to pin all of the components together as that is an extra step.
-This only occurs with handle scales, when I am doing something very similar with hidden tang handles (Wa specifically) I have had zero issues but I suspect that the lack of bandsaw usage may help
-I am not concerned about matching scale or anything
-A bit of guidance would be appreciated as I have wasted a great deal of wood and copper in the process
Click to expand...
Holes , I drill lot of holes in copper . . . . so epoxy can hold on other parts


w58wocv.jpg

e43VZnP.jpg
 
Last edited:
John Cahoon said:
View attachment 2264673

I wonder if C Cushing H. mentioned that in his mega thread on adhesives from a couple of years back. It was, shall we say, comprehensive ~ and well worth the time. If it was there and I forgot I'll remember next time, Thanks Sando Sando
Click to expand...
Actually, i have never heard of that. Maybe it gets small bubbles that are on the metal surface out of there, so more epoxy makes direct contact?
 
From what I understand it has to do with oxidation. You sand away the oxidation layer anf no new one formes because no oxigen gets trough the wet epoxy
 
Hengelo_77 said:
From what I understand it has to do with oxidation. You sand away the oxidation layer anf no new one formes because no oxigen gets trough the wet epoxy
Click to expand...
I'm super careful (I think) and I always do a fresh 60 grit sanding run before. So, I think my fails weren't oxidation.

I'm glad even C Cushing H. hadn't seen this before. I never did.

Just to prove to myself I wasn't crazy, here's the sheet that came with my latest bottles of G/flex:

IMG_7083.jpeg

So you freshly sand it so no oxidation. Then clean. Then coat it and abrade with wire brush or sandpaper.

I dunno why. I'm no chemist. My guess is that the wetting agent in the epoxy needs a little help when using metal.
 
I've had some issues with copper though I think the worst was an old batch of CA glue. As soon as I got fresh I stopped having issues.
I will say I watch really closely how I grind after adhering copper because of heat build up. It gets hot so fast.
I always use a 60 grit belt and hand abrade any metal surfaces right before denatured alcohol and application. I've tried sanding in with sandpaper and it was such a mess with G-flex I haven't tried again. A wire brush might work better.
 
Sando said:
I'm super careful (I think) and I always do a fresh 60 grit sanding run before. So, I think my fails weren't oxidation.

I'm glad even C Cushing H. hadn't seen this before. I never did.

Just to prove to myself I wasn't crazy, here's the sheet that came with my latest bottles of G/flex:

View attachment 2265551

So you freshly sand it so no oxidation. Then clean. Then coat it and abrade with wire brush or sandpaper.

I dunno why. I'm no chemist. My guess is that the wetting agent in the epoxy needs a little help when using metal.
Click to expand...
The sandpaper sounds *really* messy. If it works with a broken off wood stick, then it would not be abrasion, right? That is why i mentioned getting the bubbles away from contact with the surface (same thing as sandos comment about wetting). Just a guess though. I might run this by a friend to see if she has run across this.
 
Can you glue a sacrificial layer around the block before splitting to help with the shear forces? Something like heavy paper that could be easily ground away or G10 that could be a liner after splitting.
 
John Cahoon said:
I've done a few, love copper. Try drilling epoxy bridges in the copper, the more the better, with corresponding hole in the other scale materials. I drill the scales first (not too deep maybe 1/8" and fill them with sanding dust. Then press on the copper and flip the scale, tap out the dust onto the copper and mark it, to get the holes lined up close.

I also only use JB weld for any metal fitups, it's good to 400 degrees. I don't dip or mist in water to cool down though, the expansion / contraction can pop them apart. I hold it in a towel until it's cooled. And certainly as scarfoot said get the profile as close as possible using a scriber, just kissing the scribe line. Then hand sand the rest of the way.
Click to expand...
I love copper and use it for bolsters a lot, and have had it fail more than a few times due to heat buildup. I've just been grinding super slowly and cooling the copper constantly to fight the glue failure, but the JB Weld is a great idea! I'll give that a try.
 
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