grindable clear epoxy??

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patstag

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Feb 12, 2014
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I'm having an issue with my epoxy not holding up to the heat generated by my grinder.
I sandwhiched a piece of copper between two pieces of paper micarta with a clear two part epoxy. It held up well until I began to grind it flush. Even with light and intermittent pressure the epoxy didn't seem to hold up to the heat created from grindind.

If anyone has a suggestion of a superior adhesive I would appreciate it

Thanks
Pat
 
Use a slow setting epoxy. Don't clamp it too tight either, otherwise you'll squeeze all of the glue out. Trust me, I've over clamped before and the bond did not hold up. Also make sure the surfaces being glued are scuffed up and cleaned.
 
have you tried cyanacrylate ( crazy glue)? I use two different types. Thicker viscosity and slow set for glueing and thin and fast as a coating/ hardener. Seems to hold up very well to friction caused heat and no mixing needed.
 
I blame that on the copper creating and transferring the heat.

If you did the same with just Micarta it probably wouln't do that


Try fresh belts, less time and pressure.
 
"Use a slow setting epoxy. Don't clamp it too tight either, otherwise you'll squeeze all of the glue out. Trust me, I've over clamped before and the bond did not hold up. Also make sure the surfaces being glued are scuffed up and cleaned."

Thanks. that makes sense because I really tightened the clamps down hard
 
12345678910 said:
I blame that on the copper creating and transferring the heat.

If you did the same with just Micarta it probably wouln't do that


Try fresh belts, less time and pressure.
Click to expand...

Thanks. I thought maybe the "copper" was the "culprit" :) I will try more patience and fresh belts.
 
Yes on the slow setting epoxy. Don't tighten the clamps so hard and I prep my scales at 120 grit around the edges and more in the center.
I agree that the copper generates a lot of heat and fresh belts at slow speed will help there.

I always use G-flex epoxy these days it's a slow cure and bonds well since it was designed to be used on boats & airplanes but one of the most important things with any adhesive/epoxy is how well it is prepped before hand.
 
Yup, heat is your enemy with epoxy. Hit the magic temperature and the bond goes bye-bye. Sharp tools and slower speeds help as has been noted. Also, if you can, quenching the area constantly with a coolant such as water will help.

Just a note, slower curing epoxies tend to give more stiff bonds. The quicker setting epoxies have a little more give and I find that when any flex is involved they can be the way to go. Just depends, but overall the slower curing are the better bet in most instances.
 
In this case you are also dealing with a difference in rate of thermal expansion.

The copper is a great thermal conductor and quickly expands from heat during grinding, leaving the poor thermal conduction and differing expansion rate of the Micarta to create shear and buckling stress, which combined with the heat will pop the joint apart in an instant.

The most important thing is to keep the temperature of the two as close as you can to what it was during gluing. The second is to use a more flexible adhesive such as gflex mentioned above, to help absorb this shear/buckling stress without popping the bond.
 
Copper fittings have to be worked by hand with files and paper or there will be heat. If you have a water cooled belt, or grind dead slow, you can use a grinder...but copper gets HOT fast. No glue will hold up to that heat.

Hold a piece of copper in your fingers and try to grind down the edge on a belt grinder :)
 
bladsmth said:
Hold a piece of copper in your fingers and try to grind down the edge on a belt grinder :)
Click to expand...

Not very nice Stacy. :D

Weird metals= weird thermals. One time I used a torch to color the end of a piece of cp titanium. No problem. I put it down then came back to it a couple of minutes later. The end that I had been holding on to burned the crap out of my fingers.

Gotta account for the thermal properties of whatever we're working on I guess. :)
 
bladsmth said:
Copper fittings have to be worked by hand with files and paper or there will be heat. If you have a water cooled belt, or grind dead slow, you can use a grinder...but copper gets HOT fast. No glue will hold up to that heat.

Hold a piece of copper in your fingers and try to grind down the edge on a belt grinder :)
Click to expand...

Lol. Ya I tried to do that with a small piece and it took about one second to burn my finger. Also it seemed like the finer grit belts heated the copper faster. Thanks
 
You can hold a 12" steel rod in your bare hand and melt the other end with a torch. If you try that with copper, you will drop it as soon as the torch hits the other end.
 
patstag said:
I'm having an issue with my epoxy not holding up to the heat generated by my grinder.
I sandwhiched a piece of copper between two pieces of paper micarta with a clear two part epoxy. It held up well until I began to grind it flush. Even with light and intermittent pressure the epoxy didn't seem to hold up to the heat created from grindind.

If anyone has a suggestion of a superior adhesive I would appreciate it


Thanks
Pat
Click to expand...

Pat,
I have seen a current craze of makers using copper & brass as liners and the one thing I would like to add is personally I would never use copper or brass for liners on a knife. I have cleaned enough green crud out of spacers on old hidden and through tang hunting knives. If any moisture ever gets in there and the copper/brass starts to oxidize and grow green crud I see many problems with the scales separating from the blade tang.
 
I had the realization that I wasn't a knifemaker until I started using the slow cure gflex epoxy. lol

Joking of course, but it is sooooo worth it. I have not had a liner pop on me since I switched.

Nick
 
Rhinoknives1 said:
Pat,
I have seen a current craze of makers using copper & brass as liners and the one thing I would like to add is personally I would never use copper or brass for liners on a knife. I have cleaned enough green crud out of spacers on old hidden and through tang hunting knives. If any moisture ever gets in there and the copper/brass starts to oxidize and grow green crud I see many problems with the scales separating from the blade tang.
Click to expand...

Thanks for the input. I never thought about that even though some of my old sheaths that have copper rivets are green now. Honestly I just thought it looked pretty, but I guess its not very practical.
Do you suggest something synthetic or stainless steel for adding a little flare such as spacers or liners?
 
chavez556 said:
I had the realization that I wasn't a knifemaker until I started using the slow cure gflex epoxy. lol

Joking of course, but it is sooooo worth it. I have not had a liner pop on me since I switched.

Nick
Click to expand...

Thanks Nick, many on here seem to agree with you and I have some gflex on my next order list
 
patstag said:
Thanks for the input. I never thought about that even though some of my old sheaths that have copper rivets are green now. Honestly I just thought it looked pretty, but I guess its not very practical.
Do you suggest something synthetic or stainless steel for adding a little flare such as spacers or liners?
Click to expand...

You could try stainless like 303 or other low/no carbon stainless steels. I think that the added weight of steel.copper etc would be a deterrent unless you want the weight for some reason?

I use the disposable colored cutting boards you can buy at kitchen stores or Amazon and Kydex for liners. You can use many things that are low weight and durable. Look around?

I don't like to grind G-10 since it turns into little fish hooks and makes my hands etch and if you get any in your lungs the only way to get it out is after you have assumed room temperature!:eek:
 
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