I'm wondering what everyone's experience is with the real holding power of epoxy is where only straight pins and are used on full tangs.
For what I've "disassembled" myself, I don't feel as though there is any real bonding strength against the steel, regardless of the preparation of the tang. Big hollows/fullers, and any manner of scratch pattern at various grits don't really provide any significant peel or shear strength. Ultimately, I feel like the only real holding power is the connection between the pin and the scale.
I'm inquiring because I see a LOT of glue/pin knives all over and I wonder if I'm missing something.
I had this very same question some years ago. The answer came when I had to remove a handle because I had stacked liners and gotten the order wrong on one side. I thought it would be a fairly simple matter to drive the pins out, pop the scales off, and redo it. I was shocked by what actually happened.
Not only could I not drive the pins out, I could not pop the scales off by any means. Once I realized that I was going to have to destroy the handle I decided to see just how good the epoxy had bonded. I put the blade in a vise and tried to break off the scales with a big set of channel locks. All that did was chew up the wood. I then tried to beat the scales with a hammer to shear them. Nothing budged. And so I started grinding the scales off.
There were three vulcanized fiber liners on each side between the tang and the scale. The epoxy had completely bonded the liners such that as I was grinding, the liners appeared to be a single bonded mass. They did not peel from each other as I grinded, nor did they let go of the tang. I expected to be able to peel them but no such luck. I had to grind all the way to bare metal to remove the last traces of liner material and epoxy.
I don't worry anymore.
My prep: I scuff the tang and the 1/4" pins with a sanding block. I clean the tang, the liners, pins, and the scales with denatured alcohol. Then I put it all together with GFlex650 epoxy. I use a lot of epoxy. I treat it just like I'm fiberglassing a boat, meaning I lay the epoxy on thick and I go slowly to give everything a chance to 'wet out', meaning if any material is going to absorb any epoxy I want it to do that so that the epoxy can impregnate anything that it possibly can and fill all voids. Granted, it's not going to wet out much at all, but at least there won't be any air pockets or dry spots because I went too light on epoxy. About 20% of it squeezes out as I clamp up the knife. I don't care. In the big scheme of things epoxy is cheap- much cheaper than having to redo a handle because I wanted to save fifty cents on epoxy.
I have never had a knife come back to me with handle failure, and a large percentage of my knives are kitchen knives that are constantly wet and used hard. However, my knives don't see a lot of shock forces. If I was making camp choppers I might use corby bolts, or I'd at least test some knives to the point of destruction.