A lot of issues with scales peeling off

Once you have "true" flat you almost need no pressure at all, I also had this problem before at the same place and it is better to leave the pressure off in that area and have a small glue line (if your flatness is off) then to squeeze the epoxy out by overclamping. Also, there is a gluing video by D. Nguyen, he has no pins full tang knives and uses hidden allthread pins to enhance gluing bond.
 
Crag the Brewer said:
Aside how I'd do it differently....
Others have covered it well with Actual fasteners (not pins), not using g10 liners. I prefer micarta. Properly flattened, drilled holes for glue wells, quality stabilized wood, not some cactus juice or another.. etc. etc.

What I don't understand is

-Could somebody please explain the taper issue?
In My head, a taper is just an angled scale.
Why would That matter with the adhesion?
Thanks.
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If you dont have a consistent and full length taper on the transition to the flats of your ricasso you will need to put additional clamping force to bend the scale to the transition area, in turn you squeeze out the glue and the scale bends back once the glue can't hold the opposing force of the bent scale in place anymore. It can be almost non-visible to eye, but g10 is springy and I believe this makes it worse. Happened to me before.
 
I wonder if the failures are compounded by leverage. That is a very thin blade. Cutting a turnip, or prying out a lid from a can of olives....
Pins Will fail .
No pins will fail Sooner.

*Not My knife, but flexing it pops the scale.


 
And to my point on not all stabilization being equal. If you are going to have some movement from a scale you think it's gonna be that tapered front where you can't put a pin, corby or Loveless bolt? Or do you think it's gonna be the center of the scales where his index finger is? Me I'm going with that very thin taper. Heck might have put some heat stress in there just sanding in the taper
 
FredyCro said:
If you dont have a consistent and full length taper on the transition to the flats of your ricasso you will need to put additional clamping force to bend the scale to the transition area, in turn you squeeze out the glue and the scale bends back once the glue can't hold the opposing force of the bent scale in place anymore. It can be almost non-visible to eye, but g10 is springy and I believe this makes it worse. Happened to me before.
Click to expand...

Multiple planes, Yes....that for Sure would do it.
 
Crag the Brewer said:
I wonder if the failures are compounded by leverage. That is a very thin blade. Cutting a turnip, or prying out a lid from a can of olives....
Pins Will fail .
No pins will fail Sooner.

*Not My knife, but flexing it pops the scale.


Click to expand...
Had this one as well, learn by mistakes I guess. Also, one of the reasons I still don't sell knives. :D
 
It is always possible, that overheating a handle whilst grinding too aggressively will cause epoxy to release. I had to learn that lesson early on, but it was with 1980s adhesives.
 
The fact that the scales are warped would seem to point to a moisture issue. They might not have gone in the dishwasher but that doesn’t mean they haven’t been in the bottom of the sink while the faucet was running or something like that. They’ll be exposed to more moisture in the kitchen than just about anywhere else. A pin up front would help but I think finding a different source for stabilized wood or using a different handle material altogether would be good idea as well. I find it curious that it’s happening where you’ve ground a taper into the scale. Might be an indication that the stabilizing resin didn’t penetrate that deep.
 
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in terms of technique, one thing that I'm always careful about is to only clamp once. After the epoxy is applied, (to both surfaces) and everything is clamped together, those clamps stay in place- I don't loosen or move them around at all
 
I had this issue on my early fillet blades. Theye were .070" stock with distal taper. The flexing in fillet work caused the front of the scales to lift. I solved the issue by switching to more pins. I was using three rivets and switched to seven. On at the front and down the sides in pairs. I have since switched to four Corby bolts. Never a problem since.
 
I rough up the tang with a cut off disk in my Foredom, I rought up all the way to where the scales end.
 
fitzo said:
Glass bead blasting provides about the very best surface you could imagine for glue holding.
Click to expand...
Better than just roughing it with course grit, or a grinding stone? I have a blast cabinet but if other methods are as good, other methods don't require as much prep, and therefore time.
 
GRapp said:
Better than just roughing it with course grit, or a grinding stone? I have a blast cabinet but if other methods are as good, other methods don't require as much prep, and therefore time.
Click to expand...
That information came from a Loctite adhesives engineer many years ago, given to an inquisitive and well-respected forum member. Surface area is greater with the blasting. Necessary? Depends how much of a meticulous, futzy geek you are. YMMV.
 
GRapp said:
Better than just roughing it with course grit, or a grinding stone?
Click to expand...
If you want more information, go to the stickies at the top of Shop Talk, and at the bottom of the 2nd post there are couple of detailed threads on adhesion:
Stacy E. Apelt - Bladesmith

Important Info! Thread 'Sticky Threads - All The Good Info You Want In One Place'

The stickies have all been condensed into this new super-sticky. This will free up the top of the forum, but make all the good info just a click or two away.

Each will have its own segment, and all the info is still there.

Any additional info that you folks think should be added to the stickies can still be added by a moderator. Just send Mark or me a PM with the thread or info that you would like stickied.
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When spark changed te system a while back many older threads had a different nomenclature format (or something like that). They aren't gone, juts that they won't come up under the old links that may be in the stickys or older threads.

Whenever you get a 404 for a past thread ...
Use the custom search engine and enter the thread name.
I put "Glue Wars 2" in and this came up - https://www.bladeforums.com/threads/glue-wars-2.337504/

When I find them I try and go back to the stickys and change it to the new link format. If you or anyone else finds one, PM or email me the sticky page and the new link and I'll change it.
 
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